Mutational events of MET leading to exon 14 skipping are frequent and potentially targetable events in PSC.

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Purpose Immunotherapy with antibodies against B7/CD28 family members, including PD-1, PD-L1, and CTLA-4 has shifted the treatment paradigm for non-small-cell lung carcinoma (NSCLC) with improved clinical outcome. HHLA2 is a newly discovered member of the family. By regulating T-cell function, HHLA2 could contribute to tumor immune suppression and thus be a novel target for cancer immunotherapy. There is limited information and critical need to characterize its expression profile and clinical significance in NSCLC. Experimental Design We performed immunohistochemistry with an HHLA2-specific antibody (clone 566.1) using tissue microarrays constructed from 679 NSCLC tumor tissues, including 392 cases in the discovery set and 287 cases in the validation cohort. We also studied clinico-pathological characteristics of these patients. Results Overall, HHLA2 was not detected in most of normal lung tissue but expressed in 66% of NSCLC across different subtypes. In particular, EGFR–mutated NSCLC was significantly associated with higher tumor HHLA2 expression in both discovery (EGFR vs. WT: 76% vs. 53%, P=0.01) and validation cohorts (89% vs. 69%, P=0.01). In one of the two cohorts, HHLA2 expression was higher in lung adenocarcinoma as compared to squamous and large cell histology, non-Hispanic White vs. Hispanics, and tumors with high tumor infiltrating lymphocyte (TIL) density. In the multivariate analysis, EGFR mutation status and high TIL intensity were independently associated with HHLA2 expression in lung adenocarcinoma. Conclusion HHLA2 is widely expressed in NSCLC and is associated with EGFR mutation and high TILs in lung adenocarcinoma. It is potentially a novel target for lung cancer immunotherapy.

SUMMARY The PI3K/AKT/mTOR pathway is commonly activated in non-small-cell lung cancer. It plays important roles in promoting oncogenesis in lung cancer and mediating resistance to EGF receptor tyrosine kinase inhibitors. Targeted agents against the components of this pathway are currently in development and their clinical benefits remain to be defined. This review provides an overview of the pathway dysregulation and novel agents targeting the pathway in lung cancer. In addition, potential predictive biomarkers guiding patient selection for targeted PI3K/AKT/mTOR inhibition is also discussed.

Survival for lung cancer patients remains dismal and is largely attributed to treatment resistance. To identify novel target genes the modulation of which could modify platinum resistance, we performed a high-throughput RNAi screen and identified Yes-associated protein (YAP1), a transcription coactivator and a known oncogene, as a potential actionable candidate. YAP1 ablation significantly improved sensitivities not only to cisplatin but also to ionizing radiation, both of which are DNA-damaging interventions, in non-small cell lung cancer (NSCLC) cells. Overall YAP1 was expressed in 75% of NSCLC specimens, whereas nuclear YAP1 which is the active form was present in 45% of 124 resected NSCLC. Interestingly, EGFR-mutated or KRAS-mutated NSCLC were associated with higher nuclear YAP1 staining in comparison to EGFR/KRAS wild-type. Relevantly, YAP1 downregulation improved sensitivity to erlotinib, an EGFR inhibitor. A pharmacological inhibitor of YAP1 signaling, verteporfin also synergized with cisplatin, radiation and erlotinib in NSCLC cells by potentiating cisplatin and radiation-related double-stranded breaks and decreasing expression of YAP1 and EGFR. Taken together, our study is the first to indicate the potential role of YAP1 as a common modulator of resistance mechanisms and a potential novel, actionable target that can improve responses to platinum, radiation and EGFR-targeted therapy in lung cancer.

We identified amplification of RICTOR, a key component of the mTORC2, as the sole actionable genomic alteration in an 18-year-old never smoker with lung adenocarcinoma. It occurs in 13% of lung cancers (1016 cases) in TCGA and at a similar frequency in an independent cohort of 1,070 patients identified by genomic profiling. In the latter series, 11% of cases harbored RICTOR amplification as the only relevant genomic alteration. Its oncogenic roles were suggested by decreased lung cancer cell growth both in vitro and in vivo with RICTOR ablation, and the transforming capacity of RICTOR in a Ba/F3-cell system. The mTOR1/2 inhibitors were significantly more active against RICTOR-amplified lung cancer cells as compared to other agents targeting the PI3K/AKT/mTOR pathway. Moreover, an association between RICTOR amplification and sensitivities to mTOR1/2 inhibitors was observed. The index patient has been treated with mTOR1/2 inhibitors that led to tumor stabilization for over 18 months.

Immunotherapy targeting the PD-1/PD-L1 pathway has changed the treatment landscape of non-small cell lung carcinoma (NSCLC). We demonstrated that HHLA2, a newly identified immune inhibitory molecule, was widely expressed in NSCLC. We now compared the expression and function of PD-L1 with alternative immune checkpoints, B7x and HHLA2. Expression was examined in tissue microarrays consisting of 392 resected NSCLC tumors. Effects of PD-L1, B7x, and HHLA2 on human T-cell proliferation and cytokine production were investigated. PD-L1 expression was identified in 25% and 31% of tumors in the discovery and validation cohorts and was associated with higher stage and lymph node involvement. The multivariate analysis showed that stage, TIL status, and lymph node involvement were independently associated with PD-L1 expression. B7x was expressed in 69% and 68%, whereas HHLA2 was positive in 61% and 64% of tumors in the two sets. The coexpression of PD-L1 with B7x or HHLA2 was infrequent, 6% and 3%. The majority (78%) of PD-L1-negative cases expressed B7x, HHLA2, or both. The triple-positive group had more TIL infiltration than the triple-negative group. B7x-Ig and HHLA2-Ig inhibited TCR-mediated proliferation of CD4 and CD8 T cells more robustly than PD-L1-Ig. All three significantly suppressed cytokine productions by T cells. The majority of PD-L1-negative lung cancers express alternative immune checkpoints. The roles of the B7x and HHLA2 pathway in mediating immune evasion in PD-L1-negative tumors deserve to be explored to provide the rationale for an effective immunotherapy strategy in these tumors. .