Summary Genetic studies have established anaplastic lymphoma kinase (ALK), a cell surface receptor tyrosine kinase, as a tractable molecular target in neuroblastoma. We describe comprehensive genomic, biochemical, and computational analyses of ALK mutations across 1596 diagnostic neuroblastoma samples. ALK tyrosine kinase domain mutations occurred in 8% of samples; at three hotspots plus 13 minor sites – and correlated significantly with poorer survival in high- and intermediate-risk neuroblastoma. Biochemical and computational studies distinguished oncogenic (constitutively activating) from non-oncogenic mutations and allowed robust computational prediction of their effects. We also established differential in vitro crizotinib sensitivity of mutated variants. Our studies identify ALK genomic status as a clinically important therapeutic stratification tool in neuroblastoma, and will allow tailoring of ALK-targeted therapy to specific mutations.

Activating mutations in the anaplastic lymphoma kinase (ALK) gene were recently discovered in neuroblastoma, a cancer of the developing autonomic nervous system that is the most commonly diagnosed malignancy in the first year of life. The most frequent ALK mutations in neuroblastoma cause amino acid substitutions (F1174L and R1275Q) in the intracellular tyrosine kinase domain of the intact ALK receptor. Identification of ALK as an oncogenic driver in neuroblastoma suggests that crizotinib (PF-02341066), a dual-specific inhibitor of the ALK and Met tyrosine kinases, will be useful in treating this malignancy. Here, we assessed the ability of crizotinib to inhibit proliferation of neuroblastoma cell lines and xenografts expressing mutated or wild-type ALK. Crizotinib inhibited proliferation of cell lines expressing R1275Q-mutated ALK and a cell line with amplified and overexpressed wild-type ALK. By contrast, cell lines harboring F1174L-mutated ALK were relatively resistant to crizotinib. Biochemical analyses revealed that this reduced susceptibility of F1174L-mutated ALK to crizotinib inhibition results from an increased ATP-binding affinity (as also seen in acquired resistance to EGFR inhibitors), and should be surmountable with higher doses of crizotinib and/or with higher affinity inhibitors.

Key Points• HSCT after PD-1 blockade is feasible, although may be associated with increased early immune toxicity.• PD-1 blockade may cause persistent depletion of PD1 1T cells and alterations in T-cell differentiation impacting subsequent treatment.Anti-programmed cell death protein 1 (PD-1) monoclonal antibodies are being increasingly tested in patients with advanced lymphoma. Following treatment, many of those patients are likely to be candidates for allogeneic hematopoietic stem cell transplant (HSCT). However, the safety and efficacy of HSCT may be affected by prior PD-1 blockade. We conducted an international retrospective analysis of 39 patients with lymphoma who received prior treatment with a PD-1 inhibitor, at a median time of 62 days (7-260) before HSCT. After a median follow-up of 12 months, the 1-year cumulative incidences of grade 2-4 and grade 3-4 acute graft-versus-host disease (GVHD) were 44% and 23%, respectively, whereas the 1-year incidence of chronic GVHD was 41%. There were 4 treatment-related deaths (1 from hepatic sinusoidal obstruction syndrome, 3 from early acute GVHD). In addition, 7 patients developed a noninfectious febrile syndrome shortly after transplant requiring prolonged courses of steroids. One-year overall and progression-free survival rates were 89% (95% confidence interval [CI], 74-96) and 76% (95% CI, 56-87), respectively. One-year cumulative incidences of relapse and nonrelapse mortality were 14% (95% CI, 4-29) and 11% (95% CI, 3-23), respectively. Circulating lymphocyte subsets were analyzed in 17 patients. Compared with controls, patients previously treated with PD-1 blockade had significantly decreased PD-1 1 T cells and decreased ratios of T-regulatory cells to conventional CD4 and CD8 T cells. In conclusion, HSCT after PD-1 blockade appears feasible with a low rate of relapse. However, there may be an increased risk of early immune toxicity, which could reflect long-lasting immune alterations triggered by prior PD-1 blockade. (Blood. 2017;129(10):1380-1388

Nevoid basal cell carcinoma syndrome, or basal cell nevus syndrome (Gorlin syndrome), is a rare autosomal dominantly inherited disorder that is characterized by development of basal cell carcinomas from a young age. Other distinguishing clinical features are seen in a majority of patients, and include keratocystic odontogenic tumors (formerly odontogenic keratocysts) as well as dyskeratotic palmar and plantar pitting. A range of skeletal and other developmental abnormalities are also often seen. The disorder is caused by defects in hedgehog signaling which result in constitutive pathway activity and tumor cell proliferation. As sporadic basal cell carcinomas also commonly harbor hedgehog pathway aberrations, therapeutic agents targeting key signaling constituents have been developed and tested against advanced sporadically occurring tumors or syndromic disease, leading in 2013 to FDA approval of the first hedgehog pathway-targeted small molecule, vismodegib. The elucidation of the molecular pathogenesis of nevoid basal cell carcinoma syndrome has resulted in further understanding of the most common human malignancy.