Arvinas and Pfizer's (PFE.US) proteolysis-targeting chimera combo therapy shows positive clinical results, with a clinical benefit rate of over 62%

Arvinas and Pfizer (PFE.US) today announced preliminary data from the TACTIVE-U sub-study of the ongoing Phase 1b clinical trial evaluating the combination of the proteolysis targeting chimera (PROTAC) vepdegestrant and the CDK4/6 inhibitor abemaciclib in patients with locally advanced or metastatic estrogen receptor positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer who have received prior CDK4/6 inhibitor therapy. Preliminary results from the 16 patients in the Phase 1b sub-study showed that the combination of abemaciclib (150mg twice daily) and vepdegestrant at the Phase 3 clinical trial recommended dose (200mg once daily) was well tolerated with a clinical benefit rate of 62.5%.

Vepdegestrant is a proteolysis targeting chimera (PROTAC) in development with oral bioavailability, designed to target estrogen receptor degradation, as a single agent or in combination, for the treatment of ER+/HER2- breast cancer patients.

The overall tolerability of the combination was consistent with the known safety profile of abemaciclib, as well as the results previously observed with vepdegestrant in other clinical trials. The most common any-grade treatment-emergent adverse events (TEAEs) were diarrhea, nausea, and fatigue. No dose-limiting toxicities were observed, and no TEAEs were observed at grade 4 or 5.