Regeneron Pharmaceuticals, Inc. announced positive early data for two novel and investigational bispecific antibodies – ubamatamab (REGN4018; MUC16xCD3) in recurrent ovarian cancer and REGN5093 (METxMET) in MET-altered advanced non-small cell lung cancer (NSCLC). The initial safety and efficacy results are from the dose-escalation portions of two Phase 1/2 trials and are being presented at the European Society for Medical Oncology (ESMO) Congress 2022 in Paris. As shared in a mini-oral at ESMO, ubamatamab is a CD3-targeting bispecific under investigation for recurrent ovarian caner and designed to bridge MUC16 on cancer cells with CD3-expressing T cells to facilitate local T-cell activation.

Dose-escalation results were presented for 78 patients with recurrent ovarian cancer who had received a median of 4.5 prior treatments, including platinum-based chemotherapy and a median duration of exposure to ubamatamab was 12 weeks (range: 5% including anemia (24%), pain (23%) and neutropenia (8%)). There was one instance of a dose-limiting toxicity (neutropenia) and three deaths due to AEs, none of which were considered related to treatment by sponsor assessment. Based on these efficacy and safety data, the Phase 2 portion of the trial is enrolling patients with platinum-resistant ovarian cancer to further investigate ubamatamab as a monotherapy and in combination with Regeneron's PD-1 inhibitor Libtayo® (cemiplimab).

Preliminary first-in-human results for REGN5093 were also published in an ESMO scientific abstract, with updated data and additional response rates to be detailed in a poster session on September 12. REGN5093 is a tumor-targeting bispecific designed to bind to the MET receptor in two places and trigger rapid internalization of this complex into cancer cells to degrade the MET receptor and block its ability to support cell proliferation. As highlighted in the abstract, among 36 patients with MET-altered advanced NSCLC who received the higher dose tested to date, 6 experienced a partial response with 5 of these responses occurring in patients who had received prior anti-PD-1 treatment.

Total exposure to treatment was approximately 467 patient-weeks.