3-year invasive disease-free survival with chemotherapy de-escalation using an 18F-FDG-PET-based, pathological complete response-adapted strategy in HER2-positive early breast cancer (PHERGain): a randomised, open-label, phase 2 trial

BACKGROUND

PHERGain was designed to assess the feasibility, safety, and efficacy of a chemotherapy-free treatment based on a dual human epidermal growth factor receptor 2 (HER2) blockade with trastuzumab and pertuzumab in patients with HER2-positive early breast cancer (EBC). It used an 18fluorine-fluorodeoxyglucose-PET-based, pathological complete response (pCR)-adapted strategy.

METHODS

PHERGain was a randomised, open-label, phase 2 trial that took place in 45 hospitals in seven European countries. It randomly allocated patients in a 1:4 ratio with centrally confirmed, HER2-positive, stage I-IIIA invasive, operable breast cancer with at least one PET-evaluable lesion to either group A, where patients received docetaxel (75 mg/m2, intravenous), carboplatin (area under the curve 6 mg/mL per min, intravenous), trastuzumab (600 mg fixed dose, subcutaneous), and pertuzumab (840 mg loading dose followed by 420 mg maintenance doses, intravenous; TCHP), or group B, where patients received trastuzumab and pertuzumab with or without endocrine therapy, every 3 weeks. Random allocation was stratified by hormone receptor status. Centrally reviewed PET was conducted at baseline and after two treatment cycles. Patients in group B were treated according to on-treatment PET results. Patients in group B who were PET-responders continued with trastuzumab and pertuzumab with or without endocrine therapy for six cycles, while PET-non-responders were switched to receive six cycles of TCHP. After surgery, patients in group B who were PET-responders who did not achieve a pCR received six cycles of TCHP, and all patients completed up to 18 cycles of trastuzumab and pertuzumab. The primary endpoints were pCR in patients who were group B PET-responders after two treatment cycles (the results for which have been reported previously) and 3-year invasive disease-free survival (iDFS) in patients in group B. The study is registered with ClinicalTrials.gov (NCT03161353) and is ongoing.

FINDINGS

Between June 26, 2017, and April 24, 2019, a total of 356 patients were randomly allocated (71 patients in group A and 285 patients in group B), and 63 (89%) and 267 (94%) patients proceeded to surgery in groups A and B, respectively. At this second analysis (data cutoff: Nov 4, 2022), the median duration of follow-up was 43·3 months (range 0·0-63·0). In group B, the 3-year iDFS rate was 94·8% (95% CI 91·4-97·1; p=0·001), meeting the primary endpoint. No new safety signals were identified. Treatment-related adverse events and serious adverse events (SAEs) were numerically higher in patients allocated to group A than to group B (grade ≥3 62% vs 33%; SAEs 28% vs 14%). Group B PET-responders with pCR presented the lowest incidence of treatment-related grade 3 or higher adverse events (1%) without any SAEs.

INTERPRETATION

Among HER2-positive EBC patients, a PET-based, pCR-adapted strategy was associated with an excellent 3-year iDFS. This strategy identified about a third of patients who had HER2-positive EBC who could safely omit chemotherapy.

FUNDING

F Hoffmann-La Roche.

Clinicopathological and molecular predictors of [18F]FDG-PET disease detection in HER2-positive early breast cancer: RESPONSE, a substudy of the randomized PHERGain trial

BACKGROUND

The PHERGain study (NCT03161353) is assessing early metabolic responses to neoadjuvant treatment with trastuzumab-pertuzumab and chemotherapy de-escalation using a [18Fluorine]fluorodeoxyglucose-positron emission tomography ([18F]FDG-PET) and a pathological complete response-adapted strategy in HER2-positive (HER2+) early breast cancer (EBC). Herein, we present RESPONSE, a PHERGain substudy, where clinicopathological and molecular predictors of [18F]FDG-PET disease detection were evaluated.

METHODS

A total of 500 patients with HER2 + EBC screened in the PHERGain trial with a tumor size > 1.5 cm by magnetic resonance imaging (MRI) were included in the RESPONSE substudy. PET[-] criteria entailed the absence of  ≥ 1 breast lesion with maximum standardized uptake value (SUVmax) ≥ 1.5 × SUVmean liver + 2 standard deviation. Among 75 PET[-] patients screened, 21 with SUVmax levels < 2.5 were randomly selected and matched with 21 PET[+] patients with SUVmax levels ≥ 2.5 based on patient characteristics associated with [18F]FDG-PET status. The association between baseline SUVmax and [18F]FDG-PET status ([-] or [+]) with clinicopathological characteristics was assessed. In addition, evaluation of stromal tumor-infiltrating lymphocytes (sTILs) and gene expression analysis using PAM50 and Vantage 3D™ Cancer Metabolism Panel were specifically compared in a matched cohort of excluded and enrolled patients based on the [18F]FDG-PET eligibility criteria.

RESULTS

Median SUVmax at baseline was 7.2 (range, 1-39.3). Among all analyzed patients, a higher SUVmax was associated with a higher tumor stage, larger tumor size, lymph node involvement, hormone receptor-negative status, higher HER2 protein expression, increased Ki67 proliferation index, and higher histological grade (p < 0.05). [18F]FDG-PET [-] criteria patients had smaller tumor size (p = 0.014) along with the absence of lymph node involvement and lower histological grade than [18F]FDG-PET [+] patients (p < 0.01). Although no difference in the levels of sTILs was found among 42 matched [18F]FDG-PET [-]/[+] criteria patients (p = 0.73), [18F]FDG-PET [-] criteria patients showed a decreased risk of recurrence (ROR) and a lower proportion of PAM50 HER2-enriched subtype than [18F]FDG-PET[+] patients (p < 0.05). Differences in the expression of genes involved in cancer metabolism were observed between [18F]FDG-PET [-] and [18F]FDG-PET[+] criteria patients.

CONCLUSIONS

These results highlight the clinical, biological, and metabolic heterogeneity of HER2+ breast cancer, which may facilitate the selection of HER2+ EBC patients likely to benefit from [18F]FDG-PET imaging as a tool to guide therapy.

TRIAL REGISTRATION

Clinicaltrials.gov; NCT03161353; registration date: May 15, 2017.

Optimal [18F]FDG PET/CT Cutoff for Pathologic Complete Response in HER2-Positive Early Breast Cancer Patients Treated with Neoadjuvant Trastuzumab and Pertuzumab in the PHERGain Trial

The PHERGain trial investigated the potential of metabolic imaging to identify candidates for chemotherapy deescalation in human epidermal growth factor receptor 2 (HER2)-positive, invasive, operable breast cancer with at least 1 breast lesion evaluable by [18F]FDG PET/CT. [18F]FDG PET/CT responders were defined as patients with an SUVmax reduction (ΔSUVmax) of at least 40% in all of their target lesions after 2 cycles of trastuzumab and pertuzumab (HP) (with or without endocrine therapy). In total, 227 of 285 patients (80%) included in the HP arm showed a predefined metabolic response and received a total of 8 cycles of HP (with or without endocrine therapy). Pathologic complete response (pCR), defined as ypT0/isN0, was achieved in 37.9% of the patients. Here, we describe the secondary preplanned analysis of the best cutoff of ΔSUVmax for pCR prediction. Methods: Receiver-operating-characteristic analysis was applied to look for the most appropriate ΔSUVmax cutoff in HER2-positive early breast cancer patients treated exclusively with neoadjuvant HP (with or without endocrine therapy). Results: The ΔSUVmax capability of predicting pCR in terms of the area under the receiver-operating-characteristic curve was 72.1% (95% CI, 65.1-79.2%). The optimal ΔSUVmax cutoff was found to be 77.0%, with a 51.2% sensitivity and a 78.7% specificity. With this cutoff, 74 of 285 patients (26%) would be classified as metabolic responders, increasing the pCR rate from 37.9% (cutoff ≥ 40%) to 59.5% (44/74 patients) (P < 0.01). With this optimized cutoff, 44 of 285 patients (15.4%) would avoid chemotherapy in either the neoadjuvant or the adjuvant setting compared with 86 of 285 patients (30.2%) using the original cutoff (P < 0.001). Conclusion: In the PHERGain trial, an increased SUVmax cutoff (≥77%) after 2 cycles of exclusive HP (with or without endocrine therapy) achieves a pCR in the range of the control arm with chemotherapy plus HP (59.5% vs. 57.7%, respectively), further identifying a subgroup of patients with HER2-addicted tumors. However, the original cutoff (≥40%) maximizes the number of patients who could avoid chemotherapy.

Correlation between trophoblast cell-surface antigen-2 (Trop-2) expression and pathological complete response in patients with HER2-positive early breast cancer treated with neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab

PURPOSE

The prognostic and predictive role of trophoblast cell-surface antigen-2 (Trop-2) overexpression in human epidermal growth factor receptor 2-positive (HER2-positive) breast cancer is currently unknown. We retrospectively analyzed Trop-2 expression and its correlation with clinicopathologic features and pathological complete response (pCR) in HER2-positive early breast cancer (EBC) patients treated with neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab in the PHERGain study.

METHODS

Trop-2 expression at baseline was determined in formalin-fixed, paraffin-embedded primary tumor biopsies by immunohistochemistry and was first classified into expressing (Trop-2-positive) or not-expressing (Trop-2-negative) tumors. Then, it was classified by histochemical score (H-score) according to its intensity into low (0-9), intermediate (10-49), and high (≥ 50). The association between clinicopathologic features, pCR, and Trop-2 expression was performed with Fisher's exact test.

RESULTS

Forty-one patients with tissue evaluable for Trop-2 expression were included, with 28 (68.3%) Trop-2-positive tumors. Overall, 17 (41.46%), 14 (34.15%), and 10 (24.40%) tumors were classified as low, intermediate, and high, respectively. Trop-2 expression was significantly associated with decreased pCR rates (50.0% vs. 92.3%; odds ratio [OR] 0.05; 95% CI, 0.002-0.360]; p adjusted = 0.01) but was not correlated with any clinicopathologic features (p ≥ 0.05). Tumors with the highest Trop-2 H-score were less likely to obtain a pCR (OR 0.03; 95% CI, 0.001-0.290, p adjusted < 0.01). This association was confirmed in univariate and multivariate regression analyses.

CONCLUSION

These findings suggest a potential role of Trop-2 expression as a biomarker of resistance to neoadjuvant chemotherapy plus dual HER2 blockade and may become a strategic target for future combinations in HER2-positive EBC patients.

A single-arm study design with non-inferiority and superiority time-to-event endpoints: a tool for proof-of-concept and de-intensification strategies in breast cancer

De-escalation trials in oncology evaluate therapies that aim to improve the quality of life of patients with low-risk cancer by avoiding overtreatment. Non-inferiority randomized trials are commonly used to investigate de-intensified regimens with similar efficacy to that of standard regimens but with fewer adverse effects (ESMO evidence tier A). In cases where it is not feasible to recruit the number of patients needed for a randomized trial, single-arm prospective studies with a hypothesis of non-inferiority can be conducted as an alternative. Single-arm studies are also commonly used to evaluate novel treatment strategies (ESMO evidence tier B). A single-arm design that includes both non-inferiority and superiority primary objectives will enable the ranking of clinical activity and other parameters such as safety, pharmacokinetics, and pharmacodynamics data. Here, we describe the statistical principles and procedures to support such a strategy. The non-inferiority margin is calculated using the fixed margin method. Sample size and statistical analyses are based on the maximum likelihood method for exponential distributions. We present example analyses in metastatic and adjuvant settings to illustrate the usefulness of our methodology. We also explain its implementation with nonparametric methods. Single-arm designs with non-inferiority and superiority analyses are optimal for proof-of-concept and de-escalation studies in oncology.

Abstract P4-07-29: Olaparib plus Trastuzumab in HER2[+] BRCA-Mutated Advanced Breast Cancer Patients: The OPHELIA Study

Background: Olaparib (O) is approved for the treatment of HER2[-] patients (pts) with early or metastatic breast cancer and a germline BRCA mutation. Nevertheless, there is no evidence that HER2[+] tumors are resistant to PARPi. Preclinical data support that HER2[+] cells are sensitive to PARPi and strongly suggest that PARP inhibition augments the efficacy of trastuzumab (T). To test whether PARPi is synergistic with anti-HER2 therapy, the OPHELIA study has assessed the efficacy and safety of O in combination with T in pts with HER2[+] germinal BRCA-mutated advanced breast cancer (ABC). Methods: OPHELIA (NCT03931551) is an open-label, multicenter, single-arm, phase II trial. The study enrolled pts aged ≥18 years diagnosed of HER2[+] ABC with germinal deleterious mutations in BRCA1 or BRCA2 who had received at least one prior systemic regimen for advanced disease (including a pertuzumab- or trastuzumab emtansine based regimen). Pts received O (300 mg oral, twice daily) plus T (either loading dose of 8 mg/kg IV infusion, and subsequent 3-weekly doses of 6 mg/kg IV infusion; or 600 mg SC injection, on day 1 of every 21-day cycle) until disease progression, unacceptable toxicity, or consent withdrawal. Primary endpoint was investigator-assessed clinical benefit rate (CBR) for at least 24 weeks as per RECIST v.1.1. Secondary endpoints included overall response rate (ORR), duration of response (DoR), progression-free survival (PFS), overall survival (OS); and safety and tolerability as per NCI-CTCAE v.5.0. The primary analysis evaluated CBR (H0: ≤5%; H1: ≥30%) based on exact binomial test. Sample size was designed to attain a 90% power at 10% one-sided alpha level. Results: From Mar 25, 2019, through Mar 2, 2022, 5 pts (from a total of 42 pts evaluated) were enrolled at 17 sites in Spain. Median age was 37.0 (range 32–54) years, 1 (20.0%) patient was male, 4 (80.0%) pts carried germinal BRCA2 mutations, 4 (80.0%) pts had received ≥ 3 advanced disease treatments lines, and 4 (80.0%) pts presented ≥ 2 metastatic sites. At data cutoff (Mar 2, 2022), with a median follow-up of 18.7 months (min: 11.7; max: 22.1), 40.0% of pts remained on therapy. CBR at 24 weeks was 80.0% meeting the primary endpoint (4 of 5 pts; 95% CI, 28.4% to 99.5%, p&lt; 0.001). ORR (1 complete and 2 partial responses) was 60.0% (95% CI, 17.4% to 94.7%), and median DoR was 3.8 months (95% CI, 2.5 to 8.3 months). Two (40.0%) pts had PFS events due to disease progression at 5.2 and 1.2 months, respectively. Rest of pts were treated for 5.5, 11.2, and 19.0 months. There were 2 (40.0%) deaths at 14.0 and 18.5 months. The most common non-hematological treatment emergent adverse events (TEAEs) of any grade (G) were fatigue (60.0%; 0% G≥3), nausea (60.0%; 0% G≥3), vomiting (40.0%; 0% G≥3), and back pain (40.0%; 0% G≥3). Anemia (40.0%; 20.0% G≥3) and lymphopenia (40.0%; 20.0% G≥3) were the most frequent hematological TEAEs. One (20.0%) patient discontinued treatment because of a drug-related TEAE (leukopenia). A dose reduction of O was reported in 1 (20.0%) patient. No treatment-related deaths were reported. Conclusions: HER2 overexpression in germline BRCA-mutated ABC is infrequent. The activity observed in these 5 pts indicates that O+T combination might be of help in this group of pts. We strongly believe that randomized data are not needed, and RWE studies might help us to understand the real activity of this combination. Toxicity was as expected.

