Genomic spectrum of actionable alterations in serial cell free DNA (cfDNA) analysis of patients with metastatic breast cancer

We aimed to study the incidence and genomic spectrum of actionable alterations (AA) detected in serial cfDNA collections from patients with metastatic breast cancer (MBC). Patients with MBC who underwent plasma-based cfDNA testing (Guardant360®) between 2015 and 2021 at an academic institution were included. For patients with serial draws, new pathogenic alterations in each draw were classified as actionable alterations (AA) if they met ESCAT I or II criteria of the ESMO Scale for Clinical Actionability of Molecular Targets (ESCAT). A total of 344 patients with hormone receptor-positive (HR+)/HER2-negative (HER2-) MBC, 95 patients with triple-negative (TN) MBC and 42 patients with HER2-positive (HER2 + ) MBC had a baseline (BL) cfDNA draw. Of these, 139 HR+/HER2-, 33 TN and 13 HER2+ patients underwent subsequent cfDNA draws. In the HR+/HER2- cohort, the proportion of patients with new AA decreased from 63% at BL to 27-33% in the 2nd-4th draws (p < 0.0001). While some of the new AA in subsequent draws from patients with HR+/HER2- MBC were new actionable variants in the same genes that were known to be altered in previous draws, 10-24% of patients had new AA in previously unaltered genes. The incidence of new AA also decreased with subsequent draws in the TN and HER2+ cohorts (TN: 25% to 0-9%, HER2 + : 38% to 14-15%). While the incidence of new AA in serial cfDNA decreased with subsequent draws across all MBC subtypes, new alterations with a potential impact on treatment selection continued to emerge, particularly for patients with HR+/HER2- MBC.

Response-guided neoadjuvant sacituzumab govitecan for localized triple-negative breast cancer: results from the NeoSTAR trial

BACKGROUND

Sacituzumab govitecan (SG), a novel antibody-drug conjugate (ADC) targeting TROP2, is approved for pre-treated metastatic triple-negative breast cancer (mTNBC). We conducted an investigator-initiated clinical trial evaluating neoadjuvant (NA) SG (NCT04230109), and report primary results.

PATIENTS AND METHODS

Participants with early-stage TNBC received NA SG for four cycles. The primary objective was to assess pathological complete response (pCR) rate in breast and lymph nodes (ypT0/isN0) to SG. Secondary objectives included overall response rate (ORR), safety, event-free survival (EFS), and predictive biomarkers. A response-guided approach was utilized, and subsequent systemic therapy decisions were at the discretion of the treating physician.

RESULTS

From July 2020 to August 2021, 50 participants were enrolled (median age = 48.5 years; 13 clinical stage I disease, 26 stage II, 11 stage III). Forty-nine (98%) completed four cycles of SG. Overall, the pCR rate with SG alone was 30% [n = 15, 95% confidence interval (CI) 18% to 45%]. The ORR per RECIST V1.1 after SG alone was 64% (n = 32/50, 95% CI 77% to 98%). Higher Ki-67 and tumor-infiltrating lymphocytes (TILs) were predictive of pCR to SG (P = 0.007 for Ki-67 and 0.002 for TILs), while baseline TROP2 expression was not (P = 0.440). Common adverse events were nausea (82%), fatigue (76%), alopecia (76%), neutropenia (44%), and rash (48%). With a median follow-up time of 18.9 months (95% CI 16.3-21.9 months), the 2-year EFS for all participants was 95%. Among participants with a pCR with SG (n = 15), the 2-year EFS was 100%.

CONCLUSIONS

In the first NA trial with an ADC in localized TNBC, SG demonstrated single-agent efficacy and feasibility of response-guided escalation/de-escalation. Further research on optimal duration of SG as well as NA combination strategies, including immunotherapy, are needed.

First-Line Ipatasertib, Atezolizumab, and Taxane Triplet for Metastatic Triple-Negative Breast Cancer: Clinical and Biomarker Results

PURPOSE

To evaluate a triplet regimen combining immune checkpoint blockade, AKT pathway inhibition, and (nab-) paclitaxel as first-line therapy for locally advanced/metastatic triple-negative breast cancer (mTNBC).

PATIENTS AND METHODS

The single-arm CO40151 phase Ib study (NCT03800836), the single-arm signal-seeking cohort of IPATunity130 (NCT03337724), and the randomized phase III IPATunity170 trial (NCT04177108) enrolled patients with previously untreated mTNBC. Triplet therapy comprised intravenous atezolizumab 840 mg (days 1 and 15), oral ipatasertib 400 mg/day (days 1-21), and intravenous paclitaxel 80 mg/m2 (or nab-paclitaxel 100 mg/m2; days 1, 8, and 15) every 28 days. Exploratory translational research aimed to elucidate mechanisms and molecular markers of sensitivity and resistance.

RESULTS

Among 317 patients treated with the triplet, efficacy ranged across studies as follows: median progression-free survival (PFS) 5.4 to 7.4 months, objective response rate 44% to 63%, median duration of response 5.6 to 11.1 months, and median overall survival 15.7 to 28.3 months. The safety profile was consistent with the known toxicities of each agent. Grade ≥3 adverse events were more frequent with the triplet than with doublets or single-agent paclitaxel. Patients with PFS >10 months were characterized by NF1, CCND3, and PIK3CA alterations and increased immune pathway activity. PFS <5 months was associated with CDKN2A/CDKN2B/MTAP alterations and lower predicted phosphorylated AKT-S473 levels.

CONCLUSIONS

In patients with mTNBC receiving an ipatasertib/atezolizumab/taxane triplet regimen, molecular characteristics may identify those with particularly favorable or unfavorable outcomes, potentially guiding future research efforts.

Searching for the "Holy Grail" of breast cancer recurrence risk: a narrative review of the hunt for a better biomarker and the promise of circulating tumor DNA (ctDNA)

BACKGROUND

This paper is a narrative review of a major clinical challenge at the heart of breast cancer care: determining which patients are at risk of recurrence, which require systemic therapy, and which remain at risk in the survivorship phase of care despite initial therapy.

METHODS

We review the literature on prognostic and predictive biomarkers in breast cancer with a focus on detection of minimal residual disease.

RESULTS

While we have many tools to estimate and refine risk that are used to individualize local and systemic therapy, we know that we continue to over treat many patients and undertreat others. Many patients also experience what is, at least in hindsight, needless fear of recurrence. In this review, we frame this dilemma for the practicing breast oncologist and discuss the search for what we term the "holy grail" of breast cancer evaluation: the ideal biomarker of residual distant disease. We review the history of attempts to address this problem and the up-to-date science on biomarkers, circulating tumor cells and circulating tumor DNA (ctDNA).

CONCLUSION

This review suggests that the emerging promise of ctDNA may help resolve a crticical dilemma at the heart of breast cancer care, and improve prognostication, treatment selection, and outcomes for patients with breast cancer.

Allosteric PI3Kα Inhibition Overcomes On-target Resistance to Orthosteric Inhibitors Mediated by Secondary PIK3CA Mutations

PIK3CA mutations occur in ∼8% of cancers, including ∼40% of HR-positive breast cancers, where the PI3K-alpha (PI3Kα)-selective inhibitor alpelisib is FDA approved in combination with fulvestrant. Although prior studies have identified resistance mechanisms, such as PTEN loss, clinically acquired resistance to PI3Kα inhibitors remains poorly understood. Through serial liquid biopsies and rapid autopsies in 39 patients with advanced breast cancer developing acquired resistance to PI3Kα inhibitors, we observe that 50% of patients acquire genomic alterations within the PI3K pathway, including PTEN loss and activating AKT1 mutations. Notably, although secondary PIK3CA mutations were previously reported to increase sensitivity to PI3Kα inhibitors, we identified emergent secondary resistance mutations in PIK3CA that alter the inhibitor binding pocket. Some mutations had differential effects on PI3Kα-selective versus pan-PI3K inhibitors, but resistance induced by all mutations could be overcome by the novel allosteric pan-mutant-selective PI3Kα-inhibitor RLY-2608. Together, these findings provide insights to guide strategies to overcome resistance in PIK3CA-mutated cancers.

SIGNIFICANCE

In one of the largest patient cohorts analyzed to date, this study defines the clinical landscape of acquired resistance to PI3Kα inhibitors. Genomic alterations within the PI3K pathway represent a major mode of resistance and identify a novel class of secondary PIK3CA resistance mutations that can be overcome by an allosteric PI3Kα inhibitor. See related commentary by Gong and Vanhaesebroeck, p. 204 . See related article by Varkaris et al., p. 240 . This article is featured in Selected Articles from This Issue, p. 201.

Virtual Molecular and Precision Medicine Clinic to Improve Access to Clinical Trials for Patients With Metastatic Breast Cancer: An Academic/Community Collaboration

PURPOSE

There is a demand for improved care delivery surrounding genomic testing and clinical trial enrollment among patients with metastatic breast cancer (MBC). We sought to improve the current process via real-time informal consultation and prescreening assessment for patients with MBC treated by community and academic medical oncologists by implementing a virtual molecular and precision medicine (vMAP) clinic.

METHODS

The vMAP program used a virtual referral system directed to a multidisciplinary team with precision medicine expertise. Providers contacted vMAP regarding patients with MBC, and on receipt of referral, the vMAP team engaged in discussion to identify if further diagnostics were needed (including genomic testing) and to identify potential clinical trials or standard treatment options. Recommendations were then sent to the referring provider within 72 hours. Pre-/postsurveys were issued to network physicians to assess for barriers, clinical trial access, and vMAP referral experience. Program implementation was evaluated with the Squire 2.0 reporting guidelines for quality improvement in health care as a framework.

RESULTS

Eighty-one cases from 22 providers were referred to vMAP over a 26-month period. The average response time to the referring provider with a finalized recommendation was 1.90 ± 1.82 days. A total of 86.4% of cases had clinical trial options on vMAP prescreen, with 40.7% initiating formal screening assessments and 27 patients (33.3%) ultimately enrolling on trials. On resurvey, 92% of survey responses across community oncology referring providers said that they were very likely to use vMAP again.

CONCLUSION

In the initial 2-year period, vMAP demonstrated an efficient means to offer real-time interpretation of genomic testing and identification of clinical trials for patients with MBC, with effective clinical trial enrollment and high rates of referring provider satisfaction.

Stressed target cancer cells drive nongenetic reprogramming of CAR T cells and solid tumor microenvironment

The poor efficacy of chimeric antigen receptor T-cell therapy (CAR T) for solid tumors is due to insufficient CAR T cell tumor infiltration, in vivo expansion, persistence, and effector function, as well as exhaustion, intrinsic target antigen heterogeneity or antigen loss of target cancer cells, and immunosuppressive tumor microenvironment (TME). Here we describe a broadly applicable nongenetic approach that simultaneously addresses the multiple challenges of CAR T as a therapy for solid tumors. The approach reprograms CAR T cells by exposing them to stressed target cancer cells which have been exposed to the cell stress inducer disulfiram (DSF) and copper (Cu)(DSF/Cu) plus ionizing irradiation (IR). The reprogrammed CAR T cells acquire early memory-like characteristics, potent cytotoxicity, enhanced in vivo expansion, persistence, and decreased exhaustion. Tumors stressed by DSF/Cu and IR also reprogram and reverse the immunosuppressive TME in humanized mice. The reprogrammed CAR T cells, derived from peripheral blood mononuclear cells of healthy donors or metastatic female breast cancer patients, induce robust, sustained memory and curative anti-solid tumor responses in multiple xenograft mouse models, establishing proof of concept for empowering CAR T by stressing tumor as a promising therapy for solid tumors.

Feasibility of introducing a smartphone navigation application into the care of breast cancer patients (The FIONA Study)

PURPOSE

Patients with breast cancer (BC) face complex medical information and decisions. The Outcomes4Me mobile app provides evidence-based BC education, symptom management tracking and clinical trial matching. This study sought to evaluate the feasibility of introducing this app into routine BC care.

METHODS

In this pilot study among BC patients undergoing therapy at an academic cancer center, patients were followed for 12 weeks with survey administration and electronic health record (EHR) abstraction at baseline and completion. Feasibility was defined as 40% of patients engaging with the app 3 or more times during the study. Additional endpoints included app usability (system usability scale), patient care experience, symptom evaluation, and clinical trial matching.

RESULTS

The study enrolled 107 patients from 6/01/2020 to 3/31/2021. Utilization of the app was deemed feasible with 60% of patients engaging with the app at least 3 times. SUS score of 70 indicated above average usability. New diagnosis and higher education level was associated with greater app engagement, with usability similar across all age groups. 41% of patients found the app helped track symptoms. Cognitive and sexual symptoms were infrequently reported, but were more frequently captured in the app than in the EHR. After using the app, 33% of patients reported increased interest in clinical trial enrollment.

CONCLUSION

Introducing the Outcomes4Me patient navigation app into routine BC care is feasible and may improve the patient experience. These results support further evaluation of this mobile technology platform to improve BC education, symptom management, and decision making.

CLINICAL TRIAL REGISTRY

Clinicaltrials.gov registration #: NCT04262518.

Abstract PD1-10: Impact of Race on Clinical, Socioeconomic, and Genomic Characteristics, Clinical Trial Participation, and Receipt of Genotype-matched Therapy Among Patients with Metastatic Breast Cancer

Background: Clinical outcomes in breast cancer differ across racial and ethnic populations. We have previously demonstrated that receipt of genotype-matched therapy targeted to an actionable mutation may potentially improve patient outcomes (Vidula, CCR, 2021). We evaluated the impact of race on clinical, socioeconomic, and genomic characteristics, clinical trial participation, and receipt of genotype-matched therapy among patients with metastatic breast cancer (MBC). Methods: We conducted a retrospective study of patients with MBC at an academic institution who underwent cell-free DNA testing (cfDNA, Guardant360, 74 gene panel) as part of routine clinical care from 11/29/2016-11/2/2020. Patient demographics (including self-reported race and ethnicity) and clinical trial enrollment (at same institution) were determined by retrospective data collection. Mutations identified in cfDNA were characterized as actionable based on the variant interpretation performed by Guardant360 using vetted genomic databases, and receipt of genotype-matched therapy targeted to an actionable mutation was determined as previously described (Vidula, CCR, 2021). Pearson’s chi-squared and Wilcoxon rank-sum tests were used to compare categorical and continuous variables between groups, with p&lt; 0.05 indicating statistical significance. Results: Four hundred and twenty-five patients with MBC and cfDNA results were identified, of which 369 were White (87%), 27 Black (6.4%), 15 Hispanic (3.5%), and 14 Asian (3.3%). There were no significant differences in median age at MBC diagnosis (p=0.064), disease subtype distribution (p=0.74), proportions of de-novo/recurrent MBC (p=0.95), presence of visceral metastases (p=0.84), Charleston comorbidity index (p=0.93), menopausal status (p=0.3), and level of education (p=0.44) across racial groups. Higher proportions of non-primary English speakers were seen in Hispanic (80%) and Asian (29%) races (p&lt; 0.001). Median distance traveled to the institution also varied based on race, with White patients traveling further (White: 39.1 miles, Black: 21.8 miles, Hispanic 9.4 miles, Asian 9.1 miles, p&lt; 0.001). In addition, type of insurance varied based on race, with White patients having the highest rates of commercial insurance and Medicare, Black patients having the highest rate of state-supported insurance, and Asian patients having the highest uninsured rates (p&lt; 0.001). Clinical trial enrollment rates did not significantly differ by race (White: 44%, Black: 37%, Hispanic: 47%, and Asian 21%, p=0.34), but patients without insurance were significantly less likely to be enrolled on a trial than those with commercial insurance (p=0.03). The proportion of patients with ≥1 actionable mutation in cfDNA did not vary significantly by race (White: 78%, Black: 56%, Hispanic: 73%, Asian 86%, p=0.18) and the median number of actionable mutations found in cfDNA was similar across races (p=0.31). However, receipt of genotype-matched therapy targeted to an actionable mutation varied by race, with the highest rates of matched therapy in White patients (White: 28%, Black: 11%, Hispanic 13%, Asian 14%, p&lt; 0.001). After multivariable logistic regression adjusting for subtype, commercial insurance versus other insurance types, and proximity to the center, White patients remained significantly more likely to receive matched therapy (p=0.029). Conclusions: We observed significant race-based differences in non-English speaking status, insurance type, and median distance traveled to the institution. Racial/ethnic minority patients were less likely to receive genotype-matched therapy than White patients. Further research is needed to identify barriers and reduce disparities in access to precision medicine.

