Kazia Therapeutics expands paxalisib study to include secondary brain tumours from breast cancer

Oncology-focused drug developer Kazia Therapeutics (ASX: KZA) is expanding a phase two study of its drug paxalisib in patients with brain metastases to include those starting from breast cancer.

The genomically-guided study, led by the US-based cancer research network Alliance for Clinical Trials in Oncology, is evaluating multiple therapies in patients with brain metastases, which occur when cancer spreads from elsewhere in the body to develop secondary tumours in the brain.

Kazia today confirmed the paxalisib arm of the study is advancing to an expansion stage in breast cancer following completion of the pre-specified interim analysis.

The principal investigator of the study Dr Priscilla Brastianos said effective treatments remain elusive for brain metastases.

“This study has been designed to identify potential new therapies for patients with brain metastases, using leading genomic techniques to assign patients to the most appropriate treatment.”

“We are looking forward to continuing our exploration of paxalisib in this important disease area,” Dr Brastianos added.

Alliance study

The Alliance study is recruiting patients with brain metastases as a result of breast cancer, lung cancer and other primary tumours. Patients are assigned to receive either abemaciclib (Lilly), entrectinib (Genentech), or paxalisib (Kazia), depending on the genetic profile of their tumour.

For each drug-tumour combination (for example, paxalisib in patients with lung cancer brain metastases), the study envisages an initial stage of 10 patients for each subgroup (such as breast, lung, other).

If the pre-specified response criteria are met at the interim analysis of 10 patients per subgroup, the study expands that drug-tumour combination to enrol 11 additional patients, in order to seek definitive efficacy data.

In today’s announcement, Kazia confirmed the paxalisib arm has fully recruited the breast cancer cohort for the initial pre-specified interim analysis and has met the threshold for transition to the expansion stage of the study.

The initial stage of the study is ongoing for paxalisib in lung cancer and other tumours.

Brain metastases

According to Kazia, up to 30% of patients with metastatic cancer will develop secondary tumours (metastases) in the brain. There are an estimated 200,000 new cases of brain metastases each year in the United States alone.

Treatment options remain limited and the average survival of patients with brain metastases range from three to 27 months, depending on factors including the location of the original tumour.

Positive data from phase two study in glioblastoma

Last week, Kazia presented positive final data from a phase two study of paxalisib in newly diagnosed glioblastoma at the annual meeting of the American Society for Clinical Oncology (ASCO) in Chicago, Illinois.

Glioblastoma is the most common and most aggressive form of primary brain cancer in adults.

Kazia chief executive officer Dr James Garner said the new data provided a more complete picture of the trial and included some informative sensitivity analyses.

“In the modified intent-to-treat (mITT) population, which excludes non-evaluable patients, survival improves from 15.7 months to 15.9 months. Using the more precise mRANO criteria, PFS improves from 8.4 to 8.6 months.”

“The directionality of these analyses gives us greater confidence in the efficacy signals observed and appear encouraging for future development,” he added.