Abstract B15: Circulating tumor cells express tissue specific antigens in multiple cancers

Abstract

Abstract Definitive diagnosis of solid organ cancers is based on histopathologic analysis of tumor tissue obtained by invasive biopsies. However, invasive biopsies are associated with procedural expenses, sequelae, and risks. Though immunocytochemistry (ICC) profiling of circulating tumor cells (CTCs) has been previously attempted for diagnosis in some cancers, they have been unviable due to limited yields of CTCs. We used a novel approach for enrichment of sufficient viable CTCs that permit meaningful ICC profiling for diagnosis of cancers in suspected cases. We obtained 15 mL of venous blood draw from 965 patients with confirmed diagnosis of various solid organ cancers. CTCs were enriched from PBMCs fraction using an epigenetically activated enrichment process that is lethal towards normal (nonmalignant) cells but confers survival privilege on apoptosis-resistant CTCs. Harvested CTCs were confirmed by immunostaining for EpCAM and pan-CK. Deep ICC profiling of these CTCs was performed with organ-specific marker for various organs such as lungs (TTF-1 or Napsin), breast (GCDFP15 or GATA3), ovarian (CA125 or WT-1), pancreatic (CK19 or CA19-9), cervical (P63), liver (Hep Par-1 or Glypican), colorectal (CK20 or CDX-2), head and neck (P63), kidney (Pax-8 or RCC), and prostate (PSMA or AMACR). CTCs (EpCAM+, pan-CK+) could be obtained from 94.4% of all samples. Organ-specific markers were positive in 100% of lung cancer, 79.3% of breast cancers, 70.0% of ovarian cancers, 93.3% of pancreatic cancers, 100% of cervical cancers, 61% of hepatocellular carcinomas, 92.6% ofcColorectal cancers, 98.8% of head and neck cancers, 100% of renal cancers, and 100% of prostate cancers. Our results show that deep ICC profiling of CTCs can determine tissue of origin in solid organ cancers noninvasively to substitute conventional procedures dependent on tissue extraction. Citation Format: Dadasaheb Akolkar, Revati Patil, Darshana Patil, Pradip Fulmali, Pooja Fulmali, Shoeb Patel, Pradip Devhare, Akshay Ainwale, Vineet Datta, Cynthe Sims, Ajay Srinivasan, Rajan Datar. Circulating tumor cells express tissue specific antigens in multiple cancers [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B15.