Long-term overall survival of patients who undergo breast-conserving therapy or mastectomy for early operable HER2-Positive breast cancer after preoperative systemic therapy: an observational cohort study

Background

Understanding the survival outcomes associated with breast-conserving therapy (BCT) and mastectomy after preoperative systemic therapy (PST) enables clinicians to provide more personalized treatment recommendations. However, lack of firm survival benefit data limits the breast surgery choices of human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients who receive PST. We sought to determine whether BCT or mastectomy after PST for early operable HER2-positive breast cancer is associated with better long-term survival outcomes and determine the degree to which PST response affects this association.

Methods

In this observational cohort study, we compared the long-term survival outcomes of BCT and mastectomy after PST for HER2-positive breast cancer and evaluated the impact of PST response on the relationship between breast surgery performed and survival outcomes. Our cohort included 625 patients with early operable HER2-positive breast cancer who received PST followed by BCT or mastectomy between January 1998 and October 2009. These patients also received standard postoperative radiation, trastuzumab, and endocrine therapy as indicated clinically. We used propensity score matching to assemble mastectomy and BCT cohorts with similar baseline characteristics and used Kaplan-Meier plots and Cox proportional hazards regression to detect associations between surgery types and outcomes. Furthermore, in this study, we analyzed the original data of 625 patients using the inverse probability of treatment weighting (IPTW) method to enhance the reliability of the comparison between the mastectomy and BCT cohorts by addressing potential confounding variables.

Findings

Propensity score matching yielded cohorts of 221 patients who received BCT and 221 patients who underwent mastectomy. At the median follow-up time of 9.9 years, compared with BCT, mastectomy was associated with worse overall survival (hazard ratio, 1.66; 95% confidence interval [CI]: 1.08-2.57; P = 0.02). In patients who had axillary lymph node pathological complete response, mastectomy was associated with worse overall survival before matching (hazard ratio, 2.17; 95% CI: 1.22-3.86; P < 0.01) and after matching (hazard ratio, 2.12; 95% CI: 1.15-3.89; P = 0.02). Among patients with pathological complete response in the breast, the survival results did not differ significantly between BCT and mastectomy patients. IPTW method validated that BCT offers better overall survival in patients who had axillary lymph node pathological complete response.

Interpretation

People with HER2-positive breast cancer who have already had PST are more likely to survive after BCT, especially if they get a pathological complete response in the axillary lymph nodes. These findings underscore the necessity for further investigation into how responses to PST can inform the choice of surgical intervention and the potential impact on overall survival. Such insights could lead to the development of innovative tools that support personalized surgical strategies in the management of breast cancer.

Funding

This work was supported by grants from the Nantong Science and Technology Project (JCZ2022079), Nantong Health Commission Project (QA2021031, MSZ2023040) and National Natural Science Foundation of China (No. 82394430).

Tailoring Neoadjuvant Therapy in Human Epidermal Growth Factor Receptor 2-Positive Early Breast Cancer: Recent Advances and Strategies

Neoadjuvant HER2 Therapy: Beyond one-size-fits-all.

Next-Generation HER2-Targeted Antibody-Drug Conjugates in Breast Cancer

Human epidermal growth factor receptor 2 (HER2) tyrosine kinase is overexpressed in 20% of breast cancers and associated with a less favorable prognosis compared to HER2-negative disease. Patients have traditionally been treated with a combination of chemotherapy and HER2-targeted monoclonal antibodies such as trastuzumab and pertuzumab. The HER2-targeted antibody-drug conjugates (ADCs) trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd) represent a novel class of therapeutics in breast cancer. These drugs augment monoclonal antibodies with a cytotoxic payload, which is attached by a linker, forming the basic structure of an ADC. Novel combinations and sequential approaches are under investigation to overcome resistance to T-DM1 and T-DXd. Furthermore, the landscape of HER2-targeted therapy is rapidly advancing with the development of ADCs designed to attack cancer cells with greater precision and reduced toxicity. This review provides an updated summary of the current state of HER2-targeted ADCs as well as a detailed review of investigational agents on the horizon. Clinical trials are crucial in determining the optimal dosing regimens, understanding resistance mechanisms, and identifying patient populations that would derive the most benefit from these treatments. These novel ADCs are at the forefront of a new era in targeted cancer therapy, holding the potential to improve outcomes for patients with HER2-positive and HER2-Low breast cancer.

A new paradigm for classifying and treating HER2-positive breast cancer

BACKGROUND

Because of the phenomenal success of treatment with monoclonal antibodies and antibody-drug conjugates targeting human epidermal growth factor receptor 2 (HER2), most patients with early-stage HER2-positive breast cancer (HER2+ BC) and some with limited metastatic diseases have been cured, and those who have not been cured have achieved significant improvements in overall survival, which has weakened the role of the TNM staging system in the prognosis of HER2+ BC today. Given that the disease is now highly curable, treatment conception, classification, and modalities should differ from those of cancer types with a poor prognosis. It is warranted to build a new paradigm for classifying and treating HER2+ BC.

RECENT FINDINGS

In our personal view, we suggest that the classification system should be based not only on traditional anatomy and cancer biology but also on available treatment regimens, their exceptional outcomes, and their toxicities. In this regard, we developed a new concise classification of HER2+ BC based on the TNM staging system, a review of the literature, research results, and our clinical experience, dividing the patients into four distinct groups: curable (lymph-node negative and small (≤3 cm) early breast cancer), do our best to cure (locally advanced or tumors >3 cm early breast cancer), hope for cure (local-regional recurrent, limited metastases, and exceptional responders), and incurable (metastatic breast cancer with poor performance status or non-exceptional responders).

CONCLUSION

It will assist clinicians in developing an optimal treatment regimen at the outset, curing more HER2+ BC patients and improving their quality of life.

Association of Cardiovascular Disease Risk Factors with Late Cardiotoxicity and Survival in HER2-positive Breast Cancer Survivors

PURPOSE

Breast cancer and cardiovascular (CV) diseases often share the same risk factors. It is increasingly important to identify risk factors for CV events in patients with high-risk breast cancer and explore optimal treatment regimens.

PATIENTS AND METHODS

Early HER2-positive breast cancer patients at our institution between January 1998 and October 2009 were reviewed. Primary outcome was late-severe-CV-event-free survival, and late severe CV events were defined as cardiovascular death, cardiomyopathy, symptomatic heart failure, and myocardial infarction developing 2+ years after breast cancer diagnosis. Kaplan-Meier plots, Cox proportional hazard regressions, and restricted mean survival time were used to evaluate outcomes.

RESULTS

We identified 2,448 consecutive eligible patients with a median follow-up time of 111.0 months (interquartile range, 52.0-151.8 months). One hundred and thirty-six patients had late severe CV events and 752 died of any cause [533 (70.9%) died of primary breast cancer; 12 (1.6%) died of cardiovascular disease]. Hypertension [HR, 1.546; 95% confidence interval (95% CI), 1.030-2.320; P = 0.036] and history of coronary artery disease (CAD; HR, 3.333; 95% CI, 1.669-6.656; P < 0.001) were associated with worse late-severe-CV-event-free survival. Anthracycline-containing regimens (HR, 1.536; 95% CI, 0.979-2.411; P = 0.062) was not a significant risk factor for CV events in multivariate analysis. Regimens containing both anthracycline and anti-HER2 therapy were prognostic for better OS (HR, 0.515; 95% CI, 0.412-0.643; P < 0.001).

CONCLUSIONS

Hypertension and CAD history were independent prognostic factors for late severe CV events. Adding anti-HER2 agents to anthracycline-containing regimens did not substantially increase the risk for late severe cardiotoxicity and conferred better overall survival.

Validation of plasma metabolites associated with breast cancer risk among Mexican Americans

In our previous breast cancer case control study in Hispanics, we found 14 metabolites whose levels differed between cases and controls. To validate the results, we carried out a nested case control study of 100 incident breast cancer and 100 matched healthy women identified from the Mano-A-Mano Mexican American Cohort study. With the adjustment of parity, education, birth place, language acculturation, BMI category, smoking, drinking, physical activity, and sitting time, 4 metabolites were associated with breast cancer risk: 3-hydroxyoctanoate (Odds ratio (OR) = 1.51, 95% confidence interval (CI): 1.10, 3.47), 3-hydroxybutyrate (BHBA) (OR = 1.42, 95%CI: 1.01, 3.72), linoleate (18:2n6) (OR = 1.39, 95% CI: 1.07, 4.04), and bilirubin (OR = 0.54, 95%CI: 0.42, 0.95). Then, we used 3 non-redundant metabolites, namely 3-hydroxyoctanoate, linoleate (18:2n6), and bilirubin, to generate a metabolic risk score. Increased metabolites risk score was associated with a 1.67-fold increased risk of breast cancer (OR = 1.67, 95%CI: 1.32, 3.94). And the significant association was more evident among those who were diagnosed with cancer earlier during the follow-up (≤ 5 years) than their counterparts. In conclusion, we identified four significant metabolites which may help elucidate metabolic pathways that contribute to breast carcinogenesis. Our findings warrant further replication efforts.

Whole-genome screen identifies diverse pathways that negatively regulate ciliogenesis

We performed a high-throughput whole-genome RNAi screen to identify novel inhibitors of ciliogenesis in normal and basal breast cancer cells. Our screen uncovered a previously undisclosed, extensive network of genes linking integrin signaling and cellular adhesion to the extracellular matrix (ECM) with inhibition of ciliation in both normal and cancer cells. Surprisingly, a cohort of genes encoding ECM proteins was also identified. We characterized several ciliation inhibitory genes and showed that their silencing was accompanied by altered cytoskeletal organization and induction of ciliation, which restricts cell growth and migration in normal and breast cancer cells. Conversely, supplying an integrin ligand, vitronectin, to the ECM rescued the enhanced ciliation observed on silencing this gene. Aberrant ciliation could also be suppressed through hyperactivation of the YAP/TAZ pathway, indicating a potential mechanistic basis for our findings. Our findings suggest an unanticipated reciprocal relationship between ciliation and cellular adhesion to the ECM and provide a resource that could vastly expand our understanding of controls involving “outside-in” and “inside-out” signaling that restrain cilium assembly.

Ribociclib plus fulvestrant for advanced breast cancer: Health-related quality-of-life analyses from the MONALEESA-3 study

Purpose

In the MONALEESA-3 Phase III trial of patients with hormone receptor–positive human epidermal growth factor receptor–negative advanced breast cancer, ribociclib plus fulvestrant significantly improved progression-free survival (PFS) and overall survival (OS). Here, we present patient-reported outcomes from the trial, including health-related quality of life (HRQOL).

Methods

Patients were randomized (2:1) to receive ribociclib plus fulvestrant or placebo plus fulvestrant. Time to definitive 10% deterioration (TTD) from baseline in HRQOL (global health status [GHS] from the EORTC QLQ-C30 questionnaire) and pain (BPI-SF questionnaire) were assessed using Kaplan-Meier estimates; a stratified Cox regression model was used to estimate the hazard ratio (HR) and 95% CIs.

