Olema Oncology: Median PFS was 4.6 months in Phase 2 palazestrant study

Olema Pharmaceuticals announced results from a Phase 2 clinical study of palazestrant, or OP-1250, the company’s complete estrogen receptor antagonist and selective ER degrader, for the treatment of metastatic ER+/HER2- breast cancer. These results were presented in an oral presentation at the European Society for Medical Oncology Congress 2023 in Madrid, Spain, on October 22, 2023. The presentation, titled “Results from the phase 1/2 study of OP-1250, an oral complete estrogen receptor antagonist and selective ER degrader in patients with advanced or metastatic ER-positive, HER2-negative breast cancer”, highlighted that: Across 86 heavily pretreated patients, where 42% of patients were 4th line or later at study entry, 120 mg once-daily, monotherapy palazestrant was well tolerated and achieved a median progression-free survival of 4.6 months and clinical benefit rate of 40%, and a median PFS of 5.6 months and CBR of 52% in patients with ESR1 mutations at baseline. In a subset analysis of 49 second- or third-line patients with or without prior chemotherapy, the median PFS was 7.2 months and CBR was 48% across all patients, and the median PFS was 7.3 months and CBR was 59% ESR1-mutant patients. “These Phase 2 monotherapy study results demonstrate that palazestrant has the potential to become a best-in-class endocrine therapy and improve upon current standard of care treatments for women living with metastatic breast cancer. In addition to being well-tolerated, palazestrant has demonstrated compelling progression-free survival as monotherapy in a heavily pretreated patient population,” said Sean P. Bohen, M.D., Ph.D., President and CEO of Olema Oncology. “Going forward, we are in the process of initiating OPERA-01, our first pivotal Phase 3 clinical trial testing palazestrant as monotherapy in second- and third-line metastatic breast cancer.”