According to a new study published in the journal Pediatric Blood and Cancer, cixtumumab plus temsirolimus did not cause objective responses in pediatric and young adult patients with recurrent or refractory sarcoma.
For the phase 2 study, researchers sought to investigate the use of cixtumumab, an insulin-growth factor type 1 receptor inhibitor, and temsirolimus, a mammalian target of rapamycin inhibitor, for the treatment of pediatric and young adult patients with recurrent or refractory Ewing sarcoma, osteosarcoma, rhabdomyosarcoma, and other types of soft tissue sarcoma.
The combination had previously demonstrated positive preclinical data, and doses from a pediatric phase 1 study were used for this study. Patients received cixtumumab 6mg/kg IV and temsirolimus 8mg/m2 IV once weekly for 4 weeks, followed by cixtumumab 6mg/kg and temsirolimus 10mg/m2 for subsequent cycles. Of those enrolled, 43 patients were evaluable and received a median of 2 cycles.
Results showed that no patients experienced objective responses. Of those, 16% were progression-free at 12 weeks. The most common adverse effects were electrolyte disturbances, mucositis, and myelosuppression.
Most patients were not dose-escalated with temsirolimus due to toxicities. Because no objective responses were observed, researchers could not investigate the correlation between tissue biomarkers and objective response.
The authors evaluated the activity of the anti-IGF-1R antibody cixutumumab with the mammalian target of rapamycin (mTOR) inhibitor temsirolimus in patients with relapsed or refractory Ewing sarcoma, osteosarcoma, rhabdomyosarcoma, and other soft tissue sarcoma, using the recommended dosages from a pediatric phase I trial.