Results

Deterioration ≥10% in the EORTC-QLQ-C30 GHS was observed in 33% of patients in the ribociclib group vs 34% of patients in the placebo (reference) group (HR for TTD ≥ 10% = 0.81 [95% CI, 0.62–1.1]). Similar findings were noted for TTD ≥5% (HR = 0.79 [95% CI, 0.61–1.0]) and TTD ≥15% (HR = 0.81 [95% CI, 0.60–1.08]). TTD ≥10% in emotional functioning (HR = 0.76 [95% CI, 0.57–1.01]) trended in favor of the ribociclib group, whereas results for fatigue and pain were similar between arms. TTD ≥10% in BPI-SF pain severity index score (HR = 0.77 [95% CI, 0.57–1.05]) and worst pain item score (HR = 0.81 [95% CI, 0.58–1.12]) trended in favor of ribociclib vs placebo.

Conclusions

In addition to significantly prolonging PFS and OS compared with placebo plus fulvestrant, adding ribociclib to fulvestrant maintains HRQOL.

•

Ribociclib + fulvestrant allowed maintenance of global health status (GHS).

•

Time to deterioration (TTD) by 10% can convey duration until worsening of QOL.

•

TTD ≥10% was delayed with ribociclib in GHS and emotional functioning.

•

Ribociclib also demonstrated trends toward delayed TTD vs placebo in pain outcomes.

Immunotherapy and targeted therapy combinations in metastatic breast cancer

Immunotherapy is emerging as a new treatment modality in breast cancer. After long-standing use of endocrine therapy and targeted biological therapy, improved understanding of immune evasion by cancer cells and the discovery of selective immune checkpoint inhibitors have created novel opportunities for treatment. Single-drug therapies with monoclonal antibodies against programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) have shown little efficacy in patients with metastatic breast cancer, in part because of the low number of tumour-infiltrating lymphocytes in most breast cancers. There is growing interest in the development of combinations of immunotherapy and molecularly targeted therapies for metastatic breast cancer. In this Personal View, we review the available data and ongoing efforts to establish the safety and efficacy of immunotherapeutic approaches in combination with HER2-targeted therapy, inhibitors of cyclin-dependent kinases 4 and 6, angiogenesis inhibitors, poly(ADP-ribose) polymerase inhibitors, as well as chemotherapy and radiotherapy.

Overall Survival with Ribociclib plus Fulvestrant in Advanced Breast Cancer

BACKGROUND

In an earlier analysis of this phase 3 trial, ribociclib plus fulvestrant showed a greater benefit with regard to progression-free survival than fulvestrant alone in postmenopausal patients with hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Here we report the results of a protocol-specified second interim analysis of overall survival.

METHODS

Patients were randomly assigned in a 2:1 ratio to receive either ribociclib or placebo in addition to fulvestrant as first-line or second-line treatment. Survival was evaluated by means of a stratified log-rank test and summarized with the use of Kaplan-Meier methods.

RESULTS

This analysis was based on 275 deaths: 167 among 484 patients (34.5%) receiving ribociclib and 108 among 242 (44.6%) receiving placebo. Ribociclib plus fulvestrant showed a significant overall survival benefit over placebo plus fulvestrant. The estimated overall survival at 42 months was 57.8% (95% confidence interval [CI], 52.0 to 63.2) in the ribociclib group and 45.9% (95% CI, 36.9 to 54.5) in the placebo group, for a 28% difference in the relative risk of death (hazard ratio, 0.72; 95% CI, 0.57 to 0.92; P = 0.00455). The benefit was consistent across most subgroups. In a descriptive update, median progression-free survival among patients receiving first-line treatment was 33.6 months (95% CI, 27.1 to 41.3) in the ribociclib group and 19.2 months (95% CI, 14.9 to 23.6) in the placebo group. No new safety signals were observed.

CONCLUSIONS

Ribociclib plus fulvestrant showed a significant overall survival benefit over placebo plus fulvestrant in patients with hormone-receptor-positive, HER2-negative advanced breast cancer. (Funded by Novartis; MONALEESA-3 ClinicalTrials.gov number, NCT02422615.).

Long-Term Survival Analysis of Adjuvant Chemotherapy with or without Trastuzumab in Patients with T1, Node-Negative HER2-Positive Breast Cancer

PURPOSE

Adjuvant therapy for small, node-negative HER2-positive breast cancer (HER2⁺ BC) is controversial. We aimed to identify the subgroup that would benefit most from adjuvant chemotherapy and trastuzumab.

EXPERIMENTAL DESIGN

We reviewed records of patients with pT1N0M0 HER2⁺ BC treated at our institution from January 1, 1998, through October 31, 2009. We compared three groups: A, no adjuvant chemotherapy; B, adjuvant chemotherapy only; and C, adjuvant chemotherapy with trastuzumab. We evaluated disease-free survival (DFS), overall survival (OS), distant recurrence-free survival (DRFS), and breast cancer-specific survival (BCSS) in each group.

RESULTS

We reviewed 587 consecutive patients with a median follow-up of 123.0 months. The 10-year DFS rate was 81.0%, 65.4%, and 97.3% in groups A, B, and C, respectively (P < 0.001). The restricted mean survival time ratio did not differ between groups A and B [ratio = 0.982; 95% confidence interval (CI), 0.930-1.036; P = 0.498). Cox regression showed that adjuvant chemotherapy with trastuzumab was associated with better DFS compared with no adjuvant chemotherapy [hazard ratio (HR), 0.071; 95% CI, 0.025-0.204; P < 0.001). Larger tumor size was associated with short DFS (HR, 2.384; 95% CI, 1.549-3.056; P < 0.001); improvements in DFS, OS, DRFS, and BCSS were observed with adjuvant chemotherapy plus trastuzumab in patients with tumors ≥0.8-cm diameter. Receiving adjuvant chemotherapy with trastuzumab was not associated with improved DFS, OS, or DRFS for tumors <0.8 cm.

CONCLUSIONS

Adjuvant chemotherapy plus trastuzumab should be recommended for patients with pT1N0M0 HER2⁺ BC ≥0.8 cm in diameter; adjuvant therapy may not be necessary for tumors <0.8 cm.

Are Biosimilars the Future of Oncology and Haematology?

Biological drugs are vital but often high-cost components of cancer treatment. Several biosimilar versions of these drugs have been approved in Europe and/or the USA, with many more in development. However, there is some disconnect between the biosimilars that are approved for use and those accessible in clinical practice, with availability impacted by factors including patent litigation and complex healthcare insurance policies, particularly in the USA. Provided the barriers to widespread uptake can be overcome, biosimilars offer potential benefits including cost savings and improved patient access versus the reference product (RP). This article provides an up-to-date and focused perspective on the development and use of biosimilars in the haemato-oncology setting. European and US regulatory pathways governing biosimilar licensing demand that there are no clinically meaningful differences between a biosimilar and its RP. Pathways are rigorously enforced and involve comprehensive non-clinical evaluations and clinical trials in selected indications to establish the equivalence or non-inferiority of efficacy, and the comparability of safety, of the biosimilar versus its RP. 'Indication extrapolation' is only permitted if scientifically justifiable considering mechanism(s) of action, pharmacokinetics, immunogenicity and safety in relevant patient populations. Switching treatment from RP to biosimilar is supported by most available data, predominantly from indications other than cancer, and post-marketing pharmacovigilance programmes are warranted. Notably, the potential benefits of biosimilar cancer treatment may extend beyond direct cost savings: for example, the availability of biosimilars of common regimen components may help incentivise the evaluation and/or clinical use of new treatment approaches and novel drugs.

Clinical development of CT-P6 in HER2 positive breast cancer

Introduction: CT-P6 (trastuzumab-pkrb, Herzuma) is a trastuzumab biosimilar approved for use in HER2 positive breast cancer and HER2 positive gastric cancer. CT-P6 has been shown to exhibit similar safety and efficacy profiles to its reference product, trastuzumab. Preclinical and clinical studies have been performed to prove equivalence between CT-P6 and the trastuzumab originator. Areas Covered: In this review, we examine the evidence comparing CT-P6 with its reference product, trastuzumab. Both monoclonal antibodies function to target cells that overexpress HER2 on the cell surface. Preclinical pharmacologic modeling of CT-P6 shows a similar mechanism of action to trastuzumab, similar pharmacologic properties and a phase I trial in healthy volunteers showed similar pharmacokinetics. A multicenter phase III randomized clinical trial in patients with early breast cancer showed equivalent safety and efficacy between CT-P6 and trastuzumab. One-year follow-up of patients showed identical rates of cardiotoxicity. Expert Opinion: Preclinical and clinical studies showed CT-P6 pharmacologic profile, safety and efficacy are equivalent to trastuzumab. As such, it is a safe and effective alternative for use in patients with HER2 positive breast cancer and gastric cancer. Its implementation into clinical practice can potentially increase patient access and help financially alleviate overburdened health-care systems.

Efficacy and safety of CT-P6 versus reference trastuzumab in HER2-positive early breast cancer: updated results of a randomised phase 3 trial

PURPOSE

Neoadjuvant CT-P6, a trastuzumab biosimilar, demonstrated equivalent efficacy to reference trastuzumab in a phase 3 trial of HER2-positive early-stage breast cancer (EBC) (NCT02162667). We report post hoc analyses evaluating pathological complete response (pCR) and breast pCR alongside additional efficacy and safety measures.

METHODS

Following neoadjuvant treatment and surgery, patients received adjuvant CT-P6 or trastuzumab (6 mg/kg) every 3 weeks for ≤ 1 year.

RESULTS

In total, 271 and 278 patients received CT-P6 and trastuzumab, respectively. pCR and breast pCR rates were comparable between treatment groups regardless of age, region, or clinical stage. Overall, 47.6% (CT-P6) and 52.2% (trastuzumab) of patients experienced study drug-related treatment-emergent adverse events (TEAEs), including 17 patients reporting heart failure (CT-P6: 10; trastuzumab: 7). Two CT-P6 and three trastuzumab patients discontinued adjuvant treatment due to TEAEs.

CONCLUSION

Adjuvant CT-P6 demonstrated comparable efficacy and safety to trastuzumab at 1 year in patients with HER2-positive EBC, supporting CT-P6 and trastuzumab comparability.

Breast cancer risk in relation to plasma metabolites among Hispanic and African American women

PURPOSE

The metabolic etiology of breast cancer has been explored in the past several years using metabolomics. However, most of these studies only included non-Hispanic White individuals.

METHODS

To fill this gap, we performed a two-step (discovery and validation) metabolomics profiling in plasma samples from 358 breast cancer patients and 138 healthy controls. All study subjects were either Hispanics or non-Hispanic African Americans.

