Study to Evaluate Safety and Dosage of BTX-A51 Alone and with Fulvestrant in Adults with Advanced Solid Tumors and Metastatic Breast Cancer

What this Trial Is About

Researchers are evaluating the safety, toxicity, and pharmacokinetics of BTX-A51, alone and combined with fulvestrant, in people with advanced solid tumors and metastatic breast cancer that is estrogen receptor positive and HER2 negative. This phase 1, open-label study aims to find the safe dose levels and observe preliminary effects of the treatments in this patient group. The study includes multiple phases to carefully assess dosing and safety. The study has three phases. Phase 1a is a dose escalation phase where BTX-A51 is taken orally once daily on a schedule of 5 days on and 2 days off, in 28-day cycles. Dose levels increase sequentially to find the maximum tolerated dose. Phase 1b involves dose ranging of BTX-A51 alone in patients with specific breast cancer mutations, with dosing over 28 days. Phase 1c tests BTX-A51 combined with fulvestrant, an injection given on specific days within 28-day cycles, to evaluate combined safety. Participants will take BTX-A51 orally and may receive fulvestrant by injection if in the combination phase. Researchers will monitor adverse events, dose tolerance, and drug levels in the blood, collecting blood samples at specific times during treatment cycles. They will also assess response rates, duration of response, progression-free survival, and overall survival for up to two years after treatment. Safety follow-up continues for 30 days post-treatment, with options for continued access to BTX-A51 until disease progression or unacceptable toxicity.

A Study of BTX-A51 in People With Advanced Solid Tumor and Breast Cancer