Citation Format: José E. Alés-Martínez, Judith Balmaña, Pedro Sánchez-Rovira, Francisco Javier Salvador Bofill, José Ángel García-Sáenz, Isabel Pimentel, Serafin Morales Murillo, Adela Fernández, Ainhara Lahuerta Martínez, Neus Ferrer, Pilar Zamora, Begoña Bermejo, Tamara Díaz-Redondo, María Helena Lopez-Ceballos, María Galán, Andrea Malfettone, Laura Calabuig, Miguel Sampayo-Cordero, José Manuel Pérez-García, Javier Cortés, Antonio Llombart-Cussac. Olaparib plus Trastuzumab in HER2[+] BRCA-Mutated Advanced Breast Cancer Patients: The OPHELIA Study [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 P4-07-29.

Abstract PD8-02: Metformin (MET) for the prevention of Alpelisib (ALP)-related Hyperglycemia (HG) in PIK3CA-mutated, Hormone Receptor-Positive (HR[+]) HER2-Negative (HER2[-]) Advanced Breast Cancer (ABC): The METALLICA study

Background: HG is an on-target AE of PI3K inhibition, reported in 63.7% (36.6% G≥3) of HR[+]/HER2[-] ABC patients (pts) treated with ALP plus fulvestrant in SOLAR-1. HG was the most frequent adverse event (AE) leading to ALP discontinuation (6.3%). MET reduces systemic insulin resistance and suppress PI3K and Ras signaling. METALLICA is assessing the prophylactic use of MET for prevention of ALP-induced G3-4 HG in PIK3CA-mutated, HR[+]/HER2[-] ABC pts with normal fasting glycemia or prediabetic criteria. Methods: This is an open-label, single-arm, two-cohort, phase 2 trial. Pts aged ≥18 years, ECOG PS of 0–1, and PIK3CA-mutated, HR[+]/HER2[-] ABC, progressing to an aromatase inhibitor (AI)-containing regimen, ≤2 previous endocrine therapy (ET) and ≤1 prior chemotherapy regimens for ABC were eligible. Pts were enrolled into cohorts according to glycemia at baseline: (A) pts with normal fasting glycemia &lt; 100 mg/dL and glycosylated hemoglobin (HbA1c) &lt; 5.7%; (B) pts with prediabetic fasting glycaemia 100–140 mg/dL and/or HbA1c 5.7–6.4%. Pts received oral ALP 300 mg/day, starting from C1D8, in combination with ET; fulvestrant, letrozole, or exemestane as per standard of care; and oral MET 1000 mg/day on days 1-3 and 2000 mg/day thereafter. The primary endpoint was G3-4 HG incidence as per NCI-CTCAE v.4.03 at 2 first cycles of treatment. Assessment of glycemia was performed by rigorous self-monitoring blood glucose and local laboratory confirmation in fasting conditions. Secondary endpoints included objective response (ORR), clinical benefit rate (CBR), duration of response (DoR), progression-free survival (PFS), and safety. Sample size was based on a Simon’s two-stage design in cohorts A (H0: G3-4 HG ≥25%; H1: G3-4 HG ≤10%) and B (H0: G3-4 HG ≥40%; H1: G3-4 HG ≤15%). We planned to attain 80% power at the nominal one-sided α level of 0.05 for each cohort. Results: Between Aug 30, 2020, and Mar 10, 2022, 68 pts were enrolled at 18 sites (48 cohort A, 20 cohort B). Median age was 55 (range, 29–79) years and 58.8% pts had visceral disease and an ECOG PS 0. A total of 66 (97.1%) pts had been previously treated with a CDK4/6i and 13 (19.2%) pts had received chemotherapy for advanced disease. Sixty-three (92.6%) pts received fulvestrant as ET (45 cohort A, 18 cohort B). With a median follow-up of 8 (range, 1.6–14.9) months, 28 (41.2%) pts remain on study treatment. Disease progression was the main reason for discontinuation, reported in 32 (47.1%) pts. The primary endpoint of the study was reached, with 1 (2.1%) pts (95%CI, 0.8–9.5; p &lt; 0.001) in cohort A and 3 (15%) pts (95%CI, 4.5–33; p = 0.012) in cohort B experiencing a G3-4 HG episode over the 2 first cycles of treatment. For patients on fulvestrant, G3-4 HG rates were 1 pts (2.2%) and 3 (16.7%) pts for cohorts A and B, respectively. No ALP discontinuation related to HG was reported during the first 2 treatment cycles. Median PFS in all patients was 7.4 months (95%CI, 6–NA). Among pts with measurable disease, ORR was 14 (36.8%) pts (95%CI, 21.8–54). At the time of this analysis, DoR and CBR were still immature. The most common AEs were diarrhea (67.6%; 13.2% G≥3), nausea (67.6%; 0% G≥3), and fatigue (45.6%; 2.9% G≥3). Serious AEs occurred in 15 (22.1%) pts. The main serious AEs were rash (2.9% G≥3) and vomiting (1.5% G≥3). No additional pts reported G≥3 HG after the first 2 cycles. The dose of ALP was reduced according to the protocol in 19 (27.9%) pts. Eight (11.8%) pts permanently discontinued ALP due to AEs, none of whom related to HG. No treatment-related deaths were reported. Conclusions: Prophylactic use of MET substantially reduced the incidence and severity of ALP-related HG with no additional toxicities and could be a new standard for PIK3CA-mutated, HR[+]/HER2[-] ABC pts receiving ALP plus fulvestrant or other ET.

Citation Format: Manuel Ruiz Borrego, Pablo Tolosa, Salvador Blanch, Adela Fernández, Ander Urriticoechea, Isabel Blancas, Cristina Saura, Beatriz Rojas, Begoña Bermejo, Jose Ponce, Maria Gión, Elisenda Llabres, Elena Galve, Juan Fernando Cueva, Ana López, José L Alonso-Romero, Santiago González-Santiago, Eduardo Martínez De Dueñas, Fernando Gomez Peralta, Eva Ciruelos, José Manuel Pérez-García, Antonio Llombart-Cussac, Javier Cortés. Metformin (MET) for the prevention of Alpelisib (ALP)-related Hyperglycemia (HG) in PIK3CA-mutated, Hormone Receptor-Positive (HR[+]) HER2-Negative (HER2[-]) Advanced Breast Cancer (ABC): The METALLICA study. [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 PD8-02.

Abstract PD13-10: PD13-10 Impact of Proton Pump Inhibitors (PPI) on Palbociclib (PAL) Outcomes in Hormone Receptor-Positive, HER2-Negative Advanced Breast Cancer (HR+/HER2- ABC): Exploratory Analysis of the PARSIFAL Trial

Background The use of PPI among cancer patients (pts) is quite frequent. PAL is an oral, cyclin-dependent kinase 4 and 6 inhibitor recommended to be taken under fed conditions. PAL showed a reduced solubility when gastric pH is &gt;4.5, a level commonly achieved by PPI. Observational, retrospective studies on concomitant PPI with PAL or ribociclib showed a shorter progression-free survival (PFS) among PPI users than nonusers. In the randomized, phase 2 PARSIFAL trial, PAL plus fulvestrant demonstrated no improvement in PFS and overall survival (OS) versus PAL plus letrozole as frontline treatment in HR+/HER2- ABC pts (Llombart-Cussac et al, JAMA Oncol 2021). Here we assessed the impact of PPI on PAL efficacy and safety in pts included in the PARSIFAL study. Methods Pts with endocrine-sensitive HR+/HER2- ABC and no prior therapy in advanced setting were randomly assigned to receive PAL (hard capsule formulation) plus either fulvestrant or letrozole. Pts with ≥1 PPI received over the entire PAL-based regimen were defined as PPI users, or PPI naïve (N-PPI) if no PPI was administered over the whole study treatment. We carried out two analyses considering early PPI users (E-PPI) –composed by pts who were receiving PPI since the PAL-based regimen initiation– and long-term PPI users (LT-PPI) –composed by pts who received PPI over the entire or ≥⅔ of the PAL-based regimen. PPI users defined as neither E-PPI nor LT-PPI were excluded from the analysis to avoid biases due to the PPI limited exposition. PFS, OS, and safety were compared among groups. Landmark analysis at 3, 6, 12, 18, 24, and 30 months (mo) was used for survival estimates conditional on surviving to certain time points and adjust for immortality bias in comparison between N-PPI and PPI users. Analyses were adjusted by stratification factors and patient characteristics. Results Of 486 pts included in the study, 325 (66.9%) were N-PPI. Among 161 (33.1%) PPI users, 64 (13.2%) were E-PPI and 91 (18.7%) were LT-PPI. Omeprazole was the most prescribed PPI in 80.7% (130 of 161) of PPI users. Median exposition to PPI for PPI users, E-PPI, and LT-PPI was 13.6, 15.9, and 19.4 mo, respectively. Compared with N-PPI, E-PPI and LT-PPI were older (median age, 60.5 vs 66.5 vs 67.0 years, respectively; P&lt; 0.001) and had a worse functional status (ECOG PS of 0, 60.0% vs 34.0% vs 43.0%, respectively; P=0.002). Median follow-up for the whole population was 32 mo. Median PFS was 28.7 mo in N-PPI compared with 23.0 mo in E-PPI (HR 1.5; 95%CI 1.1–2.2; P=0.024) and 23.0 mo in LT-PPI (HR 1.4; 95%CI 1.0–1.9; P=0.035). Both PPI groups had poorer median PFS than N-PPI by landmark analysis at 3 and 12 mo. Subgroup analysis showed a consistent trend regardless of endocrine partner. Three-year OS rate was 81.1% in N-PPI compared with 63.5% in E-PPI (HR 2.2; 95%CI 1.3–3.7; P=0.003) and 62.0% in LT-PPI (HR 2.1; 95%CI 1.4–3.4; P=0.001). Both PPI groups had poorer 3-year OS rate than N-PPI by landmark analysis at 3, 6, 12, and 18 mo. Grade ≥3 hematological adverse events (AEs) occurred in 71.7% (233 of 325 pts) of N-PPI compared with 57.8% (37 of 64 pts; P=0.021) of E-PPI and 54.9% (50 of 91 pts; P=0.003) of LT-PPI. Dose reductions and delays due to hematological AEs were reported in 70.8% (230 of 325 pts) of N-PPI compared with 56.3% (36 of 64 pts; P=0.018) of E-PPI and 52.7% (48 of 91 pts; P=0.002) of LT-PPI. At 3 mo, 45.8% (149 of 325 pts) of N-PPI required a dose reduction or delay due to hematological AEs compared with 39.1% (25 of 64 pts; P=0.42) of E-PPI. Conclusions Early and sustained coadministration of PPI with PAL and endocrine therapy were associated with lower efficacy, hematological toxicities, and dose modifications. Despite the post-hoc nature of the study, these findings suggest pharmacokinetic interactions between PPI and PAL capsules. Further confirmatory studies including the tablet formulation of PAL, which is expected to assure its optimal absorption, are needed.

Citation Format: Serena Di Cosimo, José Manuel Pérez-García, Meritxell Bellet Ezquerra, Florence Dalenc, Miguel Gil Gil, Manuel Ruiz Borrego, Joaquín Gavilá, Miguel Sampayo-Cordero, Elena Aguirre, Peter Schmid, Frederik Marmé, Joseph Gligorov, Andreas Schneeweiss, Joan Albanell, Pilar Zamora, Duncan Wheatley, Eduardo Martínez De Dueñas, Vicente Carañana, Kepa Amillano, Andrea Malfettone, Javier Cortés, Antonio Llombart-Cussac. PD13-10 Impact of Proton Pump Inhibitors (PPI) on Palbociclib (PAL) Outcomes in Hormone Receptor-Positive, HER2-Negative Advanced Breast Cancer (HR+/HER2- ABC): Exploratory Analysis of the PARSIFAL 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 PD13-10.