Citation Format: Rupali Sood, Lianne Ryan, Andrzej Niemierko, Laura M. Spring, Dejan Juric, Steven J. Isakoff, Seth A. Wander, Jennifer Shin, Naomi Ko, Leif Ellisen, Beverly Moy, Aditya Bardia, Neelima Vidula. Impact of Race on Clinical, Socioeconomic, and Genomic Characteristics, Clinical Trial Participation, and Receipt of Genotype-matched Therapy Among Patients with Metastatic Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD1-10.

Abstract PD13-07: PD13-07 Combination therapy with the AKT inhibitor, ipatasertib, endocrine therapy, and a CDK4/6 inhibitor for hormone receptor positive (HR+)/HER2 negative metastatic breast cancer (MBC): results from the phase I TAKTIC trial

Background: Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in combination with endocrine therapy (ET) provide significant clinical benefit in patients with HR+/HER2- metastatic breast cancer (MBC) and have become a standard of care treatment. Prior insights from tumor profiling and preclinical analyses suggest that AKT1 activation can induce CDK4/6i resistance. We hypothesized that targeting AKT1 following CDK4/6i progression may be an effective therapeutic strategy and conducted a clinical trial to evaluate both doublet (ET+AKTi) and triplet (ET+AKTIi+CDK 4/6i) therapy in the ≥ 2nd line MBC setting. Methods: TAKTIC is an open-label phase Ib clinical trial (clinicaltrials.gov NCT03959891) evaluating the combination of the AKT inhibitor ipatasertib (ipat) with fulvestrant (Arm A), an aromatase inhibitor (Arm B), or the triplet combination (Arm C) with fulvestrant + palbociclib (palbo). The primary objective is to evaluate the safety (NCI CTCAE 5.0) and tolerability of ipat in combination with endocrine therapy +/- CDK4/6i. Secondary objectives include clinical efficacy, as determined by objective response rate (RECIST v1.1), clinical benefit rate (CBR), progression-free survival (PFS), and overall survival (OS). Key inclusion criteria include unresectable HR+/HER2- MBC; at least 1 prior therapy for MBC including any CDK4/6i; up to 2 prior lines of chemotherapy for MBC (no limit on prior endocrine therapy). Here, we present an updated interim analysis from all study arms. Results: The trial completed accrual with 77 pts enrolled from June 2019 – February 2022, including 19 on Arm A, 16 on Arm B, and 42 on Arm C. Median age was 62 (range 32-88) and 65/77 pts (84%) received prior CDK4/6i (median no. of prior lines = 3, range 1-13). 56/77 pts (73%) had measurable disease at baseline and 50/77 pts (65%) had visceral metastases in the liver/lung (68% Arm A, 44% Arm B, 71% Arm C). Pts enrolled on Arms A and B received ipat at 400mg in combination with fulvestrant or an aromatase inhibitor, respectively. In Arm C, 27/42 pts enrolled into the dose escalation phase and received ipat + palbo at varying doses in combination with fulvestrant. Two DLTs were observed in the 300mg ipat + 125mg palbo cohort (grade 4 neutropenia ≥ 7 days). ET+400mg ipat + 100mg palbo was determined to be the recommended phase 2 dose (R2PD), and the remaining 15/42 pts on Arm C were treated at this dose level in the expansion phase. Treatment was well tolerated in all arms. Grade 3 and 4 toxicities included neutropenia (39/77, 50.6%), leukopenia (15/77, 19.5%), diarrhea (11/77, 14/3%), transaminitis (7/77, 9.1%), lymphopenia (6/77, 7.8%), rash (6/77, 7.8%), and thrombocytopenia (3/77, 3.9%). As of 6/28/2022, 16/77 pts remain on treatment. The median treatment duration for all pts is estimated at 6 months (range 0.5-39). Among the 56 pts with measurable disease, 11 had partial response (PR) and 32 had stable disease (SD) as the best response. CBR, defined as percentage of pts who achieved PR or SD &gt; 6 months, was 48% across the study (53% Arm A, 31% Arm B, 57% Arm C). The median PFS was 5.5 months (95% confidence interval [CI]: 3.8 – 7.4) and the median OS was 24.5 months (95% CI: 17.1 – 33.9). Conclusions: The combination of ipat with endocrine therapy +/- palbo is well tolerated in heavily pre-treated pts, with preliminary evidence of clinical activity. This trial demonstrates how molecular insights related to CDK4/6i resistance inform potential therapy combinations. Further studies are needed to evaluate AKTi-based combinations in pts with HR+ MBC.

Citation Format: Seth A. Wander, Jennifer C. Keenan, Andrzej Niemierko, Dejan Juric, Laura M. Spring, Jeffrey Supko, Neelima Vidula, Steven J. Isakoff, Lianne Ryan, Sarah Padden, Elizabeth Fisher, Amber Newton, Beverly Moy, Leif Ellisen, Douglas S. Micalizzi, Aditya Bardia. PD13-07 Combination therapy with the AKT inhibitor, ipatasertib, endocrine therapy, and a CDK4/6 inhibitor for hormone receptor positive (HR+)/HER2 negative metastatic breast cancer (MBC): results from the phase I TAKTIC trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD13-07.

Abstract PD17-03: Cell-free DNA monitoring in a phase II study of adjuvant endocrine therapy with CDK 4/6 inhibitor ribociclib for localized HR+/HER2- breast cancer (LEADER)

Background: While adjuvant endocrine therapy (ET) reduces recurrence risk in hormone receptor-positive (HR+) breast cancer, many patients still experience disease recurrence. Adjuvant therapeutic advances are needed to improve outcomes. Meanwhile, monitoring for circulating tumor DNA (ctDNA) in the adjuvant setting may detect molecular residual disease and/or emergences of molecular recurrence from tumor dormancy. Cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitors have shown efficacy in HR+/HER2- metastatic breast cancer, and abemaciclib is now approved for adjuvant use in high-risk HR+/HER2- breast cancer. Adjuvant clinical trials have evaluated upfront use of adjuvant CDK 4/6 inhibition; however, the optimal timing of adding a CDK 4/6 inhibitor for HR+/HER2- breast cancer remains unknown. We conducted a prospective phase II clinical trial to evaluate the addition of the CDK 4/6 inhibitor ribociclib in patients with at least one remaining year of adjuvant ET regardless of duration of ET prior to trial enrollment, and we prospectively collected plasma for ctDNA analysis. Methods: Eligible patients had Stage I-III HR+/HER2- breast cancer and had been on adjuvant ET (any number of years) with at least one year of treatment remaining. Patients were randomized to one of two ribociclib schedules: continuous (400 mg daily, 28-day cycle) or intermittent (600 mg daily days 1-21, 28-day cycle) for one year. Patients were concurrently treated with an aromatase inhibitor (plus GnRH agonist, if premenopausal). Time to recurrence was calculated using the Kaplan-Meier method. ctDNA monitoring was performed using the SignateraTM platform, a tumor-informed assay based on whole exome sequencing of the primary tumor for multiplex PCR-NGS ctDNA assay design with targeting of up to 16 single nucleotide variants. Plasma samples were collected at the start of ribociclib/ET and serially during follow-up visits. Results: Among 81 patients treated with adjuvant endocrine therapy and the CDK4/6 inhibitor ribociclib, 42 patients had samples suitable for ctDNA analysis: 3 (7%) had a single ctDNA test, 17 (40%) had 2 serial ctDNA tests, and 22 (52%) had 3 serial ctDNA tests. After a median follow-up of 20 months, 2 patients who received ribociclib (intermittent dosing) experienced disease recurrence with recurrence-free survival of 100% at 1 year from study entry and 97% (95% CI 88-99%) at 2 years. ctDNA was detected exclusively in the only 2 patients that experienced recurrence, with lead times of 7 months and 8 months prior to clinical recurrence. Both patients had no detectable ctDNA at the start of ribociclib/ET. One patient had detectable ctDNA [mean tumor molecules/mL (MTM/mL) = 0.1] while on ribociclib/ET for 5 months, after which she completed a full 12 months of treatment. One month after completing ribociclib/ET (8 months after ctDNA detection), she presented with metastases in the liver and bones. The second patient had 2 negative ctDNA tests at days 0 and 147 while receiving ribociclib/ET and became ctDNA positive (MTM/mL = 0.1) at day 350. She developed CNS-only metastatic disease 7 months after completing ribociclib/ET. Among the other 40 patients who did not have detectable ctDNA, none have experienced recurrence. Conclusions: Overall, only 2 patients had detectable ctDNA, and both patients developed recurrent metastatic disease after completion of ribociclib with ET. Notably, one of these patients developed CNS-only disease. While follow-up is early, the remaining patients did not have detectable ctDNA and have not developed recurrent disease. This study suggests monitoring for ctDNA may identify patients at increased risk for recurrence in the extended adjuvant period and potentially guide therapy escalation.

Citation Format: Arielle J. Medford, Lauren Scarpetti, Andrzej Niemierko, Steven J. Isakoff, Beverly Moy, Seth A. Wander, Elizabeth Deluca, Elizabeth Abraham, Jennifer Shin, Lowell Schnipper, Amy E. Comander, Therese Mulvey, Erik Spickard, Ekaterina Kalashnikova, Angel Rodriguez, Leif Ellisen, Aditya Bardia, Laura M. Spring. Cell-free DNA monitoring in a phase II study of adjuvant endocrine therapy with CDK 4/6 inhibitor ribociclib for localized HR+/HER2- breast cancer (LEADER) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD17-03.

Abstract PD18-01: Adjuvant Trastuzumab Emtansine Versus Paclitaxel plus Trastuzumab for Stage I HER2+ Breast Cancer: 5-year results and correlative analyses from ATEMPT (TBCRC033)

Background: The ATEMPT trial primary analysis found that one year of adjuvant trastuzumab emtansine (T-DM1) achieved a 3-year iDFS of 97.8% for patients with stage I HER2+ breast cancer, but was not associated with fewer clinically relevant toxicities (CRTs) compared with paclitaxel and trastuzumab (TH). In this end-of-study analysis, we report 5-year survival outcomes and correlative analyses from the trial. Methods: Patients with stage I centrally confirmed HER2+ breast cancer were randomly assigned 3:1 to adjuvant T-DM1 for one year or TH and received T-DM1 3.6 mg/kg IV every 3 weeks for 17 cycles or paclitaxel 80 mg/m2 IV with weekly trastuzumab IV followed by trastuzumab for 9 months. The co-primary objectives were to compare the incidence of CRTs between the 2 arms and to evaluate iDFS in patients receiving T-DM1. To investigate proteomic correlates of recurrence, spatial proteomic analyses were performed on samples from 13 patients experiencing iDFS events (cases) and 24 matched controls using the NanoString GeoMx Digital Spatial Profiler. The impact of HER2 heterogeneity on outcomes was investigated among 17 cases and 51 matched controls by fluorescence in-situ hybridization (FISH). HER2 genetic heterogeneity was assessed by scrutinizing the whole tumor area and defined as the occurrence of HER2 gene amplification in &gt;5% but &lt; 50% invasive tumor cells. The risk of recurrence was evaluated centrally with the HER2DX genomic assay from 225 primary tumor samples. Germline whole genome sequencing (WGS) was conducted among 55 patients experiencing T-DM1-induced thrombocytopenia and/or bleeding and 55 matched controls to identify genomic correlates for this side effect. Results: A total of 497 patients who initiated protocol therapy were included in this analysis (383 T-DM1 and 114 TH). After a median follow up 5.8 years, among patients receiving T-DM1 there were a total of 11 iDFS events, with 3 distant recurrences. The 5-year iDFS for T-DM1 was 97.0% (95% CI, 95.3-98.8%), the 5-year recurrence-free interval (RFI) was 98.6% (95% CI: 97.4-99.8%) and the 5-year overall survival (OS) for T-DM1 was 97.8 % (95% CI, 96.3-99.3%). Although the study was not powered to evaluate the efficacy of TH, among the 114 patients receiving TH, a total of 9 iDFS events were observed, including 2 distant events; the 5-year iDFS with TH was 91.3% (95% CI: 86.0-96.9%), 5-year RFI was 93.3% (95% CI: 88.6-98.2%) and 5-year OS was 97.9% (95% CI: 95.2-100%). A total of 56 samples were evaluable for heterogeneity analyses, among which 14% (n=8) harbored HER2 genetic heterogeneity. Spatial proteomic analyses found that NF1 (adjusted p=0.72 × 10-6) and CTLA-4 (adjusted p=0.15 × 10-3) were significantly upregulated in primary samples from cases, while cleaved caspase 9, CD25, GITR, ICOS, p53 and PD-L2 were significantly upregulated in controls (all with adjusted p&lt; 0.05). Germline WGS found that the top gene associations with thrombocytopenia and thrombocytopenia or bleeding were ALMS1 (p=0,19 × 10-3) and APBA3 (p=0,23 × 10-3), respectively, although none reaching the threshold for genome wide significance. rs62143195 and rs114169776 were the top single nucleotide polymorphisms associated with thrombocytopenia and thrombocytopenia or bleeding, respectively. Data on the impact of HER2 heterogeneity and of HER2DX score on survival outcomes will be presented. Conclusion: With longer follow-up, adjuvant T-DM1 confirmed outstanding long-term outcomes among patients with stage I HER2+ breast cancer, demonstrating a 5-year RFI of 98.6%. Spatial proteomic analyses identified a potential association between NF1 and CTLA-4 expression with recurrence. Details on the impact of HER2 heterogeneity and HER2DX assay on prognosis will be presented.

