Kazia Therapeutics Expands Phase 1b Trial of Paxalisib in Advanced Breast Cancer

On May 26, 2026, Kazia Therapeutics announced the expansion of its ongoing Phase 1b clinical trial evaluating its lead asset, paxalisib, in patients with advanced triple-negative breast cancer (TNBC). Due to encouraging safety, tolerability, and clinical activity data observed to date, the company is increasing planned enrollment from 12 to 36 patients. The study evaluates paxalisib in combination with pembrolizumab and chemotherapy to further assess dose optimization, preliminary efficacy (including objective response rate and progression-free survival), and translational biomarkers. The company also noted it withdrew abstracts from the ASCO 2026 conference solely to protect its intellectual property position ahead of anticipated filings, clarifying that the withdrawal was not related to safety or clinical concerns. Paxalisib, a brain-penetrant PI3K/Akt/mTOR pathway inhibitor, is also being studied in glioblastoma and brain metastases. Kazia expects to provide additional clinical and translational updates throughout 2026 and 2027 as the expanded dataset matures.