Abstract PD7-02: Trastuzumab Deruxtecan in patients with Unstable Central Nervous System Involvement from HER2-Low Advanced Breast Cancer: The DEBBRAH Trial

Background: The antibody-drug conjugate trastuzumab deruxtecan (T-DXd) significantly improved survival outcomes of HER2-low advanced breast cancer (ABC) patients (pts) compared to standard chemotherapy in the DESTINY-Breast04 trial. DEBBRAH is assessing the efficacy and safety of T-DXd in HER2[+] and HER2-low ABC pts with a history of brain metastases (BM) and/or leptomeningeal carcinomatosis (LMC); here, we report results of HER-low ABC pts. Methods: DEBBRAH (NCT04420598) is a multicenter, open-label, five-cohort, non-comparative, phase 2 study across 18 hospitals in 2 countries. A total of 39 pts aged ≥18 years with pretreated HER2[+] or HER2-low ABC with stable, progressing, or untreated BM and/or LMC, were enrolled in 5 cohorts: (1) HER2[+] ABC with non-progressing BM after radiotherapy and/or surgery; (2) HER2[+] or HER2-low ABC with asymptomatic untreated BM; (3) HER2[+] ABC with progressing BM after local treatment; (4) HER2-low ABC with progressing BM after local treatment; (5) HER2[+] or HER2-low ABC with LMC. Pts received 5.4 mg/kg T-DXd intravenously once every 21 days until disease progression, unacceptable toxicity, or consent withdrawal. Primary endpoint for cohorts 2 and 4 was intracranial overall response rate (ORR-IC) according to RANO-BM. Secondary endpoints included overall response (ORR) according to RECIST v1.1, progression-free survival (PFS), duration of response (DoR), clinical benefit rate (CBR); and safety and tolerability as per NCI-CTCAE v.5.0. Primary analysis is the estimation of ORR-IC (H0: ORR-IC ≤5%; H1: ORR-IC ≥40%) based on the one-sided binomial exact test. Sample size was planned to attain an 80% power at a nominal α level of 0.05 in each cohort. Results from cohort 2 should be considered descriptive since formal testing has to be performed in the whole cohort of pts with HER2[+] or HER2-low ABC and asymptomatic untreated BM. Results: From Oct 23, 2020, through Feb 15, 2022, 6 pts and 7 pts were allocated into cohorts 2 and 4, respectively. One patient with LMC included in cohort 4 was excluded from analysis. Median age was 54 (range 40–73) years. Median number of previous lines of therapy for advanced disease was 7 (range, 4-8) and 3 (range, 2-4) for cohorts 2 and 4, respectively. Median follow-up was 9.5 months (range, 1.6-15.7). At data cutoff (Apr 29, 2022), no patient of cohort 2 and 3 (50.0%) pts of cohort 4 remained on therapy. In cohort 2, ORR-IC was 66.7% (4 of 6 pts had intracranial partial response [PR]; 95% CI, 22.3–95.7). In cohort 4, ORR-IC was 33.3% meeting the primary endpoint (2 of 6 pts had intracranial PR; 95% CI, 4.3–77.7; P = .033). Overall, ORR-IC in all pts was 50% (6 of 12 pts; 95% CI, 21.1-78.9) and CBR was 66.7% (8 of 12 pts; 95% CI, 34.9-90.1). Combining pts with measurable intracranial or extracranial disease from cohorts 2 and 4, ORR, CBR and median DoR were 41.7% (5 of 12 pts; 95% CI, 15.2–72.3), 50.0% (6 of 12 pts; 95% CI, 21.1–78.9), and 7.2 months (95% CI, 2.5-16.4), respectively. Median PFS was 5.7 months (95% CI, 4.7-NA) among these pts. The most common treatment emergent adverse events (TEAEs) of any grade (G) were fatigue (58.3%; 8.3% G≥3) and nausea (50.0%; 0% G≥3). Two (16.7%; 0% G≥3) cases of interstitial lung disease/pneumonitis were reported. Serious unrelated TEAEs occurred in 2 (16.7%) of 12 pts; 1 case of general pain (G3) and 1 case of venous embolism (G5) that led to death. There were no drug-related deaths due to TEAEs. Conclusions: T-DXd showed a preliminary antitumor activity in pretreated HER2-low ABC pts with asymptomatic untreated or progressing BM after local treatment. The substantial response of BM to T-DXd in this setting is promising and warrants further investigation.

Citation Format: José Manuel Pérez-García, Marta Vaz Batista, Patricia Cortez-Castedo, Manuel Ruiz Borrego, Juan Miguel Cejalvo, Juan de la Haba-Rodríguez, Laia Garrigós, Fabriccio Racca, Sonia Servitja, Salvador Blanch, Maria Gión, Mónica Nave, Adela Fernández, Alejandro Martínez-Bueno, Antonio Llombart-Cussac, Miguel Sampayo-Cordero, Andrea Malfettone, Javier Cortés, Sofía Braga. Trastuzumab Deruxtecan in patients with Unstable Central Nervous System Involvement from HER2-Low Advanced Breast Cancer: The DEBBRAH 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 PD7-02.

Abstract GS2-02: GS2-02 Trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer: Updated survival results of the randomized, phase 3 study DESTINY-Breast03

Background: Trastuzumab deruxtecan (T-DXd) is approved in the United States and European Union for use in patients (pts) with HER2+ unresectable/metastatic breast cancer (mBC) after ≥1 prior anti–HER2 regimen(s). Approval was based on the randomized, multicenter, open-label, phase 3 DESTINY-Breast03 study (NCT03529110), in which T-DXd demonstrated statistically significant and clinically meaningful improvement in progression-free survival (PFS) compared with trastuzumab emtansine (T-DM1). At the primary interim analysis (data cutoff May 21, 2021), the risk of disease progression or death was reduced by 72% with T-DXd (P &lt; 0.001; Cortes et al. N Engl J Med 2022). Overall survival (OS) data were immature for both treatment groups; although the prespecified cutoff for significance was not reached (NR), a trend toward benefit with T-DXd was observed. With further follow-up, we report results from the prespecified OS analysis of DESTINY-Breast03 (data cutoff July 25, 2022), including updated efficacy and safety.

Methods: Pts with HER2+ mBC previously treated with trastuzumab and a taxane in either the metastatic setting or (neo)adjuvant setting with progression within 6 mo of therapy, who could have received pertuzumab, were randomly assigned 1:1 to receive T-DXd 5.4 mg/kg every 3 weeks (Q3W) or T-DM1 3.6 mg/kg Q3W until disease progression. The primary endpoint was PFS by blinded independent central review (BICR). The key secondary endpoint was OS (80% powered at 2-sided significance level of 5%); other secondary endpoints included objective response rate (ORR), duration of response (DoR), PFS based on investigator assessment, and safety.

Results: 524 pts received either T-DXd (n = 261) or T-DM1 (n = 263). As of the updated data cutoff, median duration of study follow-up was 28.4 mo (range, 0.0-46.9 mo) for T-DXd and 26.5 mo (range, 0.0-45.0 mo) for T-DM1. Median treatment duration was 18.2 mo (range, 0.7-44.0 mo) for T DXd and 6.9 mo (range, 0.7-39.3 mo) for T-DM1. The risk of death was reduced by 36% (HR, 0.64; P = 0.0037) with T-DXd; median OS (mOS) was NR (95% CI, 40.5 mo-not evaluable [NE]), with 72 (27.6%) OS events, for T-DXd vs NR (95% CI, 34.0 mo-NE), with 97 (36.9%) OS events, for T-DM1. Landmark 12-mo OS rate was 94.1% (95% CI, 90.4-96.4) for T-DXd vs 86.0% (95% CI, 81.1-89.8) for T-DM1; 24-mo OS rate was 77.4% (95% CI, 71.7-82.1) for T-DXd vs 69.9% (95% CI, 63.7-75.2) for T-DM1. The P value for OS crossed the prespecified boundary (P = 0.013) and was statistically significant. mPFS by BICR was 28.8 mo (95% CI, 22.4-37.9 mo) with T-DXd, compared with 6.8 mo (95% CI, 5.6-8.2 mo) with T-DM1; HR, 0.33; nominal P &lt; 0.000001. Key efficacy and safety results are shown in the table. Grade ≥3 treatment-emergent adverse events were experienced by 56.4% of T-DXd-treated pts and 51.7% of T DM1-treated pts. Drug-related interstitial lung disease/pneumonitis, as evaluated by an independent adjudication committee, was experienced by 39 pts (15.2%) in the T-DXd arm and 8 pts (3.1%) in the T DM1 arm; no adjudicated drug-related grade 4 or 5 events were observed in pts who received T-DXd.

Conclusions: Updated results confirm the superiority of T-DXd compared with T-DM1 for pts with HER2+ mBC previously treated with an anti-HER2 therapy, with highly clinically meaningful and statistically significant benefit in OS and PFS and a manageable safety profile with longer treatment duration.

Editorial Acknowledgment

Under the guidance of authors, assistance in medical writing and editorial support was provided by Laura Halvorson, PhD, and Rachel Hood, PhD, of ApotheCom, and was funded by Daiichi Sankyo.

Funding

This study was funded by Daiichi Sankyo and AstraZeneca.

Table. Summary of Efficacy Results for T-DXd and T-DM1

Citation Format: Sara Hurvitz, Roberto Hegg, Wei-Pang Chung, Seock-Ah Im, William Jacot, Vinod Ganju, Joanne Win Yang Chiu, Binghe Xu, Erika Hamilton, Srinivasan Madhusudan, Hiroji Iwata, Sevilay Altintas, Jan-Willem Henning, Giuseppe Curigliano, José Manuel Pérez-García, Anton Egorov, Yali Liu, Jillian Cathcart, Shahid Ashfaque, Javier Cortés. GS2-02 Trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer: Updated survival results of the randomized, phase 3 study DESTINY-Breast03 [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 GS2-02.

Abstract P5-02-38: Leptin receptor (Ob-R)/leptin axis significantly modulates tumour-infiltrating lymphocytes (TILs) and PD-1 expression in early HER2+ breast cancer (BC) emerging as a new surrogate marker for immunotherapy

Leptin receptor (Ob-R)/leptin axis significantly modulates tumour-infiltrating lymphocytes (TILs) and PD-1 expression in early HER2+ breast cancer (BC) emerging as a new surrogate marker for immunotherapy. Background: There is strong pre-clinical evidence that obesity produces T-cell dysfunction and high PD-1 expression resulting in a paradoxical benefit from immunotherapy. This effect is driven, at least in part, by leptin that exerts its action through binding Ob-R, which is known to be highly expressed in HER2+ BC. TILs correlate with pathological response and long-term outcomes in BC; however the precise mechanism by which these T-cells are activated in and around tumour remains partially unknown. The primary aim of this study was to investigate the role of Ob-R/leptin axis in modulating TILs and PD-1 expression and its effect in pathological response in early HER2+ BC patients who have received neoadjuvant systemic treatment (NST). Methods: Women with HER2+ BC receiving anti-HER2-based NST followed by surgical resection were evaluated. Patient’s height and weight were measured before NST to calculate the body mass index (BMI). Based on the IHC results in diagnostic biopsy, tumors were categorized as HER2+/HR+ and HER2+/HR-. Ob-R expression was routinely measured in the diagnostic biopsy using the BOND RX Research Platform (Leica Biosystems). The Ob-R was classified as over-expressed if there were more than 50% positive cells with weak or strong staining. TILs and PD-1 expression were scored centrally in pre-treatment biopsy. TILs were considered as binary, &lt; 30.0% versus ≥30.0% and PD-1 positive (&gt;1%). Associations with pathological complete response (pCR; ypT0/isN0) were assessed using chi-squared or Wilcoxon test. Results: Of the 74 HER2+ BC patients included in the study, 47 (63.5%) had over-expression of Ob-R, 26 (35.1%) were overweight/obese (BMI ≥25kg/m2), and 42 (56.8%) had pCR status. Ob-R expression was similar regardless of menopausal status, age or HR expression. Patients with Ob-R overexpressed were 21 (80.8%) of 26 with BMI ≥25kg/m2 versus 26 (54.2%) of 48 with BMI &lt; 25Kg/m2 (p=0.023). Tumors with Ob-R overexpressed had significantly higher mean levels of TILs than those with non-overexpressed Ob-R (21.4% [IQR, 7.5-30] vs 12.4% [IQR, 5-10]; p=0.009). Despite higher rates of TILs, the rate of pCR in Ob-R overexpressed tumours (57.4% [27 of 47 patients]) was not higher than in non-overexpressed tumours (55.6% [15 of 27 patients]; p=0.874). This could be due to the fact that Ob-R-overexpressed tumours had a significant higher median PD-1 expression than Ob-R-negative tumours (2% [IQR, 0.5-7.5] vs 0% [IQR, 0-1]; p&lt; 0.001). Finally, no differences were found in terms of Ob-R expression and pathological response by hormone receptor expression. Conclusions: This multidisciplinary clinical study decodes for the first time how obesity, through the OB-R/leptin axis, might activate TILs but apparently dysfunctional as it is not translated into higher pCR; probably due to the presence of exhausted features such as high PD-1 expression. The role of Ob-R together with PD-1 as a potential biomarker for immunotherapy should be further explored.

Citation Format: Laura García-Estévez, Adela Fernández, José Palacios, Miguel Sampayo, Isabel Calvo, Eva Díaz, Marta González, Belén Pérez-Míes, Silvia González, José Manuel Pérez-García, Javier Cortés, Gema Moreno-Bueno. Leptin receptor (Ob-R)/leptin axis significantly modulates tumour-infiltrating lymphocytes (TILs) and PD-1 expression in early HER2+ breast cancer (BC) emerging as a new surrogate marker for immunotherapy. [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 P5-02-38.

Palbociclib Rechallenge for Hormone Receptor-Positive/HER-Negative Advanced Breast Cancer: Findings from the Phase II BioPER Trial

PURPOSE

To assess the efficacy and exploratory biomarkers of continuing palbociclib plus endocrine therapy (ET) beyond progression on prior palbociclib-based regimen in patients with hormone receptor-positive/HER2-negative (HR+/HER2-) advanced breast cancer (ABC).

PATIENTS AND METHODS

The multicenter, open-label, phase II BioPER trial included women who had experienced a progressive disease (PD) after having achieved clinical benefit on the immediately prior palbociclib plus ET regimen. Palbociclib (125 mg, 100 mg, or 75 mg daily orally for 3 weeks and 1 week off as per prior palbociclib-based regimen) plus ET of physician's choice were administered in 4-week cycles until PD or unacceptable toxicity. Coprimary endpoints were clinical benefit rate (CBR) and percentage of tumors with baseline loss of retinoblastoma (Rb) protein expression. Additional endpoints included safety and biomarker analysis.

RESULTS

Among 33 patients enrolled, CBR was 34.4% [95% confidence interval (CI), 18.6-53.2; P < 0.001] and 13.0% of tumors (95% CI, 5.2-27.5) showed loss of Rb protein expression, meeting both coprimary endpoints. Median progression-free survival was 2.6 months (95% CI, 1.8-6.7). No new safety signals were reported. A signature that included baseline mediators of therapeutic resistance to palbociclib and ET (low Rb score, high cyclin E1 score, ESR1 mutation) was independently associated with shorter median progression-free survival (HR, 22.0; 95% CI, 1.71-282.9; P = 0.018).

CONCLUSIONS

Maintaining palbociclib after progression on prior palbociclib-based regimen seems to be a reasonable, investigational approach for selected patients. A composite biomarker signature predicts a subset of patients who may not derive a greater benefit from palbociclib rechallenge, warranting further validation in larger randomized controlled trials.

Palbociclib with Fulvestrant or Letrozole in Endocrine-Sensitive Patients with HR-Positive/HER2-Negative Advanced Breast Cancer: A Detailed Safety Analysis of the Randomized PARSIFAL Trial

BACKGROUND

Palbociclib has gained a central role in the treatment of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). Despite its manageable toxicity profile, venous thromboembolism (VTE) or interstitial lung disease (ILD)/pneumonitis may infrequently occur. Therefore, we provide a comprehensive summary of the safety and tolerability of the combination of endocrine therapy and palbociclib among patients included in the randomized phase 2 PARSIFAL study.

MATERIALS AND METHODS

Patients with endocrine-sensitive HR+/HER2- ABC and no prior therapy in an advanced setting (n = 486) were randomly assigned 1:1 to receive fulvestrant-palbociclib (FP) or letrozole-palbociclib (LP). Laboratory tests and the incidence of adverse events (AEs) were recorded at baseline and day 1 of each cycle. Progression-free survival (PFS) was estimated for patients with and without VTE.