RESULTS

A panel of 14 identified metabolites significantly differed between breast cancer cases and healthy controls in both the discovery and validation sets. Most of these identified metabolites were lipids. In the pathway analysis, citrate cycle (TCA cycle), arginine and proline metabolism, and linoleic acid metabolism pathways were observed, and they significantly differed between breast cancer cases and healthy controls in both sets. From those 14 metabolites, we selected 9 non-correlated metabolites to generate a metabolic risk score. Increased metabolites risk score was associated with a 1.87- and 1.63-fold increased risk of breast cancer in the discovery and validation sets, respectively (Odds ratio (OR) 1.87, 95% Confidence interval (CI) 1.50, 2.32; OR 1.63, 95% CI 1.36, 1.95).

CONCLUSIONS

In summary, our study identified metabolic profiles and pathways that significantly differed between breast cancer cases and healthy controls in Hispanic or non-Hispanic African American women. The results from our study might provide new insights on the metabolic etiology of breast cancer.

Phase II trial of nivolumab with chemotherapy as neoadjuvant treatment in inflammatory breast cancer

TPS604

Background: Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer with poor prognosis and is often resistant to neoadjuvant chemotherapy with risk of early recurrence and systemic spread of disease. PD-L1 expression in IBC is frequent (Bertucci et al. Oncotarget 2015), and blockade of the PD-1/PD-L1 axis with checkpoint inhibitors has emerged as a promising treatment to enhance anti-tumor immunity and clinical response. We hypothesize that PD-1 blockade with nivolumab in combination with neoadjuvant (primary) chemotherapy will increase the rate of pathologic complete response (pCR) and reduce risk of recurrence in patients with IBC. Methods: This is a single-arm open-label multicenter phase II study of nivolumab with neoadjuvant chemotherapy in patients with non-metastatic IBC (n = 52) (ClinicalTrials.gov: NCT03742986). All breast cancer subtypes (based on ER/PR/HER2) will be allowed. Patients will receive nivolumab 360 mg IV on day 1 (21-day cycle) for four cycles in addition to standard chemotherapy. Cohort 1 (patients with triple negative breast cancer or hormone receptor-positive (HR)/HER2-negative IBC) will receive nivolumab in combination with paclitaxel followed by doxorubicin and cyclophosphamide (AC). Cohort 2 (patients with HER2-positive IBC) will receive nivolumab in combination with a taxane (docetaxel or paclitaxel), trastuzumab, and pertuzumab followed by AC. All patients will then undergo mastectomy followed by radiation. The primary study objective is pCR rate (ypT0/Tis ypN0). Secondary objectives will be safety, tolerability and invasive recurrence-free interval. Association of correlative biomarkers with pCR and sensitivity or resistance to therapy with the combination of nivolumab and chemotherapy will be evaluated. Analyses will include mutational and neoantigen load, tumor-infiltrating lymphocytes (TILs) by histopathological assessment, T-cell receptor (TCR) by immunosequencing, and immune gene profiles in the tumor. PD-L1 expression in tumor tissue is not required for enrollment but will be assessed as a predictive marker. Clinical trial information: NCT03742986.

Efficacy and Safety of Ribociclib With Letrozole in US Patients Enrolled in the MONALEESA-2 Study

BACKGROUND

In the Mammary Oncology Assessment of LEE011's (Ribociclib's) Efficacy and Safety (MONALEESA-2) study, combination treatment with the selective inhibitor of cyclin-dependent kinases 4/6 ribociclib with letrozole significantly improved progression-free survival (PFS) versus letrozole alone in postmenopausal women with hormone receptor-positive HR⁺/HER2^- advanced breast cancer (ABC). Herein we present results from the subset of US patients enrolled in MONALEESA-2.

PATIENTS AND METHODS

Postmenopausal women with HR⁺/HER2^- ABC without previous treatment for advanced disease were randomized (1:1) to ribociclib 600 mg/d (3 weeks on/1 week off) with letrozole 2.5 mg/d (continuous) or placebo with letrozole. The primary end point was locally assessed PFS.

RESULTS

Overall, 213 US patients were enrolled in MONALEESA-2 (ribociclib, n = 100; placebo, n = 113). Baseline characteristics were similar between treatment groups and consistent with the global population. With a median follow-up of 27 months, 38 (38%) and 29 (26%) patients in the ribociclib and placebo groups, respectively, had continued to receive treatment. Median PFS was 27.6 months with ribociclib and 15.0 months with placebo (hazard ratio, 0.53). The most common all-cause adverse events were neutropenia (ribociclib, 72.0% [n = 72]; placebo, 4.6% [n = 5]), nausea (ribociclib, 69.0% [n = 69]; placebo, 44.0% [n = 48]), and fatigue (ribociclib, 60.0% [n = 60]; placebo, 50.5% [n = 55]). Two patients (ribociclib, 2.0%; placebo, 0%) experienced febrile neutropenia.

CONCLUSION

In the US subset of MONALEESA-2, ribociclib with letrozole showed superior efficacy versus letrozole alone. These findings are consistent with the global population and support first-line use of ribociclib with letrozole in patients with HR⁺/HER2^- ABC.

Abstract P6-18-05: First-line ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled efficacy analysis

Background: In three separate Phase III randomized, placebo-controlled trials, ribociclib (RIB; cyclin-dependent kinase 4/6 inhibitor) + various endocrine therapy (ET) partners prolonged progression-free survival (PFS) vs placebo (PBO) + ET in patients (pts) with hormone receptor-positive (HR+), HER2-negative (HER2–) advanced breast cancer (ABC). Here we further evaluate the efficacy of RIB-based regimens of interest (i.e. with a non-steroidal aromatase inhibitor [NSAI] or fulvestrant [FUL]) in pts who were ET-naïve in the ABC setting, using pooled data from three Phase III trials: MONALEESA (ML)-2 (NCT01958021; all pts), ML-3 (NCT02422615; no prior ET for ABC subgroup only), and ML-7 (NCT02278120; RIB + NSAI subgroup only).

Methods: Postmenopausal pts with no prior ET for ABC received RIB (600 mg/day; 3-weeks-on/1-week-off) or PBO + either letrozole (2.5 mg/day) in ML-2 or FUL (500 mg every 28 days, with an additional dose on Day 15 of Cycle 1) in ML-3. In ML-7, premenopausal pts with no prior ET and ≤1 line of chemotherapy for ABC received RIB or PBO + goserelin (3.6 mg every 28 days) + NSAI (anastrozole [1 mg/day]/letrozole [2.5 mg/day]). The primary endpoint of all three trials was locally assessed PFS. Secondary endpoints included overall response rate (ORR), clinical benefit rate (CBR), and duration of response (DoR; ML-3 and -7). DoR was an exploratory endpoint in ML-2.

Results: Data were pooled for 820 pts treated with RIB + ET (ML-2: n=334; ML-3: n=238; ML-7: n=248) and 710 pts treated with PBO + ET (ML-2: n=334; ML-3: n=129; ML-7: n=247). As of the data cutoffs (ML-2: January 2, 2017; ML-3: November 3, 2017; ML-7: August 20, 2017), in the RIB + ET vs PBO + ET arms, 385 (47%) vs 234 (33%) pts remained on-treatment; the most common reason for discontinuation was disease progression (n=292 [36%] vs n=391 [55%]). In this pooled analysis, median PFS was prolonged for RIB + ET vs PBO + ET, with a hazard ratio of 0.570 (95% confidence interval [CI] 0.491–0.662); median PFS was 25.3 months (95% CI 23.9–29.6) vs 15.6 months (95% CI 14.4–16.9), respectively. Consistent PFS benefit for RIB + ET vs PBO + ET was observed across pt subgroups, including ECOG performance status, age, race, or presence/absence of liver and/or lung metastases or bone-only disease. Among all pts in the pooled analysis, the ORR was 41% for RIB + ET vs 28% for PBO + ET and the CBR was 79% vs 70%, respectively. In pts with measurable disease at baseline (RIB + ET: n=639; PBO + ET: n=542), the ORR was 51% for RIB + ET vs 37% for PBO + ET and the CBR was 79% vs 68%, respectively. In the RIB + ET vs PBO + ET arms, the median DoR was 26.7 months vs 20.0 months. A decrease in best percentage change from baseline in the sum of longest diameters per RECIST was observed in 86% of pts receiving RIB + ET vs 73% of pts receiving PBO + ET.

Conclusions: RIB in combination with various ET partners demonstrates improved clinical outcomes vs PBO + ET across a broad population of pts with HR+, HER2– ABC. These data provide further support for the use of RIB-based combinations in pre- and postmenopausal pts with HR+, HER2– ABC who have received no prior ET for advanced disease.

Citation Format: Tripathy D, Hortobagyi G, Chan A, Im S-A, Chia S, Yardley D, Esteva FJ, Hurvitz S, Kong O, Bao W, Rodriguez Lorenc K, Diaz-Padilla I, Slamon DJ. First-line ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled efficacy analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-05.

Abstract P6-18-15: Ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled safety analysis

Background: In Phase III trials, ribociclib (RIB; cyclin-dependent kinase 4/6 inhibitor) + various endocrine therapy (ET) partners has demonstrated significantly prolonged progression-free survival vs placebo (PBO) + ET in patients (pts) with hormone receptor-positive (HR+), HER2-negative (HER2–) advanced breast cancer (ABC). Here we further evaluate the safety of RIB-based regimens of interest for the proposed indication (i.e. with a non-steroidal aromatase inhibitor [NSAI] or fulvestrant [FUL]) using pooled data from three Phase III trials (MONALEESA [ML]-2 [NCT01958021], -3 [NCT02422615], and -7 [NCT02278120]).

Methods: Postmenopausal pts with HR+, HER2– ABC received RIB (600 mg/day; 3-weeks-on/1-week-off) or PBO + letrozole (LET; 2.5 mg/day; ML-2 [no prior ET for ABC]) or FUL (500 mg, Days 1 and 15 of Cycle 1, then Day 1 of every cycle thereafter; ML-3; no or ≤1 prior line of ET for ABC]). Premenopausal pts (ML-7; no prior ET and ≤1 chemotherapy for ABC]) received RIB or PBO + anastrozole (1 mg/day)/LET (2.5 mg/day) + goserelin (3.6 mg every 28 days). Adverse events (AEs) were characterized per Common Terminology Criteria for Adverse Events v4.03; safety analyses included time to first event, duration of event, and rate of associated RIB/PBO discontinuations.