Citation Format: Paolo Tarantino, Nabihah Tayob, Chau T Dang, Denise Yardley, Steven J. Isakoff, Vicente Valero, Meredith Faggen, Therese Mulvey, Ron Bose, Douglas Weckstein, Antonio C. Wolff, Katherine Reeder-Hayes, Hope Rugo, Bhuvaneswari Ramaswamy, Dan Zuckerman, Lowell Hart, Vijayakrishna K. Gadi, Michael Constantine, Kit Cheng, Audrey Merrill Garrett, Paul K. Marcom, Kathy S. Albain, Patricia DeFusco, Nadine Tung, Blair Ardman, Rita Nanda, Rachel C. Jankowitz, Mothaffar Rimawi, Vandana Abramson, Paula R. Pohlmann, Catherine Van Poznak, Andres Forero-Torres, Minetta C. Liu, Kathryn Ruddy, Yue Zheng, Romualdo Barroso-Sousa, Adrienne Waks, Michelle K. DeMeo, Molly K. DiLullo, Giuseppe Curigliano, Harold Burstein, Ann Partridge, Eric Winer, Giuseppe Viale, Winnie Hui, Elizabeth A. Mittendorf, Bryan P. Schneider, Aleix Prat, Ian Krop, Sara Tolaney. Adjuvant Trastuzumab Emtansine Versus Paclitaxel plus Trastuzumab for Stage I HER2+ Breast Cancer: 5-year results and correlative analyses from ATEMPT (TBCRC033) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD18-01.

Abstract OT2-09-01: TBCRC-055: A Phase II Study of NirAparib, Dostarlimab, and Radiotherapy in Metastatic, PD-L1 Negative or Immunotherapy-Refractory Triple-Negative Breast Cancer (NADiR) – NCT04837209

Background: Metastatic triple negative breast cancer (mTNBC) is associated with high recurrence and mortality rates. Prior studies have shown an immune checkpoint inhibitor (ICI) + chemotherapy improves progression-free survival for patients with PD-L1 positive mTNBC. There remains a need for treatment options in patients who do not respond to ICI or are PD-L1 negative. Preclinical data suggests that a PARP inhibitor (PARPi) may promote innate immune signaling, and combination with an ICI has shown a positive response in patients with mTNBC. Radiotherapy (RT) is a potent immune stimulator and used for local control in the setting of metastatic breast cancer. This phase II study (NCT04837209) proposes combination of PARPi, ICI, and RT to combat ICI resistance and improve response rates in patients with mTNBC who are PD-L1 negative or who have progressed on prior ICI. Methods: 32 patients with mTNBC defined as ER&lt; 1%, PR&lt; 1%, HER-2-neu 0-1+ by IHC or non-FISH-amplified or patients with metastatic HR+/HER2- breast cancer are anticipated to participate. Eligibility criteria for mTNBC patients includes those who are PD-L1 negative or have progressed on prior ICI. Eligibility criteria for HR+/HER2- patients is specific to those who harbor a deleterious BRCA1 or BRCA2 mutation with or without high tumor mutational burden (TMB). All trial patients should have at least 1 lesion amenable to RT and at least 1 measurable lesion that will not be radiated. Study treatment consists of 3-week cycles, with 500mg dostarlimab given on day 1 of each cycle through cycle 5, then 1000mg given every 6 weeks. RT (24 Gy) is delivered in 3 consecutive fractions starting day 1 of cycle 1. Niraparib (200mg) is dosed orally daily. Tumor biopsies are taken within 28 days pre-treatment, and at C3D1-8. Blood samples are taken at baseline and every odd cycle for cfDNA and PBMC analysis. The primary endpoint is to assess overall response rate as measured by RECIST v1.1 of the combination of niraparib, dostarlimab, and RT. Secondary objectives include assessing safety and toxicity, overall survival, progression free survival, and quality of life. Results: To date, this study has accrued 4 subjects, including 3 with mTNBC, and 1 with HR+/HER2-/BRCA mutant + TMB high mBC. The study is currently open at MGH and Sibley, and the addition of UPenn, Johns Hopkins, and Duke are in progress. Funding for this study was provided by GSK. GSK was provided the opportunity to review a preliminary version of this abstract for factual accuracy, but the authors are solely responsible for final content and interpretation. People with specific interest in the trial should reach out to Elizabeth Scott, Clinical Research Coordinator, at ecscott@mgh.harvard.edu.

Citation Format: Elizabeth Scott, Steven J. Isakoff, Alphonse G. Taghian, Jean Wright, Cesar Augusto Santa-Maria, Payal Shah, Neil Taunk, Carey Anders, Rachel Blitzblau, Gaorav Gupta, Alice Ho. TBCRC-055: A Phase II Study of NirAparib, Dostarlimab, and Radiotherapy in Metastatic, PD-L1 Negative or Immunotherapy-Refractory Triple-Negative Breast Cancer (NADiR) – NCT04837209 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-09-01.

Stressed target cancer cells drive nongenetic reprogramming of CAR T cells and tumor microenvironment, overcoming multiple obstacles of CAR T therapy for solid tumors

The poor efficacy of chimeric antigen receptor T-cell therapy (CAR T) for solid tumor is due to insufficient CAR T cell tumor infiltration, in vivo expansion, persistence, and effector function, as well as exhaustion, intrinsic target antigen heterogeneity or antigen loss of target cancer cells, and immunosuppressive tumor microenvironment (TME). Here we describe a broadly applicable nongenetic approach that simultaneously addresses the multiple challenges of CAR T as a therapy for solid tumors. The approach massively reprograms CAR T cells by exposing them to stressed target cancer cells which have been exposed to the cell stress inducer disulfiram (DSF) and copper (Cu)(DSF/Cu) plus ionizing irradiation (IR). The reprogrammed CAR T cells acquired early memory-like characteristics, potent cytotoxicity, enhanced in vivo expansion, persistence, and decreased exhaustion. Tumors stressed by DSF/Cu and IR also reprogrammed and reversed immunosuppressive TME in humanized mice. The reprogrammed CAR T cells, derived from peripheral blood mononuclear cells (PBMC) of healthy or metastatic breast cancer patients, induced robust, sustained memory and curative anti-solid tumor responses in multiple xenograft mouse models, establishing proof of concept for empowering CAR T by stressing tumor as a novel therapy for solid tumor.

Adjuvant trastuzumab and vinorelbine for early-stage HER2+ breast cancer

Background

The single-arm phase II APT trial established trastuzumab and paclitaxel (TH) as the standard adjuvant regimen for small human epidermal growth factor receptor 2 (HER2+) tumors. However, paclitaxel causes alopecia and has high rates of neuropathy and hypersensitivity reactions. In patients with metastatic HER2+ breast cancer (BC), the combination of trastuzumab and vinorelbine (TV) is effective and well tolerated. There is a need for alternative non-anthracycline/taxane-based regimens for patients with HER2+ early-stage BC, especially for those with contraindications or who wish to avoid side effects of taxane-based regimens. Here we describe our institutional experience with adjuvant TV for patients with early-stage HER2+ BC.

Methods

Clinicopathological characteristics, treatment details, and outcomes of patients with localized HER2+ BC treated with adjuvant TV from 2007 to 2021 at a large academic medical institution were collected. Study endpoints included invasive disease-free survival (IDFS), overall survival (OS), and safety/tolerability. IDFS and OS were measured from start date of TV treatment to date of event/last follow-up and date of death/last follow-up, respectively.

Results

A total of 30 patients were treated with TV. All patients received trastuzumab at standard dosing and vinorelbine at a starting dose of 25 mg/m² either on days 1/8 or on days 1/8/21 (weekly) of a 21-day cycle with four planned cycles. Median age at diagnosis was 59 years (range: 36-81). 90.3% of patients had anatomic pathologic stage IA BC and 9.7% stage IIA BC. Of the 30 patients, 24 of them opted to pursue TV due to concerns related to alopecia, neuropathy, and other toxicities, and 6 switched from treatment with TH to TV due to toxicities. Eight patients experienced neutropenia with no cases of febrile neutropenia. No patients experienced alopecia or long-term neuropathy. With a median follow-up of 68 months (5.7 years), the 5-year IDFS rate was 90.9%, with one local and one distant recurrence. The 5-year OS was 100%.

Conclusions

Trastuzumab in combination with vinorelbine in the adjuvant, early-stage setting for low-risk HER2+ BC demonstrated clinical efficacy and appeared to be well tolerated. TV warrants further evaluation as an alternative regimen to TH for patients with early-stage HER2+ BC.

Immunogenicity of SARS-CoV-2 vaccines in patients with breast cancer

Purpose

To explore the immunogenicity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in patients with breast cancer based on type of anticancer treatment.

Methods

Patients with breast cancer had anti-spike antibody concentrations measured ⩾14 days after receiving a full SARS-CoV-2 vaccination series. The primary endpoint was IgA/G/M anti-spike antibody concentration. Multiple regression analysis was used to analyze log₁₀-transformed antibody titer concentrations.

Results

Between 29 April and 20 July 2021, 233 patients with breast cancer were enrolled, of whom 212 were eligible for the current analysis. Patients who received mRNA-1273 (Moderna) had the highest antibody concentrations [geometric mean concentration (GMC) in log₁₀: 3.0 U/mL], compared to patients who received BNT162b2 (Pfizer) (GMC: 2.6 U/mL) (multiple regression adjusted p = 0.013) and Ad26.COV2.S (Johnson & Johnson/Janssen) (GMC: 2.6 U/mL) (p = 0.071). Patients receiving cytotoxic therapy had a significantly lower antibody titer GMC (2.5 U/mL) compared to patients on no therapy or endocrine therapy alone (3.0 U/mL) (p = 0.005). Patients on targeted therapies (GMC: 2.7 U/mL) also had a numerically lower GMC compared to patients not receiving therapy/on endocrine therapy alone, although this result was not significant (p = 0.364). Among patients who received an additional dose of vaccine (n = 31), 28 demonstrated an increased antibody response that ranged from 0.2 to >4.4 U/ mL.

Conclusion

Most patients with breast cancer generate detectable anti-spike antibodies following SARS-CoV-2 vaccination, though systemic treatments and vaccine type impact level of response. Further studies are needed to better understand the clinical implications of different antibody levels, the effectiveness of additional SARS-CoV-2 vaccine doses, and the risk of breakthrough infections among patients with breast cancer.

Breast Cancer, Version 3.2022, NCCN Clinical Practice Guidelines in Oncology

The therapeutic options for patients with noninvasive or invasive breast cancer are complex and varied. These NCCN Clinical Practice Guidelines for Breast Cancer include recommendations for clinical management of patients with carcinoma in situ, invasive breast cancer, Paget disease, phyllodes tumor, inflammatory breast cancer, and management of breast cancer during pregnancy. The content featured in this issue focuses on the recommendations for overall management of ductal carcinoma in situ and the workup and locoregional management of early stage invasive breast cancer. For the full version of the NCCN Guidelines for Breast Cancer, visit NCCN.org.

The Evolving Role of Neoadjuvant Therapy for Operable Breast Cancer

The role of neoadjuvant therapy (NAT) for localized breast cancer has evolved tremendously over the past several years. Currently, NAT is the preferred option for high-risk early triple-negative (TN) and HER2-positive (HER2+) breast cancers and is indicated for some estrogen receptor-positive (ER+) breast cancers. In addition to traditional absolute indications for NAT, relative indications such as the assessment of outcomes at the time of surgery and guidance of treatment escalation and de-escalation have greatly evolved in recent years. Pathologic complete response (pCR) and the Residual Cancer Burden (RCB) index are highly prognostic for disease recurrence and survival, mainly in patients with TN or HER2+ disease. Furthermore, post-NAT escalation strategies have been shown to improve long-term outcomes of patients who do not achieve pCR. Additionally, by allowing the direct assessment of drug effect on the tumor, the neoadjuvant setting has become an attractive setting for the exploration of novel agents and the identification of predictive biomarkers. Neoadjuvant trial design has also evolved, using adaptive treatment approaches that enable treatment de-escalation or escalation based on response. However, despite multiple practice-changing neoadjuvant trials and the addition of various new agents to the neoadjuvant setting for early breast cancer, many key questions remain. For example, patient selection for neoadjuvant immunotherapy in TN breast cancer, de-escalation methods in HER2+ breast cancer, and the use of gene expression profiles to guide NAT recommendations in ER+ breast cancer. This article reviews the current approach for NAT in localized breast cancer as well as evolving NAT strategies, the key remaining challenges, and the ongoing work in the field.

Baseline preferences for digital information engagement in patients with breast cancer by age and status of diagnosis

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Background: The need for improvement in education and decision-making support for patients with breast cancer is well documented. Digital health applications offer potential to address these needs through widely available smartphone technology. Understanding patients’ baseline preferences for information sources, breast cancer-related topics of interest, and current use of smartphones and how these interests may differ based on demographic and clinical factors can inform the development of a patient-centered digital navigation tool. Methods: As part of a pilot trial of the Outcomes4Me breast cancer navigation app, we conducted a baseline cross-sectional survey of patients presenting for routine breast cancer care at an academic medical center and community-based sites. Eligible patients had invasive breast cancer of any stage and were actively in treatment. Survey-specific questions addressed sources of cancer information and informational needs. Analysis is descriptive with statistical comparisons based on Fisher’s exact test. Results: Ninety out of 107 patients in the pilot trial completed the survey items of interest. The majority of patients were over age 50 (59%) and 35% had stage IV disease. Baseline reported uses for mobile devices included text (67%), email (61%), phone (47%), social media (41%), accessing the internet (18%), and apps (12%). Only 7% of patients noted using mobile apps for navigating disease and treatment options. When asked to rank the importance of cancer information sources, 88% and 42% of patients reported relying heavily on their oncologist and the rest of the care team, respectively. Forty percent of patients relied at least moderately on the internet for health information and 27% on online support groups, with patients < age 50 more likely than those > age 50 to rely on online support groups for health information (41% vs 17%, P = 0.02). The most common educational needs reported were side effects (79%), followed by prognosis (72%), healthy lifestyle (71%), treatment options (70%), general breast cancer news and research (67%), information about their current cancer status (59%), potential clinical trials (44%), and costs of treatment (14%). Patients with metastatic breast expressed greater interest in information about clinical trials compared to those without metastatic disease (64% vs 36%, P = 0.01), and less interest in information about prognosis (54% vs. 81%, P = 0.01). Conclusions: Despite reliance on their oncologist and oncology team for information, patients report multiple unmet educational needs related to their disease and treatment options. While a substantial percentage of patients with breast cancer turn to the internet for information, there is untapped potential to use mobile devices to improve patient education and awareness of treatment options, including clinical trials.

