Zentalis Announces Presentation of Positive Phase 1b Data Demonstrating Durable Responses and Favorable Safety Profile of Azenosertib in Combination with Chemotherapy at the 2023 ASCO Annual Meeting - Seite 2

Efficacy and Safety Results:

A total of 115 patients were enrolled in the study across all chemotherapy combination groups. At the data cut-off of April 10, 2023, 94 were efficacy evaluable. Across all dosing schedules, azenosertib plus paclitaxel demonstrated the highest ORR of 50.0% (mPFS of 7.4m), followed by an ORR of 38.5% (mPFS of 8.3m) for azenosertib plus gemcitabine. Azenosertib plus carboplatin demonstrated an ORR of 35.7% (mPFS of 10.4m), and azenosertib plus PLD demonstrated an ORR of 19.4% (mPFS of 6.3m).

A total of 82 response-evaluable patients had available Cyclin E1 expression data by immunohistochemistry (IHC). Cyclin E1+ status (H-score >50) was associated with a superior ORR and a longer mPFS across the total patient population (ORR of 40.0% vs 8.3%; mPFS of 9.86 vs 3.25 months, HR = 0.37; P = 0.0078), showcasing the potential synergy of WEE1 inhibition with chemotherapy in this patient population.

Overall, the tolerability of azenosertib dosed intermittently in combination with either paclitaxel or carboplatin compares favorably to historical data from standard of care chemotherapy doublets of either paclitaxel-carboplatin or PLD-carboplatin. Frequent Grade ≥3 treatment-related adverse events (%) across all azenosertib intermittent dosing groups were thrombocytopenia (27.5%), neutropenia (25.5%), anemia (15.7%), and fatigue (9.8%). A recommended Phase 2 dose was determined for each of the azenosertib combinations with paclitaxel, carboplatin, and PLD.

Based on these results, the Company is planning to initiate a Phase 3 study comparing azenosertib dosed intermittently in combination with either carboplatin or paclitaxel in patients with Cyclin E1+ platinum-sensitive ovarian cancer. The Company expects to initiate the Phase 3 study in the first quarter of 2024.

“The results thus far for azenosertib in combination with chemotherapy are very promising, as there remains high unmet need in this patient population, particularly patients with Cyclin E1+ tumors who historically have not responded well to chemotherapy,” said Joyce Liu, M.D., M.P.H., Associate Chief and Director of Clinical Research for the Division of Gynecologic Oncology at the Dana-Farber Cancer Institute. “I look forward to continuing to work with the Zentalis team to advance azenosertib in the clinic and, if approved, ultimately into medical practice as an important and novel treatment option for platinum-sensitive ovarian cancer patients.”