Results: Data for 1883 pts were pooled; 1065 pts received RIB + ET and 818 pts received PBO + ET (median exposure to study treatment: 17 and 13 months, respectively). Exposure-adjusted incidence rates for AEs of special interest were 561 and 131 per 100 pt-years in the RIB and PBO arms, respectively. The most common all-causality Grade 3/4 AEs (≥10% in any arm; RIB vs PBO) were neutropenia (59% vs 2%), leukopenia (18% vs 1%), and hypertension (13% vs 13%). A new Fridericia's corrected QT interval (QTcF) &gt;480 ms occurred in (n/N) 52/1054 (5%) vs 11/814 (1%) pts in the RIB vs PBO arms; a new QTcF &gt;500 ms occurred in 14/1054 (1%) vs 1/814 (&lt;1%) pts. Median time to first event for Grade ≥2 neutropenia, elevated alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST), and QTc prolongation in the RIB arm was 2, 12, and 2 weeks, respectively; median duration of first Grade ≥2 event was 4, 4, and 2 weeks. In the RIB arm vs PBO arms, 7% vs 3% of pts discontinued study treatment due to AEs; common all-grade AEs leading to RIB/PBO discontinuation (≥2% in any arm) were elevated ALT (4% vs &lt;1%) and elevated AST (2% vs 1%). Discontinuation due to QT prolongation occurred in 4 pts in the RIB arm and 2 in the PBO arm (both &lt;1%). All-grade serious AEs occurred in 25% of pts in the RIB arm vs 15% of pts in the PBO arm.

Conclusions: RIB in combination with various ET partners continues to demonstrate a predictable and manageable tolerability profile across a broad population of pts with HR+, HER2– ABC.

Citation Format: Burris HA, Chan A, Im S-A, Chia S, Tripathy D, Esteva FJ, Campone M, Bardia A, Kong O, Bao W, Diaz-Padilla I, Rodriguez Lorenc K, Yardley DA. Ribociclib + endocrine therapy in hormone receptor-positive, HER2-negative advanced breast cancer: A pooled safety analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-15.

Abstract P6-18-14: Patient-reported outcomes with ribociclib-based therapy in hormone receptor-positive, HER2-negative advanced breast cancer: results from the phase III MONALEESA-2, -3, and -7 trials

Background: In the Phase III MONALEESA (ML) trials, ribociclib (RIB; cyclin-dependent kinase 4/6 inhibitor) + endocrine therapy (ET) significantly improved progression-free survival (PFS) vs placebo (PBO) + ET in patients (pts) with hormone receptor-positive (HR+), HER2-negative (HER2–) advanced breast cancer (ABC). Here we report key patient-reported outcomes (PROs) for pts treated with RIB-based regimens of interest (i.e. with a non-steroidal aromatase inhibitor [NSAI] or fulvestrant [FUL]) in the ML-2, -3, and -7 trials.

Methods: Postmenopausal pts with HR+, HER2– ABC and no prior ET for advanced disease received RIB (600 mg/day; 3-weeks-on/1-week-off) + letrozole (2.5 mg/day; ML-2 [NCT01958021]), or FUL (500 mg every 28 days, with an additional dose on Day 15 of Cycle [C] 1; ML-3 [no prior ET for ABC subgroup only; NCT02422615]). Premenopausal pts with no prior ET and ≤1 line of chemotherapy for advanced disease received RIB + NSAI (anastrozole [1 mg/day]/letrozole [2.5 mg/day]) + goserelin (3.6 mg every 28 days; ML-7 [NCT02278120]). The primary endpoint for all trials was PFS. PROs were a secondary endpoint of all trials and were evaluated using EORTC QLQ-C30, QLQ-BR23 (ML-2 and ML-7), EQ-5D-5L, WPAI-GH (ML-7 only), and BPI-SF (ML-3 only) questionnaires. Changes from baseline and time to 10% deterioration (TTD) in health-related quality of life (HRQoL) were analyzed using linear mixed-effect and stratified Cox regression models, respectively.

Results: A total of 1530 pts were included in this analysis. Questionnaire compliance was high across trials (ML-2/ML-3: &gt;90%; ML-7: &gt;80%). On-treatment HRQoL (EORTC QLQ-C30 global health status/quality of life [QoL] score) was maintained from baseline up to C34, C28, and C17 in both treatment arms for ML-2, ML-3, and ML-7, respectively. In ML-7, mean overall HRQoL scores continued to improve in the RIB arm from C18 to C28, but scores decreased in the PBO arm. At end of treatment, mean overall HRQoL scores decreased in both arms across trials. Median TTD (RIB vs PBO) was similar between arms, favoring the RIB arms (ML-2: 27.7 vs 27.6 months; hazard ratio 0.944; 95% confidence interval [CI] 0.720–1.237; ML-3: not reached [NR] vs 22.4 months; hazard ratio 0.721; 95% CI 0.484–1.074; ML-7: 24.0 vs 19.4 months; hazard ratio 0.759; 95% CI 0.561–1.028). Clinically meaningful reductions in EORTC QLQ-C30 pain score (&gt;5 points from baseline) were observed in the RIB arm of ML-2 from as early as C3 and were sustained vs only at C7 and C13 in the PBO arm. Clinically meaningful reductions in pain were observed from C22 to C28 in the RIB arm of ML-7 vs only at C28 in the PBO arm. In ML-3, clinically meaningful reductions in pain were observed from C3 to C5, C11–17, and at C22 and C28 in the RIB arm vs C17–C25 in the PBO arm. Furthermore, median TTD of the BPI-SF pain severity index score was NR in either arm of ML-3 (hazard ratio 0.858; 95% CI 0.554–1.330).

Conclusions: In addition to significantly prolonging PFS, RIB consistently maintains QoL regardless of ET combination partner. RIB + ET is also associated with clinically meaningful reductions in pain vs PBO + ET across a broad population of pts with HR+, HER2– ABC.

Citation Format: Beck JT, Neven P, Esteva FJ, Bardia A, Harbeck N, Hurvitz S, O'Shaughnessy J, Verma S, Lanoue B, Alam J, Kong O, Chandiwana D, Chia S. Patient-reported outcomes with ribociclib-based therapy in hormone receptor-positive, HER2-negative advanced breast cancer: results from the phase III MONALEESA-2, -3, and -7 trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-14.

Abstract P6-17-03: 24 months results from a double-blind, randomized phase III trial comparing the efficacy and safety of neoadjuvant then adjuvant trastuzumab and its biosimilar candidate CT-P6 in HER2 positive early breast cancer (EBC)

Background CT-P6 is a proposed biosimilar to reference trastuzumab (RTZ). A double-blind, randomized, phase III trial showed similar efficacy and safety for CT-P6 and RTZ in HER2 positive EBC (NCT02162667). The primary endpoint, pathological complete response rate was within the predefined margin to demonstrate similarity (Lancet Oncol 2017). Safety and efficacy at 1 year (ESMO 2017), and cardiac toxicity at a median of 19 months (SABCS 2017) were similar between the two treatment groups. Here we report updated disease-free survival (DFS), overall survival (OS) and cardiac toxicity data with a median follow-up of 2 years.

Methods A total of 549 patients with HER2 positive EBC were randomized to receive CT-P6 (n=271) or RTZ (n=278) in combination with docetaxel (Cycles 1-4) and 5-fluorouracil, epirubicin and cyclophosphamide (Cycles 5-8). CT-P6 or RTZ was administered at 8 mg/kg (Cycle 1 only) followed by 6 mg/kg every 3 weeks. After surgery, patients received CT-P6 or RTZ monotherapy then entered the follow-up period up to 3 year of last patient enrollment. Time to event analyses were performed using Cox regression and Kaplan-Meier methods.

Results A total of 528 patients (259/271 in CT-P6 and 269/278 in RTZ) entered the follow-up period after completing therapy. The median follow-up duration was over 27 months. The number of DFS events (32 [12.4%] in CT-P6 and 26 [10.0%] in RTZ) and OS events (14 [5.2%] in CT-P6 and 12 [4.3%] in RTZ) were comparable in the ITT set. Additionally, DFS and OS were similar between CT-P6 group and RTZ group in both the per-protocol set (PPS) and the ITT set. In the ITT set, the proportion of 2-year DFS (95% CI) was 86% (80% – 90%) in CT-P6 and 90% (85% – 93%) in RTZ. The proportion of 2-year OS was 97% (93% – 98%) in CT-P6 and 98% (96% – 99%) in RTZ. Median DFS and OS have not been reached. After 1-year treatment, no new cases of heart failure were reported during the follow-up period. Left ventricular ejection fraction (LVEF) was similar in both groups (mean LVEF, more than 60%).

Table 1.Summary of Long Term Efficacy Endpoints PPSITT set CT-P6 (n=248)Reference Trastuzumab (n=256)CT-P6 (n=258)Reference Trastuzumab (n=261)Proportion of DFS1 year (95% CI)0.95 (0.91 – 0.97)0.96 (0.93 – 0.98)0.95 (0.91 – 0.97)0.96 (0.93 – 0.98)2 years (95% CI)0.86 (0.80 – 0.90)0.90 (0.85 – 0.93)0.86 (0.80 – 0.90)0.90 (0.85 – 0.93)p-value0.33240.3085 CT-P6 (n=248)Reference Trastuzumab (n=256)CT-P6 (n=271)Reference Trastuzumab (n=278)Proportion of OS1 year (95% CI)1.00 (1.00 – 1.00)1.00 (0.97 – 1.00)0.99 (0.97 – 1.00)0.99 (0.97 – 1.00)2 year (95% CI)0.97 (0.94 – 0.99)0.98 (0.96 – 0.99)0.97 (0.93 – 0.98)0.98 (0.96 – 0.99)3 year (95% CI)0.94 (0.88 – 0.97)0.93 (0.86 – 0.96)0.92 (0.86 – 0.96)0.93 (0.87 – 0.96)p-value0.93290.5057

Conclusions The efficacy and cardiac toxicity profile between CT-P6 and RTZ in EBC patients were consistent with published data. Time to event analyses as secondary efficacy endpoints supported the similarity for the two study drugs. CT-P6 was consistently well tolerated with a similar cardiotoxicity profile to that of RTZ through long duration of follow-up.

Citation Format: Esteva FJ, Lee S, Yu S, Kim M, Kim N, Stebbing J. 24 months results from a double-blind, randomized phase III trial comparing the efficacy and safety of neoadjuvant then adjuvant trastuzumab and its biosimilar candidate CT-P6 in HER2 positive early breast cancer (EBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-03.

Abstract P6-18-07: Ribociclib + endocrine therapy in patients with hormone receptor-positive, HER2-negative advanced breast cancer presenting with visceral metastases: Subgroup analysis of phase III MONALEESA trials

Background: Patients (pts) with advanced breast cancer (ABC) who present with visceral metastases (mets) have a poorer prognosis vs pts with non-visceral disease. In the Phase III MONALEESA (ML) trials, ribociclib (RIB) + endocrine therapy (ET) prolonged progression-free survival (PFS) vs placebo (PBO) + ET in hormone receptor-positive (HR+), HER2-negative (HER2–) ABC. Here we show data for pts with and without visceral mets from the ML-2, -3, and -7 trials.

