Background We conducted a clinical trial to test whether prophylactic cranial irradiation could be omitted in all children with newly diagnosed acute lymphoblastic leukemia. Methods A total of 498 evaluable patients were enrolled. Treatment intensity was based on presenting features and the level of minimal residual disease after remission induction treatment. Continuous complete remission was compared between the 71 patients who previously would have received prophylactic cranial irradiation and the 56 historical controls who received it. Results The 5-year event-free and overall survival probabilities (95% confidence interval) for all 498 patients were 85.6% (79.9% to 91.3%) and 93.5% (89.8% to 97.2%), respectively. The 5-year cumulative risk of isolated central-nervous-system (CNS) relapse was 2.7% (1.1% to 4.2%), and that of any CNS relapse (isolated plus combined) was 3.9% (1.9% to 5.9%). The 71 patients had significantly better continuous complete remission than the 56 historical controls (P=0.04). All 11 patients with isolated CNS relapse remain in second remission for 0.4 to 5.5 years. CNS leukemia (CNS-3 status) or a traumatic lumbar puncture with blasts at diagnosis and a high level of minimal residual disease (≥ 1%) after 6 weeks of remission induction were significantly associated with poorer event-free survival. Risk factors for CNS relapse included the presence of the t(1;19)[TCF3-PBX1], any CNS involvement at diagnosis, and T-cell immunophenotype. Common adverse effects included allergic reactions to L-asparaginase, osteonecrosis, thrombosis, and disseminated fungal infection. Conclusions With effective risk-adjusted chemotherapy, prophylactic cranial irradiation can be safely omitted in the treatment of childhood acute lymphoblastic leukemia.

BACKGROUND Estimation of the risk of adverse long-term outcomes such as second malignant neoplasms and infertility often requires reproducible quantification of exposures. The method for quantification should be easily utilized and valid across different study populations. The widely used Alkylating Agent Dose (AAD) score is derived from the drug dose distribution of the study population and thus cannot be used for comparisons across populations as each will have a unique distribution of drug doses. METHODS We compared the performance of the Cyclophosphamide Equivalent Dose (CED), a unit for quantifying alkylating agent exposure independent of study population, to the AAD. Comparisons included associations from three Childhood Cancer Survivor Study (CCSS)outcome analyses, receiver operator characteristic (ROC) curves and goodness of fit based on the Akaike’s Information Criterion (AIC). RESULTS The CED and AAD performed essentially identically in analyses of risk for pregnancy among the partners of male CCSS participants, risk for adverse dental outcomes among all CCSS participants and risk for premature menopause among female CCSS participants, based on similar associations, lack of statistically significant differences between the areas under the ROC curves and similar model fit values for the AIC between models including the two measures of exposure. CONCLUSION The CED is easily calculated, facilitating its use for patient counseling. It is independent of the drug dose distribution of a particular patient population, a characteristic that will allow direct comparisons of outcomes among epidemiological cohorts. We recommend the use of the CED in future research assessing cumulative alkylating agent exposure.

Purpose Two phase II studies assessed the efficacy of vismodegib, a sonic hedgehog (SHH) pathway inhibitor that binds smoothened (SMO), in pediatric and adult recurrent medulloblastoma (MB). Patients and Methods Adult patients enrolled onto PBTC-025B and pediatric patients enrolled onto PBTC-032 were treated with vismodegib (150 to 300 mg/d). Protocol-defined response, which had to be sustained for 8 weeks, was confirmed by central neuroimaging review. Molecular tests to identify patterns of response and insensitivity were performed when tissue was available. Results A total of 31 patients were enrolled onto PBTC-025B, and 12 were enrolled onto PBTC-032. Three patients in PBTC-025B and one in PBTC-032, all with SHH-subgroup MB (SHH-MB), exhibited protocol-defined responses. Progression-free survival (PFS) was longer in those with SHH-MB than in those with non-SHH–MB, and prolonged disease stabilization occurred in 41% of patient cases of SHH-MB. Among those with SHH-MB, loss of heterozygosity of PTCH1 was associated with prolonged PFS, and diffuse staining of P53 was associated with reduced PFS. Whole-exome sequencing identified mutations in SHH genes downstream from SMO in four of four tissue samples from nonresponders and upstream of SMO in two of four patients with favorable responses. Conclusion Vismodegib exhibits activity against adult recurrent SHH-MB but not against recurrent non-SHH–MB. Inadequate accrual of pediatric patients precluded conclusions in this population. Molecular analyses support the hypothesis that SMO inhibitor activity depends on the genomic aberrations within the tumor. Such inhibitors should be advanced in SHH-MB studies; however, molecular and genomic work remains imperative to identify target populations that will truly benefit.