Abstract 5676: Functional pairing of immunomodulatory targets in anaplastic thyroid cancer

Abstract

Abstract Thyroid cancer is the most common type of endocrine malignancy that has an escalating global frequency. Although most well differentiated thyroid cancers (WDTC) are manageable and respond to current therapeutic modalities, undifferentiated anaplastic thyroid cancers (ATC) exhibit a dramatically different clinical behavior and poor prognosis. With the recent development of immunotherapies, targeted, well-defined treatment plans can demonstrate promising treatment outcomes in ATC patients. Precise immunological targets in ATCs with potential clinical relevance are unknown. Major progress has been made in last 5 years toward development of immune checkpoint inhibitors using anti-CTLA-4 and anti-PD-1/PD-L1 antibodies for cancer treatment which has made immunotherapies one of the mainstream treatment choices. Few additional members of the immunoglobulin superfamily of receptors, like LAG3, TIM3 and VISTA have recently been identified as potential checkpoint targets. Interestingly some of these molecules including TIM3 and PD-L1 promote tumor progression and immune escape. Identification of specific immunotherapeutic targets requirs a better understanding of the immune microenvironment in ATC. To this end we evaluated the expression of prominent co-stimulatory and co-inhibitory cell surface molecules by RT-PCR in three thyroid cancer cell lines - TPC-1 (papillary), CGTH-W-1 (follicular) and 8505C (anaplastic). We observed that many co-inhibitory molecules were upregulated in all three tumor cell lines. CTLA4, interestingly, had the highest expression in 8505C. Additionally we observed differential expression of BTLA, LAIR1, TIM3 and VISTA between TPC-1 and 8505C. LAG3, PD-1 and PD-L1 were also upregulated in 8505C compared to TPC-1. Similar pattern was observed with the expression of co-stimulatory molecules, CD40L and GITR . GITR has been shown to have a tumor suppressor function in multiple myeloma. Another co-stimulatory molecule OX40, which has shown promise in tumor recession when targeted, was upregulated in all three cell lines and 8505C showed the highest expression. Our findings suggest that the aggressive and less immunogenic phenotype of ATC might be attributed to the differential expression of these molecules. Targeting these immunomodulatory molecules in ATC warrants a better understanding of the crosstalk between them and it might provide an efficient means for the disease management. Citation Format: Sanjukta Chakraborty, Rachana R. Maniyar, Neha Y. Tuli, Ghada Ben Rahoma, Cameron Budenz, Sarnath Singh, Jan Geliebter, Raj Tiwari. Functional pairing of immunomodulatory targets in anaplastic thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5676. doi:10.1158/1538-7445.AM2017-5676