Methods: Data were collated from 3 trials in HR+, HER2– ABC: in ML-2 (NCT01958021; data cutoff [DCO] Jan 2/4, 2017), postmenopausal pts (no prior ET for ABC) received RIB or PBO + letrozole; in ML-3 (NCT02422615; DCO Nov 3, 2017), postmenopausal pts (no prior ET for ABC subgroup only) received RIB or PBO + fulvestrant; in ML-7 (NCT02278120; DCO Aug 20, 2017), premenopausal pts (no prior ET and ≤1 chemotherapy for ABC) received RIB or PBO + goserelin + anastrozole/letrozole. Endpoints; primary: local PFS; secondary: overall response rate (ORR), clinical benefit rate (CBR), safety.

Results: Of all 820 pts treated with RIB + ET, 484 (59%) had visceral mets (ML-2 197/334; ML-3 137/238; ML-7 150/248); of all 710 pts treated with PBO + ET, 416 (59%) had visceral mets (ML-2 196/334; ML-3 77/129; ML-7 143/247). Median PFS was prolonged for RIB vs PBO in pts with and without visceral mets (Table). ORR and CBR were also higher for RIB vs PBO in pts with and without visceral mets. The most common (≥10% of pts in any arm) Grade [G] 3 and 4 adverse events (AEs) for each trial are shown in the table; no G4 AEs occurred in ≥10% of pts in ML-3.

 Visceral metsNo visceral metsML-2 Median PFS (RIB/PBO), months (95% CI)24.9 (22.2–30.9)/13.4 (12.7–16.5)25.3 (22.2–NR)/18.2 (15.0–24.6)Hazard ratio (95% CI)0.538 (0.408–0.709)0.634 (0.448–0.897) ORR (RIB/PBO),* %48/3735/17 CBR (RIB/PBO),† %79/7282/75 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia56/147/1Leukopenia19/121/&lt;1Hypertension11/1115/15 Most common (≥10% in any arm) G4 AEs (RIB/PBO), %Neutropenia10/09/0 ML-3 Median PFS (RIB/PBO), months (95% CI)NR (19.1–NR)/16.5 (9.0–NR)NR (NR–NR)/21.9 (14.8–NR)Hazard ratio (95% CI)0.610 (0.403–0.926)0.521 (0.295–0.921) ORR (RIB/PBO),* %46/2931/21 CBR (RIB/PBO),† %74/6075/81 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia50/045/0Leukopenia12/010/0Increased ALT6/012/0 ML-7 Median PFS (RIB/PBO), months (95% CI)23.8 (14.8–NR)/10.4 (7.2–12.9)27.5 (NR–NR)/19.3 (16.5–NR)Hazard ratio (95% CI)0.507 (0.367–0.700)0.609 (0.377–0.984) ORR (RIB/PBO),* %45/3630/19 CBR (RIB/PBO),† %79/5783/81 Most common (≥10% in any arm) G3 AEs (RIB/PBO), %Neutropenia54/356/4Leukopenia14/116/1 Most common (≥10% in any arm) G4 AEs (RIB/PBO), %Neutropenia11/&lt;19/0CI, confidence interval; NR, not reached. *ORR = complete response + partial response; †CBR = complete response + partial response + (stable disease + non-complete response/non-progressive disease ≥24 weeks).

Conclusions: Although the presence of visceral mets is associated with a poorer prognosis, RIB + ET is an effective and well-tolerated treatment option for pts with HR+, HER2– ABC irrespective of the presence of visceral mets.

Citation Format: Yardley DA, Chan A, Nusch A, Sonke GS, Yap Y-S, Bachelot T, Esteva FJ, Slamon DJ, Burris HA, Gaur A, Kong O, Diaz-Padilla I, Rodriguez Lorenc K, Wheatley-Price P. Ribociclib + endocrine therapy in patients with hormone receptor-positive, HER2-negative advanced breast cancer presenting with visceral metastases: Subgroup analysis of phase III MONALEESA trials [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-07.

Prognosis in different subtypes of metaplastic breast cancer: a population-based analysis

BACKGROUND

Metaplastic breast cancer (MpBC) is a rare histological subtype of breast cancer recognized as a unique pathologic entity in 2000. However, the pathogenesis, optimal therapy, and prognosis of MpBC and the potential effect of systemic treatments on different subtypes of MpBC are not well defined.

METHODS

A retrospective population-based study was performed to identify breast cancer patients with MpBC and other triple-negative breast cancers (TNBC) between 2010 and 2014 using the surveillance, Epidemiology, and End Results (SEER) database. Chi-square test was used to analyze characteristics between subgroups. Kaplan-Meier analysis and Multivariate Cox regressions were used to evaluate overall survival (OS) of MpBC, TNBC, and MpBC subgroups. Competing risk analysis and multivariate regression model of competing risk were used to assess breast cancer-specific survival (BCSS) of MpBC and TNBC RESULTS: We identified a study cohort of 22,433 patients (1112 MpBC and 21,321 TNBC). MpBC correlated with older population, larger tumor size and less lymph node involvement, and TNBC phenotype. Patients with MpBC especially with triple-negative subtype (TN-MpBC) had worse survival than the overall TNBC population. However, the prognosis of MpBC without triple-negative subtype (non-TN MpBC) was not different from that of TNBC. In Kaplan-Meier analysis, chemotherapy was not associated with significant difference in OS of TN-MpBC. In non-TN MpBC group, the 3-year OS was 79.8% for patients receiving chemotherapy and 70.5% in patients without chemotherapy, and chemotherapy was associated (P = 0.033) with improved OS. Within the MpBC patients, radiotherapy was significantly (HR 1.544; 95% CI 1.148-2.078; P = 0.004) associated with improved OS and (HR 1.474; 95% CI 1.067-2.040; P = 0.019) BCSS.

CONCLUSIONS

Patients with TN-MpBC had worse prognosis than TNBC and chemotherapy was not associated with improved survival. In contrast, non-TN MpBC may derive survival benefit from chemotherapy and radiotherapy.

High turnover of extracellular matrix reflected by specific protein fragments measured in serum is associated with poor outcomes in two metastatic breast cancer cohorts

Increased extracellular matrix (ECM) formation and matrix metalloprotease (MMP)-mediated ECM degradation are parts of tumorgenesis and generates collagen fragments that are released into circulation. We evaluated the association of specific collagen fragments measured in serum with outcomes in two independent metastatic breast cancer (MBC) cohorts. ELISAs were used to measure C1M (MMP-generated type I collagen fragment), C3M (MMP-generated type III collagen fragment), C4M (MMP-generated type IV collagen fragment), and PRO-C3 (pro-peptide of type III collagen) in pretreatment serum from a phase 3 randomized clinical trial of second-line hormone therapy (HR+, n = 148), and a first-line trastuzumab-treated cohort (HER2+, n = 55). All sites of metastases were included. The collagen fragments were evaluated by Cox-regression analysis for their association with time-to-progression (TTP) and overall survival (OS). In the HR+ cohort, higher C1M and C3M levels (75th percentile cut-off) were associated with shorter TTP; all fragments were associated with shorter OS. In the HER2+ cohort, higher levels of all fragments were associated with shorter TTP; higher PRO-C3 was associated with shorter OS. In multivariate analysis of the HR+ trial for OS, higher levels of all fragments were significant for reduced OS when added separately (C1M HR = 2.1, p < 0.001; C3M HR = 1.8, p = 0.028; C4M HR = 1.8, p = 0.018; PRO-C3 HR = 1.8, p = 0.017); none other clinical covariates were significant. In conclusion, collagen fragments quantified in pretreatment serum was associated with shorter TTP and OS in two independent MBC cohorts receiving systemic therapy. If validated, quantification of ECM remodeling in serum has potential as prognostic and/or predictive biomarkers in MBC.

Recommendations on Disease Management for Patients With Advanced Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer and Brain Metastases: ASCO Clinical Practice Guideline Update

Purpose

To update the formal expert consensus-based guideline recommendations for practicing oncologists and others on the management of brain metastases for patients with human epidermal growth factor receptor 2–positive advanced breast cancer to 2018.

Methods

An Expert Panel conducted a targeted systematic literature review (for both systemic treatment and CNS metastases) and identified 622 articles. Outcomes of interest included overall survival, progression-free survival, and adverse events. In 2014, the American Society of Clinical Oncology (ASCO) convened a panel of medical oncology, radiation oncology, guideline implementation, and advocacy experts, and conducted a systematic review of the literature. When that failed to yield sufficiently strong quality evidence, the Expert Panel undertook a formal expert consensus–based process to produce these recommendations. ASCO used a modified Delphi process. The panel members drafted recommendations, and a group of other experts joined them for two rounds of formal ratings of the recommendations.

Results

Of the 622 publications identified and reviewed, no additional evidence was identified that would warrant a change to the 2014 recommendations.

Recommendations

Patients with brain metastases should receive appropriate local therapy and systemic therapy, if indicated. Local therapies include surgery, whole-brain radiotherapy, and stereotactic radiosurgery. Treatments depend on factors such as patient prognosis, presence of symptoms, resectability, number and size of metastases, prior therapy, and whether metastases are diffuse. Other options include systemic therapy, best supportive care, enrollment in a clinical trial, and/or palliative care. Clinicians should not perform routine magnetic resonance imaging to screen for brain metastases, but rather should have a low threshold for magnetic resonance imaging of the brain because of the high incidence of brain metastases among patients with HER2-positive advanced breast cancer. Additional information is available at www.asco.org/breast-cancer-guidelines .

Systemic Therapy for Patients With Advanced Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer: ASCO Clinical Practice Guideline Update

Purpose

To update evidence-based guideline recommendations for practicing oncologists and others on systemic therapy for patients with human epidermal growth factor receptor 2 (HER2)–positive advanced breast cancer to 2018.

Methods

An Expert Panel conducted a targeted systematic literature review (for both systemic treatment and CNS metastases) and identified 622 articles. Outcomes of interest included overall survival, progression-free survival, and adverse events.

Results

Of the 622 publications identified and reviewed, no additional evidence was identified that would warrant a change to the 2014 recommendations.

Recommendations

HER2-targeted therapy is recommended for patients with HER2-positive advanced breast cancer, except for those with clinical congestive heart failure or significantly compromised left ventricular ejection fraction, who should be evaluated on a case-by-case basis. Trastuzumab, pertuzumab, and taxane for first-line treatment and trastuzumab emtansine for second-line treatment are recommended. In the third-line setting, clinicians should offer other HER2-targeted therapy combinations or trastuzumab emtansine (if not previously administered) and may offer pertuzumab if the patient has not previously received it. Optimal duration of chemotherapy is at least 4 to 6 months or until maximum response, depending on toxicity and in the absence of progression. HER2-targeted therapy can continue until time of progression or unacceptable toxicities. For patients with HER2-positive and estrogen receptor–positive/progesterone receptor–positive breast cancer, clinicians may recommend either standard first-line therapy or, for selected patients, endocrine therapy plus HER2-targeted therapy or endocrine therapy alone. Additional information is available at www.asco.org/breast-cancer-guidelines .