Adjuvant trastuzumab and vinorelbine (TV) for early-stage HER2+ breast cancer

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Background: The anti-HER2 antibody trastuzumab has vastly improved outcomes for women with early stage and advanced HER2+ breast cancer (BC) when used in combination with chemotherapy. Anthracycline and taxane-based regimens have historically made up the chemotherapy backbone for patients with localized HER2+ BC, though recent evidence suggests anthracyclines can be safely omitted. The single arm phase II APT trial established trastuzumab and paclitaxel as the standard adjuvant regimen for small HER2+ tumors. However, paclitaxel requires weekly treatment, causes alopecia, and has high rates of neuropathy and hypersensitivity reactions. In patients with metastatic HER2+ BC, the combination of trastuzumab and vinorelbine (TV) is effective and well tolerated. There is a need for alternative regimens for patients with HER2+ early-stage BC, especially for those with contraindications to anthracycline and taxane-based regimens. We conducted a retrospective study of patients with early stage HER2+ BC treated with adjuvant TV to evaluate a non-anthracycline/taxane-based, alopecia-sparing regimen. Methods: Clinicopathological characteristics, treatment details, and outcomes of patients with localized HER2+ BC treated with adjuvant TV for from 2007 to 2021 at a large academic medical institution were collected. Study endpoints included invasive disease-free survival (IDFS), overall survival (OS), and safety/tolerability. IDFS and OS were measured from start date of TV treatment to date of event or last follow-up, respectively. 5-year survival rates were generated in GraphPad Prism. Results: A total of 25 patients were treated with TV. All patients received trastuzumab at standard dosing and vinorelbine at a starting dose of 25 mg/m2 on days 1/8 of a 21-day cycle with 4 planned cycles. Median age at diagnosis was 61 years (range: 36-81). 88% of patients had anatomic pathologic Stage IA BC and 12% Stage IIA BC. Of the 25 patients, 24 of them opted to pursue TV due to concerns over alopecia, neuropathy, and other toxicities while 1 patient had received prior adriamycin and therefore opted for TV. With a median follow-up time of 68 months (5.7 years), the 5-year rate of survival from invasive disease was 90.9%, with 1 local and 1 distant recurrence. The 5-year overall survival was 100%. 76% of patients completed 4 cycles of TV without dose holds or delays and 92% completed 4 cycles without dose reductions. 2 patients required hospitalization during treatment with TV due to toxicity (diarrhea attributed to V, rigors/fever attributed to T). No patients experienced alopecia or long-term neuropathy. Conclusions: Trastuzumab in combination with vinorelbine in the adjuvant, early-stage setting for HER2+ BC is effective and well-tolerated and warrants further exploration as an alternative to taxane-based regimen.

Phase 2 study of response-guided neoadjuvant sacituzumab govitecan (IMMU-132) in patients with localized triple-negative breast cancer: Results from the NeoSTAR trial

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Background: Sacituzumab govitecan (SG), a novel antibody-drug conjugate in which the topoisomerase 1 inhibitor SN-38 (active metabolite of irinotecan) is linked to a humanized monoclonal antibody targeting the tumor antigen Trop2, is currently approved for treatment of patients (pts) with pre-treated metastatic triple negative breast cancer (TNBC). We conducted a phase 2 study evaluating neoadjuvant (NA) SG as upfront therapy for pts with localized TNBC (NCT04230109). The primary objective was to assess pathological complete response (pCR) rate in breast and lymph nodes (ypT0/isN0) with SG. Secondary objectives included assessment of radiological response rate, evaluation of the safety and tolerability (CTCAE v5.0) and event-free survival (EFS). Methods: Patients with localized TNBC (tumor size ≥1cm, or any size if node positive) with no prior treatment were eligible. SG was administered IV on Days 1, 8 of each 21-day cycle at a starting dose of 10 mg/kg for 4 cycles. After 4 cycles, patients with biopsy-proven residual disease, considered as no pCR for primary endpoint, had the option to receive additional NA therapy at the discretion of the treating physician. Radiologic response (US or MRI) was defined by RECIST version 1.1 using a composite response of CR & PR. Standard descriptive statistics were utilized, including 95% binomial confidence intervals for all rates estimated. Results: From 7/14/20 – 8/31/21, 50 pts were enrolled (median age = 48.5; 11 stage I disease, 24 stage II, 11 stage III, 4 unknown; 62% node negative). The majority (98%; n = 49) of pts completed 4 cycles of SG. Overall, the radiological response rate with SG alone was 62% (n = 31, 95% CI 48%, 77%). 26 pts proceeded directly to surgery after SG. Overall, the pCR rate with SG alone was 30% (n = 15/50, 95% CI 18%, 45%). The other 11 pts had RCB-1 (n = 3), RCB-2 (n = 5), and RCB-3 (n = 3) disease, respectively. Of the 24 pts who received additional NA therapy, 6 had a pCR (3 received anthracycline-based regimen, 2 carboplatin/taxane, and 1 docetaxel/cyclophosphamide). Among pts with a germline BRCA mutation (n = 8), 7 proceeded directly to surgery after SG and 6 had a pCR (86%, 95% CI 42%, 99%). The most common AEs with SG were nausea (82%, n = 41), fatigue (78%, n = 39), alopecia (76%, n = 38), neutropenia (58%, n = 29), anemia (36%, n = 18), and rash (48%, n = 24). 6% of pts required dose-reduction. No pts discontinued SG therapy due to disease progression or AEs; 1 discontinued due to minimal response per investigator preference. At the time of data cut-off (1/18/22), no pts experienced disease recurrence. Updated biomarker and EFS results will be presented at the meeting. Conclusions: In the first neoadjuvant trial in TNBC with an ADC, SG demonstrated single agent efficacy in localized TNBC. Further research on optimal duration of SG as well as NA combination strategies, including immunotherapy, are needed. Clinical trial information: NCT04230109.

Utilizing Natural Language Processing (NLP) to identify breast cancer associated-lung metastases from pathology reports to delineate characteristics and challenges of this common site of breast cancer recurrence

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Background: NLP (artificial intelligence) can automate the identification of records in large datasets. The purpose of this study was to evaluate the feasibility of NLP to identify breast cancer-associated lung metastases to understand clinical characteristics and challenges posed by this common site of breast cancer recurrence. Methods: Patients with pathologically confirmed breast cancer associated-lung metastases seen at a large academic center between 3/2012-5/2019 were identified using NLP of institutional pathology reports, with an IRB approved protocol. Chart review was performed to confirm breast cancer associated-lung metastases and determine clinical and pathological features. Results: Using NLP, 32 patients with pathology reports denoting breast cancer associated-lung metastases were identified, with pathologic confirmation of lung biopsy tissue in the majority of cases (24), and pleural fluid specimens (8) on the remainder. Ten of 32 (31%) were HR+/HER2-, 3/32 (9.3%) HER2+, and 19/32 (59%) TNBC. The majority were invasive ductal carcinoma (21/26) with the remainder invasive lobular carcinoma (2/26) or mixed histology (3/26). Median age at lung metastasis diagnosis was 62 years (range 31-88). The median time to development of lung metastasis following primary breast cancer was 5.6 years (range 0-24.8 years). Fifty six percent of lung metastases were detected on imaging and 44% by symptoms including dyspnea, cough, or pain. Tumor tissue genotyping results on the lung metastases were available for 8 patients showing PI3KCA (5), TP53 (3), SMARCA4 (2), ERBB2 (1), FGFR3 (1), ATM (1), CDK4 (1), MYC (1), and ESR1 (1). Treatment after diagnosis of lung metastases included hormone therapy (61%), chemotherapy (84%), lung irradiation (26%), and surgical resection of lung metastases (6%). Lung metastases were associated with considerable morbidity including pleural effusion (15%), dyspnea (6%), pneumothorax (3%), hemothorax (3%), and atelectasis (3%). Patients diagnosed with lung metastases had brain (32%), bone (35%), renal (6%), skin (3%) and adrenal (3%) metastases during disease course. Conclusions: NLP can help identify organ specific metastases from pathology reports, such as breast cancer associated-lung metastases, which can then facilitate observational, translational, and clinical research to characterize and address challenges posed by this common site of breast cancer recurrence. This cohort of patients highlights the morbidity of breast cancer associated-lung metastases and potential role of NLP for disease characterization and clinical research. (Support from ASCO Medical Student Rotation for Underrepresented Populations Award.)

An Initial Evaluation of Human Plasma cMLC-1: A Potential Protein Biomarker for Trastuzumab-Induced Cardiotoxicity, Breast Cancer Screening and Progression

Background

Trastuzumab is a targeted therapy for human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, trastuzumab-induced cardiotoxicity (TIC) has been reported when trastuzumab is administered to patients as a single agent or combined with anthracycline. Currently no means for detecting the early onset of TIC such as a protein biomarker is available. In this regard and based on promising results from a preliminary animal study, the potential of cardiac myosin light chain 1(cMLC-1) as a biomarker to predict TIC, screen patients for breast cancer and monitor tumor progression in breast cancer patients was evaluated.

Methods

Archived plasma samples collected before and after trastuzumab treatment at various fixed time points from 15 HER2⁺ patients with or without cardiotoxicity, recently collected plasma samples from 79 breast cancer patients (40 HER2⁺, 39 HER2^-), and 46 healthy donors were analyzed for cMLC-1 levels using an enzyme-linked immunosorbent assay (ELISA).

Results

An elevated plasma cMLC-1 level was found to be associated with TIC in 3 out of 7 (43%) trastuzumab-treated HER2⁺ breast cancer patients. However, this study provided an opportunity for us to study plasma cMCL-1 levels in breast cancer patients. It was demonstrated that elevated plasma cMCL-1 is associated with breast cancer. The cutoff cMLC-1 concentration is estimated to be 44.99 ng/mL with a sensitivity of 59.49% (95%CI: 48.47%-69.63%) and specificity of 71.74% (95%CI: 57.45% -82.68%). We also found a noticeable but not significantly more elevated plasma cMCL-1 level in HER2^- than in HER2⁺ breast cancer patients with the given sample sizes. As a result, improved sensitivity of 79.49% (95%CI: 64.47%-89.22%) with the specificity of 63.04% (95%CI:48.60%-75.48%) were obtained for cMLC-1 to predict HER2^- breast cancer with the cutoff at 37.17 ng/mL. Moreover, this study determined that cMLC-1 level was significantly higher in patients with metastatic breast cancer than in patients with non-metastatic breast cancer.

Conclusions

While the analysis of cMLC-1 levels in the plasma of a limited number of trastuzumab-treated HER2⁺ breast cancer patients failed to fully support its identification as a blood protein biomarker for predicting TIC, additional analyses of plasma cMLC-1 levels did significantly establish its correlations with breast cancer and disease progression. Our findings shed light on and filled, to some extent, the gap of knowledge of the potential of cMLC-1 as a blood protein biomarker for screening breast cancer and monitoring disease progression of breast cancer.

Local Therapy Outcomes and Toxicity From the ATEMPT Trial (TBCRC 033): A Phase II Randomized Trial of Adjuvant Trastuzumab Emtansine Versus Paclitaxel in Combination With Trastuzumab in Women With Stage I HER2-Positive Breast Cancer

PURPOSE

Human epidermal growth factor receptor 2 (HER2)-directed therapy improves local control among women with HER2-positive breast cancer. This retrospective analysis evaluates the safety and efficacy of radiation therapy (RT) among patients receiving adjuvant trastuzumab emtansine (T-DM1) or paclitaxel (T) plus trastuzumab (H) in the ATEMPT (Adjuvant Trastuzumab Emtansine Versus Paclitaxel in Combination With Trastuzumab) trial; Translational Breast Cancer Research Consortium (TBCRC) 033.

METHODS AND MATERIALS

Patients with stage I HER2-positive breast cancer were randomized 3:1 to receive adjuvant T-DM1 or TH after mastectomy or breast-conserving surgery (BCS). Breast RT was required after BCS and permitted after mastectomy. Patients receiving T-DM1 began RT after 12 weeks of therapy and received RT concurrently with T-DM1. Patients receiving TH began RT after paclitaxel, but concurrent with trastuzumab. RT records were retrospectively reviewed to determine details of radiation delivery and acute RT-related toxicity.

RESULTS

Protocol therapy was initiated by 497 patients. Among the 299 BCS patients, 289 received whole breast RT (WBRT) and 10 partial breast. Among WBRT patients, 40.2% in the T-DM1 arm and 41.5% of TH patients received hypofractionated (≥2.5 Gy/fraction) RT. Eight mastectomy patients received RT, all conventional fractionation. Skin toxicity (grade ≥2) was seen in 33.9% of patients in the T-DM1 arm and 23.2% in the TH arm (P = .11). In conventionally fractionated WBRT patients, 44.7% had a grade ≥2 skin toxicity compared with 17.9% of patients receiving hypofractionation (P < .001). Five patients experienced pneumonitis after RT (T-DM1: n = 4, 1.0%; TH: n = 1, 0.9%). Three-year invasive disease-free survival was 97.8% for T-DM1 (95% confidence interval, 96.3-99.3) and 93.4% for TH (95% confidence interval, 88.7-98.2). Among the 18 invasive disease-free survival events, 7 were isolated locoregional recurrences (2, T-DM1; 5, TH).

CONCLUSIONS

RT was well-tolerated when given concurrently with either T-DM1 or TH. Among BCS patients, hypofractionation resulted in lower grade ≥2 acute skin toxicity even with concurrent anti-HER2 therapy. Although follow-up was short, local recurrences were uncommon, attesting to the efficacy of HER2-directed therapy combined with RT.

Functional Mapping of AKT Signaling and Biomarkers of Response from the FAIRLANE Trial of Neoadjuvant Ipatasertib plus Paclitaxel for Triple-Negative Breast Cancer

PURPOSE

Despite extensive genomic and transcriptomic profiling, it remains unknown how signaling pathways are differentially activated and how tumors are differentially sensitized to certain perturbations. Here, we aim to characterize AKT signaling activity and its association with other genomic or IHC-based PI3K/AKT pathway biomarkers as well as the clinical activity of ipatasertib (AKT inhibitor) in the FAIRLANE trial.

EXPERIMENTAL DESIGN

In FAIRLANE, 151 patients with early triple-negative breast cancer (TNBC) were randomized 1:1 to receive paclitaxel with ipatasertib or placebo for 12 weeks prior to surgery. Adding ipatasertib did not increase pathologic complete response rate and numerically improved overall response rate by MRI. We used reverse-phase protein microarrays (RPPA) to examine the total level and/or phosphorylation states of over 100 proteins in various signaling or cell processes including PI3K/AKT and mTOR signaling. One hundred and twenty-five baseline and 127 on-treatment samples were evaluable by RPPA, with 110 paired samples at both time points.

RESULTS

Tumors with genomic/protein alterations in PIK3CA/AKT1/PTEN were associated with higher levels of AKT phosphorylation. In addition, phosphorylated AKT (pAKT) levels exhibited a significant association with enriched clinical benefit of ipatasertib, and identified patients who received benefit in the absence of PIK3CA/AKT1/PTEN alterations. Ipatasertib treatment led to a downregulation of AKT/mTORC1 signaling, which was more pronounced among the tumors with PIK3CA/AKT1/PTEN alterations or among the responders to the treatment.

CONCLUSIONS

We showed that the high baseline pAKT levels are associated with the alterations of PI3K/AKT pathway components and enriched benefit of ipatasertib in TNBC.

