VITAS: Atezolizumab in Combination With Chemotherapy for Pediatric Relapsed/Refractory Solid Tumors

In this study, we will test the combination of atezolizumab with chemotherapy for relapsed solid tumors in childhood. The combination of vincristine, irinotecan, temozolomide, and atezolizumab has not been tested. Thus, the trial will have two sequential cohorts: (1) a feasibility cohort, and (2) a rhabdomyosarcoma (RMS) efficacy cohort. In the first cohort, we will determine the feasibility of administering vincristine, irinotecan, temozolomide, and atezolizumab simultaneously in children with relapsed or refractory solid tumors, regardless of histology or PD-L1 status. We will accrue 6 patients and will determine that the therapy is feasible if no more than 2 patients develop a dose-limiting toxicity. Provided that we meet our primary safety endpoint in the feasibility cohort, we will next accrue patients in the RMS efficacy cohort. We will accrue 17 patients in the RMS efficacy cohort. Patients in the feasibility cohort with RMS will be included in this number. We will determine the objective response rate, duration of response, and progression-free survival for all children with relapsed or refractory solid tumors treated with vincristine, irinotecan, temozolomide, and atezolizumab.