Pediatric phase II cancer chemotherapy trials: A pediatric oncology group study

Purpose: This study reviewed the Pediatric Oncology Group experience with phase II clinical trials in children (<21 years of age) with refractory tumors. Patients and Methods: Patients registered in Pediatric Oncology Group phase II studies were evaluated. Patients had to be <21 years of age with recurrent and refractory measurable disease. Tumor types and response rates were determined. Death on therapy from either drug toxicity, progressive disease, infection, or hemorrhage was measured. Tumor-specific, disease-free survival curves were calculated by Kaplan-Meier analysis. Results: Between 1984 and 1994, 2,465 patient entries were made on 45 phase II trials. Malignancies registered included acute lymphocytic leukemia (ALL) (16.7%), acute myeloid leukemia (AML) (22.0%), osteogenic sarcoma (7.8%), neuroblastoma (7.2%), astrocytoma (7.2%), medulloblastoma (7.1%), glioma (6.7%), ependymoma (6.1%), and others (29.2%). The overall response rate was 19.6% (CR + PR) for children entered on phase II trials. Tumor-specific response rates ranged from 62.1% (23/37) for children with Hodgkin's disease to no responses (0/23) in patients with hepatoblastoma. When comparing single versus multiagent trials, a significantly better initial response rate was seen in the latter studies. However, 5-year survival was comparable. Progression-free survival for all tumor histologies were 12.9% and 9.2% at 2 and 5 years, respectively. Death on study was seen in 11.6% of the patients; however, only three deaths were directly related to drug toxicity. There were no significant gender differences in regards to response, progressive disease, or death on study. Conclusion: Phase II studies conducted in children offer a considerable likelihood of therapeutic benefit without exposing these patients to untoward toxicity.