Abstract P2-14-17: A phase 1b study of PVX-410 vaccine in combination with pembrolizumab in metastatic triple negative breast cancer (mTNBC)

Background: Immunotherapy with checkpoint inhibition is active in mTNBC. Both pembrolizumab and atezolizumab are FDA approved for programmed cell death ligand 1 positive (PDL1+) mTNBC. Vaccines may further induce host immune response and enhance therapeutic activity of checkpoint inhibitors. PVX-410 (PVX) (OncoPep, Inc.) is a novel, HLA-A2 restricted, tetra-peptide vaccine, with 3 of its 4 antigens (XBP1[2 splice variants] and CD138) commonly overexpressed in TNBC. We present results from a phase 1b study evaluating the immune response, safety and tolerability, and clinical activity of PVX and pembrolizumab (PEM) in mTNBC. Methods: Eligibility for this phase 1b multi-center, single-arm study included HLA-A2+, PD-L1 unselected female patients (pts) ≥18 years with metastatic or inoperable locally advanced TNBC, measurable disease, and any number of prior therapies, including prior checkpoint inhibitor therapy. Pts received 6 doses of 800µg PVX emulsified in Montanide ISA 720 VG by subcutaneous injection co-administered with intramuscular Hiltonol weekly for 6 weeks (wks) followed by booster vaccine doses at wks 10 and 28, with concurrent intravenous 200 mg PEM every 3 wks starting with the second PVX dose. Therapy was given until progressive disease, unacceptable toxicity or a maximum of 24 months. Blood samples were scheduled for immune response assessment at baseline and at weeks 2, 5, 10, 28, and 52 post-treatment initiation. The primary objective was PVX- specific immune response at week 10. Immune response was defined as a ≥2-fold change over baseline in the proportion of CD3+CD8+ T cells that expressed IFNγ and the proportion of CD3+CD8+ T cells positive for PVX tetramers following an in vitro stimulation of PBMC with PVX peptides using a flow cytometric assay. Secondary objectives were immune response at wk 28, safety and tolerability, and clinical endpoints (RR, CBR, DCR, DoR, PFS, and OS). Results: Between 3/2018 and 8/2020, 19 pts enrolled. Median age was 62 yrs (range 46-79), with median 2 (range 0-9) lines of prior therapy for metastatic disease. Median disease-free interval among 16 pts with prior early TNBC was 3.3 years. Among 19 enrolled patients, 16 were available for analysis at the time of abstract submission. Among the 16, 10 pts were evaluable at week 10 and 7(70%) demonstrated a PVX specific immune response. There were 6 patients who progressed before week 10, of whom 3 (50%) had a positive immune response at the EOT visit. Immune response persisted in all evaluable pts assessed at week 28 (n=4). Immune response data for all evaluable patients will be updated at the presentation. Among 19 patients evaluable for safety analysis, the most common adverse events (AEs) attributable to PVX (grade ≥2) included: fatigue (21%), arthralgia (11%) injection site reaction (5 %) pain (5%) lymphocyte count decreased (5%), maculopapular rash (5%) and skin infection (5%) . There were two grade 3 AEs attributed to PEM (AST elevation, hyponatremia) and one grade 4 AE (ALT elevation). There were no grade 5 AEs. The clinical benefit rate (CR+PR+SD for ≥16 weeks) was 31.6% with no confirmed partial or complete responses. Best overall response was SD in 9 (47%) patients. Analysis of additional clinical endpoints including PFS and OS is ongoing and will be presented at the meeting. Conclusions: PVX plus PEM is safe with manageable toxicity in pts with mTNBC. No new unexpected adverse events were identified. Immune response data show PVX induces antigen-specific T cell expansion as observed by increases in PVX tetramer and IFN positive T cells. Clinical disease control was observed with a CBR of 31.6%. Based on these promising immune response results in this pretreated population, a phase 2 study with PVX+PEM in combination with standard chemotherapy in treatment naïve, PD-L1+ mTNBC is underway (NCT04634747).

Citation Format: Steven J Isakoff, Nadine M. Tung, Jun Yin, Nabihah Tayob, Joanne Parker, Julie Rosenberg, Aditya Bardia, Laura Spring, Hannah Park, Maya Collins, William T. Barry, Mariano Severgnini, Doris Peterkin, Sara M. Tolaney. A phase 1b study of PVX-410 vaccine in combination with pembrolizumab in metastatic triple negative breast cancer (mTNBC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-14-17.

Abstract P1-18-22: AKT inhibition in combination with endocrine therapy and a CDK4/6 inhibitor (CDK4/6i) in patients with hormone receptor positive (HR+)/HER2 negative metastatic breast cancer (MBC) and prior CDK4/6i exposure: A translational investigation

Background: The cyclin-dependent kinase 4/6 inhibitors, with endocrine therapy (ET), have become the standard of care for patients with HR+/HER2- MBC. Prior insight from tumor biopsies and preclinical analyses suggest that AKT1 activation can provoke CDK4/6i resistance, highlighting a potential therapeutic role for AKT inhibition (AKTi) in this setting. However, combinatorial inhibition can be associated with significant toxicity and identification of the optimal biological dose is often challenging. In this translational co-clinical study, we evaluated escalating doses of AKTi combination with CDK 4/6i in parallel patient-derived pre-clinical models as well as a phase 1b clinical trial. Methods: In an open-label phase Ib dose-escalation clinical trial (TAKTIC, NCT03959891), we evaluated the safety, tolerability and efficacy of escalating doses of the AKT1 inhibitor ipatasertib (ipat) in combination with palbociclib (palbo) and fulvestrant (fulv) for patients with HR+/HER2- MBC. Inclusion criteria include unresectable or metastatic disease, at least 1 prior therapy for MBC including any CDK4/6i, and up to 2 prior lines of chemotherapy for MBC (no limit on prior endocrine therapy). In addition, response to escalating doses of ipat and palbo (with fulv) were explored in vitro via an ATP-based viability assay in tumor cell lines derived from circulating tumor cells (CTC) isolated from patients with endocrine-refractory HR+ MBC. Results: In the dose-escalation portion of the phase 1b clinical trial, 23 patients received the triplet combination of ipat, palbo, and fulv (median number of prior lines = 4.3, range 1-7; 100% with prior CDK4/6i): 3 pts received ipat at 200mg + 125mg palbo, 15 pts received 300mg + 125mg palbo, and 5 pts received 400mg + 100mg palbo, all with fulv (500 mg). Among the 23 patients, 20 patients (86.9%) had disease control (4 partial response and 16 stable disease) as the best response, per RECIST. Grade 3/4 toxicities included neutropenia (n=20), lymphopenia (n=3), diarrhea (n=3), thrombocytopenia (n=2), transaminitis (n=2), and rash (n=2). Two DLTs were observed in the 300mg ipat + 125mg palbo cohort (grade 4 neutropenia ≥ 7 days), but none at 400mg + 100mg palbo. The combination of ipat and palbo demonstrated an additive effect in vitro, with increased sensitivity to lower doses of palbo in the presence of ipat. Based on the totality of data, 400mg ipat + 100mg palbo + fulv 500 mg was selected as the recommended phase II dose (RP2D) in the post-CDK4/6i setting. Conclusions: The triplet combination of endocrine therapy with AKTi and lower dose CDK4/6i appears to be well tolerated in heavily pre-treated pts, with preliminary evidence of clinical activity. Further study is needed to evaluate biomarkers associated with higher AKTi benefit in order to guide rational development of combination therapy for patients with HR+/HER2- MBC in the post-CDK4/6i setting. Overall, this translational study demonstrates how insight into the molecular mechanisms of CDK4/6i resistance and combinatorial modeling can be leveraged to develop actionable therapeutic regimens for patients with MBC.

Citation Format: Seth A. Wander, Douglas S. Micalizzi, Taronish Dubash, Dejan Juric, Laura M. Spring, Neelima Vidula, Jennifer Keenan, Maureen Beeler, Elene Viscosi, Dante Che, Elizabeth L. Fisher, Rachel A. Hepp, Beverly Moy, Steven J. Isakoff, Leif W. Ellisen, Jeffrey G. Supko, Shyamala Maheswaran, Daniel A. Haber, Aditya Bardia. AKT inhibition in combination with endocrine therapy and a CDK4/6 inhibitor (CDK4/6i) in patients with hormone receptor positive (HR+)/HER2 negative metastatic breast cancer (MBC) and prior CDK4/6i exposure: A translational investigation [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-18-22.

Abstract P4-12-08: Accuracy of Patient Self-Reported Breast Cancer Disease Characteristics Compared to the Medical Record in a Trial of the Outcomes4MeDigital Health App

Background: Patients’ understanding of their breast cancer (BC) diagnosis is important in improving treatment adherence, shared decision-making, and clinical trial matching. However, studies have reported discrepancies between electronic medical record (EMR) and patient reported information. Using data collected from a pilot study of the Outcomes4Me patient empowerment and clinical trial matching App, we analyzed concordance of patient reported disease characteristics compared to EMR data. Methods: Data was analyzed from a single institution pilot study (NCT04262518) evaluating the feasibility of introducing the Outcomes4Me app into routine BC care. Eligibility included BC patients with any subtype or stage of invasive cancer presenting with a new diagnosis or for follow-up on active therapy. We compared patient reported characteristics within a study specific survey and/or the Outcomes4Me app for stage (metastatic or not metastatic), recurrence history, hormone receptor status, HER2, and surgery history with the data recorded in the EMR. All statistics were descriptive. We conducted the same comparison between patient reported clinical characteristics among real world users of the Outcome4Me app and EMR records downloaded by that cohort of patients. Results: Between June 2020 and December 2020, 107 patients were enrolled. Baseline demographics: 90% White, 4% Black, 3% Asian; 37% with a college degree, and 43% with post college education; 66% hormone positive/HER2-, 20% HER2+, and 13% triple negative BC; 31% were stage 4. Concordance between the survey or App questionnaire and the EMR is shown in the Table. Comparing EMR and survey data, 62% of patients matched on both HER2 and HR status, and 94% of patients matched with the EMR on metastatic and recurrence status. When surgery and treatment information was included with these features, only 57% of patients matched across all these characteristics. Similar concordance was observed between the App questionnaire and EMR. Excluding the 21% of patients reporting “unsure” HER2 status improved the concordance to 85%. Overall concordance of recurrent or metastatic status was higher than for receptor status. Despite the discordance between EMR and patient-reported disease information, 97% of patients reported that they somewhat or strongly understood their cancer diagnosis. A similar pattern of concordance between the App questionnaire and EMR was observed among a real-world cohort of 636 patients using the Outcomes4Me App who provided medical record access. Conclusion: Self report of hormone receptor and HER2 status had limited concordance with the EMR, in contrast to a high degree of accuracy for self-report of metastatic disease. The limited accuracy of self-report suggests a need for improved patient education regarding their cancer characteristics and a need for caution when relying on self-report for clinical trials matching and targeted patient education. The use of a digital platform that integrates self-report with medical record access may help address these critical needs impacting patient empowerment and care.

Concordance Between App Questionnaire, Study Survey and EMR (% of patients)Disease Characteristic Matching CriteriaApp v. EMR (n=85)Survey v. EMR (n=107)App Real World Cohort (n=636)HER2 Status73%66%79%HR Status80%85%80%Combined Receptor Status67%62%73%Metastatic Status94%(n=79)97%(n=98)94%Surgery History83%(n=47)95%96%(n=310)Recurrent Status98%(n=48)97%(n=98)98%(n=411)Recurrent/Metastatic Status93%(n=42)94%(n=98)98%(n=411)Receptor/Recurrent Metastatic Status and Surgery History74%(n=33)57%(n=93)70%(n=201)

Citation Format: Steven J Isakoff, Eva Glieberman, Maya Said, Agnes H. Kwak, Emily A. O’Rourke, Amanda Stroiney, Laura Spring, Beverly Moy, Aditya Bardia, Nora Horick, Jeffrey Peppercorn. Accuracy of Patient Self-Reported Breast Cancer Disease Characteristics Compared to the Medical Record in a Trial of the Outcomes4MeDigital Health App [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-12-08.

Abstract PD5-11: Pilot study to assess prolonged nightly fasting in breast cancer survivors (LONGFAST)

Background: Prior, retrospective analysis of nightly fasting among women with breast cancer suggests that fasting less than 13 hours per night may be associated with higher risk of breast cancer recurrence. Small studies suggest that fasting duration can influence inflammation, obesity, sleep, and other potential mediators of breast cancer recurrence risk. Prolonged overnight fasting is a simple, nonpharmacological behavioral intervention strategy that may be doable for most patients. We designed this pilot study to prospectively evaluate the feasibility of prolonged overnight fasting among breast cancer survivors. Methods: We designed a single-arm, pilot study to evaluate the feasibility of fasting for 13 hours overnight for a 12-week period among women with a history of early stage breast cancer (I to III) who had completed initial cancer therapy at least 6 months prior. Baseline and end of study assessments included measurements of body mass index (BMI), quality of life (QOL) (Functional Assessment of Cancer Therapy - General (FACT-G)), mood (Hospital Anxiety and Depression Scale (HADS)), fatigue (Functional Assessment of Chronic Illness Therapy (FACIT) - Fatigue), levels of physical activity (Godin Leisure-Time Exercise Questionnaire), and blood biomarkers (expanded lipid profile, hemoglobin A1c, C-reactive protein, interleukin-6, tumor necrosis factor alpha, leptin, adiponectin). Patient-reported outcome (PRO) surveys were also administered at 6 weeks. Feasibility was defined as ≥ 60% of participants documenting fasting in the food diary for 13 hours on at least 70% of nights during the study period. Changes in study measures from baseline were evaluated using Wilcoxon signed-rank tests. Results: Between July 2020 and January 2021, we enrolled 40 women with a history of breast cancer. Participants had a median age of 59.9 (range 34.9-76.3) and median time since diagnosis was 4.5 years (range 0.8-20.7). At baseline, BMI was normal (18.5-24.9) in 40.0%, overweight (25-29.9) in 37.5%, and obese (≥30) in 22.5%. Forty-two and a half percent had Stage I cancer, 42.5% stage II, and 15.0% stage III. Sixty-five percent were on hormonal therapy. Ninety-five percent of participants fasted ≥ 13 hours for at least 70% of study days (95% CI 83%-99%). At 6 weeks, there was a statistically significant improvement in anxiety (p=.0007). No other significant changes were seen in PROs. At 12 weeks, there were statistically significant improvements in BMI (p=.0072), anxiety (p=.0141), depression (p=.0048), and fatigue (p=.0105). There was no association between change in BMI during the study and baseline BMI category, age, or endocrine therapy. There was no significant change in overall QOL, physical activity levels, or blood biomarkers at 12 weeks. Conclusions: Prolonged overnight fasting is feasible in the breast cancer population and may improve BMI, mood, and fatigue without a detrimental effect on overall QOL. The data from this study support the need for a larger, longer randomized study of prolonged overnight fasting in the breast cancer population to further evaluate the effects on body composition, mood, QOL, metabolic markers, and risk of recurrence.

Table 1.Impact of Prolonged Overnight Fasting among Breast Cancer SurvivorsStudy AssessmentMedian at baselineMedian at 12 weeksMedian within-participant changep-valueBody Mass Index (kg/m2)26.4225.80-0.380.0072HADS - Depression1.001.00-1.000.0048HADS - Anxiety4.504.00-0.500.0141FACIT - Fatigue47.5049.821.000.0105FACT-G - Quality of Life95.2096.840.910.4933Physical Activity Level40.5039.000.000.3340Hemoglobin A1c (mg/dL)5.455.400.000.2758High-density lipoprotein (mg/dL)72.0073.00-2.000.4688Low-density lipoprotein (mg/dL)92.0099.001.000.5626Total Cholesterol (mg/dL)193.00192.003.000.6569C-reactive protein (mg/L)1.500.90-0.100.1043Interleukin-6 (pg/mL)2.001.90-0.300.1213Tumor Necrosis Factor α (pg/mL)0.740.74-0.050.2898Adiponectin (ug/mL)12.0012.000.000.0682Leptin (ng/mL)7.158.30-0.100.8418

Citation Format: Elizabeth K. O'Donnell, Yael N. Shapiro, Amy Comander, Steven J. Isakoff, Beverly Moy, Laura Spring, Seth Wander, Irene Kuter, Jennifer Shin, Jerry Younger, Michelle Specht, Chryssanthi Kourniotis, Carol Sullivan, Loren Winters, Nora Horick, Jeffrey Peppercorn. Pilot study to assess prolonged nightly fasting in breast cancer survivors (LONGFAST) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD5-11.

