Kazia Therapeutics Ltd. (KZIA) delivered a clinical update Tuesday that should have investors paying attention: its experimental drug paxalisib is showing real promise in one of oncology's toughest challenges—late-stage triple-negative breast cancer.
The company's ongoing Phase 1b study is testing paxalisib alongside pembrolizumab (that's Merck & Co. Inc.'s (MRK) blockbuster Keytruda) and chemotherapy in patients with Stage IV metastatic triple-negative breast cancer, or TNBC. And the early results look genuinely encouraging.
The Response Data
Here's what matters: three patients treated with paxalisib-based regimens have demonstrated meaningful clinical responses. Two of the two evaluable patients enrolled in the Phase 1b trial achieved partial responses. That's a 100% response rate in this small but significant early cohort.
Even more striking, one advanced metastatic TNBC patient achieved a confirmed complete metabolic response after being re-treated with the pembrolizumab/chemotherapy plus paxalisib combination under an expanded access protocol. These responses aren't happening in easy cases either—patients showing improvement have visceral disease and multi-organ metastases.
The median time on treatment so far is approximately 6.1 months, and here's the kicker: all patients were still continuing therapy when this update dropped.
Safety Profile Looks Clean
Any oncology drug can potentially work if you're willing to tolerate terrible side effects. What makes these results more interesting is that paxalisib continues to demonstrate a generally favorable safety and tolerability profile when combined with pembrolizumab and chemotherapy at the 30 mg daily dose.
At that dosing level, there's been one case of Grade 1 hyperglycemia (that's elevated blood sugar) requiring no intervention. Two serious adverse events have been reported, but both were deemed unrelated to paxalisib. That's about as clean as you could hope for in advanced cancer trials.
What Comes Next
Kazia expects to activate two additional clinical sites by April 2026, with two more planned for mid-2026. The company continues to target enrollment of twelve TNBC patients by the end of 2026, with topline data readout anticipated in early 2027.
The company isn't putting all its eggs in one basket, either. Kazia is also evaluating paxalisib in additional breast cancer populations, including earlier-stage TNBC and hormone receptor-positive, HER2-negative breast cancer, where dysregulation of the PI3K/mTOR pathway is well established.
This isn't the first time paxalisib has shown promise. Back in July 2025, a 61-year-old woman with metastatic triple-negative breast cancer localized to the left upper lobe of the lung showed highly encouraging preliminary results at 21 days, with a greater than 50% reduction in circulating tumor cells and a notable decrease in CTC clusters.
Following the Money
In December 2025, Kazia Therapeutics raised approximately $46.5 million in capital, which the company will use to support continued clinical development of its lead program, paxalisib.
Price Action: KZIA stock surged to as high as $8.73 before pulling back 10.21% to $7.120 at the last check on Tuesday.
