Dr Slomovitz on the Investigation of Letrozole Plus Ribociclib in Low-Grade Serous Ovarian Carcinoma

Brian M. Slomovitz, MD, director, Gynecologic Oncology, co-chair, the Cancer Research Committee, Mount Sinai Medical Center, professor, Obstetrics and Gynecology, Florida International University, discusses the evaluation of letrozole and ribociclib (Kisqali) from the phase 2 GOG 3026 trial (NCT03673124) in recurrent low-grade serous ovarian carcinoma.

Patients enrolled on the trial were treated with 600 mg of ribociclib on a 3-weeks-on/1-week-off schedule, plus 2.5 mg of oral letrozole once per day in 28-day cycles. Findings presented at the 2023 Society of Gynecologic Oncology Annual Meeting on Women’s Cancer showed that the combination elicited an overall response rate of 23% (90% CI, 13.4%-35.1%) and a clinical benefit rate of 79% (90% CI, 67.2%-88.2%). The median duration of response was 19.1 months. The median progression-free survival was 19.1 months, and the median overall survival was not yet reached.

Low-grade serous ovarian carcinoma is a rare subtype of ovarian cancer with limited treatment options , Slomovitz begins. Unlike high-grade ovarian cancer, which responds favorably to chemotherapy, the response rates to chemotherapy within this patient population are historically between 0% and 15%, Slomovitz notes, adding that response rates with hormonal therapy are also low in this patient population.

The response rate generated by letrozole and ribociclib was comparable to MEK inhibition, Slomovitz explains. Notably, the median PFS and DOR observed with the combination serve as an improvement on what would be expected with currently available therapies for patients with recurrent low-grade serous carcinoma, Slomovitz adds.

Regarding safety, letrozole and ribociclib was well tolerated, Slomovitz says, explaining that the adverse effect (AE) profile was similar to prior data and grade 3 or higher toxicities were limited. The most common any-grade AEs included decreased neutrophil count (63%), decreased white blood cell count (46%), anemia (42%), and nausea (42%). Decreased neutrophil count (44%) was the only grade 3 or higher AE reported in more than 10% of patients.