Planned Enrollment to Increase from 12 to 36 Patients Following Continued Encouraging Safety and Tolerability Data

Kazia Therapeutics Limited (NASDAQ: KZIA) ("Kazia" or the "Company"), a clinical-stage oncology company advancing therapies designed to reprogram cancer biology and overcome treatment resistance, announced plans to expand its ongoing Phase 1b clinical trial evaluating lead asset paxalisib in combination with standard-of-care therapies in patients with advanced triple negative breast cancer ("TNBC"). Based on continued encouraging safety, tolerability and clinical activity data observed to date, planned enrollment has increased from 12 to 36 patients.

The expansion is intended to further evaluate the safety, tolerability, dose optimization and preliminary efficacy of the paxalisib-based combination regimen with pembrolizumab and chemotherapy. The expanded dataset is expected to provide a more meaningful assessment of objective response rate ("ORR"), progression-free survival ("PFS") and translational biomarkers. Additional clinical trial updates are anticipated throughout 2026 and into 2027.

"We remain encouraged by the safety and tolerability data observed to date, and expanding enrollment allows us to generate a broader clinical and translational dataset as we advance paxalisib in difficult-to-treat advanced breast cancer, such as TNBC," said Dr. John Friend, CEO, Kazia Therapeutics. "Paxalisib's mechanism, modulating key resistance and immune-related pathways, addresses the very reasons that current therapies fail, and we believe it holds meaningful potential for an underserved patient population. While we planned to present scientific progress at ASCO 2026, we made the decision to withdraw our abstracts solely to protect our intellectual property position ahead of anticipated filings. The withdrawal was not related to any safety or clinical concerns. We expect to share additional clinical and translational updates in the coming months."

The Phase 1b study is evaluating paxalisib in combination with established breast cancer regimens across multiple dose cohorts. The trial expansion is supported by a recently published preclinical study in Molecular Cancer Therapeutics, a journal of the American Association for Cancer Research ("AACR"), demonstrating that dual PI3K/mTOR inhibition with paxalisib altered tumor cell state and immune signaling in preclinical TNBC models. TNBC accounts for approximately 15 to 20 percent of all breast cancer diagnoses and is associated with poorer outcomes relative to other breast cancer subtypes.