RESULTS

A total of 483 patients were analyzed. Neutropenia, leukopenia, anemia, asthenia, arthralgia, fatigue, and diarrhea were the most frequent AEs in both groups. Febrile neutropenia occurred in 3 (1.2%) patients of the FP group and in 1 (0.4%) patient in the LP group. Six (2.5%; 0.4% grade 3) patients in the FP group and 6 patients (2.5%; 0.4% grade 3) in the LP group experienced ILD/pneumonitis. Pulmonary embolism was reported in 12 (5.0%) patients in the FP group and 6 (2.5%) patients in the LP group. Advanced age at baseline was the only factor significantly associated with an increased risk of pulmonary embolism (P < .01).

CONCLUSION

The PARSIFAL data confirmed the favorable safety profile of both palbociclib regimens. VTE and ILD/pneumonitis were occasionally reported, and their early detection allowed patients to continue treatment effectively without detriment to efficacy.

CLINICALTRIALS.GOV IDENTIFIER

NCT02491983; https://clinicaltrials.gov/ct2/show/NCT02491983).

Pembrolizumab in combination with tocilizumab in high-risk hospitalized patients with COVID-19 (COPERNICO): A randomized proof-of-concept phase II study

OBJECTIVES

Severe COVID-19 is associated with immune dysregulation and hyperinflammation (lymphocyte exhaustion and elevated interleukin 6. Pembrolizumab (P; immune-activating anti-programmed cell death-1 antibody) plus tocilizumab (TCZ; anti- interleukin 6 receptor antibody) might interrupt the hyperinflammation and restore cellular immunocompetence. We assessed the efficacy and safety of P + TCZ + standard of care (SOC) in high-risk, hospitalized patients with COVID-19 pneumonia without mechanical ventilation.

METHODS

Randomized, controlled, open-label, phase II trial in patients with severe SARS-CoV-2 infection to assess the hospitalization period to discharge.

RESULTS

A total of 12 patients were randomized (P + TCZ + SOC, n = 7; SOC, n = 5). Nine (75%) were males, with a median age of 68 (41-79) years. The median time to discharge for P + TCZ + SOC and SOC was 10 and 47.5 days (P = 0.03), with zero (n = 1 patient had P-related grade 5 myositis) and two COVID-19-related deaths, respectively.

CONCLUSION

The addition of P and TCZ to SOC reduced the hospitalization period, with higher and faster discharges without sequelae than SOC alone.

Trastuzumab and pertuzumab without chemotherapy in early-stage HER2+ breast cancer: a plain language summary of the PHERGain study

WHAT IS THIS SUMMARY ABOUT?

This is a summary of a publication about the PHERGain study, which was published in The Lancet Oncology in May 2021. The study includes 376 women with a type of breast cancer called HER2-positive breast cancer that can be removed by surgery. In the study, researchers wanted to learn if participants could be treated with two medicines called trastuzumab and pertuzumab without the need for chemotherapy. To identify HER2-positive tumors with more sensitivity to anti-HER2 therapies, the researchers used a type of imaging called a FDG-PET scan to check how well the treatments were working.

WHAT HAPPENED IN THE PHERGAIN STUDY?

Participants took a treatment before surgery, consisting of either chemotherapy (docetaxel and carboplatin) plus trastuzumab and pertuzumab (group A) or trastuzumab and pertuzumab alone (plus hormone therapy if the tumor was hormone receptor-positive; group B). After two cycles of treatment, participants underwent a FDG-PET scan. Participants assigned to group A completed 6 cycles of treatment regardless of ¹⁸F-FDG-PET results. Participants in group B continued the same treatment until surgery if their FDG-PET scan showed the treatment was working. While participants who did not show a response started treatment with chemotherapy in addition to trastuzumab and pertuzumab. All participants then had surgery.

WHAT WERE THE RESULTS?

The results revealed that, of the participants in group B who showed a response using FDG-PET scan, 37.9% achieved a disappearance of all invasive cancer in the breast and axillary lymph nodes. This rate appears to be higher than those reported in previous studies evaluating the same treatment. These participants also had less side effects and improved overall quality of life compared with participants taking chemotherapy plus trastuzumab and pertuzumab.

WHAT DO THE RESULTS OF THE STUDY MEAN?

Early monitoring of how well participants respond to treatment by FDG-PET scan seems to identify participants with operable HER2-positive breast cancer who were more likely to benefit from trastuzumab and pertuzumab without the need to have chemotherapy. The PHERGain study is still ongoing and results on long-term survival are expected to be released in 2023. Clinical Trial Registration: NCT03161353 (ClinicalTrials.gov).

Safety interim analysis (SIA) of atractib: A phase 2 trial of first-line (1L) atezolizumab (A) in combination with paclitaxel (P) and bevacizumab (B) in metastatic triple-negative breast cancer (mTNBC)

1084

Background: A substantial benefit from adding an immune checkpoint inhibitor to chemotherapy (CT) was reported in mTNBC patients (pts) with PD-L1+ tumors. However, many pts still have a poor outcome. ATRACTIB is exploring the synergism between A (anti-PD-L1 antibody) and B (a VEGF-targeted antibody) with P in mTNBC irrespective of PD-L1 status. We report results from protocol-specified SIA. Methods: ATRACTIB is an open-label, single-arm, phase 2 trial (NCT04408118). Pts aged ≥18 years, with unresectable locally advanced or mTNBC, ECOG performance status of 0–1, who had received no prior systemic therapy or ≥12 months since (neo)adjuvant taxane-based CT are eligible. Pts receive A (840 mg IV, days 1, 15) with P (90 mg/m2 IV, days 1, 8, 15), and B (10 mg/kg IV, days 1, 15) on each 28-day cycle until disease progression, unacceptable toxicity, or patient withdrawal. Primary endpoint is investigator-assessed progression-free survival (PFS) as per RECIST v.1.1. Secondary endpoints include objective response and clinical benefit rates, overall survival, and safety. The trial was designed to detect a treatment effect in terms of median PFS (H0: ≤7 months; H1: ≥9.5 months) and 100 pts are needed to attain 80% power at a nominal one-sided α level of 5%. One SIA was planned for evaluating safety as per CTCAE v.5.0 on the first 20 pts who had completed a 3-month follow-up or reached the end of study. Results: From Oct 5, 2020, through Nov 21, 2021, 34 pts were enrolled at 13 sites in Spain and Germany and received at least 1 dose of study treatment. Median age was 57.5 (range 40–84) years, 23 (67.6%) pts had received prior CT for early disease, and 19 (56.0%) had visceral disease. At data cutoff (Sep 30, 2021), 25 (71.4%) pts were still receiving the drug regimen. Adverse events (AEs) led to drug discontinuation in 3 (8.8%) pts. Mean relative dose intensity was 90.2% for A, 96.5% for P, and 95.7% for B. P dose reduction was reported in 7 (20.6%) pts. Five (14.7) pts required a dose delay due to AEs (11.8% for A, 11.8% for P, and 8.8% for B). The most common AEs of any grade (G) were fatigue (47.1%; 8.8% G≥3), diarrhea (38.2%; 0% G≥3), and neurotoxicity (35.3%; 8.8% G≥3). Anemia (20.6%; 0% G≥3) and neutropenia (17.6%; 8.8% G≥3) were the most frequent hematological AEs. AEs of clinical interest (AECI) for B were hypertension (17.6%; 5.9% G≥3) and pulmonary embolism (2.9%; 0% G≥3). AECI for A were pneumonitis (2.9%; 0% G≥3), autoimmune hepatitis (2.9%; 2.9% G≥3), and alanine aminotransferase increased (2.9%; 2.9% G≥3). No treatment-related deaths were reported. Conclusions: The addition of A to P and B as 1L therapy for mTNBC shows a tolerable safety profile which is consistent with known safety profile of each agent without a significant synergistic toxicity. Based on the independent data monitoring committee recommendation, patient recruitment is ongoing. Clinical trial information: NCT04408118.

Trastuzumab deruxtecan in patients with central nervous system involvement from HER2-positive breast cancer: The DEBBRAH trial

BACKGROUND

Trastuzumab deruxtecan (T-DXd) has shown durable antitumor activity in pretreated patients with HER2-positive advanced breast cancer (ABC), but its efficacy has not yet been evaluated in patients with active brain metastases (BMs). DEBBRAH aims to assess T-DXd in patients with HER2-positive or HER2-low ABC and central nervous system involvement.

METHODS

This ongoing, five-cohort, phase II study (NCT04420598) enrolled patients with pretreated HER2-positive or HER2-low ABC with stable, untreated, or progressing BMs, and/or leptomeningeal carcinomatosis. Here, we report findings from HER2-positive ABC patients with non-progressing BMs after local therapy (n = 8; cohort 1), asymptomatic untreated BMs (n = 4; cohort 2), or progressing BMs after local therapy (n = 9; cohort 3). Patients received 5.4 mg/kg T-DXd intravenously once every 21 days. The primary endpoint was 16-week progression-free survival (PFS) for cohort 1 and intracranial objective response rate (ORR-IC) for cohorts 2 and 3.

RESULTS

As of October 20, 2021, 21 patients received T-DXd. In cohort 1, 16-week PFS rate was 87.5% (95%CI, 47.3-99.7; P < .001). ORR-IC was 50.0% (95%CI, 6.7-93.2) in cohort 2 and 44.4% (95%CI, 13.7-78.8; P < .001) in cohort 3. Overall, the ORR-IC in patients with active BMs was 46.2% (95%CI, 19.2-74.9). Among patients with measurable intracranial or extracranial lesions at baseline, the ORR was 66.7% (12 out of 18 patients; 95%CI, 41.0-86.7), 80.0% (95%CI, 28.4-99.5) in cohort 1, 50.0% (95%CI, 6.7-93.2) in cohort 2, and 66.7% (95%CI, 29.9-92.5) in cohort 3. All responders had partial responses. The most common adverse events included fatigue (52.4%; 4.8% grade ≥3), nausea (42.9%; 0% grade ≥3), neutropenia (28.6%; 19% grade ≥3), and constipation (28.6%; 0% grade ≥3). Two (9.5%) patients suffered grade 1 interstitial lung disease/pneumonitis.

CONCLUSIONS

T-DXd showed intracranial activity with manageable toxicity and maintained the quality of life in pretreated HER2-positive ABC patients with stable, untreated, or progressing BMs. Further studies are needed to validate these results in larger cohorts.

Abstract OT1-12-07: A phase 2 study of chemotherapy de-escalation using a pathological response-guided strategy in patients with HER2-positive, low-risk early breast cancer: PHERGain-2

Background: The introduction of trastuzumab (H) and pertuzumab (P) and ado-trastuzumab emtansine (T-DM1) has drastically improved clinical outcomes in patients (pts) with HER2-positive early breast cancer, allowing to explore chemotherapy-sparing approaches in this population. PHERGain trial is evaluating the efficacy of dual HER2-blockade with HP as both neoadjuvant and adjuvant treatment using an 18F-fluorodeoxyglucose-PET-based and a pathological response-adapted strategy [Pérez-García JM et al., Lancet Oncol. 2021;22:858-871]. PHERGain-2 study is an additional step forward and aims to assess the feasibility of chemotherapy de-escalation with neoadjuvant HP followed by adjuvant HP or T-DM1 using a pathological response-adapted strategy in low-risk HER2-positive early breast cancer pts. Trial Design: PHERGain-2 is a multicenter, open-label, non-comparative, phase 2 trial. Eligible participants are patients aged ≥18 years with previously untreated, centrally confirmed, HER2-positive (immunohistochemical score 3+), invasive, node-negative breast cancer (&gt;0.5 and &lt;2.5 cm in tumor size). Eastern Cooperative Oncology Group performance status of 0 or 1, left ventricular ejection fraction of at least 55%, and adequate organ function are also required. Pts will receive the fixed-dose combination of HP for subcutaneous injection (1200 mg P plus 600 mg H loading dose, followed by 600 mg P plus 600 mg H maintenance doses) administered every 3 weeks for 8 cycles as neoadjuvant treatment. Hormone receptor-positive pts will be additionally given letrozole (2.5 mg/day orally) if postmenopausal or tamoxifen (20 mg/day orally) plus gonadotropin-releasing hormone analogue if pre-/peri-menopausal or men. Centrally reviewed MRI will be performed at screening and within 2 weeks prior to surgery. Surgery will be done within 4 weeks after the last dose of study treatment. After surgery, pts who achieve a pathologic complete response in breast and axilla (ypT0/is, ypN0) will continue HP for a total of 18 cycles; pts with residual invasive breast disease and/or ypN0(i+/mol+), ypN1mi will receive T-DM1 for 10 cycles; and pts with ypN1-3 will receive T-DM1 for 10 cycles and, at investigator’s discretion, chemotherapy before starting T-DM1. Adjuvant endocrine therapy and radiotherapy will be administered as per hormone receptor status and institutional practices. The primary efficacy and safety endpoints are 3-year recurrence-free interval (RFI) as per STEEP criteria and patient-reported outcomes after 1 year from neoadjuvant treatment initiation as measured by the EORTC-QLQ-C30 scale in the overall population. Key secondary endpoints include pathologic complete response, residual cancer burden, breast-conserving surgery rate; 3-year and 5-year event-free survival, relapse-free survival, distant relapse-free survival, disease-free survival, invasive disease-free survival, breast cancer-specific survival, overall survival; and safety and tolerability as per CTCAE 5.0. A total of 393 pts will be enrolled. The sample size was calculated with the log-minus-log Kaplan-Meier method. The analysis will test the null hypothesis that the 3-year RFI rate is ≤94% and the alternative hypothesis that 3-year RFI rate is ≥98%. With the expectation a 20% dropout rate, a sample size of 393 pts is necessary to attain 80% power at nominal level of two-sided alpha of 0.05. The analysis for the primary efficacy and safety endpoints will be conducted with 95% confidence intervals based on Kaplan-Meier estimator. This trial was opened to accrual in May 2021.

Citation Format: José Manuel Pérez-García, Ángel Guerrero-Zotano, Jacques Medioni, Andreas Schneeweiss, Marco Colleoni, Miguel Sampayo-Cordero, Andrea Malfettone, Javier Cortés, Antonio Llombart-Cussac. A phase 2 study of chemotherapy de-escalation using a pathological response-guided strategy in patients with HER2-positive, low-risk early breast cancer: PHERGain-2 [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 OT1-12-07.

