Regulatory authorities in the United States and Europe have approved a new clinical trial for men with metastatic castrate-resistant prostate cancer (mCRPC).

The trial will evaluate masitinib, an oral medication, in combination with the chemotherapy drug docetaxel to determine if it can delay cancer progression and extend survival. The study will involve 600 patients across multiple global centers, randomly assigned to receive either masitinib with docetaxel or docetaxel with a placebo. The primary goal is to measure radiographic progression-free survival, which tracks how long patients remain free of cancer growth on imaging scans.

Overall survival will also be monitored as a key secondary outcome. To participate, patients must have alkaline phosphatase (ALP) levels of 250 IU/L or lower. ALP, an enzyme in the blood, often rises when prostate cancer spreads extensively to bones or other tissues. Lower ALP levels indicate less advanced metastatic disease, making it a critical marker for identifying patients likely to benefit from masitinib.

A previous Phase 3 trial (AB12003) demonstrated that masitinib plus docetaxel improved progression-free survival by 21% (hazard ratio 0.79, p=0.0087) in patients with ALP ≤ 250 IU/L, with a 47% reduced risk of progression in those with ALP ≤ 100 IU/L (hazard ratio 0.53, p=0.002).

These findings led the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) to validate the ALP biomarker for this new trial.Masitinib works by targeting immune cells that may drive cancer growth, offering a novel approach compared to current treatments. If successful, this could become the first targeted therapy approved for use with docetaxel in mCRPC in nearly 20 years, addressing a long-standing need for new options.

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