A phase II trial of radiation and cetuximab followed by irinotecan/cetuximab for children with newly diagnosed diffuse pontine tumors and high-grade astrocytomas.

Abstract

10030 Background: Diffuse intrinsic pontine gliomas (DIPG) and high-grade astrocytomas (HGA) have dismal prognoses. We previously demonstrated in a phase 1 study that cetuximab and irinotecan was a safe and tolerable regimen. Consequently, we initiated this 2-strata phase 2 trial to investigate the safety and efficacy of weekly cetuximab given with involved field external beam radiation therapy followed by 10 cycles of cetuximab and irinotecan for DIPG and HGA as determined by the 1-year progression-free survival. Methods: Eligible patients aged 3-21 years with newly diagnosed HGA or DIPG were enrolled to parallel strata. All patients received radiation therapy (5940 cGy) with concurrent cetuximab at 250mg/m2 IV weekly for 6 weeks. Following radiation, patients received cetuximab (250mg/m2 IV) weekly and irinotecan (16mg/m2/day IV) daily x 5 for two weeks every 21 days for 30 weeks. Tumor, serum, and CSF samples were collected for correlative studies. Sera collected at the onset of rash were analyzed for inflammatory and immune-related cytokines. Results: Forty-eight patients (27 DIPG, 21 HGA) were enrolled and 45 were treated (median age 8 years; range: 3–19). Toxicities were manageable; the most common adverse events were fatigue, gastrointestinal complaints, neutropenia, rash, headache, electrolyte abnormalities, elevated ALT/AST, and fever. Grade 3-4 events in ≥10% of patients were hypokalemia and lymphopenia. 4 patients experienced cetuximab-related hypersensitivity reactions (2 grade 3 reactions). The median PFS was 9.5 months (95% CI: 7.0-12.2) for HGA and 7.8 months (7.0-8.6) for DIPG with a 1-year PFS±SE of 24±10% and 25%±10% respectively. The median OS for HGA was 17.7 months (95% CI: 14.1-18.0) and 11.5 months (8.8-14.2) for DIPG. Biological correlative studies will be presented. Conclusions: Cetuximab and radiation therapy followed by cetuximab and irinotecan is well tolerated in children. Based on the 1-year PFS, this regimen may deserve further investigation in patients with DIPG. Biological correlative studies will delineate the mechanisms of the rash and possible implications for EGFR-targeted therapeutics in such patients. Clinical trial information: NCT01012609.