Abstract P5-13-30: Analysis of αβ and γδ circulating T cells in the PHERGain randomized phase 2 trial for patients with HER2-positive early breast cancer receiving neoadjuvant trastuzumab and pertuzumab without chemotherapy: LINGain

Background: The presence of stromal tumor-infiltrating lymphocytes (TILs) represents an independent prognostic factor in HER2-positive early-stage breast cancer (EBC) treated with trastuzumab/pertuzumab-containing regimens. Among distinct subsets of TILs, conventional CD8+ αβ T cells require TCR signaling as a part of adaptive immunity, while γδ T cells display also innate-like activity via the NKG2D receptor contributing to a very rapid tumor immunosurveillance. Specific γδ T cell subsets were associated with remission and improved overall survival of patients with triple-negative breast cancer. However, very little is known about circulating αβ and γδ T cells and their immunological status in HER2-positive breast cancer. In this substudy, we aimed to characterize the αβ and γδ T cell subsets and the association with clinical outcome in peripheral blood of patients with HER2-positive EBC enrolled in the PHERGain trial, which assessed the possibility of chemotherapy de-escalation with neoadjuvant dual HER2 blockade with trastuzumab and pertuzumab using an 18F-fluorodeoxyglucose-PET and pathological response-adapted strategy. Methods: Peripheral blood was obtained from 24 consecutive patients who were assigned to the trastuzumab and pertuzumab group (+/- endocrine therapy as per hormone receptor status) before randomization (baseline) and after 2 treatment cycles (6 weeks). Blood samples were also collected from 48 age-matched healthy donors who represented the control group. Absolute numbers of CD3+, CD3+/CD4+, CD3+/CD8+, and CD3+/CD56+ according to the TCR expression, and annexin V apoptotic rate on αβ and γδ T cells were evaluated by flow cytometry. Subset distribution of T cell differentiation within naïve, central memory, effector memory, and terminally differentiated effector memory cells was also determined. The changes in the frequency of peripheral T cells and rate of apoptotic subsets between timepoints, patients, and healthy donors were compared with Wilcoxon test. The analyses were set at two-sided 0.05 level of significance. Results: Among 24 patients with evaluable blood samples at both timepoints, median age was 50.5 years (IQR 45.8-61), 45.8% had node-positive disease, 79.2% had hormone receptor-positive status, 79.2% had tumors with HER2 IHC 3+ status, and 54.2% achieved a pathological complete response (ypT0/is ypN0) after treatment. At baseline, levels of αβ and γδ T cells in EBC patients were significantly lower than levels in healthy subjects (P ≤0.05). After 6 weeks of study treatment, these levels in EBC patients did not significantly differ from those at baseline. Baseline rates of apoptotic subsets were higher in EBC patients than rates in healthy subjects (P &lt;0.01), but after 6 weeks of study treatment all apoptotic subsets were significantly reduced in EBC patients compared with those at baseline (P ≤0.05). No evidence of association was found between peripheral T cells and pathological complete response in EBC patients. Conclusions: These data suggest a potential involvement of T cell apoptosis on the mechanism of action mediated by dual HER2 blockade with trastuzumab and pertuzumab in patients with HER2-positive EBC. However, further validation is required. Additional data on the subset distribution of T cell differentiation status will be presented at the meeting.

Citation Format: Juan Carlos Andreu-Ballester, José Manuel Pérez-García, Begoña Bermejo, Vicente Carañana, Vega Iranzo, Joaquín Gavilà, Ana Santaballa, María Carmen Gómez-Soler, Miguel Sampayo-Cordero, Andrea Malfettone, Javier Cortes, Antonio Llombart-Cussac. Analysis of αβ and γδ circulating T cells in the PHERGain randomized phase 2 trial for patients with HER2-positive early breast cancer receiving neoadjuvant trastuzumab and pertuzumab without chemotherapy: LINGain [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 P5-13-30.

Abstract PD4-06: Trastuzumab deruxtecan in patients with HER2[+] or HER2-low-expressing advanced breast cancer and central nervous system involvement: Preliminary results from the DEBBRAH phase 2 study

Background: Approximately 30% to 40% of patients (pts) with HER2[+] advanced breast cancer (ABC) will develop brain metastases (BM) during the course of their disease. Trastuzumab deruxtecan (T-DXd; DS-8201) is an antibody-drug conjugate containing an anti-HER2 antibody, a cleavable tetrapeptide-based linker, and a topoisomerase I inhibitor payload. In the phase 2 DESTINY-Breast01 trial, T-DXd showed efficacy in the subgroup of HER2[+] ABC pts with stable BM at baseline. DEBBRAH is assessing the efficacy and safety of T-DXd in HER2[+] and HER2-low-expressing ABC pts with a history of BM and/or leptomeningeal carcinomatosis (LMC). Here, we report primary results from cohorts A and C. Methods: This is an ongoing, multicenter, open-label, 5-cohort, non-comparative, phase 2 study across 18 hospitals in 2 countries. A total of 39 pts aged ≥18 years with pretreated HER2[+] or HER2-low-expressing ABC with stable, progressing, or untreated BM and/or LMC are being enrolled in 5 cohorts: (A) HER2[+] ABC with non-progressing BM after radiotherapy and/or surgery; (B) HER2[+] or HER2-low-expressing ABC with asymptomatic untreated BM; (C) HER2[+] ABC with progressing BM after local treatment; (D) HER2-low-expressing ABC with progressing BM after local treatment; (E) HER2[+] or HER2-low-expressing ABC with LMC. In cohorts A and C, pts must have received prior taxane and ≥1 HER2-targeted therapy for ABC. Pts received 5.4 mg/kg T-DXd intravenously on day 1 of a 21-day cycle until disease progression, unacceptable toxicity, or consent withdrawal. The primary endpoint for cohort A is 16-week progression-free survival (PFS) per local assessment using RANO-BM for central nervous system (CNS) lesions and RECIST v.1.1 for extracranial lesions (H0: 5%); for cohort C, CNS overall response rate (ORR; H0: 10%). A single-arm binomial design is used for cohorts A and C. A futility interim analysis has been planned in cohort A after accrual of 4 pts. Sample size was planned to attain an 80% power at nominal level of one-sided α of 0.05 in each cohort. Results: Between Jun 29, 2020, and Feb 18, 2021, 26 pts were allocated in the study. Enrollment is complete in cohorts A (n=8 pts) and C (n=9 pts), and ongoing in the remaining cohorts. At data cutoff (May 21, 2021), median follow-up for the cohort A was 5.5 months (IQR 4.4-6.9) and 6.2 months (IQR 5.1-6.4) for the cohort C. In the cohort A, 6 (75.0%) of 8 pts were alive without disease progression at 16 weeks, reaching the primary endpoint (p&lt;0.01). In the cohort C, the CNS ORR was 55.6% (5 pts with partial response), also meeting the primary endpoint (p&lt;0.01). At the time of this analysis, 75.0% of pts of the cohort A and 55.6% of the cohort C remained on therapy. The most frequent adverse events of any grade in 26 pts who received at least 1 dose of T-DXd were fatigue (11 [42.3%]; 3.8% of grade 3), nausea (10 [38.5%]), a decreased neutrophil count (9 [34.6%]; 11.5% of grade 3), and anemia (6 [23.1%]). Treatment-related serious adverse events occurred in 1 (3.8%) of 26 pts due to grade 1 pneumonitis. No treatment-related deaths were reported. Conclusions: T-DXd demonstrated preliminary efficacy with manageable toxicity in pretreated pts with HER2[+] ABC with stable and progressing BM after local treatment. Further investigation is required in larger cohorts to validate these findings. The assessment of the T-DXd antitumor activity in cohorts B, D, and E is currently ongoing.

Citation Format: Marta Vaz Batista, Patricia Cortez, Manuel Ruiz, Juan Miguel Cejalvo, Juan de la Haba, Laia Garrigós, Fabricio Racca, Sonia Servitja, Salvador Blanch, Iris Teruel, José Manuel Pérez-García, María Gion, Monica Nave, Antonio Llombart-Cussac, Miguel Sampayo-Cordero, Andrea Malfettone, Javier Cortes, Sofia Braga. Trastuzumab deruxtecan in patients with HER2[+] or HER2-low-expressing advanced breast cancer and central nervous system involvement: Preliminary results from the DEBBRAH phase 2 study [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 PD4-06.

Abstract OT2-19-06: Phase 2 study of abemaciclib in combination with endocrine therapy with or without paclitaxel induction in patients with hormone receptor-positive, HER2-negative advanced breast cancer and aggressive disease criteria: ABIGAIL

Background: Endocrine therapy (ET) is the preferred therapy option for patients (pts) with hormone receptor-positive (HR[+]) advanced breast cancer (ABC), except for pts with visceral crisis who often receive chemotherapy to achieve rapid symptom control. Cyclin-dependent kinases 4/6 inhibitors have improved the effectiveness of ET across all subgroups of pts with ABC by targeting potential mechanisms of resistance. An exploratory analysis revealed that the addition of abemaciclib to ET conferred the largest benefit in pts with poor prognostic characteristics (liver metastases, high grade tumors, or progesterone receptor-negative status) [Di Leo, NPJ Breast Cancer 2018; 4: 41]. ABIGAIL aims to provide consistent evidence that abemaciclib plus ET is superior or non-inferior to paclitaxel in terms of early overall response as first-line regimen in HR[+], HER2-negative ABC pts with poor prognosis. Trial Design: This is a multicenter, randomized, open-label, phase 2 trial. Eligible participants are men and women of any menopausal status aged ≥18 years with HR[+], HER2-negative ABC who had no prior systemic therapy in the advanced setting and at least one of the following aggressive disease criteria: (i) Visceral disease; (ii) High histological grade and/or progesterone receptor-negative status; (iii) Lactate dehydrogenase &gt;1.5 × the upper limit of normal; (iv) Relapse while on or within 36 months of completing adjuvant ET. Eastern Cooperative Oncology Group performance status of 0 or 1, measurable disease as per RECIST 1.1, and adequate organ function are also required. A total of 160 pts will be randomly assigned (1:1) to receive abemaciclib (300 mg/day orally during each 28-day cycle) plus ET as per investigator’s criteria (either letrozole [2.5 mg/day orally] or fulvestrant [500 mg intramuscularly on days 1, 15 of cycle 1, and on day 1 thereafter], or paclitaxel (90 mg/m² intravenously on days 1, 8, 15). Men and pre-/peri-menopausal women will receive a gonadotropin-releasing hormone agonist if randomized to abemaciclib plus ET. At investigator’s discretion, pts in the paclitaxel arm could receive abemaciclib plus ET at any point after the first 12 weeks or extend chemotherapy for a total of 6 cycles. Randomization will be stratified according to the presence of visceral disease and endocrine therapy. The primary endpoint is 12-week overall response rate (ORR) as per RECIST 1.1. Key secondary endpoints include ORR, clinical benefit rate, 12-week progression-free survival, progression-free survival, time to response, duration of response, overall survival, time to first subsequent therapy, time to second subsequent therapy, and time to first chemotherapy for pts in abemaciclib plus ET arm, patient-reported outcomes, and safety as per NCI-CTCAE 5.0. The sample size assumes the comparison of two proportions in an asymptotical normal test. We expect that 12-week ORR will be higher in the abemaciclib plus ET arm than paclitaxel arm (30% vs. 15%), with the assumption of a 5% non-inferiority margin. Based on a 10% dropout rate, a sample size of 160 pts is necessary to attain 80% power at nominal level of two-sided alpha of 0.05. We will test the superiority of abemaciclib plus ET as compared with paclitaxel if the non-inferiority is achieved. Both analyses, will be conducted with the Newcombe hybrid score method for confidence intervals. This trial was opened to accrual in May 2021.

Citation Format: Antonio Llombart-Cussac, Joseph Gligorov, Serena Di Cosimo, Cinta Albacar, Patricia Cortez, Eduardo Martinez-De Dueñas, Ana López, Vicente Carañana, Jacques Medioni, Luigi Cavanna, Marina Elena Cazzaniga, Sofia Braga, Passos Coelho, Miguel Sampayo-Cordero, Andrea Malfettone, José Manuel Pérez-García, Javier Cortes. Phase 2 study of abemaciclib in combination with endocrine therapy with or without paclitaxel induction in patients with hormone receptor-positive, HER2-negative advanced breast cancer and aggressive disease criteria: ABIGAIL [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 OT2-19-06.

Surrogate endpoints for early-stage breast cancer: a review of the state of the art, controversies, and future prospects

Drug approval for early-stage breast cancer (EBC) has been historically granted in the context of registration trials based on adequate outcomes such as disease-free survival and overall survival. Improvements in long-term outcomes have made it more difficult to demonstrate the clinical benefit of a new cancer drug in large, randomized, comparative clinical trials. Therefore, the use of surrogate endpoints rather than traditional measures allows for cancer drug trials to proceed with smaller sample sizes and shorter follow-up periods, which reduces drug development time. Among surrogate endpoints for breast cancer, the increase in pathological complete response (pCR) rates was considered appropriate for accelerated drug approval. The association between pCR and long-term outcomes was strongest in patients with aggressive tumor subtypes, such as triple-negative and human epidermal growth factor receptor 2 (HER2)-positive/hormone receptor-negative breast cancers. Whereas in hormone receptor-positive/HER2-negative EBC, the most accepted surrogate markers for endocrine therapy-based trials include changes in Ki67 and the preoperative endocrine prognostic index. Beyond the classic endpoints, further prognostic tools are required to provide EBC patients with individualized and effective therapies, and the neoadjuvant setting provides an excellent platform for drug development and biomarker discovery. Nowadays, the availability of multigene signatures is offering a standardized quantitative and reproducible tool to potentiate the efficacy of standard treatment for high-risk patients and develop de-escalated treatments for patients at lower risk of relapse. In this article, we first evaluate the surrogacies used for long-term outcomes and the underlying evidence supporting the use of each surrogate endpoint for the accelerated or regular drug approval process in EBC. Next, we provide an overview of the most recent studies and innovative strategies in a (neo)adjuvant setting as a platform to accelerate new drug approval. Finally, we highlight some clinical trials aimed at tailoring systemic treatment of EBC using prognosis-related factors or early biomarkers of drug sensitivity or resistance.

Fulvestrant-Palbociclib vs Letrozole-Palbociclib as Initial Therapy for Endocrine-Sensitive, Hormone Receptor-Positive, ERBB2-Negative Advanced Breast Cancer: A Randomized Clinical Trial

Importance

The cyclin-dependent kinase 4 and 6 inhibitor palbociclib in combination with letrozole has become a standard first-line treatment for patients with endocrine-sensitive, hormone receptor-positive, ERBB2-negative advanced breast cancer. Meanwhile, the antiestrogen fulvestrant was shown to be superior to anastrozole in the absence of cyclin-dependent kinase 4 and 6 inhibition for this patient population.

