The MAINTAIN trial was designed to assess endocrine therapy with or without ribociclib after progression on a CDK4/6 inhibitor in patients with unresectable or metastatic hormone receptor–positive, HER2-negative breast cancer.
At the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting, CancerNetwork® spoke with Kevin Kalinsky, MD, MS, an associate professor in the Department of Hematology and medical oncology at Emory University School of Medicine; Louisa and Rand Glenn Family Chair in Breast Cancer Research; director of Glenn Family Breast Center; and director of Breast Medical Oncology at the Winship Cancer Institute of Emory University. During the interview, Kalinsky discussed key findings from the phase 2 MAINTAIN trial (NCT02632045), which assessed ribociclib (Kisqali) with or without endocrine therapy after progression on a CDK4/6 inhibitor for patients with unresectable or metastatic hormone receptor–positive, HER2-negative breast cancer.
The trial randomized 119 patients. Median progression-free survival (PFS)—the study’s primary end point—was 2.76 months (95% CI, 2.66-3.25) in the placebo arm vs 5.29 months (95% CI, 3.02-8.12) in the ribociclib arm (HR, 0.57; 95% CI, 0.39-0.95; P = .006). At 6 months, the PFS rate was 23.9% vs 41.2%, respectively, and at 12 months, the rates were 7.4% vs 24.6% in each respective arm.
The MAINTAIN trial is a study for patients who had tumors that have progressed on any CDK4/6 inhibitor and any endocrine therapy, where they were randomized to endocrine therapy with ribociclib vs endocrine therapy plus placebo. The primary end point was investigator assessed [PFS]. This was a positive study in which we saw a statistically significant improvement in the participants who were randomized to ribociclib compared with those who were randomized to placebo with a hazard ratio of less than 0.6.
We looked at various ways of assessing tolerability including treatment-related adverse effects, as well as discontinuation [of treatment] and there were no surprises, meaning the main [adverse] effect we saw with ribociclib was the neutropenia; there were only 2 patients who had febrile neutropenic events. There was other no surprises [observed in the trial]. This seemed to be a manageable and safe combination, similar to what we see in patients who are CDK4/6 inhibitor naïve.
Kalinsky K, Accordino MK, Chiuzan C, et al. A randomized, phase II trial of fulvestrant or exemestane with or without ribociclib after progression on anti-estrogen therapy plus cyclin-dependent kinase 4/6 inhibition (CDK 4/6i) in patients (pts) with unresectable or hormone receptor–positive (HR+), HER2-negative metastatic breast cancer (MBC): MAINTAIN trial. J Clin Oncol. 2022;40(suppl 17):LBA1004. doi:10.1200/JCO.2022.40.17_suppl.LBA1004