Context Therapeutics Inc. announced that two patients have achieved a confirmed partial response (PR) among the first 12 patients (9 evaluable) enrolled in the Phase 2 OATH clinical trial evaluating the potential of Context's oral progesterone receptor antagonist onapristone extended release (ONA-XR) in combination with anastrozole (ANA) to treat hormone receptor positive (HR+) metastatic endometrial cancer (EC). Metastatic EC is an aggressive cancer of the uterus that is the fourth leading cause of cancer-related mortality in women and results in approximately 13,000 deaths per year in the United States. Current treatments are limited, with platinum plus taxane combination chemotherapy being the standard of care for first line metastatic disease.

After first-line therapy, patients are typically treated with additional toxic infusion therapies, including chemotherapy or Lenvima® (lenvatinib) plus Keytruda® (pembrolizumab) combination therapy. Clinician and patient feedback indicates a high unmet need for a novel orally administered therapeutic that provides toxic therapy-like efficacy but with fewer debilitating side effects. Grade 3 or higher adverse events (AE) with standard EC therapies include diarrhea, nausea, vomiting, and hypertension.

Preliminary data from the ongoing Phase 2 OATH clinical trial evaluating the combination of ONA-XR with ANA in HR+ EC found that ONA-XR plus ANA demonstrated a 4-month progression free survival (PFS) rate of 77% and an overall response rate (ORR) of 22%. These results suggest that ONA-XR plus ANA exhibits favorable efficacy and tolerability relative to historical data that evaluated physician's choice of chemotherapy (doxorubicin or paclitaxel) versus Lenvima plus Keytruda combination therapy in a similar treatment setting of metastatic EC. Updated data regarding the Phase 2 OATH trial is expected to be provided in second quarter of 2023.