American Association for Cancer Research
ccr-23-1209_supplementary_figure_s1_suppfs1.pdf (167.55 kB)

Supplementary Figure S1 from Overall Survival and Exploratory Biomarker Analyses of Abemaciclib plus Trastuzumab with or without Fulvestrant versus Trastuzumab plus Chemotherapy in HR+, HER2+ Metastatic Breast Cancer Patients

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posted on 2024-01-05, 08:20 authored by Sara M. Tolaney, Shom Goel, Jorge Nadal, Hannelore Denys, Manuel R. Borrego, Lacey M. Litchfield, Jiangang Liu, Adams K. Appiah, Yanyun Chen, Fabrice André

REMARK (Reporting Recommendations for Tumor Marker Prognostic Studies) diagram for patients in the monarcHER trial.



The monarcHER trial has shown that abemaciclib, a cyclin-dependent kinase 4 and 6 inhibitor, combined with fulvestrant and trastuzumab, improves progression-free survival (PFS) in hormone receptor–positive (HR+), HER2-positive (HER2+) advanced breast cancer (ABC) compared with standard-of-care (SOC) chemotherapy combined with trastuzumab. We report the final overall survival (OS) analysis, updated safety and efficacy data, and exploratory biomarker results from monarcHER. monarcHER (NCT02675231), a randomized, multicenter, open-label, phase II trial, enrolled 237 patients across Arm A (abemaciclib, trastuzumab, fulvestrant), Arm B (abemaciclib, trastuzumab), and Arm C (SOC chemotherapy, trastuzumab). Following the statistical plan, OS and PFS were estimated in all arms. RNA sequencing (RNA-seq) was performed on archival tissue. Median OS was 31.1 months in Arm A, 29.2 months in Arm B, and 20.7 months in Arm C [A vs. C: HR, 0.71; 95% confidence interval (CI), 0.48–1.05; nominal two-sided P value 0.086; B vs. C: HR 0.83 (95% CI, 0.57–1.23); nominal two-sided P value 0.365]. Updated PFS and safety findings were consistent with previous results. The most frequently reported treatment-emergent adverse events included diarrhea, fatigue, nausea, neutrophil count decrease, and anemia. In exploratory RNA-seq analyses, Luminal subtypes were associated with longer PFS [8.6 vs. 5.4 months (HR, 0.54; 95% CI, 0.38–0.79)] and OS [31.7 vs. 19.7 months (HR, 0.68; 95% CI, 0.46–1.00)] compared with non-Luminal. In this phase II trial, abemaciclib + trastuzumab ± fulvestrant numerically improved median OS in women with HR+, HER2+ ABC compared with SOC chemotherapy + trastuzumab.

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