Chemotherapies are limited by a narrow therapeutic index resulting in suboptimal exposure of the tumor to the drug and acquired tumor resistance. One approach to overcome this is through Antibody Drug Conjugates (ADCs); that facilitate greater potency via target specific chemotherapy delivery. In this study, we used a bioinformatics approach to identify Lymphocyte antigen 6, locus E, (LY6E), an interferon-inducible glycosylphosphatidylinositol (GPI)-linked cell membrane protein, as a promising ADC target. Immunohistochemical analysis revealed LY6E was overexpressed in a number of tumor types, such as, breast, including triple negative breast cancer, lung, gastric, ovarian, pancreatic and head/neck carcinomas. Characterization of the endocytic pathways for LY6E revealed rapid uptake of the LY6E specific antibody into cells leading to lysosomal accumulation. Consistent with this, a LY6E specific ADC inhibited in vitro cell proliferation and produced durable tumor regression in vivo in high LY6E expressing cancers. Our results identify LY6E as a highly promising molecular ADC target for a variety of solid tumor types with current unmet medical need.

Citation Format: Jyoti Asundi, Lisa Crocker, Jarrod Tremayne, Paul Polakis, Ron Firestein. An antibody drug conjugate (ADC) directed to lymphocyte antigen 6 complex, locus E (LY6E) delivers targeted chemotherapy to a wide range of solid tumor malignancies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 947. doi:10.1158/1538-7445.AM2015-947