Ghazalpour, Anatole

572 Background: Renal medullary carcinoma (RMC) is an aggressive malignancy affecting predominantly young African Americans with sickle cell trait (SCT) or disease (SCD), while a pathologically similar collecting duct carcinoma (CDC) affects patients without sickle cell trait. Clinical responses to chemotherapy and IL-2 in RMC/CDC are poor and novel therapies are needed. Methods: 9 patients with RMC (ages 13-58 y. o., all male) and 15 patients (ages 26-74 y. o., M:F = 13:2) with collecting duct carcinoma (CDC) were studied. Expression of PD-L1 was evaluated with 2 monoclonal antibodies (SP142 and SP263) and tumor infiltrating lymphocytes (TIL) were evaluated for PD1 expression (MRQ-22 antibody) using immunohistochemistry (IHC). Additional studies included ALK protein expression (D5F3 antibody), gene translocation (break apart FISH), next generation sequencing (NGS), and microsatellite instability (MSI). Results: Cancer cell PD-L1 expression above the threshold ( ≥ 2+, ≥ 5%) was seen in 7/9 RMC and 5/13 CDC cases. Concordance between 2 PD-L1 antibodies was 94.4%. PD-1+ TIL were absent in 6/18 cases and variably present in 12/18 cases (from 1 to > 15 TIL/40x power field). No MSI was detected in any of the cases tested (0/6). No case expressed ALK protein, but one case of CDC showed ALK gene re-arrangement. Mutations were identified in SMARCB1, FH, TP53 (3x), ATM, BRCA2, CHEK2 (2x), NF2 (3x), SETD2, and CDKN2A. No mutations in VHL or KDR were detected. One patient with RMC (and SCT) achieved complete clinical remission after treatment with bevacizumab plus paclitaxel. Conclusions: RMC and CDC strongly express PD-L1 in the majority of cases (12/22), suggesting that these patients may benefit from targeting the PD-L1/PD1 interaction. The absence of MSI in these cancers indicates a different mechanism of PD-L1 upregulation from colorectal carcinomas. Consistent with our previous study that showed frequent activation of (pseudo)hypoxia-induced pathways in RMCs (Human Pathology 2011;42:1979), we describe a case of RMC successfully treated with anti-VEGF therapy.

Abstract Introduction: Malignant phyllodes tumors are rare breast malignancies (0.1% of all breast tumors) with limited effective treatment options for recurrent and metastatic disease. Recent trials indicated a potential for anti-angiogenic therapy in soft tissue sarcomas, which led us to investigate these pathways. Materials and Methods: Thirty-five malignant phyllodes tumors (including two cases with matched primary and metastatic tumors) were profiled using gene sequencing (Next-generation and Sanger), gene copy number analysis (in-situ hybridization), whole genome RNA expression, and protein expression (immunohistochemical assay). Results: RNA microarray assay showed consistent over-expression of genes involved in angiogenesis including VEGFA, Angiopoietin2, VCAM1, PDGFRA, PTTG1, and CYP3A5 in all cases analyzed (n=5). No mutations in KDR (VEGFR2) were detected (0/26). EGFR protein overexpression was observed in 25/26 (96%) of cases with amplification of the EGFR gene in 8 cases (33%). EGFR gene mutations were identified in 2 cases (8%) including one case with presumed pathogenic V774M mutation and one case with EGFRvIII mutation. The most common mutations included those of TP53 (50%) and PIK3CA (15%) while other mutations (BRCA1, BRCA2, RET, CDH1, MLH1, ATM) were rare affecting single phyllodes cases. Two cases with matched primary and metastatic cancers harbored the same mutations in both sites (PIK3CA/KRAS and RB1 gene mutations, respectively). Conclusions: Comprehensive multiplatform profiling approach to phyllodes tumors identifies various molecular alterations of which some are potentially actionable. Our data suggests that anti-angiogenic therapy may also be effective in patients with malignant phyllodes tumor. Evaluation of EGFR pathway discovered consistent protein over-expression but rare activating mutations, which necessitates refinement in patient selection targeting these pathways. Citation Format: Gatalica Z, Vranic S, Ghazalpour A, Xiu J, Ocal I, McGill J, Bender R, Discianno E, Sanati S, Reddy S, Pockaj B. Comprehensive multiplatform molecular profiling identifies potentially targetable biomarkers in malignant phyllodes tumors of the breast. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-19.

Abstract Background: The development of novel chemotherapeutic agents has significantly improved the prognosis and survival of patients with breast cancer. ER positive or luminal tumors represent around two thirds of all breast cancers and these cancers are comprised of different histologies including differing gene expression and mutational profiles. This study examined biomarkers involved in immune evasion including PD-L1 and its association with other biological pathways as potential treatment options for luminal breast cancer patients. Methods: We analyzed 1311 breast samples using a multiplatform approach including whole genome mRNA expression (HumanHT-12 v4 BeadChip Illumina Inc., San Diego, CA), protein expression (immunohistochemistry), gene copy number changes (in situ hybridization) and gene sequencing and an additional 304 breast samples were tested for PD-1 and PD-L1 by IHC. The mRNA expression data was based on whole tumor and represents cell type heterogeneity. Heat map analysis was done to look at differential gene expression between the PD-L1 high vs low luminal breast cancers. Results: Based on expression of ER, PR and HER2 by IHC, we subdivided the data into sub- cohorts. Elevated mRNA expression of immune markers including PD-L1, CTLA4, B7H-3, and IDO1 was noted in the ER+HER2- luminal population including ER+ PR- and ER+PR+ cohort. Positive correlation was found between PD-L1 and other immune regulators including CTLA-4, B7-H3 and IDO1 (Spearman correlations of 0.49, 0.36 and 0.46). Protein expression of PD-L1 was found to be specific to the HER2 negative cohort with no expression in the HER2 positive cohort regardless of ER status. Within the ER+HER2- cohort, PD-L1 expression was 5% {ER+PR+ was 5% (4/81) and the ER+PR- was 6% (2/34)}. In contrast, PD-L1 expression was higher in the triple negative cohort, 17% (13/75). The expression of PD-1 on the other hand was present throughout the different cohorts. PD-1 expression ranged from 43% in the ER+HER2- cohort {41% (14/34) in ER+PR-HER2-; 43% (35/81) in ER+PR+HER2-} to 33% in the ER+HER2+ cohort {44% (4/9) in ER+PR-Her2+; and 17% (1/6) in ER+PR+HER2+}. In the ER-HER2+ cohort PD-L1 expression was 75%{6/8 in ER-PR-HER2+ and 0/0 in ER-PR+HER+} and 63%(47/75) in the triple negative cohort. Pathway analysis of the PD-L1 negative vs positive luminal population identified 127 genes involved in various cancer pathways including EGFR and VEGF signaling network (P=7.47e-09). Conclusions: The expression of immune regulatory targets in the breast cancer population suggests that immune- targeted therapies with anti PD-1/PD-L1, CTLA4, B7-H3 and IDO1 may be effective especially in the luminal cohort. Our study further shows that ER+HER2- breast cancer patients may be better candidates for immunotherapy with checkpoint inhibitors as compared to ER+HER2+ due to lack of PD-L1 expression in the HER2 positive cohort. Further validation of our findings is ongoing. Citation Format: Gargi D Basu, Anatole Ghazalpour, Randal Vader, Sandeep Reddy, Karen Anderson, Ann McCullough, Barbara Pockaj. Expression of novel immunotherapeutic targets in luminal breast cancer patients [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-04-08.