Sharma, Janaki

Immunotherapy has transformed lung cancer management, but PSC remains an aggressive subtype with a poor prognosis. This study investigates the differential expression of PD-L1 and alternative immune checkpoints (ICs; B7x, B7-H3, and HHLA2), and genetic alterations in PSCs. Tumor specimens of 41 PSC patients were evaluated. PD-L1, B7x, B7-H3, and HHLA2 were positive in 75.0%, 67.6%, 73.0%, and 91.9% of tumors, respectively. PD-L1 expression was significantly higher in the epithelial compared to the sarcomatoid component (median TPS: 50% vs. 0%, p = 0.010). Expression of PD-L1 in both components was only seen in 32.1% of patients. However, at least one IC was expressed in 92.9% of epithelial and 100% of sarcomatoid components. Furthermore, METex14 was detected in 19.5% of patients and was associated with a higher sarcomatoid percentage. Our preclinical studies revealed that METex14 induced PD-L1 expression via MAPK or PI3K/Akt pathways, and MET inhibitors decreased PD-L1 expression. Our findings demonstrate distinct expressions of ICs in PSC subcomponents. Thus, combination IC inhibition as a therapeutic strategy in PSC warrants further exploration. A high percentage of METex14 in PSC and its role in regulating PD-L1 expression reveal different therapeutic targets in this aggressive NSCLC subtype.

64 Background: According to recent reports, ~1 in 4 patients with metastatic prostate cancer may harbor alterations in DNA damage repair (DDR) genes. Clinical trial data demonstrates that prostate cancer patients with DDR mutations may respond to poly-ADP ribose polymerase (PARP) inhibitors. Less is known about the mutational profile in minority patients with prostate cancer. We sought to determine the genomic profile of prostate cancer in an ethnically diverse patient population at a single center. Methods: We performed a retrospective review of men with prostate cancer at the Montefiore-Einstein Cancer Center who had next generation sequencing (NGS) with FoundationOne solid tumor testing between 2/2016 - 8/2019. Individual chart review was used to obtain clinical and demographic data including self-reported race/ethnicity. Results: NGS was attempted on archival tissue from 95 patients and results were obtained for 85. Among patients with results, the self-reported race/ethnicity was: Hispanic (H) 37.6%, Non-Hispanic Black (NHB) 52.9%, Non-Hispanic White (NHW) 4.7%, and Other (O) 4.7%. At the time of tissue sampling, 61 patients had metastatic disease and 10 were castration-resistant. 63 samples were from the prostate, 7 from bone, 7 from lymph node, 3 from liver and 5 from other soft tissue sites. The most commonly altered genes included: TP53 (26%), TMPRSS2-ERG fusion (23%), and PTEN (17%). Alterations in the androgen receptor were identified in 5 samples (all with CRPC). 32.8% had alterations in DDR genes including BRCA2 9 (10.6%), ATM 7 (8.2%), ATR 4 (4.7%), BRIP1 2 (2.3%), CDK12 3 (3.5%), FANCA 2 (2.3%), and PALB2 1 (1.2%). Alterations in mismatch repair genes (MSH2, MLH1, MSH6, PMS2) were present in 4 (4.7%) patients (3 of these were MSI-H). In samples where tumor mutational burden (TMB) was reported, 4 (4.7%) were TMB-high (3 MSI-H and 1 with POLE mutation). Conclusions: DDR gene mutations are common in this primarily minority population. As DDR mutations become more common in the CRPC setting, our data may underestimate the frequency of DDR mutations as only 10 patients had CRPC at the time of tissue sampling. Minority men, like all men, with prostate cancer should be considered for genomic analysis as results are likely to guide therapeutic decisions.