Benzinga | Dec 10, 2021 10:40AM EST

Arvinas, Pfizer's ARV-471 Shows Clinical Benefit Rate Of 40% In Pretreated Breast Cancer Patients

* Arvinas Inc (NASDAQ:ARVN) and Pfizer Inc (NYSE:PFE) posted updated data from Phase 1 dose-escalation trial of ARV-471 for locally advanced or metastatic ER-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer (ER+/HER2-).

* ARV-471 demonstrated antitumor activity in CDK4/6 inhibitor-pretreated patients with a clinical benefit rate (CBR) of 40% in 47 evaluable patients.

* The heavily pretreated patient group had a median of four prior therapies.

* Three patients exhibited confirmed partial responses (PR) among the 38 patients with response evaluation criteria in solid tumors (RECIST) measurable lesions and at least one on-treatment tumor assessment.

* ARV-471 continues to demonstrate a favorable tolerability profile. Robust ER degradation was observed at all dose levels, reaching an 89% reduction of ER.

* ARV-471 is expected to enter two Phase 3 registrational clinical trials in 2022.

* Related Link: Arvinas, Pfizer Announce $2.4B Licensing Agreement For Protein-Degrader Based Breast Cancer Therapy.

* Price Action: ARVN shares are down 3.24% at $69.80, PFE stock is down 0.20% at $51.98 during the market session on the last check Friday.