KEY TAKEAWAYS
- Phase 2, nextMONARCH 1 open-label, controlled, randomized trial of abemaciclib alone or with tamoxifen in endocrine-refractory HR+, HER2- MBC women.
- There was a more significant improvement in OS when tamoxifen was combined with abemaciclib than when either drug was used alone.
- The A+T group had a median OS of 24.2 months, the A-150 group had 20.8 months, and the A-200 group had 17.0 months.
- The 24-month PFS and ORR results matched the primary analysis, and the safety profile aligned with what had been reported previously.
- This study confirmed the single-agent activity of abemaciclib in heavily pretreated women with endocrine-refractory HR +, HER2- MBC.
For patients with hormone receptor-positive (HR +), HER 2 negative (HER 2 -) metastatic breast cancer (MBC), resistance to endocrine therapy is a significant therapeutic problem. Here researchers provide the final overall survival (OS) rates at 24 months, as well as revised estimates of progression-free survival (PFS) and objective response rate (ORR).
Women with endocrine-refractory HR+, HER2- MBC who have undergone prior chemotherapy will be eligible to participate in nextMONARCH, a randomized, open-label Phase 2 research of abemaciclib alone or combination with tamoxifen. Abemaciclib 150 mg plus tamoxifen 20 mg (A + T), abemaciclib 150 mg (A-150), or abemaciclib 200 mg plus prophylactic loperamide were the three treatment groups that patients were randomly assigned to receive (A-200). The primary predefined secondary endpoint was OS. Primary analysis results were compared to 24-month results for PFS, ORR, and safety.
When the data were collected, 12 out of 234 were getting trial treatment (28 Jun 2019). The average length of time between visits was 27.2 months. The A+T group had a median OS of 24.2 months, the A-150 group had a median OS of 20.8 months, and the A-200 group had a median OS of 17.0 months (A+T versus A-200: HR 0.62; 95%CI [0.40, 0.97], P = 0.03; A-150 against A-200: HR 0.96; 95%CI [0.64, 1.44], P = 0.83). The 24-month PFS and ORR results matched those of the primary analysis. Consistent with prior findings, the safety profile was satisfactory. There was a bigger improvement in OS when tamoxifen was combined with abemaciclib than when either drug was used alone. This trial corroborated the previously published primary PFS and ORR outcomes of abemaciclib in severely pretreated women with endocrine-refractory HR+, HER2-MBC, and no new safety signals were found.
Source:https://pubmed.ncbi.nlm.nih.gov/35829935/
Clinical Trial:https://clinicaltrials.gov/ct2/show/NCT02747004
Hamilton E, Cortes J, Ozyilkan O, Chen SC, Petrakova K, Manikhas A, Jerusalem G, Hegg R, Huober J, Zhang W, Chen Y, Martin M. nextMONARCH Phase 2 randomized clinical trial: overall survival analysis of abemaciclib monotherapy or in combination with tamoxifen in patients with endocrine-refractory HR + , HER2- metastatic breast cancer. Breast Cancer Res Treat. 2022 Aug;195(1):55-64. doi: 10.1007/s10549-022-06662-9. Epub 2022 Jul 12. PMID: 35829935; PMCID: PMC9338008.