Objective

To assess whether fulvestrant is superior to letrozole when combined with palbociclib in the first-line scenario.

Design, Setting, and Participants

In this international, randomized, open-label, phase 2 clinical study conducted from July 30, 2015, to January 8, 2018, patients with hormone receptor-positive, ERBB2-negative advanced breast cancer with no prior therapy in the metastatic setting and endocrine-sensitive criteria were recruited from 47 centers in 7 countries. Data were analyzed from February 11 to May 15, 2020.

Interventions

Patients were randomly assigned (1:1 ratio) to receive palbociclib with either fulvestrant or letrozole. Stratification factors were type of disease presentation (de novo vs recurrent) and the presence of visceral involvement (yes vs no).

Main Outcomes and Measures

The primary end point was investigator-assessed progression-free survival determined by Response Evaluation Criteria in Solid Tumors, version 1.1.

Results

A total of 486 women (median age, 63 years [range, 25-90 years]; 3 Asian women [0.6%]; 4 Black women [0.8%]; 461 White women [94.9%]; 18 women of unknown race [3.7%]) were randomized (243 to fulvestrant-palbociclib and 243 to letrozole-palbociclib). Median investigator-assessed progression-free survival was 27.9 months (95% CI, 24.2-33.1 months) in the fulvestrant-palbociclib group vs 32.8 months (95% CI, 25.8-35.9 months) in the letrozole-palbociclib group (hazard ratio, 1.13; 95% CI, 0.89-1.45; P = .32). This result was consistent across the stratification factors. No significant differences were observed in objective response rate (46.5% vs 50.2%) and 3-year overall survival rate (79.4% vs 77.1%) for fulvestrant-palbociclib and letrozole-palbociclib, respectively. Grade 3-4 adverse events were comparable among treatment groups, and no new safety signals were identified. No treatment-related deaths were reported.

Conclusions and Relevance

Although fulvestrant-palbociclib demonstrated significant antitumor activity, this randomized clinical trial failed to identify an improvement in progression-free survival with this regimen over letrozole-palbociclib in patients with endocrine-sensitive, hormone receptor-positive, ERBB2-negative advanced breast cancer.

Trial Registration

ClinicalTrials.gov Identifier: NCT02491983.

High Levels of Heavy Metals detected in Feathers of an Avian Scavenger Warn of a High Pollution Risk in the Atacama Desert (Chile)

The Atacama Desert represents the highest levels of mining exploitation in Chile, which inexorably results in high levels of pollution. Raptors, and particularly scavengers, have shown their usefulness to evaluate exposure to environmental contaminants in polluted scenarios. In this study, we used primary feathers from a local avian scavenger, turkey vulture Cathartes aura, to evaluate the exposure to cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) in two locations from the southern Atacama Desert (coastal and inland) and a third location from the bordering semiarid region, in northern Chile. All metals were detected in all analyzed samples (n = 54). Mean concentrations in Coastal Atacama were 0.68 ± 0.84 ppm for Cd; 1.97 ± 2.01 ppm for Pb; 59.11 ± 80.69 ppm for Cu; and 107.96 ± 51.00 ppm for Zn, while mean concentrations in Inland Atacama were 0.55 ± 0.42 ppm for Cd; 3.37 ± 2.61 ppm for Pb; 91.66 ± 77.74 ppm for Cu; and 214.03 ± 99.08 ppm for Zn. Mean concentrations in Coastal Coquimbo were 0.63 ± 0.69 ppm for Cd; 1.57 ± 0.92 ppm for Pb; 18.09 ± 6.12 ppm for Cu; and 149.37 ± 105.56 ppm for Zn. These differences could be explained by differences on abundance of mining settlements among areas. According to the literature, these values are very high for all metals, exceeding in some cases those values referred as responsible of health disorders in birds. We strongly recommend further research looking at potential adverse effects caused by heavy metal pollution on the health of human and wildlife populations in the southern Atacama Desert.

The Impact of Excluding Nonrandomized Studies From Systematic Reviews in Rare Diseases: "The Example of Meta-Analyses Evaluating the Efficacy and Safety of Enzyme Replacement Therapy in Patients With Mucopolysaccharidosis"

Nonrandomized studies are usually excluded from systematic reviews. This could lead to loss of a considerable amount of information on rare diseases. In this article, we explore the impact of excluding nonrandomized studies on the generalizability of meta-analyses results on mucopolysaccharidosis (MPS) disease. A comprehensive search of systematic reviews on MPS patients up to May 2020 was carried out (CRD42020191217). The primary endpoint was the rate of patients excluded from systematic reviews if only randomized studies were considered. Secondary outcomes included the differences in patient and study characteristics between randomized and nonrandomized studies, the methods used to combine data from studies with different designs, and the number of patients excluded from systematic reviews if case reports were not considered. More than 50% of the patients analyzed have been recruited in nonrandomized studies. Patient characteristics, duration of follow-up, and the clinical outcomes evaluated differ between the randomized and nonrandomized studies. There are feasible strategies to combine the data from different randomized and nonrandomized designs. The analyses suggest the relevance of including case reports in the systematic reviews, since the smaller the number of patients in the reference population, the larger the selection bias associated to excluding case reports. Our results recommend including nonrandomized studies in the systematic reviews of MPS to increase the representativeness of the results and to avoid a selection bias. The recommendations obtained from this study should be considered when conducting systematic reviews on rare diseases.

Nobody dares stopping clinical research, not even COVID-19

In the global health emergency caused by the COVID-19, clinical trial management has proven to be critical for the pharmaceutical industry, sponsors, and healthcare professionals. Our experience as a sponsor managing interventional oncology clinical studies has provided us with some data and insights. Though limited by sample size, our data emphasize the importance of quickly adopting measures that first prioritize patient safety and data validity, then consider contingency measures such as telemedicine, virtual medical review, and remote monitoring. Successful adaptations of healthcare and patient management in response to COVID-19 have been fundamental to ensuring continuing clinical cancer research.

Abstract PS10-27: A phase II proof-of-concept study of palbociclib (P) rechallenge in patients (pts) with hormone receptor (HR)[+]/HER2[-] metastatic breast cancer (MBC) and clinical benefit to prior P-based treatment (BIOPER)

Background: The addition of a cyclin-dependent kinase 4-6 inhibitor (CDK4/6i) to letrozole or fulvestrant significantly improves progression-free survival (PFS) and overall survival (OS) in HR[+]/HER2[-] MBC pts. At present, the optimal endocrine treatment (ET) after progression on a CDK4/6i remains unknown. However, preliminary findings revealed drivers of adaptive resistance more frequently related to ET than to CDK4/6i. BIOPER explored the efficacy and safety of continuing the same CDK4/6i in combination with a different ET agent beyond progression on prior P-based regimen in HR[+]/HER2[-] MBC and assessed predictive biomarkers to identify those pts who are more likely to benefit from this strategy. Methods: BIOPER (NCT03184090) is a multicenter, non-controlled, phase II trial. Eligible pts included pre- and post-menopausal women aged ≥18 years with HR[+]/HER2[-] MBC that showed a confirmed progressive disease (PD) after having achieved clinical benefit (response or stable disease ≥24 weeks) on immediately prior P plus ET-based regimen. Up to two prior ET lines and not more than one line of prior chemotherapy for MBC were allowed. Pts received P (oral, 75/100/125 mg/day 3 weeks on/1 week off) combined with ET of physician’s choice (including tamoxifen, exemestane, fulvestrant, anastrozole, or letrozole) until PD or unacceptable toxicity. Co-primary endpoints were clinical benefit rate (CBR) -in terms of complete or partial response [PR] and stable disease lasting ≥24 weeks as per RECIST 1.1 (H0: CBR≤5% versus H1: CBR≥20%)- and tumor molecular alterations in the cyclin D-CDK 4/6-retinoblastoma pathway detected at baseline as markers of resistance and sensitivity to P rechallenge. Secondary endpoints included investigator-assessed PFS, objective response rate (ORR), OS, and safety using the Common Terminology Criteria for Adverse Events (AEs) 4.03. Results: Between June 15, 2017 and April 25, 2019, a total of 33 pts from 21 centers in 2 countries were enrolled. Among the 33 pts who were included in the safety set, 1 patient who did not achieve clinical benefit on prior P-based regimen was excluded from the efficacy analysis (n=32). The median age was 59.5 years (range 42-80 years) and all pts were post-menopausal. A total of 25 (78.1%) pts had visceral disease (56.3% of whom with liver metastases), 16 (50%) had ECOG 0, and 19 (59.4%) presented ≥3 metastatic sites. Of 32 pts, 15 (46.9%) received letrozole, 14 (43.8%) received fulvestrant, and 3 (9.4%) exemestane. The median PFS for the prior P-based regimen was 13.8 months (mo) (95% confidence interval [CI] 5.6-47.1 mo). The median number of prior ET and chemotherapy lines for MBC was 2 (range 1-4). By the data cutoff date, 26 PFS events occurred, 5 pts were still on treatment, and 1 patient discontinued treatment because of investigator’s decision. The CBR was 34.4% (95% CI 18.6-53.2%) reaching the prespecified primary endpoint. The ORR was 3.1% (95% CI 0.1-16.2%) with 1 patient with PR. The median PFS was 2.6 mo (95% CI 1.8-5.5 mo). With a median follow-up of 11.8 mo, the OS data were immature with a total of 8 deaths (25%). The incidence of all grade (G) and G 3 or 4 (G3-4) AEs were 90.9% and 48.5%, respectively. The most common G3-4 AEs were neutropenia (42.4%) and leukopenia (6.1%). No discontinuations due to AEs and treatment-related deaths occurred. A comprehensive molecular tumor profiling will be presented during the symposium. Conclusions: Prolonging CDK4/6 blockade beyond progression on prior P-based treatment achieved the prespecified clinical benefit among pts with HR[+]/HER2[-] MBC. This strategy is currently being evaluated in the randomized phase II PALMIRA trial. Further research is ongoing to identify patient subgroups who could benefit from this treatment strategy.

Citation Format: Antonio Llombart-Cussac, Javier Cortés, Beatriz Bellosillo Paricio, Miguel Gil Gil, Giuseppe Curigliano, José Manuel Pérez-García, Laura Comerma Blesa, Manuel Ruíz Borrego, Enrique Espinosa, Lourdes Calvo, Begoña Bermejo, Meritxell Bellet, Federico Rojo Todo, Juan de la Haba, Vanesa Quiroga, Alessandro Minisini, Ana Santaballa, Miguel Sampayo, Andrea Malfettone, Joan Albanell. A phase II proof-of-concept study of palbociclib (P) rechallenge in patients (pts) with hormone receptor (HR)[+]/HER2[-] metastatic breast cancer (MBC) and clinical benefit to prior P-based treatment (BIOPER) [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 PS10-27.

Abstract PS10-17: Palbociclib (P) in combination with fulvestrant (F) or letrozole (L) in endocrine-sensitive patients (pts) with hormone receptor (HR)[+]/HER2[-] metastatic breast cancer (MBC): detailed safety analysis from a multicenter, randomized, open-label, phase II trial (PARSIFAL)

Background: P led to a meaningful improvement in clinical outcomes when used in combination with endocrine therapy for first- or later-line regimen in HR[+]/HER2[-] MBC. Grade 3-4 neutropenia was the most common adverse event (AE) in the P-containing regimens. Although venous thromboembolic events (VTE) have been rarely reported in registrational trials, a systematic review and meta-analysis of randomized controlled trials demonstrated a higher rate of these AEs. Moreover, rare but severe cases of interstitial lung disease (ILD)/pneumonitis have been observed during post-approval use of P. Here, we present a comprehensive toxicity profile of pts included in the PARSIFAL study, with particular emphasis given to AEs of special interest of the overall safety population. Methods: A total of 486 pts with HR[+]/HER2[-] MBC with no prior therapy in the advanced setting and endocrine sensitive criteria (relapse &gt;12 months [mo] after the end of adjuvant endocrine therapy or diagnosed with de novo metastatic disease) were randomly assigned 1:1 to receive P (oral 125 mg/day [d]; 3 weeks on/1 week off) plus either F (intramuscular injection 500 mg/d; d 0, 14, 28, and then every 28 ds) or L (oral 2.5 mg/d). Pts were stratified by visceral involvement and type of disease presentation (de novo/recurrent). Safety assessments included blood analysis and collection of vital signs at screening, d1 of each cycle, and end of treatment/withdrawal. Severity was graded as per the NCI Common Terminology Criteria for Adverse Events v.4.03. Results: The incidence rate of any grade, grade 3-4, and serious AEs was 99.6%, 80.9%, and 29.9%, respectively, in the FP arm, and 99.2%, 78.5%, and 21.1% in the LP arm. Discontinuations due to AEs were 5.4% in the FP arm and 2.1% in the LP arm. Neutropenia, leukopenia, anemia, asthenia, arthralgia, fatigue, and diarrhea were the most frequent AEs in both arms. Febrile neutropenia was reported in 1.2% (3 pts) and 0.4% (1 patient) in the FP and LP arms, respectively. The rate of VTE of any grade was 5.8% (14 pts) in the FP arm and 4.5% (11 pts) in the LP arm (p = 0.531). Among 18 pts who had grade ≥ 3 pulmonary embolism (PE), the incidence reported in the FP and LP arms was 5% (12 pts) vs 2.5% (6 pts), respectively, and many of them (n=16, 88.9%) were unrelated PE. Asymptomatic grade 3 PE was reported in 10 pts of the entire study population on every 3-mo CT scan. Further, in 5 pts PE was detected in the context of progressive disease. Median time from the first dose of study drugs to occurrence of PE was 4.1 mo (range 1.4-32.0 mo) in the FP arm and 7 mo (range 1.8-19.3 mo) in the LP arm. Analysis of baseline characteristics in the whole population revealed that older pts had a significantly increased risk for developing PE (69.5 years [range 47-84 years]; p &lt; 0.01). ECOG performance status, menopausal status, metastatic disease, visceral involvement, number of disease sites, and prior therapies including antithrombotic agents did not significantly increase the risk for developing PE. Grade 3 ILD/pneumonitis was rarely observed in the FP and LP arms (0.8% vs 1.2%, respectively) with no grade 4 AE. Conclusions: First-line treatment with FP and LP for HR[+]/HER2[-] MBC in the PARSIFAL study confirmed the favorable safety profile, with neutropenia representing the most common AE. Although rare, ILD/pneumonitis can be a side effect of P-based regimens. VTE and PE incidence rates were low and consistent with age-specific analyses from PALOMA trials and breast cancer population. Early detection of these AEs may assist in optimizing their management.

