Arvinas, Pfizer announce initial Phase 1b data from TACTIVE-U sub-study

Arvinas (ARVN) and Pfizer (PFE) announced preliminary data from the ongoing Phase 1b portion of the TACTIVE-U sub-study of vepdegestrant in combination with abemaciclib among patients with locally advanced or metastatic estrogen receptor positive/human epidermal growth factor receptor 2 negative breast cancer. These data will be presented in a poster at the 2024 San Antonio Breast Cancer Symposium, SABCS, in San Antonio, Texas. Preliminary results from 16 patients in the Phase 1b sub-study demonstrated a tolerable safety profile for the combination of abemaciclib 150 mg twice daily with the recommended Phase 3 monotherapy dose of vepdegestrant. An encouraging clinical benefit rate of 62.5% was observed among patients with both mutant ESR1 and wild-type ESR1 disease who had all been previously treated with a CDK4/6 inhibitor.