AB Science confirmed that it has received the green light from both the U.S. Food and Drug Administration and the European Medicines Agency to launch a confirmatory Phase III clinical trial of masitinib in combination with docetaxel for patients with metastatic castration-resistant prostate cancer (mCRPC). The dual approval represents an important step for a treatment strategy that could change outcomes in one of the most difficult stages of prostate cancer.

Why this matters for patients

Prostate cancer is among the most common cancers in men worldwide. While early-stage disease is often well controlled with surgery, radiation, or hormone therapy, many patients eventually progress to advanced forms where the cancer no longer responds to testosterone-lowering drugs. This stage is called metastatic castration-resistant prostate cancer. At this point, treatment options are limited. Docetaxel chemotherapy has long been a standard, but the benefits are often temporary and side effects can be significant.

The addition of masitinib, an oral tyrosine kinase inhibitor, may offer a new dimension of control by targeting specific molecular pathways involved in tumor growth and resistance. For patients who have exhausted conventional options, this trial could provide a chance at better outcomes.

The scientific rationale

Masitinib works by selectively inhibiting kinases involved in tumor cell survival, proliferation, and the tumor microenvironment. Preclinical studies suggested that masitinib might improve the sensitivity of cancer cells to chemotherapy. Earlier clinical work, including exploratory analyses, hinted that patients with lower baseline levels of alkaline phosphatase (a blood marker often linked to bone involvement in prostate cancer) might particularly benefit from the combination of masitinib and docetaxel.

By focusing on these patients, the new Phase III trial aims to answer whether masitinib truly enhances the effects of standard chemotherapy, potentially delaying disease progression or extending overall survival.

Design of the confirmatory trial

The newly approved study is expected to recruit patients internationally, with regulatory agencies in both the United States and Europe supporting its design. Participants will be randomized to receive either docetaxel alone or docetaxel in combination with masitinib. Primary endpoints will likely include progression-free survival and overall survival, while secondary endpoints will track safety, tolerability, quality of life, and biomarker responses.

Close monitoring will be required to balance potential benefits with risks. Kinase inhibitors, including masitinib, can sometimes cause side effects such as gastrointestinal disturbances, skin reactions, or blood abnormalities. In advanced cancer patients who are already weakened by disease and chemotherapy, safety remains a central concern.

Implications for oncology

The decision by two major regulatory bodies to allow this confirmatory trial underscores the level of promise seen in preliminary data. It also reflects a broader trend in oncology: combining targeted therapies with traditional chemotherapy in hopes of enhancing effectiveness without dramatically increasing toxicity.

If successful, this trial could set a precedent for more personalized approaches in prostate cancer, identifying subgroups of patients most likely to benefit from specific drug combinations. For oncologists, this would add another layer of precision to treatment planning. For patients, it could mean longer disease control and potentially improved survival at a stage where options are few.

Looking ahead

The road from regulatory approval of a trial to eventual approval of a drug combination is long. Recruitment, follow-up, and data analysis will take years, and there is no guarantee that masitinib plus docetaxel will outperform current standards. However, the launch of this Phase III trial gives the prostate cancer community renewed hope that new therapeutic avenues are on the horizon.

For now, attention will be on how the trial is implemented, how patients are selected, and whether the early promise of masitinib can be confirmed in a larger and more rigorous study. Should the results prove positive, this combination could mark a new chapter in the treatment of advanced prostate cancer.