Antibody-drug conjugates in triple negative breast cancer

Triple negative breast cancer (TNBC) is a heterogeneous disease that comprises 15-20% of all breast cancers and is more frequently seen in younger women, African-Americans, and BRCA1 expression. Advanced TNBC carries aggressive features and is associated with overall poor outcomes. Unfortunately, there are no targeted therapies available for non-BRCA associated TNBC, which remains a high unmet therapeutic need. One emerging treatment modality includes antibody-drug conjugates which are highly selective monoclonal antibodies conjugated to cytotoxic agents, designed to deliver cytotoxic drugs to antigen-expressing tumor cells. This review will highlight three antibody-drug conjugates currently being evaluated in TNBC (CDX-011, SGN-LIV1a, IMMU-132), including one that has been given Breakthrough Therapy designation from the US FDA.

Phase III Randomized Study of Ribociclib and Fulvestrant in Hormone Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative Advanced Breast Cancer: MONALEESA-3

Purpose

This phase III study evaluated ribociclib plus fulvestrant in patients with hormone receptor–positive/human epidermal growth factor receptor 2–negative advanced breast cancer who were treatment naïve or had received up to one line of prior endocrine therapy in the advanced setting.

Patients and Methods

Patients were randomly assigned at a two-to-one ratio to ribociclib plus fulvestrant or placebo plus fulvestrant. The primary end point was locally assessed progression-free survival. Secondary end points included overall survival, overall response rate, and safety.

Results

A total of 484 postmenopausal women were randomly assigned to ribociclib plus fulvestrant, and 242 were assigned to placebo plus fulvestrant. Median progression-free survival was significantly improved with ribociclib plus fulvestrant versus placebo plus fulvestrant: 20.5 months (95% CI, 18.5 to 23.5 months) versus 12.8 months (95% CI, 10.9 to 16.3 months), respectively (hazard ratio, 0.593; 95% CI, 0.480 to 0.732; P < .001). Consistent treatment effects were observed in patients who were treatment naïve in the advanced setting (hazard ratio, 0.577; 95% CI, 0.415 to 0.802), as well as in patients who had received up to one line of prior endocrine therapy for advanced disease (hazard ratio, 0.565; 95% CI, 0.428 to 0.744). Among patients with measurable disease, the overall response rate was 40.9% for the ribociclib plus fulvestrant arm and 28.7% for placebo plus fulvestrant. Grade 3 adverse events reported in ≥ 10% of patients in either arm (ribociclib plus fulvestrant v placebo plus fulvestrant) were neutropenia (46.6% v 0%) and leukopenia (13.5% v 0%); the only grade 4 event reported in ≥ 5% of patients was neutropenia (6.8% v 0%).

Conclusion

Ribociclib plus fulvestrant might represent a new first- or second-line treatment option in hormone receptor–positive/human epidermal growth factor receptor 2–negative advanced breast cancer.

Efficacy and safety of the trastuzumab biosimilar candidate CT-P6

Trastuzumab is an anti-HER2 monoclonal antibody indicated for the treatment of HER2-overexpressing breast and gastric cancers. Despite its clinical efficacy, access to the biological drug can be limited due to its relatively high price, especially in low-income countries. CT-P6 (Herzuma®) is a biosimilar candidate of originator or ‘reference’ trastuzumab, which may offer an alternative, more cost-effective treatment option. This article reviews the unmet needs of patients eligible to receive reference trastuzumab and the potential place of a trastuzumab biosimilar within the market. The review also summarizes the available clinical evidence supporting the biosimilarity of CT-P6 and reference trastuzumab with respect to pharmacokinetics, efficacy, safety and immunogenicity.

Trastuzumab-Resistant HER2+ Breast Cancer Cells Retain Sensitivity to Poly (ADP-Ribose) Polymerase (PARP) Inhibition

HER2-targeted therapies, such as trastuzumab, have increased the survival rates of HER2⁺ breast cancer patients. However, despite these therapies, many tumors eventually develop resistance to these therapies. Our lab previously reported an unexpected sensitivity of HER2⁺ breast cancer cells to poly (ADP-ribose) polymerase inhibitors (PARPi), agents that target homologous recombination (HR)-deficient tumors, independent of a DNA repair deficiency. In this study, we investigated whether HER2⁺ trastuzumab-resistant (TR) breast cancer cells were susceptible to PARPi and the mechanism behind PARPi induced cytotoxicity. We demonstrate that the PARPi ABT-888 (veliparib) decreased cell survival in vitro and tumor growth in vivo of HER2⁺ TR breast cancer cells. PARP-1 siRNA confirmed that cytotoxicity was due, in part, to PARP-1 inhibition. Furthermore, PARP-1 silencing had variable effects on the expression of several NF-κB-regulated genes. In particular, silencing PARP-1 inhibited NF-κB activity and reduced p65 binding at the IL8 promoter, which resulted in a decrease in IL8 mRNA and protein expression. Our results provide insight in the potential mechanism by which PARPi induces cytotoxicity in HER2⁺ breast cancer cells and support the testing of PARPi in patients with HER2⁺ breast cancer resistant to trastuzumab. Mol Cancer Ther; 17(5); 921-30. ©2018 AACR.

Total pathological complete response versus breast pathological complete response in clinical trials of reference and biosimilar trastuzumab in the neoadjuvant treatment of breast cancer

INTRODUCTION

Trastuzumab is a key drug in the neoadjuvant treatment of breast cancers that overexpress the human epidermal growth factor receptor 2 (HER2). Pathological complete response (pCR) is commonly used as an endpoint in neoadjuvant clinical trials of trastuzumab as evidence suggests it may be a surrogate for long-term survival. Several biosimilar candidates of originator or 'reference' trastuzumab are in development and have used pCR as a primary endpoint to assess therapeutic equivalence between treatments. The exact definition of pCR has varied across studies. Areas covered: Here we look at the clinical relevance of pCR and compare rates of total pCR (defined as ypT0/is ypN0) and breast pCR (defined as ypT0/is) in clinical trials of reference and biosimilar trastuzumab. Expert commentary: In order to evaluate the efficacy of neoadjuvant systemic therapies in a uniform way, standardization of trial endpoints is necessary. Future studies in HER2-positive breast cancer should include full assessment of the breast and lymph node basin before and after neoadjuvant systemic therapy, and the use of total pCR as the primary outcome.

Abstract P5-20-14: Cardiotoxicity in 1 year of treatment with reference trastuzumab and its biosimilar candidate CT-P6 in HER2 positive early stage breast cancer (EBC) patients

Background CT-P6 is a proposed biosimilar to reference trastuzumab. This trial (NCT02162667) evaluated the similarity of CT-P6 and reference trastuzumab for both efficacy and safety in HER2 positive EBC patients. The primary endpoint, pathological complete response (pCR) rate was entirely within the pre-defined equivalence margin (Stebbing et al., Lancet Oncology 2017). Efficacy and safety were similar between the two treatment groups. We aimed to investigate the cardiotoxicity in the 1 year treatment and follow-up period.

Methods A total of 549 patients with HER2 positive EBC were randomized to receive CT-P6 (n=271) or reference trastuzumab (n=278) in combination with docetaxel (Cycles 1-4) and 5-fluorouracil, epirubicin and cyclophosphamide (FEC, Cycles 5-8) in the neoadjuvant setting. CT-P6 or reference trastuzumab was administered at 8 mg/kg (Cycle 1 only) followed by 6 mg/kg every 3 weeks. After surgery, patients received monotherapy of CT-P6 or reference trastuzumab up to 10 cycles in the adjuvant setting. Left ventricular ejection fraction (LVEF) was evaluated by ECHO or MUGA at baseline, every 3 or 4 cycles during treatment and every 6 months thereafter. If LVEF decreased by ≥10 points from baseline and &lt;50%, a reassessment was performed within 3 weeks and the patient was withdrawn from the study treatment if the cardiac toxicity was confirmed.

Results Median follow-up period was 19 months. In total, 96% of patients completed 8 cycles of taxane and anthracycline combination therapy during the neoadjuvant period and 90% of patients in each group received 1-year treatment of CT-P6 or reference trastuzumab.

The relative dose intensity of study drug was similar, indicating good tolerability of CT-P6 and reference trastuzumab (97.5% and 97.3% during the neoadjuvant period; 98.5% and 98.8% during the adjuvant period). Docetaxel and FEC combination therapies were administered approximately 96% of dose intensity in the two groups.

All patients had normal LVEF (≥55%) at baseline. Mean LVEF value was maintained more than 60% during 1-year treatment and follow-up period. Heart failure cases with LVEF decrease (≥10 points from baseline and &lt;50%) were reported to be similar between two groups. Three patients in each group were withdrawn due to LVEF decrease. Adverse events of cardiac disorders were reported to be similar between two groups. All cases were mild or moderate except two cases.

Table 1. Summary of heart failure with LVEF decrease and cardiotoxicity CT-P6 (N=271)Reference Trastuzumab (N=278)LVEF decrease ≥ 10 points and below 50%9 (3.3%)7 (2.5%)- Asymptomatic9 (3.3%)6 (2.1%)- Symptomatic01 (0.4%)- Confirmed2 (0.7%)4 (1.4%)- Withdrawn3 (1.1%)3 (1.1%)Cardiac disorder by AEs31 (11.4%)38 (13.7%)- Grade 1 to 230 (11.0%)37 (13.3%)- Grade 3 to 51 (0.4%)11 (0.4%)21 Grade 3 of Adams-Strokes syndrome occurring 5 months after the completion of 1-year treatment; 2 Grade 5 of acute myocardial infarction occurring 10 days after Cycle 1 of the neoadjuvant therapy

Conclusions Combination therapy of CT-P6 with taxane/anthracycline and monotherapy of CT-P6 over 1 year period were well tolerated and cardiotoxicity was similar to reference trastuzumab.

Citation Format: Esteva FJ, Chung HC, Royce ME, Lee SY, Lee SJ, Stebbing J. Cardiotoxicity in 1 year of treatment with reference trastuzumab and its biosimilar candidate CT-P6 in HER2 positive early stage breast cancer (EBC) patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-20-14.

Prognostic role of elevated mir-24-3p in breast cancer and its association with the metastatic process

MicroRNAs have been shown to play important roles in breast cancer progression and can serve as biomarkers. To assess the prognostic role of a panel of miRNAs in breast cancer, we collected plasma prospectively at the time of initial diagnosis from 1,780 patients with stage I-III breast cancer prior to definitive treatment. We identified plasma from 115 patients who subsequently developed distant metastases and 115 patients without metastatic disease. Both groups were matched by: age at blood collection, year of blood collection, breast cancer subtype, and stage. The median follow up was 3.4 years (range, 1-9 years). We extracted RNA from plasma and analyzed the expression of 800 miRNAs using Nanostring technology. We then assessed the expression of miRNAs in primary and metastatic breast cancer samples from The Cancer Genome Atlas (TCGA). We found that, miR-24-3p was upregulated in patients with metastases, both in plasma and in breast cancer tissues. Patients whose primary tumors expressed high levels of miR-24-3p had a significantly lower survival rate compared to patients with low mir-24-3p levels in the TCGA cohort (n=1,024). RNA-Seq data of the samples with the highest miR-24-3p expression versus those with the lowest miR-24-3p in the TCGA cohort identified a specific gene expression signature for those tumors with high miR-24-3p. Possible target genes for miR-24-3p were predicted based on gene expression and binding site, and their effects on cancer pathways were evaluated. Cancer, breast cancer and proteoglycans were the top three pathways affected by miR-24-3p overexpression.

