Arvinas and Pfizer Announce Interim Data from Phase 1b Trial of Vepdegestrant in Combination with Palbociclib (IBRANCE) and Plans to Expand Vepdegestrant Development Program

Arvinas, Inc. and Pfizer Inc. announced clinical data for vepdegestrant (ARV-471), a novel oral PROteolysis TArgeting Chimera (PROTAC) estrogen receptor (ER) degrader, in combination with palbociclib (IBRANCE). Interim results from the Phase 1b combination cohort demonstrate encouraging clinical activity in heavily pre-treated patients with a median of four lines of therapy across disease settings with locally advanced or metastatic ER positive/human epidermal growth factor 2 (HER2) negative (ER+/HER2-) breast cancer. These data will be presented in a spotlight presentation at the 2023 San Antonio Breast Cancer Symposium (SABCS).

“We are thrilled to see this level of clinical activity in such a heavily pre-treated patient population,” said John Houston, Ph.D., chairperson, chief executive officer, and president at Arvinas. “Vepdegestrant is the only PROTAC ER degrader in late-stage clinical development. The results from this trial evaluating vepdegestrant in combination with palbociclib help advance our goals of benefitting patients with ER+/HER2- breast cancer. It is encouraging to see preliminary signals of activity in both wild-type and ESR1 mutant tumors, with manageable tolerability and low rates of discontinuation.”

Vepdegestrant is a PROTAC® ER degrader designed to directly harness one of the cell’s natural protein disposal processes to specifically target and degrade the estrogen receptor. Vepdegestrant is being co-developed by Arvinas and Pfizer and is currently being evaluated as a monotherapy in the second-line setting in the ongoing Phase 3 VERITAC-2 trial and in the first-line setting in combination with palbociclib in the ongoing study lead-in cohort of the Phase 3 VERITAC-3 trial.

“Our goal is to develop a novel, tolerable next-generation estrogen-targeting agent that can help patients with ER+/HER2- breast cancer address disease progression,” said Adam Schayowitz, Ph.D., vice president, development head, breast cancer, colorectal cancer and melanoma, Pfizer. “Collectively, the data presented this year at SABCS for vepdegestrant, especially in combination with palbociclib, show the potential of this investigational innovative therapeutic option. Our ongoing collaboration with Arvinas exemplifies our shared commitment to bringing new therapies to patients with ER+/HER2- breast cancer, who may feel uncertain and vulnerable in the face of recurrent advanced disease.”

Pending additional data and agreement with regulatory authorities, Arvinas and Pfizer plan to broaden development of vepdegestrant to include new combinations with cyclin-dependent kinase (CDK) inhibitors in both the first- and second-line settings. The companies plan to initiate a new second-line Phase 3 trial of vepdegestrant in combination with palbociclib and potentially other CDK4/6 inhibitors, and a new first-line Phase 3 trial of vepdegestrant plus Pfizer’s novel CDK4 inhibitor (PF-07220060).