Abstract P3-23-02: Immunogenicity of SARS-CoV-2 vaccines in patients with breast cancer receiving CDK 4/6 inhibitors

Background: CDK 4/6 inhibitors have transformed the landscape of breast oncology. A CDK 4/6 inhibitor in combination with endocrine therapy is recommended as 1st line therapy for patients with metastatic hormone receptor positive breast cancer. CDK 4/6 inhibitors have purported immunomodulatory effects and while effective, myelosuppression is a common adverse effect of CDK 4/6 inhibitor treatment of breast cancer. The impact of CDK 4/6 inhibitor therapy on immunogenicity of vaccines is not known. In this study, we evaluated the spike antibody response to SARS-CoV-2 vaccines among patients with breast cancer receiving endocrine therapy with or without CDK 4/6 inhibitors.Methods: In the Cancer COVID and Vaccine (CANVAX) study eligible patients included patients with breast cancer who had completed all scheduled doses of SARS-CoV-2 vaccines. Chart review was conducted to identify patients who had received endocrine therapy with or without CDK 4/6 inhibitor. We used validated assays to measure anti-SARS-CoV-2 total IgA/M/G spike antibodies and virus neutralization. We evaluated the magnitude of antibody response based on geometric mean concentrations (GMCs) as well as the % of patients with inadequate seroconversion (defined as levels &lt;100 U/ml). Independent T-test based on log-transformed antibody values was utilized to compare the spike antibody levels and p value of ≤ 0.05 was considered statistically significant.Results: Between April 2021 and June 2021, 203 patients with breast cancer were enrolled. As of the cut-off date (2nd July 2021), results were available for 73 patients treated with endocrine therapy alone (N = 23), or with CDK 4/6 inhibitor-based therapy (N = 50). Most were females (98.6%), white (83.6%), and had metastatic breast cancer (68.5%). 49.3% had received BNT162b2 (Pfizer), 37% mRNA1273 (Moderna), and 13.7% Ad26.COV2.S (Johnson and Johnson/Janssen) vaccines. Overall, the mean spike antibody levels were similar between patients treated with endocrine therapy alone vs CDK 4/6 inhibitor-based therapy (GMC: 326 vs. 719 U/mL; p=0.704). Mean spike antibody levels were higher in patients with early breast cancer vs. metastatic breast cancer (GMC: 555 vs. 465 U/mL; p=0.031). However, patients who received Ad26.COV2.S had lower levels of mean spike antibody levels (GMC 47 U/ml), compared with patients treated with BNT162b2 (GMC 400 U/ml) or mRNA1273 (GMC 2203 U/mL; P&lt;0.01 for both comparisons). Comparison of neutralization titers in 66 individuals supported the above results. 11 (15.1%) patients had low antibody titers (&lt;100U/ml) of seroconversion and 3 received a booster vaccine, with 1 having available repeat titer results thus far demonstrating a significant improvement.Conclusions: The majority of patients receiving CDK 4/6 inhibitor have adequate antibody response to SARS-CoV-2 vaccines, particularly mRNA vaccines. However, a minority of patients may require booster vaccine to augment immunity. Monitoring spike antibody levels could be helpful to identify patients with inadequate seroconversion and guide mitigation strategies for patients with breast cancer.

Citation Format: Elyssa Denault, Erika Nakajima, Vivek Naranbhai, Alejandro Balazs, Lindsey Mortensen, Elizabeth Niehoff, Caroline Barabell, Jennifer A. Hutchinson, Seth A. Wander, Aron S. Rosenstock, Leif W. Ellisen, Beverly Moy, Steven J. Isakoff, Justin F. Gainor, A. John Iafrate, Aditya Bardia, Laura M. Spring. Immunogenicity of SARS-CoV-2 vaccines in patients with breast cancer receiving CDK 4/6 inhibitors [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-23-02.

Abstract P1-14-02: Phase II study of adjuvant endocrine therapy with CDK 4/6 inhibitor, ribociclib, for localized ER+/HER2- breast cancer (LEADER, part 1)

Background: CDK 4/6 inhibitors have demonstrated substantial efficacy in treating ER+/HER2- metastatic breast cancer. Therefore, there is great interest in exploring their ability to reduce recurrence risk in early breast cancer. However, conflicting results were observed in the large adjuvant phase 3 clinical trials investigating combination of endocrine therapy and CDK 4/6 inhibitor (PALLAS, MONARCH-E). While these adjuvant clinical trials evaluated upfront use of CDK 4/6 inhibitor, the optimal timing of adding CDK 4/6 inhibitor for HR+/HER2- breast cancer remains unknown. We conducted a prospective phase II clinical trial to evaluate the addition of a CDK 4/6 inhibitor, ribociclib, in patients who were already on adjuvant endocrine therapy. Methods: In part 1 of the clinical trial, eligibility included patients with localized stage I-III ER+ (≥ 10%), HER2- breast cancer; completed surgery; and were on adjuvant endocrine therapy (any number of years) with at least one year or more of treatment remaining. Patients were randomized to two different ribociclib schedules: continuous (400 mg daily of 28-day cycle; arm 1) or intermittent (600 mg daily on days 1-21 of 28-day cycle; arm 2) for one year. Patients were concurrently treated with an aromatase inhibitor (plus GnRH agonist if premenopausal). Tolerance was evaluated via CTCAE version 4.03 and proportion of subjects who discontinued CDK 4/6 treatment early. Stratification factors for statistical analysis included: disease stage (III vs lower), duration of prior endocrine therapy (within 2 years; 2-5 years vs &gt; 5 years), and whether the patient received prior chemotherapy or not. Baseline characteristics and risk factors for recurrence and for early discontinuation were compared between the arms of the study using Pearson's chi-squared test. Actuarial analysis of time to recurrence was done using the Kaplan-Meier estimator. The primary objective of part 1 was to estimate adherence to ribociclib treatment in the adjuvant setting. Results: In total, 81 patients were enrolled between February 2018 and September 2019, and 25 (31%) discontinued ribociclib treatment early, with no significant difference between study arms. The most common grade 3 or greater adverse events (AEs) leading to study discontinuation were neutropenia (44%), alanine aminotransferase increase (28%), and aspartate aminotransferase increase (16%). Among patients who discontinued early, neutropenia was more frequent in the 600 mg arm, 9 of 12 patients (75%), versus 2 of 13 patients (15%) in the 400 mg arm. No patients discontinued early due to prolonged QTc. Ribociclib was dose reduced for 22 patients (27%), with no significant difference between study arms (p = 0.12). After a median follow-up of 20 months, two patients have experienced disease recurrence with recurrence-free survival of 100% at 1 year and 97% (95% CI 88-99%) at 2 years. Biomarker (ctDNA) results will be reported at the meeting. Conclusions: Results demonstrate that while serious AEs with one year of adjuvant ribociclib are low, a substantial number of patients discontinued adjuvant CDK 4/6 inhibitor within 1 year. Overall, with limited follow-up, only two patients had recurrent disease since completion of ribociclib treatment. Tolerability and identifying patient subsets who will most benefit need to be carefully considered with CDK 4/6 inhibitors in the adjuvant setting.

Citation Format: Laura M Spring, Lauren Scarpetti, Andrzej Niemierko, Steven J Isakoff, Beverly Moy, Seth A Wander, Elisabeth Smith, Elizabeth Abraham, Jennifer Shin, Jaymin M Patel, Amy Comander, Therese Mulvey, Aditya Bardia. Phase II study of adjuvant endocrine therapy with CDK 4/6 inhibitor, ribociclib, for localized ER+/HER2- breast cancer (LEADER, part 1) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-14-02.

Immunogenicity and Reactogenicity of SARS-CoV-2 Vaccines in Patients With Cancer: The CANVAX Cohort Study

PURPOSE

The immunogenicity and reactogenicity of SARS-CoV-2 vaccines in patients with cancer are poorly understood.

METHODS

We performed a prospective cohort study of adults with solid-organ or hematologic cancers to evaluate anti-SARS-CoV-2 immunoglobulin A/M/G spike antibodies, neutralization, and reactogenicity ≥ 7 days following two doses of mRNA-1273, BNT162b2, or one dose of Ad26.COV2.S. We analyzed responses by multivariate regression and included data from 1,638 healthy controls, previously reported, for comparison.

RESULTS

Between April and July 2021, we enrolled 1,001 patients; 762 were eligible for analysis (656 had neutralization measured). mRNA-1273 was the most immunogenic (log10 geometric mean concentration [GMC] 2.9, log10 geometric mean neutralization titer [GMT] 2.3), followed by BNT162b2 (GMC 2.4; GMT 1.9) and Ad26.COV2.S (GMC 1.5; GMT 1.4; P < .001). The proportion of low neutralization (< 20% of convalescent titers) among Ad26.COV2.S recipients was 69.9%. Prior COVID-19 infection (in 7.1% of the cohort) was associated with higher responses (P < .001). Antibody titers and neutralization were quantitatively lower in patients with cancer than in comparable healthy controls, regardless of vaccine type (P < .001). Receipt of chemotherapy in the prior year or current steroids were associated with lower antibody levels and immune checkpoint blockade with higher neutralization. Systemic reactogenicity varied by vaccine and correlated with immune responses (P = .002 for concentration, P = .016 for neutralization). In 32 patients who received an additional vaccine dose, side effects were similar to prior doses, and 30 of 32 demonstrated increased antibody titers (GMC 1.05 before additional dose, 3.17 after dose).

CONCLUSION

Immune responses to SARS-CoV-2 vaccines are modestly impaired in patients with cancer. These data suggest utility of antibody testing to identify patients for whom additional vaccine doses may be effective and appropriate, although larger prospective studies are needed.

Ipatasertib plus paclitaxel for PIK3CA/AKT1/PTEN-altered hormone receptor-positive HER2-negative advanced breast cancer: primary results from cohort B of the IPATunity130 randomized phase 3 trial

PURPOSE

PI3K/AKT pathway alterations are frequent in hormone receptor-positive (HR+) breast cancers. IPATunity130 Cohort B investigated ipatasertib-paclitaxel in PI3K pathway-mutant HR+ unresectable locally advanced/metastatic breast cancer (aBC).

METHODS

Cohort B of the randomized, double-blind, placebo-controlled, phase 3 IPATunity130 trial enrolled patients with HR+ HER2-negative PIK3CA/AKT1/PTEN-altered measurable aBC who were considered inappropriate for endocrine-based therapy (demonstrated insensitivity to endocrine therapy or visceral crisis) and were candidates for taxane monotherapy. Patients with prior chemotherapy for aBC or relapse < 1 year since (neo)adjuvant chemotherapy were ineligible. Patients were randomized 2:1 to ipatasertib (400 mg, days 1-21) or placebo, plus paclitaxel (80 mg/m², days 1, 8, 15), every 28 days until disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed progression-free survival (PFS).

RESULTS

Overall, 146 patients were randomized to ipatasertib-paclitaxel and 76 to placebo-paclitaxel. In both arms, median investigator-assessed PFS was 9.3 months (hazard ratio, 1.00, 95% CI 0.71-1.40) and the objective response rate was 47%. Median paclitaxel duration was 6.9 versus 8.8 months in the ipatasertib-paclitaxel versus placebo-paclitaxel arms, respectively; median ipatasertib/placebo duration was 8.0 versus 9.1 months, respectively. The most common grade ≥ 3 adverse events were diarrhea (12% with ipatasertib-paclitaxel vs 1% with placebo-paclitaxel), neutrophil count decreased (9% vs 7%), neutropenia (8% vs 9%), peripheral neuropathy (7% vs 3%), peripheral sensory neuropathy (3% vs 5%) and hypertension (1% vs 5%).

CONCLUSION

Adding ipatasertib to paclitaxel did not improve efficacy in PIK3CA/AKT1/PTEN-altered HR+ HER2-negative aBC. The ipatasertib-paclitaxel safety profile was consistent with each agent's known adverse effects. Trial registration NCT03337724.

Phase II trial of veliparib and temozolomide in metastatic breast cancer patients with and without BRCA1/2 mutations

PURPOSE

We evaluated the efficacy and safety of poly-(adenosine diphosphate-ribose) polymerase (PARP) 1 and 2 inhibitor veliparib and temozolomide in metastatic breast cancer patients with and without germline BRCA1/2 mutations.

METHODS

In this single-arm phase II trial, patients with metastatic breast cancer received veliparib 30 to 40 mg twice daily on days 1 to 7 with concurrent temozolomide 150 mg/m² on days 1 to 5 of a 28-day cycle. The primary cohort was unselected for BRCA mutation status, and an expansion cohort enrolled only BRCA1/2 carriers. The primary endpoint was objective response rate (ORR) in each cohort. Secondary endpoints included progression-free survival (PFS), clinical benefit rate (CBR), and evaluation of safety and tolerability.

RESULTS

In the primary cohort of 41 unselected patients, which included 9 BRCA mutation carriers, the ORR was 10% and clinical benefit rate at 4 months (CBR) was 27%. In the expansion cohort of 21 BRCA1/2 carriers, the ORR was 14% and CBR was 43%. Among all 30 BRCA1/2 carriers, the ORR was 23% versus 0% among non-carriers. In the subset of BRCA1/2 carriers, the ORR was 32% among platinum-naïve patients versus 9% among platinum-exposed patients. The median PFS was 3.3 months among BRCA1/2 carriers compared to 1.8 months among non-carriers (HR: 0.48, p = 0.006). A longer median PFS of 6.2 months was observed among BRCA1/2 carriers who had no prior platinum therapy. The most common grade 3 and 4 toxicities were thrombocytopenia (32%) and neutropenia (21%) that generally improved with dose modifications.

CONCLUSION

Veliparib and temozolomide demonstrated clinical activity in platinum-naïve BRCA-associated metastatic breast cancer with manageable toxicity at doses of veliparib well below the single-agent active dose. Although the study did not meet its primary endpoint in unselected nor BRCA-associated breast cancer, this regimen was further evaluated in the BROCADE 2 study.

TRIAL REGISTRATION

NCT01009788 (ClinicalTrials.gov), November 9, 2009.

Parallel Genomic Alterations of Antigen and Payload Targets Mediate Polyclonal Acquired Clinical Resistance to Sacituzumab Govitecan in Triple-Negative Breast Cancer

Sacituzumab govitecan (SG), the first antibody-drug conjugate (ADC) approved for triple-negative breast cancer, incorporates the anti-TROP2 antibody hRS7 conjugated to a topoisomerase-1 (TOP1) inhibitor payload. We sought to identify mechanisms of SG resistance through RNA and whole-exome sequencing of pretreatment and postprogression specimens. One patient exhibiting de novo progression lacked TROP2 expression, in contrast to robust TROP2 expression and focal genomic amplification of TACSTD2/TROP2 observed in a patient with a deep, prolonged response to SG. Analysis of acquired genomic resistance in this case revealed one phylogenetic branch harboring a canonical TOP1 ^E418K resistance mutation and subsequent frameshift TOP1 mutation, whereas a distinct branch exhibited a novel TACSTD2/TROP2 ^T256R missense mutation. Reconstitution experiments demonstrated that TROP2^T256R confers SG resistance via defective plasma membrane localization and reduced cell-surface binding by hRS7. These findings highlight parallel genomic alterations in both antibody and payload targets associated with resistance to SG. SIGNIFICANCE: These findings underscore TROP2 as a response determinant and reveal acquired SG resistance mechanisms involving the direct antibody and drug payload targets in distinct metastatic subclones of an individual patient. This study highlights the specificity of SG and illustrates how such mechanisms will inform therapeutic strategies to overcome ADC resistance.This article is highlighted in the In This Issue feature, p. 2355.