Citation Format: José Manuel Pérez-García, Antonio Llombart-Cussac, Meritxell Bellet, Florence Dalenc, Miguel J. Gil Gil, Manuel Ruiz Borrego, Joaquín Gavilá, Miguel Sampayo-Cordero, Elena Aguirre, Peter Schmid, Frederik Marmé, Serena Di Cosimo, Joseph Gligorov, Andreas Schneeweiss, Joan Albanell, Pilar Zamora, Duncan Wheatley, Eduardo Martínez-De Dueñas, Vicente Carañana, Kepa Amillano, Andrea Malfettone, Javier Cortés. Palbociclib (P) in combination with fulvestrant (F) or letrozole (L) in endocrine-sensitive patients (pts) with hormone receptor (HR)[+]/HER2[-] metastatic breast cancer (MBC): detailed safety analysis from a multicenter, randomized, open-label, phase II trial (PARSIFAL) [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 PS10-17.

Trastuzumab Emtansine Plus Non-Pegylated Liposomal Doxorubicin in HER2-Positive Metastatic Breast Cancer (Thelma): A Single-Arm, Multicenter, Phase Ib Trial

Simple Summary

Considering the favorable overall safety profile of trastuzumab emtansine (T-DM1), the low expected rate of cardiotoxicity, and the synergistic effect of anthracyclines with Human Epidermal Growth Factor Receptor 2 (HER2)-targeting agents, it is hypothesized that T-DM1 may be safely combined with non-pegylated liposomal doxorubicin (NPLD). In the THELMA trial, the effect of adding NPLD to T-DM1 was evaluated with the aim of enhancing T-DM1 efficacy using an extensive cardiological assessment in trastuzumab- and taxane-pretreated patients with HER2-positive metastatic breast cancer. Despite an unlikely drug synergism, this combination was generally well tolerated without clinically relevant worsening of cardiac function. No relationship was identified between early predictors of heart failure and left ventricular ejection fraction changes. Thus, the combination of T-DM1 plus NPLD is safe, but this regimen does not seem to improve T-DM1 antitumor activity in this setting.

Abstract

The paper assesses the dose-limiting toxicities and the maximum tolerated dose (MTD) of trastuzumab emtansine (T-DM1) combined with non-pegylated liposomal doxorubicin (NPLD) in HER2-positive (HER2+) metastatic breast cancer (MBC). This single-arm, open-label, phase Ib trial (NCT02562378) enrolled anthracycline-naïve HER2+ MBC patients who had progressed on trastuzumab and taxanes. Patients received a maximum of 6 cycles of NPLD intravenously (IV) at various dose levels (45, 50, and 60 mg/m²) in the “3 plus 3” dose-escalation part. During expansion, they received 60 mg/m² of NPLD every 3 weeks (Q3W) plus standard doses of T-DM1. The MTD was T-DM1 3.6 mg/kg plus NPLD 60 mg/m² administered IV Q3W. No clinically relevant worsening of cardiac function was observed. Among all evaluable patients, the overall response rate was 40.0% (95%CI, 16.3–67.7) with a median duration of response of 6.9 months (95%CI, 4.8–9.1). Clinical benefit rate was 66.7% (95%CI, 38.4–88.2) and median progression-free survival was 7.2 months (95%CI, 4.5–9.6). No significant influence of NPLD on T-DM1 pharmacokinetics was observed. The addition of NPLD to T-DM1 is feasible but does not seem to improve the antitumor efficacy of T-DM1 in HER2+ MBC patients.

The Value of Case Reports in Systematic Reviews from Rare Diseases. The Example of Enzyme Replacement Therapy (ERT) in Patients with Mucopolysaccharidosis Type II (MPS-II)

BACKGROUND

Case reports are usually excluded from systematic reviews. Patients with rare diseases are more dependent on novel individualized strategies than patients with common diseases. We reviewed and summarized the novelties reported by case reports in mucopolysaccharidosis type II (MPS-II) patients treated with enzyme replacement therapy (ERT).

METHODS

We selected the case reports included in a previous meta-analysis of patients with MPS-II treated with ERT. Later clinical studies evaluating the same topic of those case reports were reported. Our primary aim was to summarize novelties reported in previous case reports. Secondary objectives analyzed the number of novelties evaluated in subsequent clinical studies and the time elapsed between the publication of the case report to the publication of the clinical study.

RESULTS

We identified 11 innovative proposals in case reports that had not been previously considered in clinical studies. Only two (18.2%) were analyzed in subsequent nonrandomized cohort studies. The other nine novelties (81.8%) were analyzed in later case reports (five) or were not included in ulterior studies (four) after more than five years from their first publication.

CONCLUSIONS

Case reports should be included in systematic reviews of rare disease to obtain a comprehensive summary of the state of research and offer valuable information for healthcare practitioners.

Axillary staging based on molecular analysis: Results of the B-CLOSER-II study

INTRODUCTION

Axillary staging (pN) is a strong predictor of outcome in early stage breast cancer yet following the publication of the Z0011 trial there has been an increasing tendency to spare lymph node dissection. Automated molecular detection of cytokeratin 19mRNA by one-step nucleic acid amplification (OSNA) has been demonstrated to be an accurate method to assess sentinel lymph node (SLN) metastasis. In this study we compare histological and molecular methods following complete axillary lymph node dissection (cALND), determine whether molecular axillary staging affects survival, and evaluate the predictive and prognostic value of total tumor load in ALND (AD-TTL) and in all positive nodes (G-TTL).

MATERIAL AND METHODS

Axillary lymph nodes were collected from 102 patients with primary breast cancer with histological confirmation of axillary involvement (cN+) or positive SLN. The central 1-mm portion of each non-SLN was processed for hematoxylin-eosin staining and the remaining tissue was analyzed by OSNA.

RESULTS

Non-SLNs were diagnosed as positive in 72 out of 102 patients (70.6 %) on OSNA compared with only 53 (52 %) on histology (p < 0.01). Thirteen patients would have changed staging if the diagnoses provided had been by molecular methods (p < 0.01), but without a change in prognosis. AD-TTL and G-TTL were predictive of recurrence and mortality.

CONCLUSIONS

Compared to molecular detection, histological examination significantly underestimates the frequency of axillary node metastases. However, the increase in pN did not show a clinical effect on survival in those patients.

PARSIFAL: A randomized, multicenter, open-label, phase II trial to evaluate palbociclib in combination with fulvestrant or letrozole in endocrine-sensitive patients with estrogen receptor (ER)[+]/HER2[-] metastatic breast cancer

1007

Background: The CDK4/6 inhibitor palbociclib (P) in combination with letrozole (L) has become a standard first-line treatment for patients (pts) with luminal metastatic breast cancer (MBC) (PALOMA-1 & 2 trials). Meanwhile, the anti-estrogen fulvestrant (F) showed to be superior to anastrozole in the same population (FALCON trial). We aimed to identify the best endocrine agent to combine with P in this first-line scenario. Methods: A total of 486 pts with ER[+]/HER2[-] MBC with no prior therapy in the advanced setting and endocrine sensitive criteria (relapse > 12 months [mo] after the end of adjuvant endocrine therapy or diagnosed with “de novo” metastatic disease) were randomly assigned (1:1 ratio) to receive P (oral 125 mg/day [d]; 3 wks on/1 wk off) plus F 500 mg/d (I.M Days 0, 14, 28, and then every 28 d) or PL (oral 2.5 mg/d). Pts were stratified by visceral involvement and type of disease presentation (“de novo”/recurrent). Primary endpoint was investigator-assessed progression-free survival (PFS). Secondary endpoints included overall survival (OS), overall response rate (ORR), clinical benefit rate (CBR), and safety. 254 events were needed with 80% power to detect a hazard ratio (HR) ≤0.7 in favor of PF (2-sided α = 0.05). Results: By March 9th, 2020, 256 PFS events occurred. Pts characteristics were well balanced. Median age was 62 years (range: 25–90), 56.6% were ECOG 0, 40.7% had “de novo” metastatic disease, 48% had visceral disease, and 43.6% with ≥3 organ sites involved. At median follow-up of 32 mo, median PFS was 27.9 mo (95% confidence interval [CI], 24.2-33.1) with PF and 32.8 mo (95% CI, 25.8-35.9) with PL (HR: 1.1; 95% CI, 0.9-1.5; P = 0.321). No differences were observed for pts with or without visceral involvement (HR: 1.3 and HR: 0.97 respectively, interaction P = 0.275), and for “de novo” or recurrent metastatic disease (HR: 1.1 and HR: 1.1 respectively, P = 0.979). The 4-year OS rate was 67.6% in PF and 67.5% in PL arm (HR: 1; 95% CI, 0.7-1.5; P = 0.986). No differences were observed in ORR or CBR between arms. Grade ≥3 adverse events were similar in both arms, being neutropenia and leukopenia the most frequent. No treatment-related deaths were reported. Conclusion: This study was not able to identify an improvement in PFS for PF over PL in patients with endocrine-sensitive ER[+]/HER2[-] MBC. As both arms demonstrated comparable 4 years-OS, PF is a reasonable alternative to PL in this setting. Clinical trial information: NCT02491983 .

Chemotherapy (CT) de-escalation using an FDG-PET/CT (F-PET) and pathological response-adapted strategy in HER2[+] early breast cancer (EBC): PHERGain Trial

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Background: Dual trastuzumab plus pertuzumab (HP) has shown promising pathologic complete response (pCR) rates in HER2[+] EBC although lower to CT regimens. Identification of new markers of sensitivity to HP could help to de-escalate CT. PHERGain assessed early metabolic response by F-PET to neoadjuvant HP and the opportunity of CT de-escalation with a response-adapted strategy in patients (pts) with HER2[+] EBC. Methods: PHERGain randomized (1:4 ratio) centrally-confirmed HER2[+] stage I-III EBC pts to receive either docetaxel (T), carboplatin (C), and HP (cohort A) or HP ± endocrine therapy (ET) (cohort B). Randomization was stratified by hormone receptor (HR) status. Pts with subclinical metastases by F-PET were included in a different cohort (cohort C). Centrally-reviewed F-PET was performed prior to randomization and after 2 cycles of TX (cohorts A/B). Cohort A pts completed a total of 6 cycles regardless of F-PET results. Cohort B/PET-responder (RX) pts continued with HP ± ET for 6 cycles, while PET-non-RX pts were switched to receive 6 cycles of TCHP. After surgery, cohort B/PET-RX pts who did not achieve a pCR received 6 cycles of TCHP and all pts from cohorts A/B completed 18 cycles of HP. Cohort C pts received 6 cycles of TCHP. Co-primary endpoints were breast/axilla pCR rate (ypT0/isN0) among cohort B/PET-RX pts and 3-year invasive disease-free survival (iDFS) in pts allocated to cohort B. Results: A total of 376 pts were included (71 pts in cohort A, 285 pts in cohort B, and 20 pts in cohort C). In cohort B, median age was 50 years, 49.2% had node-positive disease, and 67.4% had HR+ tumors. pCR in cohort A was achieved in 41 pts (57.7%, 95% CI 47.4-69.4%) and it was observed in 101 pts included in cohort B (35.4%, 95% CI 29.9-41.3%). Among cohort B pts, 227 (79.6%) were PET-RX; 86 of them (37.9%, 95% CI 31.6-44.5%) obtained a pCR. Among PET-non-RX pts, 15 (25.9%, 95% CI 15.3-39%) achieved a pCR after adding CT (TCHP). PET-RX pCR by HR status was 44.3% for HR[-] and 35% for HR[+] (p = 0.184). The incidence of commonly reported adverse events (AEs) was higher in pts allocated to cohort A (grade≥3 AEs 58.8 vs 12%; serious AEs 29.4 vs 4.6%). The rate of pts with a ≥10% global health status decline in cohorts A and B were 40.8 and 23.5%, respectively. Conclusions: F-PET identify pts with HER2[+] EBC who are more likely to benefit from CT-free dual HER2-blockade with HP. Follow-up is ongoing for iDFS endpoint. Depending on the results of this second co-primary endpoint, this strategy could select a group of HER2[+] EBC pts who would not need CT. Clinical trial information: NCT03161353 .

Abstract OT2-09-01: A multicenter, randomized, phase II trial evaluating the efficacy of eribulin monotherapy and eribulin plus endocrine therapy in locally-recurrent or metastatic breast cancer patients after progression on endocrine therapy (REVERT study)

BACKGROUND: Previous studies have shown prolonged overall survival (OS) in patients with metastatic breast cancer (MBC) treated with eribulin, without a clear improvement in progression-free survival (PFS), which might indicate an eribulin-mediated suppression of further spread of metastasis. In addition, it was shown that 44.1% of patients with luminal B-like tumors who received neoadjuvant eribulin converted to the luminal A-like subtype, which might be associated to a more endocrine-sensitive behavior. The aim of this trial is to explore the efficacy of eribulin in combination with the same drug administered in the last endocrine therapy (ET) regimen in hormone receptor (HR)-positive (+) / human epidermal growth factor receptor 2 (HER2)-negative (-), locally-recurrent or MBC patients who had previously shown progression while on an aromatase inhibitor (AI)-containing regimen in the metastatic setting or within six months from their last AI dose in the adjuvant setting. TRIAL DESIGN: This is an open-label, randomized, multicenter phase II trial. Patients will be randomized 1:1 to receive either eribulin alone (Arm A) or eribulin in combination with the last AI administered either in the metastatic or adjuvant setting (Arm B). Patients will receive eribulin intravenously on days 1 and 8 of every 21-day cycle, alone or in combination with exemestane, letrozole, or anastrozole, until disease progression or unacceptable toxicity. Main selection criteria are: (1) Pre- or post-menopausal women, who received an AI +/- gonadotropin-releasing hormone analogue in the last ET regimen; (2) HR+ / HER2-, unresectable locally advanced or MBC; (3) Measurable disease according to the Response Evaluation Criteria In Solid Tumors (RECIST) criteria v. 1.1; (4) At least one taxane or anthracycline regimen in either the neoadjuvant or adjuvant setting; (5) Patients with no prior line of chemotherapy in the metastatic setting; (6) At least 1 and up to 3 prior lines of ET in the metastatic setting. The primary objective of the study is to assess the overall response rate (ORR) in treatment Arm B, defined as the proportion of patients with confirmed complete or partial response according to the RECIST criteria v.1.1. Secondary objectives include: (1) PFS, PFS-2, OS, clinical benefit rate, duration of response, change in maximum tumor shrinkage in both arms, and ORR in Arm A; (2) Safety-related outcome as per Common Terminology Criteria for Adverse Events v. 5.0. Patients will be accrued in a Simon’s two-stage admissible design. In stage I, the accrual goal will be a total of 22 patients. If there are at least 2 responders out of 11 in Arm B, accrual will continue to stage II until completion. Assuming an ORR of 10% in Arm A and 30% in Arm B, a sample size of 60 subjects will provide the necessary statistical precision for the observed differences between treatment arms. ClinicalTrials.gov identifier: NCT03795012.First patient enrolled on June 24th, 2019.

