Arvinas's ARV-471 Achieves Clinical Benefit Rate Of 38% In Breast Cancer Setting - Arvinas (NASDAQ:ARVN)

Arvinas Inc ARVN announced initial results from the Phase 2 cohort expansion portion of a phase 1/2 study with ARV-471 in collaboration with Pfizer Inc PFE for locally advanced or metastatic ER-positive/human epidermal growth factor receptor 2 (HER2) negative (ER+/HER2-) breast cancer.
This disclosure was initially planned for December 8. However, the 2022 San Antonio Breast Cancer Symposium (SABCS) incorrectly published the abstract, omitting a key safety data table, and inadvertently released the corresponding full data presentation.
ARV-471 shows a favorable tolerability profile and demonstrates a clinical benefit rate of 38% (total n=71), the primary endpoint in the trial.
Patients had a median of four lines of prior therapies in a population where 100% of patients were treated with prior cyclin-dependent kinase (CDK4/6) inhibitors, 79% with prior fulvestrant, and 73% with prior chemotherapy.
ARV-471 administered at 200 mg (n=35) and 500 mg (n=36) demonstrated:
- Antitumor activity in 100% CDK4/6 inhibitor-pretreated patients, as measured by a CBR of 38% (total n=71) in all patients and 51.2% in patients with mutant ESR1 tumors (n=41).
- Preliminary median progression-free survival of 3.7 months, a key secondary endpoint, in all evaluable patients and 5.7 months in patients with mutant ESR1 tumors (n=41).
- A favorable tolerability profile, with most treatment-related adverse events reported as Grade 1 or 2.
Price Action: ARVN shares are down 2.76% at $41.89 on the last check Tuesday.

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