KEY TAKEAWAYS
- The phase II study focused on assessing the efficacy of ribociclib and letrozole treatment in low-grade serous ovarian cancer.
- The study’s primary endpoint was the overall response rate.
- The combination of ribociclib and letrozole demonstrated substantial efficacy in treating low-grade serous ovarian cancer, with encouraging outcomes in response rate, progression-free survival, and response duration compared to previously studied agents.
The single-arm GOG 3026 study enrolled 51 individuals diagnosed with recurrent low-grade serous ovarian cancer. Patients (pts) were granted the opportunity to have undergone an unlimited number of prior therapies, the median count being one prior regimen, with the exception of previous use of CDK4/6 inhibitors or letrozole.
The enrolled pts received a daily dosage of 600 mg of ribociclib for three weeks, followed by a one-week interval without treatment, concomitant with a daily intake of 2.5 mg of letrozole, within a 28-day treatment cycle until disease progression. The primary objective of the overall response rate was 23% for the 48 assessable participants, all categorized as partial responses; in terms of clinical benefit, the rate was established at 79%. The median duration of response was calculated as 19.1 months, displaying a range from 4.8 to 35.8 months. Progression-free survival was 19.1 months, and median overall survival was not reached.
Upon focusing the analysis solely on the subset of 42 subjects who underwent confirmatory assessments involving two computed tomography (CT) scans, the observed response rate escalated to 26%, while the clinical benefit rate elevated to 90%. The median time to response was 7.9 months, with an observed span ranging from 2 to 22 months. Among the 42 patients displaying confirmed responses, 64% exhibited a reduction in the size of target lesions. Notably, close to 40% of the patient cohort sustained their participation in the study.
The observed toxicity profile was consistent with the anticipated effects of these agents. The most common grade (gr) 3 adverse events (AEs) encompassed reductions in neutrophil counts (44%) and white blood cell counts (8%). In general, the combination was remarkably well tolerated.
The combination of ribociclib and letrozole demonstrates notable effectiveness in low-grade serous ovarian cancer. The overall rate of response, progression-free survival, and length of response exhibit favorable comparisons with the most potent agents that have been previously studied.
Clinical Trial: https://classic.clinicaltrials.gov/ct2/show/NCT03673124
Slomovitz BM, Deng W, Killion J, et al
