The objective is to compare the efficacy and safety of masitinib at 12 mg/kg/day to sunitinib at 50 mg/day in the treatment of patients with gastro-intestinal stromal tumor (GIST) after progression with imatinib.

Masitinib is a selective tyrosine kinase inhibitor with potent activity against wild-type c-Kit, the juxta membrane domain of c-Kit, and PDGFR. Masitinib is also thought to promote survival via modulation of immunostimulation-mediated anticancer effects and modulation of the tumor microenvironment. The objective is to compare the efficacy and safety of masitinib at 12 mg/kg/day with respect to sunitinib at 50 mg/day in the treatment of imatinib-resistant gastro-intestinal stromal tumor (GIST).

Main inclusion criteria include:

• Patient with histological proven metastatic GIST or non-operable locally advanced GIST
• Patient with c-Kit (CD117) positive tumor detected immuno-histochemically
• Patient after at least one progression with imatinib at a dose up to 800mg. Progression is defined as a RECIST 1.1 and/or CHOI disease progression while receiving imatinib treatment.

Main exclusion criteria include:

• Patient treated for a cancer other than GIST within 5 years before enrolment, with the exception of basal cell carcinoma or cervical cancer in situ
• Patient with active central nervous system (CNS) metastasis or with history of CNS metastasis
• Pregnant, or nursing female patient