Arvinas,Pfizer update Phase 1b data on vepdegestrant palbociclib combination

Arvinas (ARVN) and Pfizer (PFE) updated clinical data from a Phase 1b combination cohort evaluating vepdegestrant, an investigational oral PROteolysis TArgeting Chimera, or PROTAC, estrogen receptor – ER – degrader, in combination with palbociclib. After six months of additional follow-up, these data are consistent with data presented at the SABCS in December 2023, and show that vepdegestrant plus palbociclib continue to demonstrate encouraging clinical activity in heavily pre-treated patients with a median of four lines of prior therapy with locally advanced or metastatic ER positive/human epidermal growth factor 2 – HER2 – negative breast cancer. These updated data were presented at the 2024 European Society for Medical Oncology Breast Cancer Annual Congress. Vepdegestrant is an investigational PROTAC ER degrader designed to harness the body’s natural protein disposal system to specifically target and degrade the estrogen receptor. Vepdegestrant is being co-developed by Arvinas and Pfizer. After six months of additional follow-up, clinical benefit rate of 63%, overall response rate of 41.9%, median progression-free survival of 11.2 months, and safety profile of vepdegestrant in combination with palbociclib were consistent with data previously reported at SABCS in December 2023. At the recommended Phase 3 dose of 200 mg vepdegestrant in combination with palbociclib, patients achieved a median progression-free survival of 13.9 months. Across all vepdegestrant dose groups, circulating tumor DNA analyses showed marked reduction in tumor fraction after one treatment cycle, regardless of ESR1 gene mutation status; at the 200 mg vepdegestrant dose, robust on-treatment decreases in mutant ESR1 circulating tumor DNA were sustained through multiple treatment cycles. The safety profile of vepdegestrant plus palbociclib was consistent with what was previously reported.