Phase 1b clinical trial of ado-trastuzumab emtansine and ribociclib for HER2-positive metastatic breast cancer

Patients with HER2+ metastatic breast cancer are often treated with a multitude of therapies in the metastatic setting, and additional strategies to prolong responses to anti-HER2 therapies are needed. Preclinical evidence suggests synergy between cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitors and anti-HER2 therapies. We conducted a phase 1b study of ribociclib and ado-trastuzumab emtansine (T-DM1) in patients with advanced/metastatic HER2-positive breast cancer previously treated with trastuzumab and a taxane in any setting, with four or fewer prior lines of therapy in the metastatic setting. A standard 3 + 3 dose-escalation design was used to evaluate various doses of ribociclib in combination with T-DM1, starting at 300 mg. The primary objective was to determine the maximum tolerated dose and/or recommended phase 2 dose (RP2D) of ribociclib in combination with T-DM1. A total of 12 patients were enrolled. During dose-escalation, patients received doses of ribociclib of 300 mg (n = 3), 400 mg (n = 3), 500 mg (n = 3), and 600 mg (n = 3). No dose-limiting toxicities were observed. The majority of toxicities were Grade 1 and 2, and the most common Grade 3 toxicities were neutropenia (33%), leukopenia (33%), and anemia (25%). After a median follow-up of 12.4 months, the median PFS was 10.4 months (95% confidence interval, 2.7-19.3). Based on the pharmacokinetic analysis, adverse events, and dose reductions, 400 mg was determined to be the RP2D for ribociclib given on days 8-21 of a 21-day cycle with T-DM1.

A phase II study of efficacy, toxicity, and the potential impact of genomic alterations on response to eribulin mesylate in combination with trastuzumab and pertuzumab in women with human epidermal growth factor receptor 2 (HER2)+ metastatic breast cancer

PURPOSE

There are limited data on trastuzumab-pertuzumab (HP)-based treatments beyond the first-line, HER2+ metastatic breast cancer (MBC) setting. We conducted a phase II study of eribulin mesylate, which extends survival in MBC, with HP in patients with previously treated HER2+ MBC to evaluate efficacy, toxicity, and genomic alterations driving therapeutic response.

METHODS

After a run-in phase for eribulin dosing, two cohorts were enrolled (Cohort A-no prior pertuzumab; Cohort B-prior pertuzumab). All patients received eribulin 1.4 mg/m² on days 1, 8 with standard-dose HP on day 1 (21-day cycles). The primary endpoint was objective response rate (ORR). Genomic characterization via whole exome sequencing (WES) was completed on tumor DNA and matched germline DNA from 19 patients.

RESULTS

The six-patient run-in established a dose of eribulin 1.4 mg/m² with HP. Cohorts A and B enrolled 17 and 7 patients, respectively. Accrual stopped early due to an evolving treatment landscape and slow enrollment. The ORR was 26.3% (95% Confidence Interval [CI] 9.2-51.2%) in Cohort A and 0% in Cohort B (95% CI 0-41.0%). WES revealed more frequent alterations in TP53 (p < 0.05, q > 0.05) in patients without clinical benefit (disease control for < 24 weeks) which was not significant after multiple hypothesis correction.

CONCLUSION

Eribulin-HP had manageable toxicity and modest clinical activity in patients without prior pertuzumab exposure. This study provides a preliminary landscape of somatic alterations in this patient cohort. Our data add to the literature on how genomic alterations may predict for therapy response/resistance, as we work to individualize choices in a quickly evolving HER2+ MBC treatment landscape.

TRIAL REGISTRATION

www.clinicaltrials.gov , NCT01912963. Registered 24 July 2013.

Final results of the double-blind placebo-controlled randomized phase 2 LOTUS trial of first-line ipatasertib plus paclitaxel for inoperable locally advanced/metastatic triple-negative breast cancer

PURPOSE

In LOTUS (NCT02162719), adding the oral AKT inhibitor ipatasertib to first-line paclitaxel for locally advanced/metastatic triple-negative breast cancer (aTNBC) improved progression-free survival (PFS; primary endpoint), with an enhanced effect in patients with PIK3CA/AKT1/PTEN-altered tumors (FoundationOne next-generation sequencing [NGS] assay). We report final overall survival (OS) results.

METHODS

Eligible patients had measurable previously untreated aTNBC. Patients were stratified by prior (neo)adjuvant therapy, chemotherapy-free interval, and tumor immunohistochemistry PTEN status, and were randomized 1:1 to paclitaxel 80 mg/m² (days 1, 8, 15) plus ipatasertib 400 mg or placebo (days 1-21) every 28 days until disease progression or unacceptable toxicity. OS (intent-to-treat [ITT], immunohistochemistry PTEN-low, and PI3K/AKT pathway-activated [NGS PIK3CA/AKT1/PTEN-altered] populations) was a secondary endpoint.

RESULTS

Median follow-up was 19.0 versus 16.0 months in the ipatasertib-paclitaxel versus placebo-paclitaxel arms, respectively. In the ITT population (n = 124), median OS was numerically longer with ipatasertib-paclitaxel than placebo-paclitaxel (hazard ratio 0.80, 95% CI 0.50-1.28; median 25.8 vs 16.9 months, respectively; 1-year OS 83% vs 68%). Likewise, median OS favored ipatasertib-paclitaxel in the PTEN-low (n = 48; 23.1 vs 15.8 months; hazard ratio 0.83) and PIK3CA/AKT1/PTEN-altered (n = 42; 25.8 vs 22.1 months; hazard ratio 1.13) subgroups. The ipatasertib-paclitaxel safety profile was unchanged.

CONCLUSIONS

Final OS results show a numerical trend favoring ipatasertib-paclitaxel and median OS exceeding 2 years with ipatasertib-paclitaxel. Overall, results are consistent with the reported PFS benefit; interpretation within biomarker-defined subgroups is complicated by small sample sizes and TNBC heterogeneity.

RASAL2 Confers Collateral MEK/EGFR Dependency in Chemoresistant Triple-Negative Breast Cancer

PURPOSE

While chemotherapy remains the standard treatment for triple-negative breast cancer (TNBC), identifying and managing chemoresistant tumors has proven elusive. We sought to discover hallmarks and therapeutically actionable features of refractory TNBC through molecular analysis of primary chemoresistant TNBC specimens.

EXPERIMENTAL DESIGN

We performed transcriptional profiling of tumors from a phase II clinical trial of platinum chemotherapy for advanced TNBC (TBCRC-009), revealing a gene expression signature that identified de novo chemorefractory tumors. We then employed pharmacogenomic data mining, proteomic and other molecular studies to define the therapeutic vulnerabilities of these tumors.

RESULTS

We reveal the RAS-GTPase-activating protein (RAS-GAP) RASAL2 as an upregulated factor that mediates chemotherapy resistance but also an exquisite collateral sensitivity to combination MAP kinase kinase (MEK1/2) and EGFR inhibitors in TNBC. Mechanistically, RASAL2 GAP activity is required to confer kinase inhibitor sensitivity, as RASAL2-high TNBCs sustain basal RAS activity through suppression of negative feedback regulators SPRY1/2, together with EGFR upregulation. Consequently, RASAL2 expression results in failed feedback compensation upon co-inhibition of MEK1/2 and EGFR that induces synergistic apoptosis in vitro and in vivo. In patients with TNBC, high RASAL2 levels predict clinical chemotherapy response and long-term outcomes, and are associated via direct transcriptional regulation with activated oncogenic Yes-Associated Protein (YAP). Accordingly, chemorefractory patient-derived TNBC models exhibit YAP activation, high RASAL2 expression, and tumor regression in response to MEK/EGFR inhibitor combinations despite well-tolerated intermittent dosing.

CONCLUSIONS

These findings identify RASAL2 as a mediator of TNBC chemoresistance that rewires MAPK feedback and cross-talk to confer profound collateral sensitivity to combination MEK1/2 and EGFR inhibitors.

Chemotherapy-related amenorrhea (CRA) after adjuvant ado-trastuzumab emtansine (T-DM1) compared to paclitaxel in combination with trastuzumab (TH) (TBCRC033: ATEMPT Trial)

PURPOSE

Chemotherapy-related amenorrhea (CRA) is a surrogate for ovarian toxicity and associated risk of infertility and premature menopause. Here, we compare CRA rate with paclitaxel (T)-trastuzumab (H) to that with ado-trastuzumab emtansine (T-DM1).

METHODS

Patients with T1N0 HER2 + early-stage breast cancer (eBC) enrolled on the ATEMPT trial and were randomized 3:1 to T-DM1 3.6 mg/kg IV every (q) 3 weeks (w) × 17 vs. T 80 mg/m² with H IV qw × 12 (4 mg/kg load → 2 mg/kg), followed by H (6 mg/kg IV q3w × 13). Enrollees who self-reported as premenopausal were asked to complete menstrual surveys at baseline and every 6-12 months for 60 months. 18-month CRA (no periods reported during prior 6 months on 18-month survey) was the primary endpoint of this analysis.

RESULTS

Of 512 ATEMPT enrollees, 123 who began protocol therapy and answered baseline and at least one follow-up menstrual survey were premenopausal at enrollment. 76 had menstrual data available at 18 months without having received a gonadotropin-releasing hormone agonist or undergone hysterectomy and/or oophorectomy. Median age was 45 (range 23-53) among 18 who had received TH and 46 (range 34-54) among 58 who had received T-DM1. The 18-month rate of CRA was 50% after TH and 24% after T-DM1 (p = 0.045).

CONCLUSION

Amenorrhea at 18 months was less likely in recipients of adjuvant T-DM1 than TH. Future studies are needed to understand how T-DM1 impacts risk of infertility and permanent menopause, and to assess amenorrhea rates when T-DM1 is administered after standard HER2-directed chemotherapy regimens.

Adjuvant Trastuzumab Emtansine Versus Paclitaxel in Combination With Trastuzumab for Stage I HER2-Positive Breast Cancer (ATEMPT): A Randomized Clinical Trial

PURPOSE

The ATEMPT trial was designed to determine if treatment with trastuzumab emtansine (T-DM1) caused less toxicity than paclitaxel plus trastuzumab (TH) and yielded clinically acceptable invasive disease-free survival (iDFS) among patients with stage I human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC).

METHODS

Patients with stage I centrally confirmed HER2+ BC were randomly assigned 3:1 to T-DM1 or TH and received T-DM1 3.6 mg/kg IV every 3 weeks for 17 cycles or T 80 mg/m² IV with H once every week × 12 weeks (4 mg/kg load →2 mg/kg), followed by H × 39 weeks (6 mg/kg once every 3 weeks). The co-primary objectives were to compare the incidence of clinically relevant toxicities (CRTs) in patients treated with T-DM1 versus TH and to evaluate iDFS in patients receiving T-DM1.

RESULTS

The analysis population includes all 497 patients who initiated protocol therapy (383 T-DM1 and 114 TH). CRTs were experienced by 46% of patients on T-DM1 and 47% of patients on TH (P = .83). The 3-year iDFS for T-DM1 was 97.8% (95% CI, 96.3 to 99.3), which rejected the null hypothesis (P < .0001). Serially collected patient-reported outcomes indicated that patients treated with T-DM1 had less neuropathy and alopecia and better work productivity compared with patients on TH.

CONCLUSION

Among patients with stage I HER2+ BC, one year of adjuvant T-DM1 was associated with excellent 3-year iDFS, but was not associated with fewer CRT compared with TH.

Feasibility of integrating the Outcomes4Me smartphone navigation application into the care of breast cancer patients (FIONA)

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Background: Patients diagnosed with breast cancer (BC) face complex decisions about their care and many studies have shown that improved patient engagement results in increased satisfaction and better outcomes. Patient engagement includes education, treatment option selection, symptom tracking and reporting, and clinical trial opportunities. We conducted a pilot study to determine the feasibility of introducing the Outcomes4Me patient engagement app into the standard of care experience of BC patients. Methods: This was a pilot study (NCT04262518) conducted at an academic medical center. Eligible patients had any subtype of stage 1-4 BC and were on any type of chemo-, hormonal-, targeted-, or radiation-therapy for BC during the study period. Participants downloaded the app on their smartphone and their app usage was evaluated. Surveys were administered at baseline and end of study. Clinicians caring for patients using the app were surveyed at the end of the study. The primary endpoint was feasibility, defined as at least 40% of patients engaging with the app at least 3 times over the 12-week study period. Additional endpoints included usability, satisfaction, correlation of patient reported data with the EHR, clinical trial matching, and patient experience. Results: Between June 2020 and December 2020, 107 patients enrolled; results are reported for 90 patients with complete data as of 1/24/21. Baseline demographics: median age 53 (range: 27-77); 90% White, 4% Black, 3% Asian; 66% had hormone positive/HER2-, 20% HER2+, and 13% triple negative BC; 31% had stage 4 disease. At study entry, 93% had never used an app to help with their disease or treatment options. Over the 12 week study period, 58% of patients engaged with the app at least 3 times, meeting the primary feasibility endpoint. Patients engaged with the app on average 5.5 days (range: 0-40) with 20% engaging on more than 10 days during the study. The mean System Usability Score was 71 (median = 76) and was similar across age groups. The 5 app features deemed most (‘somewhat’ or ‘very’) helpful were: background about their BC (76%), information about treatment options (74%), newsfeed about their BC (70%), symptom tracking (65%), and clinical trial information (65%). 53% said that the app helped them keep track of symptoms and 33% said they are more likely to explore or enroll in a clinical trial after using the app. Conclusions: Integration of the Outcomes4Me app into the care management of BC patients is feasible with acceptable usability. Our results suggest that use of a patient smartphone app may be helpful for many aspects of patient education and engagement for patients with BC. The results also suggest that this type of intervention can help patients better track their symptoms and make them aware of clinical trials, potentially facilitating the management of side effects and accelerating clinical trials recruitment. Clinical trial information: NCT04262518.

Phase II Single-Arm Study to Assess Trastuzumab and Vinorelbine in Advanced Breast Cancer Patients With HER2-Negative Tumors and HER2-Positive Circulating Tumor Cells

PURPOSE

Human epidermal growth factor receptor 2 (HER2)-directed treatments improve outcomes for patients with HER2-positive metastatic breast cancer (MBC). Current identification of patients with HER2-positive disease relies on tumor tissue testing, which can be inaccurate because of tumor heterogeneity or tumor evolution. Circulating tumor cells (CTCs) are often present in patients with cancer. We hypothesized that HER2 assessment of CTCs in patients with HER2-negative breast cancer could identify a subset of patients with HER2-positive CTCs who could benefit from HER2-directed treatments.