DUSP4 is associated with increased resistance against anti-HER2 therapy in breast cancer

The majority of patients develop resistance against suppression of HER2-signaling mediated by trastuzumab in HER2 positive breast cancer (BC). HER2 overexpression activates multiple signaling pathways, including the mitogen-activated protein kinase (MAPK) cascade. MAPK phosphatases (MKPs) are essential regulators of MAPKs and participate in many facets of cellular regulation, including proliferation and apoptosis. We aimed to identify whether differential MKPs are associated with resistance to targeted therapy in patients previously treated with trastuzumab. Using gene chip data of 88 HER2-positive, trastuzumab treated BC patients, candidate MKPs were identified by Receiver Operator Characteristics analysis performed in R. Genes were ranked using their achieved area under the curve (AUC) values and were further restricted to markers significantly associated with worse survival. Functional significance of the two strongest predictive markers was evaluated in vitro by gene silencing in HER2 overexpressing, trastuzumab resistant BC cell lines SKTR and JIMT-1. The strongest predictive MKPs were DUSP4/MKP-2 (AUC=0.75, p=0.0096) and DUSP6/MKP-3 (AUC=0.77, p=5.29E-05). Higher expression for these correlated to worse survival (DUSP4: HR=2.05, p=0.009 and DUSP6: HR=2, p=0.0015). Silencing of DUSP4 had significant sensitization effects – viability of DUSP4 siRNA transfected, trastuzumab treated cells decreased significantly compared to scramble-siRNA transfected controls (SKTR: p=0.016; JIMT-1: p=0.016). In contrast, simultaneous treatment with DUSP6 siRNA and trastuzumab did not alter cell proliferation. Our findings suggest that DUSP4 may represent a new potential target to overcome trastuzumab resistance.

A phase I trial of ganetespib in combination with paclitaxel and trastuzumab in patients with human epidermal growth factor receptor-2 (HER2)-positive metastatic breast cancer

BACKGROUND

Targeted therapies in HER2-positive metastatic breast cancer significantly improve outcomes but efficacy is limited by therapeutic resistance. HER2 is an acutely sensitive Heat Shock Protein 90 (HSP90) client and HSP90 inhibition can overcome trastuzumab resistance. Preclinical data suggest that HSP90 inhibition is synergistic with taxanes with the potential for significant clinical activity. We therefore tested ganetespib, a HSP90 inhibitor, in combination with paclitaxel and trastuzumab in patients with trastuzumab-refractory HER2-positive metastatic breast cancer.

METHODS

In this phase I dose-escalation study, patients with trastuzumab-resistant HER2-positive metastatic breast cancer received weekly trastuzumab (2 mg/kg) and paclitaxel (80 mg/m²) on days 1, 8, 15, and 22 of a 28-day cycle with escalating doses of ganetespib (100 mg/m², 150 mg/m², and a third cohort of 125 mg/m² if needed) on days 1, 8, and 15. Therapy was continued until disease progression or toxicity. The primary objective was to establish the safety and maximum tolerated dose and/or recommended phase II dose (RP2D) of this therapy. The secondary objectives included evaluation of the effects of ganetespib on the pharmacokinetics of paclitaxel, and to make a preliminary assessment of the efficacy of the combination therapy.

RESULTS

Dose escalation was completed for the two main cohorts without any observed dose-limiting toxicities. Nine patients received treatment. The median prior lines of anti-HER2 therapy numbered three (range 2-4), including prior pertuzumab in 9/9 patients and ado-trastuzumab emtansine (T-DM1) in 8/9 patients. The most common grade 1/2 adverse events (AEs) were diarrhea, fatigue, anemia, and rash. There were no grade 4 AEs related to ganetespib. The overall response rate was 22% (2/9 patients had partial response) and stable disease was seen in 56% (5/9 patients). The clinical benefit rate was 44% (4/9 patients). The median progression-free survival was 20 weeks (range 8-55).

CONCLUSION

The RP2D of ganetespib is 150 mg/m² in combination with weekly paclitaxel plus trastuzumab. The combination was safe and well tolerated. Despite prior taxanes, pertuzumab, and T-DM1, clinical activity of this triplet regimen in this heavily pretreated cohort is promising and warrants further study in HER2-positive metastatic breast cancer.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02060253 . Registered 30 January 2014.

Abstract LB-165: Personalized prognostic prediction models for breast cancer recurrence and survival incorporating multidimensional data

Background: In this study, we developed integrative, personalized prognostic models for breast cancer recurrence and overall survival (OS) that consider receptor subtypes, epidemiological data, quality of life (QoL), and treatment.

Methods: 15,314 women with stage I to III invasive primary breast cancer treated at The University of Texas MD Anderson Cancer Center between 1997 and 2012 was used to generate prognostic models by Cox regression analysis including 10,809 women as discovery population (median follow-up: 6.09 years, 1,144 recurrence and 1,627 deaths) and 4,505 women as validation population (median follow-up: 7.95 years, 684 recurrence and 1,095 deaths). Model performance was assessed by calculating the area under the curve (AUC) and calibration analysis and compared with Nottingham Prognostic Index (NPI) and PREDICT.

Results: In addition to the known clinical/pathological variables, the model for recurrence included alcohol consumption while the model for OS included smoking status and physical component summary score. The AUCs for recurrence and OS were 0.813 and 0.810 in the discovery and 0.807 and 0.803 in the validation, respectively, compared to AUC of 0.761 and 0.753 in discovery and 0.777 and 0.751 in validation for NPI. Our model further showed better calibration compared to PREDICT. We also developed race-specific and receptor subtype-specific models with comparable AUC. Racial disparity was evident in the distributions of many risk factors and clinical presentation of the disease.

Conclusions: Our integrative prognostic models for breast cancer exhibit high discriminatory accuracy and excellent calibration and are the first to incorporate receptor subtype, epidemiological and QoL data.

Citation Format: Xifeng Wu, Yuanqing Ye, Carlos H. Barcenas, Wong-Ho Chow, Qing H. Meng, Mariana Chavez Mac Gregor, Michelle Hildebrandt, Hua Zhao, Xiangjun Gu, Yang Deng, Elizabeth A. Wagar, Francisco J. Esteva, Debu Tripathy, Gabriel N. Hortobagyi. Personalized prognostic prediction models for breast cancer recurrence and survival incorporating multidimensional data [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-165. doi:10.1158/1538-7445.AM2017-LB-165

Personalized Prognostic Prediction Models for Breast Cancer Recurrence and Survival Incorporating Multidimensional Data

Background

In this study, we developed integrative, personalized prognostic models for breast cancer recurrence and overall survival (OS) that consider receptor subtypes, epidemiological data, quality of life (QoL), and treatment.

Methods

A total of 15 314 women with stage I to III invasive primary breast cancer treated at The University of Texas MD Anderson Cancer Center between 1997 and 2012 were used to generate prognostic models by Cox regression analysis in a two-stage study. Model performance was assessed by calculating the area under the curve (AUC) and calibration analysis and compared with Nottingham Prognostic Index (NPI) and PREDICT.

Results

Host characteristics were assessed for 10 809 women as the discovery population (median follow-up = 6.09 years, 1144 recurrence and 1627 deaths) and 4505 women as the validation population (median follow-up = 7.95 years, 684 recurrence and 1095 deaths). In addition to the known clinical/pathological variables, the model for recurrence included alcohol consumption while the model for OS included smoking status and physical component summary score. The AUCs for recurrence and OS were 0.813 and 0.810 in the discovery and 0.807 and 0.803 in the validation, respectively, compared with AUCs of 0.761 and 0.753 in discovery and 0.777 and 0.751 in validation for NPI. Our model further showed better calibration compared with PREDICT. We also developed race-specific and receptor subtype-specific models with comparable AUCs. Racial disparity was evident in the distributions of many risk factors and clinical presentation of the disease.

Conclusions

Our integrative prognostic models for breast cancer exhibit high discriminatory accuracy and excellent calibration and are the first to incorporate receptor subtype and epidemiological and QoL data.

Double-blind, randomized phase III study to compare the efficacy and safety of CT-P6, trastuzumab biosimilar candidate versus trastuzumab as neoadjuvant treatment in HER2 positive early breast cancer (EBC)

510

Background: CT-P6 (C) is a proposed biosimilar to trastuzumab. This trial (NCT02162667) evaluated the similarity of C and trastuzumab in efficacy and safety for HER2+ EBC. Methods: 549 patients with HER2+ EBC were randomized to receive C (n=271) or trastuzumab (n=278) in combination with docetaxel (Cycles 1-4) and 5-fluorouracil, epirubicin, and cyclophosphamide (Cycles 5-8). C or trastuzumab was administered at 8 mg/kg (Cycle 1 only) followed by 6 mg/kg every 3 weeks. The primary endpoint was pathological complete response (pCR) rate at surgery. Secondary endpoints were overall response rate (ORR), PK, PD and safety. After surgery, patients received adjuvant C or trastuzumab to complete a total of 1-year treatment. Results: The pCR rate was 46.8% for C and 50.4% for trastuzumab. The 95% CIs for the risk ratio estimate were within the equivalence margin (0.74, 1.35) in PPS and ITT analyses. Other efficacy endpoints were similar between C and trastuzumab. The proportion of patients with at least 1 treatment-emergent SAE was 6.6% for C and 7.6% for trastuzumab. Only 1 patient in each group withdrew treatment due to significant LVEF decrease. Infusion-related reaction was reported for 8.5% of patients in C and 9.0% of patients in trastuzumab. Conclusions: This study demonstrated the similarity of efficacy in terms of pCR between CT-P6 and trastuzumab in EBC patients. Secondary efficacy endpoints also supported the similarity between CT-P6 and trastuzumab. CT-P6 was well tolerated with a similar safety profile to that of trastuzumab during the neoadjuvant period. Clinical trial information: NCT02162667. [Table: see text]

A randomized phase II trial of fulvestrant with or without ribociclib after progression on aromatase inhibition plus cyclin-dependent kinase 4/6 inhibition in patients with unresectable or metastatic hormone receptor positive, HER2 negative breast cancer

TPS1112

Background: CDK4/6i, including palbociclib and ribociclib (R), have demonstrated remarkable benefit in progression free survival (PFS) in patients (pts) with HR+, HER2- MBC with anti-estrogen therapy. Switching between anti-estrogen therapies at disease progression is standard of care in the treatment of HR+ MBC. We evaluate the strategy of switching anti-estrogen therapy to fulvestrant (F) and maintaining CDK4/6 inhibition with R in pts with HR+, HER2- MBC who have progressed on an AI + CDK4/6i. Methods: Trial Design Phase II, multi-center, randomized, double-blind, placebo-controlled trial to evaluate F +/- R in pts with HR+, HER2- MBC who have previously progressed on any AI + CDK4/6i: Screened at 2 different scenarios: Scenario 1: Before receiving any CDK4/6i Scenario 2: Time of progression of disease (POD) while being treated with an AI + CDK4/6i Intervention At randomization, pts assigned 1:1 to either a) F + R or b) F + placebo, with treatment given in 4-week cycles. Major Eligibility Criteria 1, Metastatic BC, 2. HR+ HER2-, 3. Measurable or unmeasurable disease Specific Aims Primary: PFS. Secondary: Objective response rate, clinical benefit rate, overall survival, and duration of response. Biomarker assessment: amplification of cyclin D1 and cyclin E, phosphoRb and TK1 expression, Rb1 and p16 loss, and ctDNA for ESR1 and PIK3CA mutations. Statistical Methods Assuming a median PFS of 3.8 months with F alone, we predict that F + R will lead to a median PFS of at least 6.5 months. A one-sided log-rank test with a sample size of N = 120 and alpha = 0.025, achieves 80% power to detect a difference in PFS of 2.7. With a 10% dropout, n = 132. Clinical trial registry number NCT02632045.

