Wong, Jenna

PURPOSE Cancer of unknown primary (CUP) is a syndrome comprising metastatic cancers without a clinically identified primary site. Although patients with CUP have an unfavorable prognosis, treatment with site-specific therapies guided by clinical features, standard pathology, and molecular assays can improve overall survival. The 92-gene assay (CancerTYPE ID) is a gene expression–based classifier that helps identify the tissue of origin for metastatic cancers with unknown or uncertain diagnoses. This study reports the frequency of selected molecular aberrations of oncogenes, including KRAS, IDH1/2, BRCA1/2, and BRAF, in patients with CUP in the MOSAIC database to highlight potential treatment options. METHODS MOSAIC is a database of patients with CUP submitted for CancerTYPE ID testing and NeoTYPE biomarker testing. Tumor biopsy samples were analyzed by CancerTYPE ID for tumor type identification and further tested for molecular aberrations of oncogenes, including KRAS, IDH1/2, BRCA1/2, and BRAF. RESULTS CancerTYPE ID identified a specific tumor type in 92.5% (2,929 of 3,168) of CUP cases in the MOSAIC database. The most commonly identified histological type was adenocarcinoma (75.4%), with pancreaticobiliary being the most common molecularly diagnosed cancer (24.9%). Aberrations in KRAS, IDH1/2, BRCA, and BRAF genes were identified in 18.8% (n = 597) of biopsies. A cancer-specific US Food and Drug Administration (FDA)–approved or investigational targeted therapy was potentially available for 24.6% (n = 147) of these patients. CONCLUSION This retrospective analysis supports incorporating CancerTYPE ID into the evaluation for patients with CUP to help determine the tissue of origin and identify actionable genetic alterations. This approach may allow more patients with CUP to benefit from site-specific FDA-approved targeted therapies or enrollment into clinical trials.

e15118 Background: Melanoma, non-small cell lung cancer (NSCLC), colorectal adenocarcinoma and thyroid tumors frequently harbor BRAF mutations and are tumor types eligible for treatment with FDA-approved BRAF inhibitors. Although there are many ongoing clinical trials with BRAF inhibitors in various advanced tumor types, currently eligibility requires both tumor type identification and BRAF mutation confirmation. The 92-gene assay (CancerTYPE ID) is a gene expression-based classifier of 50 tumor types and subtypes for metastatic patients with diagnostic ambiguity. Multimodal biomarker testing, including NGS, IHC and FISH, enables identification of actionable biomarkers to guide targeted therapy selection. Here, a database of metastatic cases integrating tumor type with biomarker analysis was used to identify patients eligible for BRAF inhibitor treatment. Methods: MOSAIC (Molecular Synergy to Advance Individualized Cancer Care) is an IRB-approved, de-identified database of diagnostically ambiguous cases submitted for CancerTYPE ID testing with tumor type-guided multimodal biomarker testing (Neogenomics). In this study, metastatic cancers of various tumor types with BRAF mutations were identified. Results: CancerTYPE ID determined 27 different tumor types in 2929 (92.5%) of 3168 cases. BRAF mutations were identified in 87 cases across 18 tumor types and subtypes. Out of the 87 cases, 22 (25.3%) had BRAF mutations in a tumor type eligible for FDA-approved BRAF inhibitor treatment, including melanoma, NSCLC, colorectal adenocarcinoma and thyroid cancer. Another 26 (29.9%) BRAF-mutated cases were detected in a tumor type with ongoing BRAF inhibitor clinical trials, including lymphoma, pancreaticobiliary and ovarian cancer (Table). Conclusions: This analysis identified patients with metastatic cancer with actionable BRAF mutations eligible for FDA-approved therapy, and patients who may be eligible for investigational BRAF inhibitors based on tumor type and mutation status. Notably, cancer type identification is critical given that FDA-approved BRAF inhibitor treatment regimens vary based on the tumor-specific indication. These findings support the clinical utility of molecular tumor type classification by CancerTYPE ID combined with biomarker profiling to identify additional treatment options for patients with metastatic cancer.[Table: see text]