Kazia reports clinical benefit in six breast cancer patients

SYDNEY - Kazia Therapeutics Limited announced that six patients with advanced triple-negative breast cancer displayed positive results in a Phase 1b trial of their drug paxalisib, according to a press release. Out of the six patients, five experienced an objective response, characterized by at least a 30% decrease in tumor size, including one complete response and four partial responses, amounting to an 83% objective response rate.

One patient showed stable disease. The trial examines paxalisib in combination with pembrolizumab and chemotherapy. Patients experienced improvements across various metastatic sites, such as lung, liver, bone, lymph nodes, and central nervous system, with responses appearing roughly three months after treatment initiation. One patient achieved a complete metabolic response without any remaining disease since November 2025, and this response has persisted in subsequent evaluations.

All six patients showed significant reductions in circulating tumor cells and terminally exhausted T cells, with median reductions of 83% and 51% respectively. Notably, total CD8+ T cell counts remained stable, indicating that existing cells may be regaining functionality rather than being replaced. No serious adverse events related to paxalisib were observed, and no grade 3 or higher hyperglycemia, stomatitis, or mucositis occurred.

The Phase 1b study is expected to conclude enrollment by July 2027, with interim clinical updates planned throughout 2026 and 2027. Paxalisib was licensed from Genentech in late 2016 and has been involved in over 15 clinical trials. The drug has been designated as an orphan drug and fast-tracked by the FDA for glioblastoma and solid tumor brain metastases with PI3K pathway mutations.