Project Summary This proposal addresses three major challenges in adoptive cellular therapy: 1) T cell persistence; 2) Tumor immune resistance and 3) Target epitope identification for solid tumors, bringing together the expertise of Dr. Yee in T cell therapy, Dr. Rai in epigenetics and Dr. Morelli in clinical trials. We have established a strategy for generating memory T cells from peripheral blood of patients, via an ACT modality known as Endogenous T Cell (ETC) therapy pioneered in the Yee lab, allowing us to target HORMAD1, a cancer testis antigen broadly expressed in gastric and esophageal cancer, which in its advanced stages represents a significant unmet need. By applying rationally designed combinations of epigenetic modulators we plan to optimize the replicative capacity and memory properties of HORMAD1-specific CTL (HMD-CTL) generate ex vivo to address the challenge of limited in vivo T cell persistence (UG3 Aim 1). One of the dominant extrinsic factors mediating tumor immune resistance in gastric and esophageal cancer is the influence of TGF-β in the tumor microenvironment. In addressing this challenge, we propose the use of a dominant negative TGF-β receptor to sequester TGF-β by engineering expression of the TGFBDNR2 gene into HORMAD1-specific CTL using a retroviral transduction strategy that is well-established in the Cell Therapy Manufacturing Center (UG3 Aim 2). Finally, addressing the challenge of targeting gastric and esophageal cancers was borne out of an ongoing antigen discovery pipeline developed over 5 years examining the portfolio of tandem mass spectrometric defined epitopes eluted from MHC of over 30 tumor samples. From this pipeline we have empirically validated both an HLA-A2 and HLA-A11 epitopes of HORMAD1, demonstrated high affinity with CTL generated using the ETC workflow and propose the use of HORMAD1-specific CTL for this trial, allowing us to cover more than 25% of all gastric and esophageal patients given the prevalence of HORMAD1 expression in these tumors (> 40%) and HLA allele expression (> 65%). At completion of the UG3 portion of this proposal, we will identify an optimal epigenetic program (Aim 1) and TGFBDNR2 transduction workflow (Aim 2) that fulfills the metrics for a Go/ No-Go decision. In the clinical trial component (UH3) these strategies will be assembled to allow us to evaluate safety and duration of in vivo persistence, comparing HORMAD1-specific CTL and TGFBDNR2-engineered HORMAD-1-specitic CTL in two cohorts, while assessing for preliminary efficacy in an Expansion arm. The ETC platform provides greater flexibility than other ACT modalities in its agility to direct specificity to almost any desired target epitope, demonstrated evidence of antigen-spreading, minimal toxicities, and has an established memory potential proven to be sustained in several clinical trials. We anticipate, that with an enhanced epigenetic memory program and, endowed with a mechanism to undermine at least one feature of tumor immune resistance, ETC therapy can provide a vehicle for advancing adoptive cellular therapy for the treatment of solid tumors in a systematic and stepwise fashion.

Project Narrative We propose to enhance the effectiveness of adoptive cellular therapy in three ways: 1) increasing the memory properties of T cells, 2) engineering T cells to resist TGF-β , a T cell suppressive factor found in many cancers, and 3) identifying T cell targets for solid tumors. We will plan to treat patients with stomach and esophageal cancers whose tumors have high levels of TGF-β in a clinical trial using T cells that target a novel antigen found among stomach and esophageal cancers. We believe that this approach, if successful, can be applied to T cells targeting other solid tumors so that we may treat greater numbers of patients who have an unmet need in advanced stages of their disease.