Pilot Study of Intensive Chemotherapy With Peripheral Hematopoietic Cell Support for Children Less Than 3 Years of Age With Malignant Brain Tumors, the CCG-99703 Phase I/II Study. A Report From the Children's Oncology Group.

Abstract Background The primary goals of the Children's Cancer Group 99703 study were to assess the feasibility and tolerability of—as well as the response rate to—a novel dose-intensive chemotherapy regimen. Methods Between March 1998 and October 2004, 92 eligible patients were enrolled. Following biopsy/resection, patients received three identical cycles of Induction chemotherapy (vincristine, cyclophosphamide, etoposide, and cisplatin) administered every 21-28 days. Patients without tumor progression then received three consolidation cycles of marrow-ablative chemotherapy (thiotepa and carboplatin) followed by autologous hematopoietic cell rescue. Results The maximum tolerated dose of thiotepa was 10 mg/kg/day × 2 days per cycle. The toxic mortality rate was zero during induction and 2.6% during consolidation. Centrally evaluated response rates to induction and consolidation in evaluable patients with residual tumor were 73.3% and 66.7%, respectively. Disease progression rates on induction and consolidation were 4%. Five-year event-free survival and overall survival were 43.9 ± 5.2% and 63.6 ± 5% respectively. Gross total resection versus less than gross total resection were the only significant outcome comparisons: 5-year maximum tolerated dose and overall survival of 54.4 ± 7% versus 28.9 ± 7% ( P  = 0.0065) and 75.9 ± 8% versus 48.7 ± 8% ( P  = 0.0034), respectively. The 5-year maximum tolerated dose for localized (M0) versus metastatic (M1+) medulloblastoma was 67.5 ± 9.5% versus 30 ± 14.5% ( P  = 0.007). The 5-year maximum tolerated dose and overall survival for desmoplastic medulloblastoma patients versus other medulloblastoma were 78.6 ± 11% versus 50.5 ± 12% ( P  = 0.038) and 85.7 ± 9.4% versus 60.6 ± 11.6% ( P  = 0.046), respectively. Conclusions This phase I dose-escalation study of marrow-ablative thiotepa regimen determined a maximum tolerated dose that had acceptable toxicity. Overall survival data justify this strategy for current Children's Oncology Group studies.