MAPK pathway mutations in head and neck cancer affect immune microenvironments and ErbB3 signaling.

MAPK pathway mutations affect one-fifth of head and neck squamous cell carcinoma (HNSCC). Unexpectedly, MAPK pathway aberrations are associated with remarkably long patient survival, even among patients with TP53 mutations (median ∼14 yr). We explored underlying outcome-favoring mechanisms with omics followed by preclinical models. Strikingly, multiple hotspot and non-hotspot MAPK mutations (A/BRAF, HRAS, MAPK1, and MAP2K1/2) all abrogated ErbB3 activation, a well-established HNSCC progression signal. Inhibitor studies functionally defined ERK activity negatively regulating phospho-ErbB3 in MAPK-mutants. Furthermore, pan-pathway immunoprofiling investigations identified MAPK-mutant tumors as the only "CD8+ T-cell-inflamed" tumors inherently bearing high-immunoreactive, constitutive cytolytic tumor microenvironments. Immunocompetent MAPK-mutant HNSCC models displayed active cell death and massive CD8+ T-cell recruitment in situ. Consistent with CD8+ T-inflamed phenotypes, MAPK-mutant HNSCC patients, independent of tumor-mutational burden, survived 3.3-4 times longer than WT patients with anti-PD1/PD-L1 immunotherapies. Similar prognosticity was noted in pan-cancers. We uncovered clinical, signaling, and immunological uniqueness of MAPK-mutant HNSCC with potential biomarker utilities predicting favorable patient survival.

A Pan-Cancer Review of ALK Mutations: Implications for Carcinogenesis and Therapy.

The anaplastic lymphoma kinase (ALK) is a druggable target for cancer therapy. By and large, the oncogenic activation of ALK in human tumors is known to occur by gene rearrangement (e.g. EML4-ALK, NMP-ALK, etc.). Clinical use of ALK inhibitors for "ALK-rearranged" lung cancers has remarkably improved patient survival. To date, much has been known about ALK gene rearrangement in human carcinogenesis and its drug sensitivity relationship. However, emerging genomic data from the Cancer Genome Atlas (TCGA, USA) are now revealing common ALK point mutations (~3.06%) in various cancer types other than lung cancer. Importantly, several recent studies have demonstrated that ALK point mutations, independent of ALK-gene rearrangement, can be oncogenic. Thus, ALK mutations can be pathogenically and perhaps therapeutically important for various cancer types. Here, we summarized the latest ALK mutation frequencies and mutation patterns across 17 human cancer types stemming from TCGA. Unlike many other oncogenes with high frequency of hotspot mutations, ALK point mutations tend to span along the entire gene. Up till now, several recurrent mutations (G263, R401, R551, P968 and E1242) and mutation-rich cluster regions have been identified, but their functional effects remain unknown. We also conducted a comprehensive review of all ALK-mutated human cancer cell lines (from the Cell Line Encyclopedia (CCLE) and the NCI-60 panel), which can be used as model systems for ALK mutation biology and drug screening studies. Lastly, we summarized both the preclinical and clinical findings of ALK mutations on carcinogenesis and drug sensitivity, which may provide important insight into new treatment strategies and prompt future ALK mutation studies in various cancer types.