Citation Format: José Manuel Pérez-García, Alfonso Cortés Salgado, Elena López Miranda, Antonio Antón, Pedro Sánchez Rovira, Beatriz Castelo Fernández, Ana López González, Isabel Garau, Alejandro Martínez, Miguel Corbellas Aparicio, Sonia Del Barco, Miguel Sampayo, François Riva, Andrea Malfettone, Antonio Llombart-Cussac, Javier Cortés. A multicenter, randomized, phase II trial evaluating the efficacy of eribulin monotherapy and eribulin plus endocrine therapy in locally-recurrent or metastatic breast cancer patients after progression on endocrine therapy (REVERT study) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT2-09-01.

Abstract P4-10-17: Baseline and pharmacodynamic changes of circulating exosomal microRNAs predict early versus late progression to palbociclib plus endocrine therapy in patients with metastatic breast cancer. A sub-analysis of the PARSIFAL-1 trial

BACKGROUND: Palbociclib in combination with endocrine therapy (ET) is the first- or second-line standard of care for patients (pts) with hormone receptor (HR)-positive (+)/human epidermal growth factor receptor 2 (HER2)-negative (-) metastatic breast cancer (MBC). No clinically validated markers of long-term benefit from palbociclib have been established and the clinically relevant resistance mechanisms to cyclin-dependent kinases 4 and 6 inhibitors remain undefined. In the present study, we explored candidate circulating exosomal microRNAs (miRNAs) as putative predictors of benefit and/or resistance to palbociclib in combination with ET in pts included in the PARSIFAL-1 trial (ClinicalTrials.gov identifier: NCT02491983). MATERIALS AND METHODS: PARSIFAL-1 was a randomized, open-label, phase II trial aimed at evaluating the efficacy and safety of palbociclib plus either fulvestrant or letrozole in HR+/HER2- MBC pts. For the study of exosomal miRNAs, forty-five consenting pts were selected based on primary endocrine resistance according to the ABC-4 criteria. Nine pts who progressed within the first six months after treatment initiation in the absence of an objective response were considered Resistant and thirty-six pts who progressed more than six months after starting therapy were classified as Sensitive. Exosomes were isolated from plasma samples collected at study entry (baseline) and after 12 weeks of treatment initiation. Differences in miRNA expression between Resistant and Sensitive pts as well as miRNA pharmacodynamic changes between baseline and 12-week samples were assessed. Ribonucleic acid (RNA) was isolated using the miRNeasy plasma kit and the library preparation was done using the QIAseq miRNA library kit according to manufacturer’s instructions. All experiments were conducted at QIAGEN Genomic Services in Germany. Differential expression of miRNA between different conditions was studied using EdgeR statistical software package from Bioconductor. Estimated p-values for significantly differentially expressed miRNAs were adjusted using Benjamini-Hochberg’s False Discovery Rate (FDR). Differences in expression of miRNA with an FDR below 0.05 were considered significant. RESULTS: Sequencing of exosomal RNA and preparation of miRNA libraries were successful for all included samples, with good technical performance. On average, 2.8 million Unique Molecular Index-corrected reads were obtained for each sample and the average percentage of mappable reads was 34.5%. Overall, expression of miRNAs was higher in Resistant compared with Sensitive pts. Eight miRNAs were called as differentially expressed between the two groups. Four miRNAs (miR-1246; miR-375; miR-193a-5p; miR-181d-5p) were differentially expressed at baseline, three (miR-196a-5p, miR-200a-3p, miR-320d) were differentially expressed at 12 weeks, and expression of one miRNA (miR-141-3p) was consistently higher across both time points in Resistant pts. Significant pharmacodynamic changes in miRNA expression were observed both in Resistant and Sensitive pts. Seven miRNAs (miR-224-5p, miR-16-5p, let-7a-5p, miR-381-3p, miR-200c-3p, miR-493-3p, let-7b-5p) in Sensitive pts and three miRNAs (miR-223-3p, miR-126-3p, miR-320b) in Resistant pts were differentially expressed between baseline and 12-week samples. CONCLUSIONS: Circulating exosomal miRNA profiling is feasible in liquid biopsies from MBC pts. Differential expression of selected miRNAs at baseline or their pharmacodynamic modulation may predict benefit from palbociclib combined with ET in pts with HR+/HER2- MBC. Validation of the most promising miRNAs by custom quantitative PCR is warranted.

Citation Format: David Casadevall, Joan Albanell Mestres, Federico Rojo, Beatríz Bellosillo, Abel González, Violeta Serra, Meritxell Bellet, Miguel Angel Gil, Miquel Angel Pujana, Angelo Gámez, Enrique Espinosa, Peter Schmid, Joseph Gligorov, Frederik Marmé, Carlos L. Arteaga, Leonardo Mina, Andrea Malfettone, Miguel Sampayo, José Manuel Pérez-García, Javier Cortés, Antonio Llombart-Cussac. Baseline and pharmacodynamic changes of circulating exosomal microRNAs predict early versus late progression to palbociclib plus endocrine therapy in patients with metastatic breast cancer. A sub-analysis of the PARSIFAL-1 trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-10-17.

Maintenance Therapy in HER2-Negative Metastatic Breast Cancer: A New Approach for an Old Concept

The aim of this article is to discuss the role of maintenance therapy with chemotherapy, endocrine therapy, or bevacizumab-based combination therapy in patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer. The optimization of maintenance therapy in patients with HER2-negative metastatic breast cancer must be based on disease profile (tumor subtype and endocrine-sensitive status), the prior use of bevacizumab-containing regimens, and the number of prognostic risk factors. Chemotherapy should be used in patients with triple-negative breast cancer and endocrine-resistant hormone receptor-positive metastatic breast cancer, whereas endocrine therapy is the preferred option for patients with endocrine-sensitive hormone receptor-positive metastatic breast cancer. After first-line bevacizumab plus chemotherapy, bevacizumab may be continued until disease progression or unacceptable toxicity, and endocrine therapy or capecitabine may be added. The goals of maintenance therapy in patients with HER2-negative metastatic breast cancer are to improve and maintain clinical response, increase time to progression, extend overall survival, relieve tumor-related symptoms, and delay the use of aggressive therapies, without compromising quality of life. Maintenance therapy, using chemotherapy, endocrine therapy, and combined therapy with bevacizumab, is a reasonable strategy to achieve these goals in patients with either triple-negative breast cancer or hormone receptor-positive and HER2-negative metastatic breast cancer. Ongoing clinical studies of new molecular-targeted therapies may provide additional pharmacological options for future maintenance strategies in these patients.

Phase II, Multicenter, Single-arm Trial of Eribulin as First-line Therapy for Patients With Aggressive Taxane-pretreated HER2-Negative Metastatic Breast Cancer: The MERIBEL Study

BACKGROUND

Eribulin has efficacy in patients with progression after ≥ 1 chemotherapeutic regimen for metastatic breast cancer (MBC). A short disease-free interval (DFI) and previous use of taxanes in the neoadjuvant or adjuvant setting have been associated with worse outcomes for patients receiving first-line chemotherapy for HER2-negative MBC. The aim of the present trial was to evaluate the efficacy and safety of eribulin as first-line therapy for patients with HER2-negative MBC with these poor prognostic factors.

PATIENTS AND METHODS

Eribulin monotherapy was administered until disease progression or unacceptable toxicity. The principal selection criteria were HER2 negativity without previous chemotherapy for MBC, the previous use of taxanes for early-stage breast cancer, and a DFI of < 36 months (subsequently amended to 48 months). The primary endpoint was the investigator-assessed time to progression. The secondary endpoints included overall survival, progression-free survival, objective response rate, clinical benefit rate, duration of response, and toxicity profile. A total of 53 patients were enrolled and received ≥ 1 dose of eribulin.

RESULTS

The median patient age was 47 years (range, 23-82.8 years). The median DFI was 15.7 months (range, 0.1-46.4 months). The median investigator-assessed time to progression was 4.1 months (range, 0.2-27.8 months; 95% confidence interval, 3.2-6.2 months). The objective response and clinical benefit rate was 20.8% and 26.4%, respectively. All-grade and grade 3/4 adverse events developed in 96.2% and 69.8% of patients, respectively. The most common treatment-related adverse events were neutropenia, leukopenia, alopecia, nausea, and anemia.

CONCLUSION

Eribulin is effective and safe as first-line therapy for aggressive taxane-pretreated HER2-negative MBC.

Per- and polyfluoroalkyl substances in plasma and feathers of nestling birds of prey from northern Norway

Plasma samples from nestlings of two top predators, White-tailed eagle (Haliaeetus albicilla) and Northern goshawk (Accipiter gentilis) from northern Norway were analysed for a wide range of per- and polyfluoroalkyl substances (PFASs). Body feathers from the White-tailed eagles were also analysed and significant associations between specific PFASs in blood plasma and body feathers were found (0.36 <R² < 0.67; all p < 0.05). This result suggests that analysing body feathers of White-tailed eagle could potentially be a useful non-invasive strategy to monitor PFASs exposure in nestlings of this species. White-tailed eagles showed significantly higher levels of contaminants than Northern goshawks (plasma ∑PFASs Median = 45.83 vs 17.02ngmL^-1, p <0.05). The different exposure between both species seemed to be related to different dietary input, as quantified by stable carbon and nitrogen isotope analysis of body feathers. A priori, the bird of prey populations studied are not at risk for PFASs, since the levels in plasma of both species were hundreds to thousand times lower than the toxic reference values reported for predatory birds. However, further studies on larger sample sizes are needed to confirm this hypothesis since toxic thresholds for nestling birds of prey are not established.

Recent advances in the treatment of melanoma with BRAF and MEK inhibitors

Selective inhibition of the mitogen activated protein kinase (MAPK) pathway with either BRAF or MEK inhibition has emerged as the key component for the treatment of BRAF-mutant metastatic melanoma. New evidence from several phase III trials suggests that the combination of BRAF and MEK inhibitors improves tumor response rate and progression-free survival (PFS). Some of the serious adverse events, in particular, the incidence of cutaneous squamous cell carcinoma seen with the monotherapy treatment with a BRAF inhibitor are attenuated with combination therapy, whereas milder side effects such as pyrexia can be more common with combination therapy. Although dose reductions and dose interruptions are slightly more common with combination therapy, overall data supports the notion that combination therapy is safe and improves the outcomes for metastatic melanoma patients compared to single agent BRAF inhibitors.

Abstract P5-08-06: PI3K blockade enhances the antitumor activity of eribulin in PIK3CA-mutant eribulin-resistant tumor xenografts

Eribulin is a recently approved microtubule-targeting agent (MTA) for the management of heavily pretreated metastatic breast cancer (BC) patients. Constitutive PI3K/Akt/mTOR survival pathway activation, either via mutational activation of the PI3K catalytic subunit (PIK3CA) or via inactivation of the tumor suppressor PTEN, may confer resistance to MTAs. Hence, we hypothesized that PI3K-pathway activation limits the antitumor activity of eribulin in HER2-negative BC and that PI3K inhibition enhances the efficacy of this chemotherapeutic agent.

The predictive value of PIK3CA mutation or PTEN loss towards eribulin response was interrogated in vitro, using a panel of fourteen HER2-negative BC cell lines, and in vivo using six tumor models from cell-line or patient-derived tumors. While PIK3CA mutation did not seem to be predictive in vitro, the PIK3CA-mutated xenograft models underwent tumor progression upon single-agent eribulin therapy (Table 1). In the absence of concomitant PIK3CA mutation, PTEN loss was neither predictive in vitro nor in vivo. Moreover, eribulin induced PI3K-pathway activation in tumor xenografts, a potential escape mechanism to MTA-therapy. To validate the negative predictive value of PIK3CA mutation, BC tumors from patients treated with eribulin in the neoadjuvant and in the metastatic setting are being queried, as the pharmacodynamic activation of the PI3K-pathway upon eribulin treatment.

Class I pan-PI3K (BKM120) or PI3K-a-specific (BYL719) inhibitors were used in vitro to block the PI3K-pathway concomitantly with eribulin treatment, resulting in enhanced antiproliferative and proapoptotic activity. Strikingly, in PIK3CA mutant xenograft models, while eribulin alone exhibited limited antitumor activity compared to PIK3CA-wild type models, co-administration of a PI3K inhibitor induced marked tumor regression (BKM120 data in Table 1, BYL719 data will be reported). Moreover, addition of the PI3K inhibitor at progression with eribulin single-agent also resulted in tumor regression. Of note, PIK3CA-wild type models also exhibited increased antitumor activity with the combined therapy compared to single-agent treatments. The precise mechanism by which the combination of eribulin and a PI3K-targeting agent results in tumor regression is currently under investigation, embracing both the induction of mitotic catastrophe in tumor cells and the regularization of the tumor vasculature.

These results support the clinical development of therapeutic regimens combining PI3K-inhibitors to the approved MTA eribulin and might be predictive of clinical benefit both in the PIK3CA-mutant and -wild type breast cancer population.

Table 1. Percentage change in tumor volume.StatusPIK3CA mutantPIK3CA mutant and PTEN-lowPTEN-lowWTModel/ TreatmentMCF7LPDX44CAL51MDA-MB-468PDX88PDX98Eribulin39 ± 9683 ± 51364 ± 127-47 ± 14-26 ± 34-36 ± 33BKM120501 ± 169116 ± 111119 ± 73-9 ± 23128 ± 3787 ± 112Eribulin + BKM120-70 ± 27-80 ± 1051 ± 46-75 ± 12-94 ± 5-65 ± 13Patient- (PDX) and cell line-derived tumor xenografts were treated with eribulin mesylate (0.1mg/kg, 3IW) and/or BKM120 (27.5 mg/kg, 6IW) for 26-31 days.. IW, in week.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-06.

Design of a suture anchor based on the superelasticity of the Ni-Ti alloy

We have designed and manufacture a prototype of a new anchoring system for soft bone tissue fixation, based on the superelasticity of the Ni-Ti alloy. The anchoring capability has been observed in femoral hips by radiographs. The performance of this new anchor have been measured by tensile experiments and contrasted with finite element model. The results point out that keeping the fixation capacity, the new configuration presents advantages concerning to a minor damaged volume bone, a reduction of the manufacture cost and a simpler insertion.