Two siblings with familial neuroblastoma with distinct clinical phenotypes harboring an ALK germline mutation

Germline ALK variations are associated with a poor prognosis in glioma and IDH-wildtype glioblastoma

BACKGROUND

Glioma is the most common primary brain tumor. Clear classification is crucial for accurate diagnosis and individualized treatment. Histopathological characteristics and genetic alterations have shown to be related to prognosis and treatment response. Germline variants are important components of genetic alterations. However, the distribution of germline variations in glioma patients and their association with survival remain unknown.

METHODS

We carried out whole-exome sequencing on 99 cases to explore germline variants in glioma. We also analyzed the association of germline variants with clinicopathological features and other prognostic indicators.

RESULTS

All the glioma cases harbored rare germline variants. Germline ALK variants (gALK-Mut) were identified in 12/99 (12.12%) patients. The gALK-Mut patients had significantly shorter overall survival than germline ALK wildtype (gALK-WT) patients in the all glioma group (99 cases) and the subset of patients with IDH-wildtype glioblastoma (IDH-WT-GBM, 39 cases) (P = 0.013 and 0.027, respectively). The gALK-Mut patients also had higher frequency of BIRC5, PIK3CA and RPN1 somatic mutations than the gALK-WT patients in IDH-WT-GBM. Other confounding factors appeared to contribute to patient survival. The subgroup of patients in IDH-WT-GBM with gALK-Mut/TP53-Mut had worse prognosis than the gALK-WT/TP53-Mut subgroup (P = 0.031); The gALK-Mut/TERT-WT and gALK-Mut/TERT-Mut subgroups both had a worse prognosis than the gALK-WT/TERT-Mut subgroup (P = 0.031 and 0.018, respectively).

CONCLUSIONS

Our study revealed ALK variation was an independent indicator of poor prognosis in glioma and IDH-WT-GBM. It could be a promising biomarker and tractable therapeutic target for this deadly disease.

Targeting anaplastic lymphoma kinase in neuroblastoma

Over the last decade, anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase (RTK), has been identified as a fusion partner in a diverse variety of translocation events resulting in oncogenic signaling in many different cancer types. In tumors where the full‐length ALK RTK itself is mutated, such as neuroblastoma, the picture regarding the role of ALK as an oncogenic driver is less clear. Neuroblastoma is a complex and heterogeneous tumor that arises from the neural crest derived peripheral nervous system. Although high‐risk neuroblastoma is rare, it often relapses and becomes refractory to treatment. Thus, neuroblastoma accounts for 10–15% of all childhood cancer deaths. Since most cases are in children under the age of 2, understanding the role and regulation of ALK during neural crest development is an important goal in addressing neuroblastoma tumorigenesis. An impressive array of tyrosine kinase inhibitors (TKIs) that act to inhibit ALK have been FDA approved for use in ALK‐driven cancers. ALK TKIs bind differently within the ATP‐binding pocket of the ALK kinase domain and have been associated with different resistance mutations within ALK itself that arise in response to therapeutic use, particularly in ALK‐fusion positive non‐small cell lung cancer (NSCLC). This patient population has highlighted the importance of considering the relevant ALK TKI to be used for a given ALK mutant variant. In this review, we discuss ALK in neuroblastoma, as well as the use of ALK TKIs and other strategies to inhibit tumor growth. Current efforts combining novel approaches and increasing our understanding of the oncogenic role of ALK in neuroblastoma are aimed at improving the efficacy of ALK TKIs as precision medicine options in the clinic.