Phase II trial of pembrolizumab in combination with nab-paclitaxel in patients with metastatic HER2-negative breast cancer

TPS1124

Background: Immunotherapy has shown therapeutic promise in several cancers, including breast cancer. Monotherapy with anti-PD-1/anti-PD-L1 antibodies has demonstrated durable responses in patients with metastatic triple-negative breast cancer (mTNBC) (Nanda et al, JCO 2016) and metastatic estrogen receptor-positive (mER+)/HER2-negative breast cancer (Rugo et al, SABCS 2015). Furthermore, response rates have been increased with combination approaches with chemotherapy (Adams et al, ASCO 2016). Based on these results, we seek to study the anti-tumor efficacy and safety of pembrolizumab (anti-PD-1 antibody) and nab-paclitaxel, the impact of therapy on the tumor microenvironment, and predictive markers of response. Methods: This is an ongoing single-arm open-label multi-cohort phase II study of pembrolizumab and nab-paclitaxel in patients treated with ≤2 prior lines of therapy for metastatic HER2-negative breast cancer (n = 50) (ClinicalTrials.gov: NCT02752685). Thirty patients with mTNBC and 20 patients with mER+/HER2-negative breast cancer will be enrolled. Enrollment of patients with metaplastic breast cancer is encouraged. Patients will receive pembrolizumab 200 mg IV on day 1 plus nab-paclitaxel 100 mg/m2 IV on day 1 and 8 (21-day cycle). Prior taxane therapy given > 3 months before cycle 1 is allowed. Primary objective is treatment efficacy, as determined by overall response rate (RECIST 1.1). Secondary objectives include safety, progression-free survival, overall survival, and duration of response. Serial tumor biopsies will be performed to assess changes in the tumor microenvironment from baseline with chemotherapy alone (cycle 1) and then with chemoimmunotherapy (cycle 2 and subsequent cycles). Mutational and neoantigen load, TILs by histopathological assessment, TCR by immunosequencing, and immune gene profiles in tumors will be evaluated. PD-L1 expression in tumor tissue is not required for enrollment but will be assessed as a predictive marker. The potential role of the gut microbiome in modulating the immune response will also be evaluated by 16S rRNA. An initial safety run-in with 12 subjects has been completed with no unexpected toxicity. Clinical trial information: NCT02752685.

Circulating PD-L1 (programmed death-ligand 1) and outcomes in a HER2-positive metastatic breast cancer cohort treated with first-line trastuzumab

1024

Background: Recently the immune checkpoint inhibitors (ICIs) have demonstrated efficacy across a wide variety of cancers, but have been less effective in breast cancer. PD-L1 (B7-H1, CD274) is a ligand produced by many tumor cells and some immune cells, and suppresses the T cell immune response. This allows tumor cells to escape immune detection. PD-L1 is used as a companion tumor tissue IHC biomarker for patient selection for some of the FDA-approved ICIs (pembrolizumab), but not for others (nivolumab, atezolizumab). Circulating PD-L1 has been detected in multiple myeloma, renal, lung, and gastric cancer, but not in breast cancer. Here we correlated serum PD-L1 levels with outcome in a HER2-positive metastatic breast cancer cohort treated with trastuzumab. Methods: Pretreatment serum was obtained from 63 metastatic breast cancer patients before starting first-line trastuzumab-containing therapy. A novel ELLA microfluidic channel immunoassay platform (ProteinSimple, San Jose, CA) was employed to quantitate serum PD-L1. Serum PD-L1 levels were analyzed using continuous, quartile, and dichotomous (25%, median, and 75%) cutpoints. Progression-free survival (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. Results: On a continuous basis, patients with higher serum PD-L1 had a significantly reduced PFS (p = 0.045) and overall survival OS (p = 0.004) compared to patients with lower serum PD-L1 levels. Patients with the higher quartiles of serum PD-L1 also trended to have reduced PFS (0.11) and significantly reduced OS (p = 0.015) compared to the lower quartiles of serum PD-L1. Finally, using either the 25th or 75th percentile of serum PD-L1 as dichotomous cutpoint, patients with higher serum PD-L1 had significantly reduced OS (p = 0.04). Conclusions: Higher circulating PD-L1 levels were prognostic for reduced PFS and OS in HER2-positive metastatic breast cancer patients treated with first-line trastuzumab. Circulating PD-L1 deserves further study for prognostic and predictive biomarker utility in larger trials of immune checkpoint inhibitors and other immunotherapies in breast and other cancers. AA, LK contributed equally.

RNF11 sequestration of the E3 ligase SMURF2 on membranes antagonizes SMAD7 down-regulation of transforming growth factor β signaling

The activity of the E3 ligase, SMURF2, is antagonized by an intramolecular, autoinhibitory interaction between its C2 and Hect domains. Relief of SMURF2 autoinhibition is induced by TGFβ and is mediated by the inhibitory SMAD, SMAD7. In a proteomic screen for endomembrane interactants of the RING-domain E3 ligase, RNF11, we identified SMURF2, among a cohort of Hect E3 ligases previously implicated in TGFβ signaling. Reconstitution of the SMURF2·RNF11 complex in vitro unexpectedly revealed robust SMURF2 E3 ligase activity, with biochemical properties previously restricted to the SMURF2·SMAD7 complex. Using in vitro binding assays, we find that RNF11 can directly compete with SMAD7 for SMURF2 and that binding is mutually exclusive and dependent on a proline-rich domain. Moreover, we found that co-expression of RNF11 and SMURF2 dramatically reduced SMURF2 ubiquitylation in the cell. This effect is strictly dependent on complex formation and sorting determinants that regulate the association of RNF11 with membranes. RNF11 is overexpressed in certain tumors, and, importantly, we found that depletion of this protein down-regulated gene expression of several TGFβ-responsive genes, dampened cell proliferation, and dramatically reduced cell migration in response to TGFβ. Our data suggest for the first time that the choice of binding partners for SMURF2 can sustain or repress TGFβ signaling, and RNF11 may promote TGFβ-induced cell migration.

Expression of human endogenous retrovirus-K is strongly associated with the basal-like breast cancer phenotype

Human endogenous retroviruses (HERVs), which make up approximately 8% of the human genome, are overexpressed in some breast cancer cells and tissues but without regard to cancer subtype. We, therefore, analyzed TCGA RNA-Seq data to evaluate differences in expression of the HERV-K family in breast cancers of the various subtypes. Four HERV-K loci on different chromosomes were analyzed in basal, Her2E, LumA, and LumB breast cancer subtypes of 512 breast cancer patients with invasive ductal carcinoma (IDC). The results for all four loci showed higher HERV-K expression in the basal subtype, suggesting similar mechanisms of regulation regardless of locus. Expression of the HERV-K envelope gene (env) was highly significantly increased in basal tumors in comparison with the also-upregulated expression of other HERV-K genes. Analysis of reverse-phase protein array data indicated that increased expression of HERV-K is associated with decreased mutation of H-Ras (wild-type). Our results show elevation of HERV-K expression exclusively in the basal subtype of IDC breast cancer (as opposed to the other subtypes) and suggest HERV-K as a possible target for cancer vaccines or immunotherapy against this highly aggressive form of breast cancer.

Abstract P5-08-22: DUSP4 is associated with increased resistance against anti-HER2 therapy in breast cancer

Background. The majority of patients develop resistance against suppression of HER2-mediated signaling by trastuzumab in HER2 positive breast cancer (BC). HER2 overexpression activates multiple signaling pathways, including the mitogen-activated protein kinase (MAPK) cascade. MAPK phosphatases (MKPs) are essential regulators of MAPKs and participate in many facets of cellular regulation, including proliferation and apoptosis. We aimed to identify whether differential MKPs are associated with resistance to targeted therapy in patients previously treated with trastuzumab.

Methods. Using Affymetrix HGU133plus2 gene chip data of 88 HER2-positive, trastuzumab treated BC patients, candidate MKPs were identified by Receiver Operator Characteristics analysis performed in R. Genes were ranked using their achieved area under the curve (AUC) values and were further constricted to those markers significantly associated to worse survival. Functional significance of the two strongest predictive biomarkers was evaluated in vitro experiments after gene silencing in the HER2 overexpressing, trastuzumab resistant breast cancer cell lines SKBR-3-TR and JIMT-1.

Results. Out of 10 investigated MKPs, the strongest predictive genes were DUSP4/MKP2 (AUC=0.75, p=0.0096) and DUSP6/MKP3 (AUC=0.77, p=5.29E-05). Furthermore, higher expression for these correlated to worse survival in 221 HER2 positive BC patients (DUSP4: HR=1.6, p=0.04 and DUSP6: HR=1.8, p=0.0053). Silencing of DUSP4 had significant sensitization effects - viability of DUSP4 siRNA transfected, trastuzumab treated cells decreased significantly compared to scramble-siRNA transfected, trastuzumab treated controls (SKBR-3-TR: p=0.016; JIMT-1: p=0.016). In contrast, simultaneous treatment with DUSP6 siRNA and trastuzumab did not alter cell proliferation.

Conclusions. Our findings suggest that DUSP4 is involved in the development of trastuzumab resistance in HER2 positive BC.

Citation Format: Györffy B, Munkacsy G, Esteva FJ, Miquel TP, Menyhart O. DUSP4 is associated with increased resistance against anti-HER2 therapy in breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-22.