Dr O'Cearbhaill on Results With Ubamatamab Plus Cemiplimab in Recurrent Ovarian Cancer

Roisin E. O'Cearbhaill, MD, gynecologic oncologist, cellular therapist, associate attending physician, research director, Gynecologic Medical Oncology Service, clinical director, Solid Tumor, Cellular Therapy Service, Memorial Sloan Kettering Cancer Center, discusses key findings from a phase 1/2 dose escalation study (NCT03564340) of ubamatamab (REGN4018) plus cemiplimab (Libtayo) in patients with recurrent ovarian cancer.

This first-in-human study evaluated the safety and initial activity of the MUC16xCD3 bispecific antibody ubamatamab both alone and in combination with the PD-L1 inhibitor cemiplimab for patients with recurrent platinum-experienced ovarian cancer, O'Cearbhaill begins. Patients received a weekly dose of intravenous (IV) ubamatamab at a dose range of 1 mg to 450 mg after initial step-up dosing, followed by 350 mg of IV cemiplimab every 3 weeks.

Findings from an exploratory analysis presented at the 2023 ESMO Congress showed that ubamatamab produced responses at doses of 10 mg to 250 mg, O'Cearbhaill reports. Patients treated with the combination experienced an overall response rate of 18.2% (95% CI 5.2%-40.3%) and a median duration of response of 8.3 months (95% CI 4.2–not estimable). The CA125 response rate was 22.7% (95% CI, 7.8%-45.4%). Additionally, the 6- and 12-month progression-free survival rates were 47.6% (95% CI 25.7%-66.7%) and 23.8% (95% CI 8.7%-43.1%), respectively. The pharmacokinetics of ubamatamab were not impacted by cemiplimab.

In patients with heavily pretreated ovarian cancer, ubamatamab at doses of 1 mg to 250 mg combined with cemiplimab was associated with an acceptable safety profile, O'Cearbhaill continues. The most common adverse effects – pain and cytokine release syndrome – occurred during ubamatamab step-up dosing. The addition of cemiplimab, after 4 to 5 weeks of ubamatamab monotherapy, was generally well tolerated, she notes.

Overall, the combination of ubamatamab and cemiplimab was associated with an acceptable safety profile and generated durable responses in heavily pretreated patients with ovarian cancer, O'Cearbhaill emphasizes. These results support further investigation of the combination in an ongoing randomized phase 2 expansion study.

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