METHODS

This was a single-arm, two-stage, phase II trial. Patients with HER2-negative progressive MBC with HER2-positive CTC (defined as HER2/CEP17 ratio ≥ 2.0 by fluorescence in situ hybridization), ≥ 1 prior chemotherapy regimen for MBC, and no prior vinorelbine received trastuzumab in combination with vinorelbine on days 1, 8, and 15 of a 21-day cycle. The primary end point was objective response rate.

RESULTS

From January 2013 to June 2014, we prospectively screened CTCs from patients with HER2-negative MBC. CTCs were detected in 201 of 311 patients (65%). The median number of CTCs was 10 (interquartile range, 3-57). Sixty-nine of 311 patients (22%) had HER2+ CTCs, with a median of three HER2+ CTCs (range 1-21). Twenty patients with HER2+ CTCs were treated on study. At data cutoff (January 13, 2017), no patients remained on study therapy. The objective response rate was 5% (95% CI, 0.1 to 24.9), with one of 20 patients experiencing a partial response. The clinical benefit rate was 20.0% (1 partial response and 3 stable diseases > 24 weeks, 95% CI, 5.7% to 43.7%). The median progression-free survival was 2.7 months.

CONCLUSION

CTC analysis of patients with HER2-negative MBC identifies a subset with HER2-amplified CTCs. However, clinical activity of an HER2-directed regimen in this population was low. The functional significance of HER2-positive CTCs remains uncertain.

Scalp cooling to reduce alopecia as a barrier to chemotherapy

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Background: Chemotherapy induced alopecia (CIA) is one of the most distressing adverse events reported by patients undergoing chemotherapy, yet there is limited data addressing the impact of CIA on treatment acceptance. Scalp cooling (SC) has been shown to decrease CIA. Here we report our assessment of CIA as a barrier to chemotherapy and the efficacy of SC using pre- and post-treatment surveys of patient reported outcomes. Methods: Patients who received alopecia-inducing chemotherapy and utilized SC between November 2018 and September 2020 at our institution were enrolled in a prospective IRB approved registry. Surveys including the Chemotherapy Induced Alopecia Distress Scale (CADS) were administered before and within two weeks after treatment. Using the CADS survey, patients were asked about their hesitation to receive chemotherapy and the burden they feel about alopecia as a side effect of chemotherapy. Results: Of 90 patients who completed the first or last treatment survey, the most common treatment regimens were docetaxel/cyclophosphamide (TC), docetaxel/carboplatin/trastuzumab/ pertuzumab (TCHP), and paclitaxel/trastuzumab (TH). The most common disease type was breast cancer (92.2%) and all participants were females. Of 74 SC patients who completed the pre-treatment survey, the median age was 50.5 (range 26-75) and included 65 (87.8%) Caucasian, 4 (5.4%) Black, and 3 (4.0%) Asian patients. 89.2% used Paxman SC and 10.8% used Penguin SC. Of those who completed the CADS survey prior to treatment, 8 (10.8%) reported ‘quite a bit’ to ‘very high’ hesitation, and 34 (46.0%) reported feeling that alopecia was either ‘quite’ or ‘very much’ a burden of chemotherapy. All 40 SC patients (median age 53.5, range 31-76) who completed the post-treatment survey were Caucasian and used Paxman SC. Self-reported efficacy of SC in these 40 patients was less than 10% hair loss in 10 (25.0%), 11-25% hair loss in 7 (17.5%), 26-50% hair loss in10 (25.0%), 51-75% hair loss in 9 (22.5%), and 76-100% hair loss in 4 (10%). Overall, 27 (67.5%) patients reported SC limited alopecia ‘a lot’ to ‘perfectly’. Conclusions: In our study, alopecia was identified as a notable burden to nearly half our SC patients and 10.8% hesitated when making their decision to receive chemotherapy. After using SC during treatment, 67.5% of patients reported less than 50% hair loss, and 67.5% reported that SC reduced alopecia ‘a lot’ or ‘perfectly’. Our study highlights the significance of alopecia as a chemotherapy burden and potential barrier to accepting treatment, and suggests SC may be efficacious in decreasing CIA, which may allow patients to feel less hesitation towards chemotherapy.

NCCN Guidelines® Insights: Breast Cancer, Version 4.2021

The NCCN Guidelines for Breast Cancer include up-to-date guidelines for clinical management of patients with carcinoma in situ, invasive breast cancer, Paget disease, phyllodes tumor, inflammatory breast cancer, male breast cancer, and breast cancer during pregnancy. These guidelines are developed by a multidisciplinary panel of representatives from NCCN Member Institutions with breast cancer-focused expertise in the fields of medical oncology, surgical oncology, radiation oncology, pathology, reconstructive surgery, and patient advocacy. These NCCN Guidelines Insights focus on the most recent updates to recommendations for adjuvant systemic therapy in patients with nonmetastatic, early-stage, hormone receptor-positive, HER2-negative breast cancer.

Abstract PS17-02: Molecular alterations in the androgen receptor and associated clinical outcomes in hormone receptor-positive/HER2- metastatic breast cancer

Background: Although the androgen receptor (AR) is frequently co-expressed with ER and PR in hormone receptor-positive (HR+)/HER2- breast cancer, the biological significance of detectable AR alterations (ARalt) in metastatic disease (MBC) remains poorly understood. The primary objective of this study was to evaluate the association of ARalt status with clinical outcomes among women with HR+/HER2- MBC.

Methods: Retrospective review was performed on patients with HR+/HER2- MBC treated at an academic institution, for whom genotyping information was available. ARalt status was determined using Guardant360, a 73-gene next-generation sequencing assay that detects both AR mutations and amplifications in circulating tumor DNA. Women with positive or unknown HER2 status and triple-negative breast cancer were excluded from analysis, as were cases of male breast cancer. Time-to-progression on the therapy initiated immediately following Guardant testing was compared based on ARalt status, excluding patients treated with androgen-directed therapies given potential for confounding. Cumulative incidence plots were generated and analyzed by Gray’s test, and propensity score-adjusted competing risk models were generated with the probability of treatment as a function of age at metastatic diagnosis, presence of visceral metastasis, presence of de novo metastases, as well as number of prior therapies. Additional analysis was performed to assess progression stratified by treatment type (endocrine or non-endocrine based).

Results: Among women with HR+/HER2- MBC (n=222), 16 patients (7%) had detectable ARalt (12 point mutations, 4 amplifications). No baseline differences were observed between women with ARalt and those without AR alterations (ARwt), with respect to age at primary or metastatic diagnosis, menopause status, time to onset of metastasis or de novo metastatic disease, presence of visceral metastases, or number of endocrine/chemotherapies received prior to Guardant testing. ARalt tumors had a higher frequency of detected mutations (14% vs. 5%, p&lt;0.01), and frequently co-altered genes included TP53, PIK3CA, ERBB2, SMAD4, and NF1. Genes with a tendency towards co-alteration in ARalt but not in ARwt included MAP2K2, ARAF1, MAPK1, SMAD4, MYC, ROS1, TERT, and NRAS. In a multivariable model adjusting for age, de novo metastases, visceral metastases, and number of prior therapies, ARalt status was associated with a higher rate of progression (HR 2.5; 95% CI 1.2-5.0, p=0.01), particularly among patients treated with endocrine-based therapies following Guardant testing (HR 4.2, 95% CI 2.4-7.2, p&lt;0.0005) but was not statistically different in women treated with non-endocrine based therapies (HR 1.6; 95% CI 0.5-4.9, p=0.4).

Conclusions: ARalt tumors demonstrate a higher rate of progression on endocrine-based therapy as compared to ARwt tumors, highlighting a potential role of AR in mediating resistance to endocrine therapy in HR+/HER2- disease. Further translational investigations are warranted to determine whether ARalt/HR+/HER2- disease represents a unique biological subtype that predominantly relies on AR signaling and may thus benefit from blockade with AR antagonists.

Table 1. Multivariable competing risks model for endocrine progression.CovariatePFSMultivariableHR95% CIP-valuePositive ARalt status4.172.43-7.17&lt;0.01Age at metastatic dx1.000.97-1.020.89De novo metastasesYes1.770.96-3.260.07No[ref]Visceral metastasesYes1.250.72-2.160.43No[ref]No. of prior therapies1.060.93-1.210.98

Citation Format: Charles Dai, Andrzej Niemierko, Neelima Vidula, Laura M Spring, Seth A Wander, Arielle J Medford, Katherine A Hesler, Giuliana Malvarosa, Jeffrey Peppercorn, Dejan Juric, Steven J Isakoff, Beverly Moy, Leif W Ellisen, Aditya Bardia. Molecular alterations in the androgen receptor and associated clinical outcomes in hormone receptor-positive/HER2- metastatic breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-02.

Abstract PS5-06: Prospective testing for PIK3CA/AKT1/PTEN alterations in tumor tissue from 1440 patients with advanced hormone receptor-positive HER2-negative breast cancer (HR+/HER2- BC) or triple-negative breast cancer (TNBC) screened for the IPATunity130 randomized phase 3 trial

Background The PI3K/AKT signaling pathway plays a significant role in both HR+ BC and TNBC. IPATunity130 is a double-blind, placebo-controlled, randomized phase 3 trial of ipatasertib in combination with paclitaxel in patients with PI3K/AKT1/PTEN-altered HR+ or TNBC. A next-generation sequencing (NGS)-based assay from Foundation Medicine Inc. (FMI) was used to select patients prospectively for enrollment in this trial.Patients and methods An investigational clinical trial assay (CTA) of a composite 3-gene biomarker signature [Kim, Lancet Oncol 2017] based on the FoundationOne® CDx assay was used to identify patients with PI3K/AKT pathway-activated tumors as eligible for enrollment in IPATunity130 (NCT03337724). Qualifying alterations for the 3-gene signature (referred to as ‘biomarker-positive’) comprised activating mutations in PIK3CA and/or AKT1, and/or loss of function (LOF) alterations in PTEN represented by homozygous or heterozygous deletions, dominant-negative mutations, or inactivating mutations under loss of heterozygosity. Study sites were required to submit formalin-fixed paraffin-embedded archival or fresh biopsy tissue derived from primary or metastatic tumors for patient screening. IPATunity130 includes three independent cohorts: Cohort A (biomarker-positive TNBC); Cohort B (biomarker-positive HR+/HER2– BC); and Cohort C (biomarker-negative TNBC). Results In total, 1736 patients were screened, from whom 1690 samples were tested by FMI. Of these, 1475 (87%) produced a valid NGS result. The remaining 215 (13%) failed quality control for reasons including insufficient tissue, DNA yield, lab error, and computational failure. Alteration status for PIK3CA and/or AKT1 and/or PTEN was positive in 703 (49%) of 1440 CTA-evaluable samples. In the HR+/HER2– cohort, the breakdown of CTA-positive samples was 301/356 (85%) PIK3CA/AKT1 mutations and 86/356 (24%) PTEN LOF alterations. In TNBC, 183/347 (53%) had PIK3CA/AKT1 mutations and 193/347 (56%) had PTEN LOF alterations. CTA results according to baseline characteristics are shown overall and by subtype below.

The most common mutations detected outside the 3-gene biomarker signature in the screened population were in the TP53, BRCA1, RB1, BRCA2, and NF1 genes in the TNBC cohort and the TP53, GATA3, CDH1, MAP3K1, and ESR1 genes in the HR+/HER2– cohort. In the HR+/HER2– cohort, 30 (14%) of 213 metastatic tumors had ESR1 mutations compared with 10/414 (2%) primary tumors. Tumor BRCA1 mutations were more common in patients aged ≤50 years whereas MAP3K1 mutations were more common in those aged &gt;50 years.Conclusions IPATunity130 is the first reported pivotal trial to utilize the 3-gene biomarker CTA in HR+/HER2– BC and TNBC to screen for patients with PI3K/AKT pathway-activated tumors. The 3-gene biomarker CTA detected alterations in 49% of screened patients, with a higher prevalence of PIK3CA/AKT1/PTEN alterations in HR+/HER2– BC than TNBC. Additional analyses are planned to assess correlations between clinical outcomes and tumor characteristics.

SubgroupPIK3CA/AKT1/PTEN alteration, n/N (%)OverallHR+/HER2–TNBCAll patient samples703/1440 (49)356/647 (55)347/793 (44)Age, years≤50219/475 (46)99/195 (51)120/280 (43)&gt;50484/965 (50)257/452 (57)227/513 (44)Sample sourcePrimary456/941 (48)232/414 (56)224/527 (43)Metastatic222/448 (50)112/213 (53)110/235 (47)Geographic regionNorth America60/102 (59)33/49 (67)27/53 (51)Asia-Pacific172/330 (52)81/145 (56)91/185 (49)Europe301/633 (48)171/310 (55)130/323 (40)Rest of world170/375 (45)71/143 (50)99/232 (43)

Citation Format: Heidi Savage, Wendy Lin, Mafalda Oliveira, Carlos Barrios, Joyce O’Shaughnessy, Nicholas Turner, Rebecca Dent, Steven J Isakoff, Shigehira Saji, Qinshu Lian, Denise Bradley, Sarah-Jayne Reilly, Heather Hinton, Matthew J Wongchenko, Aruna Mani, Sung-Bae Kim. Prospective testing for PIK3CA/AKT1/PTEN alterations in tumor tissue from 1440 patients with advanced hormone receptor-positive HER2-negative breast cancer (HR+/HER2- BC) or triple-negative breast cancer (TNBC) screened for the IPATunity130 randomized phase 3 trial [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS5-06.

The adjuvant use of capecitabine for residual disease following pre-operative chemotherapy for breast cancer: Challenges applying CREATE-X to a US population

INTRODUCTION

The CREATE-X study, conducted in Japan and South Korea, established capecitabine as an adjuvant treatment option for patients with triple negative breast cancer (TNBC) who have residual disease (RD) following neoadjuvant anthracycline or taxane-based chemotherapy. However, there are no reports on the tolerability and outcomes of adjuvant capecitabine in the US setting following publication of the CREATE-X data.

METHODS

We retrospectively collected treatment and tolerability data from the medical records of the first 23 TNBC patients who received adjuvant capecitabine for RD post neoadjuvant chemotherapy at our institution. Disease-free survival was assessed using the Kaplan-Meier method.

RESULTS

The median starting dosage of capecitabine was 1871 mg/m²/day, most commonly divided into two daily doses on days 1-14 of each 21 day cycle. 34.8% of patients completed the treatment as prescribed. Side effects associated with treatment were common with 69.6% of patients experiencing hand-foot syndrome, 39.1% of patients experiencing diarrhea, and 13.0% of patients requiring hospitalization for side effects. Of 23 patients treated with adjuvant capecitabine, 34.8% completed the planned dose, 30.4% completed with dose reduction, and 34.8% discontinued early. At a median follow-up time of 14 months, the median disease-free survival was 22 months, with 30.4% of patients experiencing recurrence.

CONCLUSION

Tolerability was poor overall compared to the CREATE-X cohort. Administering adjuvant capecitabine for TNBC patients with residual disease in the United States is challenging given differences in tolerability. More research is needed to understand how poor tolerability will affect the efficacy of this approach in the US population.