Abstract 1429: Preclinical characterization of a KK-LC-1-specific T cell receptor for the treatment of epithelial cancers

T cell receptor (TCR) gene therapy can mediate tumor regression in patients; however, successful treatment of epithelial cancers has been limited. We studied the targeting of Kita-Kyushu lung cancer antigen 1 (KK-LC-1), a cancer germline antigen expressed in multiple epithelial cancers, with TCR gene-engineered T cells. We thoroughly vetted KK-LC-1 expression in both cancerous and healthy tissue by pulling data from BioGPS and cBioPortal and analyzing a broad range of patient samples, primary cancer lines, and healthy tissue by both qRT-PCR and fluorescence in situ hybridization. Our findings show that KK-LC-1 is expressed in numerous epithelial cancers including breast, lung, cervical, ovarian, melanoma, and prostate whereas expression in healthy tissue is limited to immune-privileged sites including the epididymis and testis. We identified an HLA-A*01:01-restricted KK-LC-152-60-specific TCR isolated from the tumor infiltrating lymphocytes of a patient with metastatic cervical adenocarcinoma. T cells from two healthy donors were transduced with the KK-LC-1 TCR and tested for in vitro targeting of tumor cell lines. The KK-LC-1 TCR recognized the HLA-A*01:01+, KK-LC-1+ cell lines 4156, EKVX, and PC-3, as determined by IFN-γ release. The HLA-A*01:01- cell lines, HeLA, DU-145, and MDA-MD-468, were initially not recognized by the KK-LC-1 TCR; however, following stable transduction with HLA-A*01:01, these cell lines were targeted. The HLA-A*01:01+, KK-LC-1- cell lines, PC-3 and 3748, were not recognized by the KK-LC-1 TCR. To assess the TCR’s potential for off-target activity, we used amino acid scanning to determine the recognition motif, allowing for subsequent targeted in silico searches to identify peptides containing the same recognition motif. Using NCBI Blast and the ScanProsite database, 10 peptides with homologous essential but different non-essential residues were identified. A retroviral vector encoding the KK-LC-152-60 TCR was used to genetically engineer peripheral blood T cells. No peptide recognition by the TCR was observed when dendritic cells were pulsed with the individual peptides and co-cultured with KK-LC-1 TCR-transduced T cells. Finally, we assessed if human genetically engineered T cells expressing the KK-LC-1 TCR could mediate in vivo tumor regression in an NSG mouse model. Genetically engineered T cells expressing the KK-LC-1 TCR induced tumor regression in both a melanoma and cervical cancer line in a dose-dependent manner. Collectively, these findings indicate that KK-LC-1 is a suitable target for TCR gene therapy and they provide preclinical support for testing of the KK-LC-1 TCR in a phase I clinical trial. Citation Format: Bridget Marcinkowski, Carylinda Serna, Benjamin Jin, Scott Norberg, Christian Hinrichs. Preclinical characterization of a KK-LC-1-specific T cell receptor for the treatment of epithelial cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1429.