France-based AB Science (Euronext Paris: AB) received a formal grant from the US Patent and Trademark Office for US patent 12,648,944, covering methods of treating metastatic castrate-resistant prostate cancer with masitinib in combination with docetaxel. Protection extends to May 2042, providing approximately 17 years of remaining exclusivity on this specific therapeutic use. The grant is strategically significant because it anchors IP protection to a biomarker-defined patient subpopulation — those with baseline alkaline phosphatase levels at or below 250 IU/L — a claim structure that mirrors the pre-specified primary analysis population from AB Science’s Phase III study AB12003 and is materially difficult to design around without replicating the same clinical context. The US grant complements European patent EP4175639, already in force, with counterpart applications pending in other major markets.
The patent’s claims are grounded in data from study AB12003, a prospective, double-blind, placebo-controlled Phase III trial evaluating masitinib at 6.0 mg/kg/day in combination with docetaxel as first-line treatment in chemotherapy-naïve mCRPC patients who had progressed on prior abiraterone or were otherwise indicated for chemotherapy. The primary analysis population was pre-specified as patients with baseline ALP at or below 250 IU/L, comprising 450 of the 712 total enrolled patients.
In that targeted subgroup, masitinib plus docetaxel demonstrated a statistically significant progression-free survival benefit, with a hazard ratio of 0.79 (95% CI: 0.64–0.97; p=0.0087), corresponding to a 21% reduction in the risk of progression relative to control. The effect was progressive across lower ALP thresholds: patients with baseline ALP at or below 100 IU/L showed a 47% reduced risk of progression (hazard ratio 0.53; p=0.002). PFS rate improvements at 12, 18, and 24 months were reported at 1.6-fold, 1.9-fold, and 1.9-fold respectively, each reaching statistical significance. The safety profile was consistent with the known masitinib profile, with no new safety signals identified.
Masitinib is a selective tyrosine kinase inhibitor prostate cancer researchers have studied across multiple indications, targeting KIT, PDGFR, LYN, and FAK, among other kinases. In the mCRPC setting, its activity is attributed primarily to KIT and PDGFR inhibition, pathways implicated in the tumor microenvironment and potentially in resistance mechanisms to androgen-deprivation therapy. The compound is already registered for veterinary medicine and is in active clinical development across oncology, neurological, inflammatory, and viral disease indications.
AB Science is positioning masitinib as the first agent to demonstrate a statistically significant PFS benefit in combination with docetaxel in chemotherapy-eligible mCRPC patients — a claim that, if supported through regulatory review, would address a gap that multiple prior combination attempts have failed to fill.