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PO011LBA/#1512  Ubamatamab (MUC16XCD3 bispecific antibody) with or without cemiplimab (Anti-PD-1 antibody) in recurrent ovarian cancer: phase 1 clinical and biomarker results
  1. Joyce Liu1,
  2. David O’Malley2,
  3. Els Van Nieuwenhuysen3,
  4. Kathleen Moore4,
  5. Erika Hamilton5,
  6. Oladapo Yeku6,
  7. Sara Bouberhan6,
  8. June Hou7,
  9. David Schröder8,
  10. Bin Wang9,
  11. Suk-Young Yoo10,
  12. Shilpa Govindraj11,
  13. Jurriaan Brouwer-Visser12,
  14. Mary Peterman13,
  15. Tamara Schmidt13,
  16. Brigid Barnes13,
  17. Israel Lowy13,
  18. Thomas Uldrick13,
  19. Elizabeth Miller13 and
  20. Roisin O’Cearbhaill14
  1. 1Dana-Farber Cancer Institute, Division of Gynecologic Oncology, Boston, USA
  2. 2The Ohio State University and The James Cancer Center, Division of Gynecologic Oncology In Obstetrics and Gynecology, Columbus, USA
  3. 3Leuven Cancer Institute, Gynaecology and Obstetrics, Leuven, Belgium
  4. 4University of Oklahoma Health Sciences Center/Sarah Cannon Research Institute, Stephenson Cancer Center, Oklahoma City, USA
  5. 5Sarah Cannon Research Institute, Tennessee Oncology, Breast and Gynecologic Cancer Research, Nashville, USA
  6. 6Massachusetts General Hospital, Gynecologic Oncology Program, Boston, USA
  7. 7Columbia University Medical Center, Division of Gynecologic Oncology, New York, USA
  8. 8Grand Hôpital de Charleroi, Charleroi, Service D’oncologie-hématologie, Belgium, Belgium
  9. 9Regeneron Pharmaceuticals, Inc., Biostatistics, Tarrytown, USA
  10. 10Biostatistics, Regeneron Pharmaceuticals, Inc., Tarrytown, USA
  11. 11Regeneron Pharmaceuticals, Inc., Global Patient Safety, Tarrytown, USA
  12. 12Regeneron Pharmaceuticals, Inc., Precision Medicine, Tarrytown, USA
  13. 13Regeneron Pharmaceuticals, Inc., Oncology Clinical Development, Tarrytown, USA
  14. 14Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, Gynecologic Medical Oncology Service, New York, USA


Introduction Ubamatamab (REGN4018; mucin16 [MUC16] x CD3 bispecific antibody) promotes T-cell-mediated killing of ovarian cancer (OC) cells in preclinical studies. This activity is enhanced by the anti-PD-1 antibody cemiplimab. We present first-in-human ubamatamab +/- cemiplimab dose escalation results in recurrent OC.

Methods Patients with recurrent platinum-experienced OC received weekly intravenous ubamatamab 0.3–800 mg after step-up dosing. Patients in combination cohorts received intravenous cemiplimab 350 mg every 3 weeks beginning Day 29–36. Endpoints assessed safety (primary), clinical activity (secondary), and correlatives of tumor MUC16 immunohistochemistry and serum CA125 (exploratory).

Results 109 patients (N=74 monotherapy/N=35 combination) were enrolled. Median number of prior therapies was 5 (range 1–17). Commonest treatment-related adverse events of any grade occurred in the first 4 weeks of treatment, including pain (75.2%; Grade 1–2 56.9%; Grade 3 18.3%) and cytokine release syndrome (72.5%; all Grade 1–2) (table 1), with few of these events after addition of cemiplimab. In efficacy analyses (n=42 monotherapy/n=22 combination), ORR was 14.3%/18.2%, median duration of response was 13.7/8.3 months, and CA125 response (GCIG criteria) was 31.0%/22.7%. All patient tumors expressed MUC16 by immunohistochemistry. Responses with ubamatamab monotherapy were observed across a range of MUC16 expression levels. Response rates and PFS increased with increasing number and intensity of MUC16+ cells. CA125 response was associated with improved PFS (monotherapy: hazard ratio 0.35; 95% CI 0.17–0.72).

Conclusion/Implications Ubamatamab +/- cemiplimab demonstrated acceptable safety and evidence of clinical activity in heavily pretreated OC. An ongoing randomised Phase 2 study is evaluating ubamatamab alone and with cemiplimab.

Abstract PO011LBA/#1512 Table 1

Treatment-related TEAEs occurring in >10% of monotherapy and combination therapy patients combined during the first 4 weeks of treatment

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