A combination of the insulin growth factor-receptor (IGF-1R) antibody cixutumumab and the mTOR inhibitor temsirolimus show promise for the treatment of Ewing's sarcoma, according to the results of a 20-patient Phase I study conducted at the University of Texas MD Anderson Cancer Center and Wayne State University reported at the AACR Annual Meeting (Abstract LB 124).
Seven patients (35%) achieved either a complete or partial response, or stable disease for more than five months. Patients experienced tumor regression of 23% to 100%, and the time to treatment failure ranged from two to 22 months.
The most frequent possibly drug-related toxicities were thrombocytopenia (85%), mucositis (80%), hypercholesterolemia (75%), hypertriglyceridemia (70%), and hyperglycemia (65%), all mostly Grade 1-2.
Four of the seven best responders developed Grade 3 mucositis, myelosuppression, or hyperglycemia, which was controlled without dose reduction.
Cixutumumab was given at a dose of 6 mg/kg IV weekly, and temsirolimus was given at doses of 25 mg to 37.5 mg IV weekly, in four week cycles.