Millis, Sherri Z.

603 Background: Anal squamous cell carcinoma (Anal SCC) is a rare, HPV-associated malignancy accounting for 2.4% of digestive system cancers. In most cases, these malignancies are detected in the early stages and successfully managed with chemoradiation therapy. Uncommonly, these cancers recur or present with metastases. In this setting, cisplatin and 5-fluorouracil represent the only endorsed regimen. Once beyond standard therapy, few therapeutic options exist for those patients with aggressive disease. The purpose of this study is to identify other novel, potential targets and therapeutic options for this disease, utilizing a multiplatform approach. Methods: 206 anal SCC specimenswere tested via a multiplatform profiling service (Caris Life Sciences, Phoenix, AZ) consisting of gene sequencing (Sanger or next generation sequencing [NGS]), protein expression (immunohistochemistry [IHC]) and gene amplification (CISH or FISH). 6 cases were documented as positive for HPV or HIV; status was not provided on the remaining 200. Results: Key results are shown in the table below, shown as percent change/total cases. Conclusions: Multiplatform tumor profiling identified a low incidence of gene mutations. Protein expression aberrations identified potential treatment options not routinely considered, such as topoisomerase inhibitors and taxanes. Mutations in PIK3CA, Akt1, and FBXW7 as well as PTEN loss indicate potential for targeting the PI3 kinase pathway. Additionally, immunomodulatory agents may be a therapeutic option, based on PD-1 expression levels. Targeting the ErbB-family receptors, namely with anti-EGFR agents or newer generation pan-HER - inhibitors, may represent another option, given EGFR and HER2 amplification as well as EGFR overexpression. It should be mentioned that differences in anal carcinomas whose etiology is of viral origin may present different treatment options based on the driver mutations. [Table: see text]

501 Background: Predictive biomarkers of response to targeted therapy are lacking in renal cell carcinoma (RCC). We evaluated a cohort of RCC patients referred for molecular profiling to identify potentially actionable recurrent molecular aberrations. Methods: 166 consecutive renal cases referred to Caris Life Sciences over 2 yrs were evaluated with central pathology review. Cases were subtyped into clear cell (ccRCC), n=100, papillary (PRCC), n=20, sarcomatoid, n=10, translocation, n=6, medullary, n=4 or unclassified, n=26. 63% of cases were metastatic. Testing included a combination of sequencing (Sanger or next generation sequencing [NGS]), protein expression (immunohistochemistry [IHC]), and/or gene amplification (CISH or FISH). Results: ccRCC had a 52% loss of PTEN, while PRCC had a 21% loss (p value=0.02). 100% of ccRCC with sarcomatoid features (4) showed aberrant expression of PD-L1 and were infiltrated with PD-1+ tumor infiltrating lymphocytes; 100% of 10 non-ccRCC sarcomatoids also had aberrant expression of PD-L1. Loss of PBRM1 expression was observed in 60% of ccRCC. Loss of histone 3 lysine 36 trimethylation (H3K36me3), which is associated with SETD2 mutations, was observed in 30% of ccRCC. TOP2A was overexpressed in ccRCC at 30% and in non-ccRCC at 50%. 100% of ccRCC and PRCC overexpressed EGFR; a single unclassified renal cell carcinoma did not overexpress EGFR. 50% of cases had cMET overexpression, amplification, or mutation. HER2 was not amplified or overexpressed in any RCC; a single rare HER2 mutation (R816H) was found in a collecting duct carcinoma. VHL mutations were identified in 50% of ccRCC tumors. We observed lower rates of TP53 (14%), ATM (6%), and PIK3CA(4% ccRCC, 7% PRCC) mutations compared to other cancers. Conclusions: Multiplatform molecular profiling of renal cell carcinoma identifies potential predictive biomarkers in ccRCC. The documented activity of everolimus in ccRCC (RECORD-1 trial) may be attributable to PIK3CA pathway alterations. RCC with sarcomatoid features may respond to PD1/PD-L1 targeted immunotherapies. The impact of molecular profiling in ccRCC to predict responses to currently available targeted therapy has important implications for trial design and patient selection.

Abstract Monoclonal antibodies that target the programmed death-1 (PD-1)–programmed death ligand-1 (PD-L1) axis have antitumor activity against multiple cancers. The presence of sarcomatoid differentiation in renal cell carcinoma (RCC) is associated with resistance to targeted therapy and poor responses to IL2 immunotherapy. Given the aggressive nature of RCC with sarcomatoid differentiation and the exclusion of sarcomatoid histology from metastatic RCC clinical trials, less is understood regarding selection of therapies. Here, we characterized the PD-1/PD-L1 axis in RCC with sarcomatoid differentiation. We directly compared two PD-L1 antibodies and found concordance of PD-L1 positivity in 89% of tested RCCs with sarcomatoid differentiation. Coexpression of PD-L1 on neoplastic cells and the presence of PD-1–positive tumor-infiltrating lymphocytes were identified in 50% (13 of 26) of RCCs with sarcomatoid differentiation. In contrast, only 1 of 29 clear cell RCCs (3%) had concurrent expression of PD-L1 and PD-1 (P = 0.002). Our study suggests that RCC with sarcomatoid differentiation may express PD-1/PD-L1 at a higher percentage than RCC without sarcomatoid differentiation, and patients with these tumors may be good candidates for treatment with anti–PD-1/PD-L1 therapies. Cancer Immunol Res; 3(12); 1303–7. ©2015 AACR.