Potential actionable targets in appendiceal cancer detected by immunohistochemistry (IHC), fluorescent in situ hybridization (FISH) and mutational analysis. Erkut Borazanci1*, Sherri Z. Millis2*, Rebecca Feldman-Moreno2, Anatole Ghazalpour2, Daniel Von Hoff1, Ramesh K Ramanathan1 *co 1st authorship; 1Virginia G. Piper Cancer Center/TGen, Scottsdale, AZ; 2Caris Life Sciences, Phoenix, AZ Background Appendiceal cancers are rare, occurring in 1 percent of appendectomy specimens1 Heterogeneous cancer: Most common histological subtype is adenocarcinoma (54%), then carcinoid, signet ring cell carcinoma, lymphoma, and secondary cancers2 Treatment varies among the different histological subtypes For appendiceal adenocarcinoma (either mucinous or colon-type) other than surgery, no standard therapy exists (outside of following guidelines colorectal adenocarcinoma)3 Understanding the molecular characterization of this cancer type might allow the development of more effective treatment options Table 4: Treatment options based upon targets in appendiceal carcinoma Figure 4: Drug associations using Caris Molecular Intelligence™ recommendation based on biomarker status and published level of evidence. Abstract Background: Appendiceal cancers are rare and consist of carcinoid, mucocele, pseudomyxoma peritonei, goblet cell carcinoma, lymphoma, and adenocarcinoma histologies. Current treatment involves surgical resection or debulking, but no standard exists for adjuvant chemotherapy or treatment for metastatic disease. Methods: Samples were identified from 60,000 global tumors analyzed at a referral molecular profiling CLIA-certified laboratory. 460 samples with appendix primary tumor sites were identified (male/female ratio of 2:3; mean age = 55). 62% of samples were adenocarcinomas (used for analysis); the rest consisted of 9% goblet cell, 15% mucinous; 6% pseudomyxoma, and less than 5% carcinoids and 2% neuroendocrine. Tests included sequencing (Sanger or next generation sequencing [NGS]), protein expression (immunohistochemistry [IHC]), and gene amplification (FISH or CISH). Results: % positive of total adenocarcinoma cohort are shown: Conclusions: Appendiceal adenocarcinomas show high levels of drug resistance proteins (BCRP and MRP1), which highlight the difficulty in treating these tumors and suggest an individualized approach to treatment. Therapeutic options include TOPO1 inhibitors (irinotecan/topotecan), PDGFR antagonists (regorafenib, axitinib), MGMT (temozolomide), and SPARC (nab-paclitaxel). These findings indicate the need to evaluate patient samples for patterns in marker expression and alteration, in order to better understand the molecular biology and formulate a personalized therapy approach in these difficult to treat cancers (supported by a grant from Caris Life Sciences). Results Table 1: Potential targets identified by IHC in appendiceal carcinoma Target Treatment TS 5-FU, capecitabine TOPO1 irinotecan, topotecan EGFR erlotinib, cetuximab SPARC Taxanes, Nab-paclitaxel PDGFR Regorafenib, axitinib MGMT temozolomide BRAF vemurafenib, dabrafenib ERCC oxaliplatin, cisplatin, carboplatin RRM1 gemcitabine TOPO2 doxorubicin, epirubicin, doxil KIT Sorafenib, sunitinib, imatinib TLE3 docetaxel, paclitaxel ATM DNA damaging agents Methods Samples were identified from >60,000 tumors submitted from 59 countries between 2008-2013 to Caris Life Sciences, a CLIA-certified multiplatform molecular profiling laboratory 460 samples with primary tumor sites of appendix were identified. Breakdown by primary versus metastatic status is shown (Fig. 1) Immunohistochemistry (IHC) assays (n=425) were performed with up to 30 biomarkers Fluorescent in situ hybridization (FISH) (n=40-158) for ALK, c-Myc, cMET, EGFR, HER2 and/or TOPO2A gene copy amplifications Sequencing was performed by Sanger (n= 50-300) for KRAS, EGFR, PIK3CA, and BRAF. Or by NGS (n=80) on a panel of 45 genes Conclusions In almost all patients (96%) a treatment regimen can be formulated through multiplatform-based molecular profiling Multiple technologies yield a wide range of potential targets Molecular profiling of appendiceal carcinoma can yield targets which are potentially actionable Mucinous adenocarcinoma was by far the most common appendiceal cancer subtype The high levels of drug resistance proteins (BCRP and MRP1) highlight the difficulty in treating these tumors Figure 1: Metastatic status. 89% of patients have metastatic disease, based on documentation provided at intake. #Positive/ #Tested Percent Amplified Gene 1/22 5 EGFR Table 2: Potential targets identified by FISH in Appendiceal Carcinoma; also tested with 0 positive included HER2, cMET, cMYC, TOP2A, ALK Demographics Table 3: Potential targets identified by NGS in patients with appendiceal carcinoma. Figure 2. Gender distribution. Figure 3. Histology distribution References Connor SJ, Hanna GB, Frizelle FA. Appendiceal tumors: retrospective clinicopathologic analysis of appendiceal tumors from 7,970 appendectomies. DisColon Rectum. 1998 Jan;41(1):75-80. Turaga KK, Pappas SG, Gamblin T. Importance of histologic subtype in the staging of appendiceal tumors. Ann Surg Oncol. 2012 May;19(5):1379-85. Cortina R, McCormick J, Kolm P, Perry RR. Management and prognosis of adenocarcinoma of the appendix. Dis Colon Rectum. 1995 Aug;38(8):848-52.   APC ATM BRAF FBXW7 GNAS KRAS PIK3CA SMAD4 TP53 Total Positive 8 6 4 13 188 7 16 Total Cases 79 80 335 74 373 127 73 % Positive 10.1% 7.5% 1.8% 5.0% 17.6% 50.4% 5.5% 16.5% 21.9% 40% 60% Mean age: 55 years old BRAF, KIT, KRAS, NRAS, PIK3CA include Sanger and NGS test results; the remaining were evaluated by NGS; 1 mutant found in a single case for: AKT1, cKIT, cMET, ERBB2, JAK3, SMO; No mutations found: ABL1, ALK, CDH1, CSF1R, CTNNB1, EGFR, ERBB4, FGFR1, FGFR2, FLT3, GNA11, GNAQ, HNF1A, HRAS, IDH1, JAK2, KDR, MLH1, MPL, NOTCH1, NPM1, NRAS, PDGFRA, PTEN, PTPN11, RB1, RET, SMARCB1, STK11, VHL Disclosures: Von Hoff, Daniel.: Employment/Leadership Role – Caris Life Sciences (U) (L); Consultant/Advisory Role – Caris Life Sciences; Stock Ownership – Caris Life Sciences