Arvinas, Inc. (NASDAQ: ARVN) shares experienced a notable rebound during after-hours trading on Wednesday, with shares climbing 6.48% to reach $24.00. This partial recovery came after ARVN had reported an 8.34% loss in regular trading hours, closing at $22.54. The positive movement was attributed to the release of encouraging preliminary clinical trial data that spurred investor optimism.
Positive Results from the TACTIVE-U Study
This week, Arvinas (ARVN) and Pfizer Inc. released encouraging first findings from the TACTIVE-U sub-study’s continuing Phase 1b component. The trial is investigating the use of vepdegestrant in combination with abemaciclib for patients with locally advanced or metastatic estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer. The information will be made public during the 2024 San Antonio Breast Cancer Symposium (SABCS) in San Antonio, Texas.
Profile of Clinical Benefit and Safety
Preliminary results from 16 patients demonstrated a tolerable safety profile for the combination of abemaciclib (150 mg twice daily) and the recommended Phase 3 dose of vepdegestrant (200 mg once daily).
The combination therapy yielded a clinical benefit rate of 62.5%, which was observed in both ESR1-mutant and wild-type patients who had previously undergone treatment with a CDK4/6 inhibitor. These findings underline the potential of this combination treatment to provide significant benefits to patients who have limited options following prior treatments.
Ongoing Evaluation and Future Prospects
The feasibility of the combination was further supported by pharmacokinetic data, which showed no significant drug-drug interaction between vepdegestrant and abemaciclib. The safety profile was consistent with what has been previously observed in other clinical trials involving these drugs.
The promising Phase 1b results set the stage for the Phase 2 portion of the study, which will continue to evaluate the combination of vepdegestrant and abemaciclib in post-CDK4/6 advanced breast cancer patients. Arvinas (ARVN) and Pfizer are also exploring additional combinations within the TACTIVE-U trial, which could offer new treatment avenues for metastatic breast cancer.
