Immune-checkpoint blockade therapies has had impressive results in the clinic and are approved in multiple cancer indications. However, meaningful responses remain elusive in several solid tumor types and durable responses in some of these indications, or subtypes, are rarely observed. It has been postulated that this is in part due to elaborate poorly understood immunosuppressive mechanisms that the therapeutic approach must overcome to elicit the desired durable responses. Chimeric Antigen Receptor T (CAR-T) cell therapies had been therapeutically highly successful in haematological malignancies but such successes have not been replicated yet in solid tumors, primarily due to immune suppressive mechanisms in the tumor microenvironment (TME) of these settings. To address these issues in developing our CAR-T therapeutics, we deployed tissue cytometry to conduct a multiplex analysis of 30 markers on the same tissue sections from each patient from a set of patients from various solid tumor indications expressing the antigen GD2 (e.g. SCLC, Melanoma, Neuroblastoma), a disialoganglioside to which we have developed a selective CAR. The panel aimed to characterize and phenotype key players within the TME (i.e. tumour cells, T cells, DCs, macrophages, MDSCs, CAFs, as well as endothelial cells). We then deployed machine learning analytics to assist in inferring about potential interactions the different cell types have in the 3D context of the tumor tissue which allowed the identification of therapeutically relevant elements in the TMEs of these indications. Next, we generated CAR-T cells from healthy donors targeting GD2, an antigen we validated its expression in multiple solid tumor types. A first generation GD2 CAR is currently being developed in the clinic for the treatment of Neuroblastoma. We proceeded to incorporate a CCR module (IL7R chimeric protein designed to improve cell persistence), a dnTGFβ (dominant negative TGF-βRII protein designed to block inhibitor signals from TGFβ), and other function enhancing modules into the GD2 CAR. The multi module CAR-T cells showed potent in vitro activity against human patient derived cancer cell lines as measured by both tumor lysis and cytokine secretion. These CAR-T cells also demonstrated enhanced tumor infiltration and anti-tumor activity in vivo in xenografts mouse models. Our findings suggest that GD2 targeted CAR-T cell therapy is a viable novel approach for the treatment of multiple solid tumors indications.
Citation Format: Margarida Neves, Lukas Stanczuk, Alireza Alavi, Meggan Czapiga, Rebecca Moore, Frederick Vargas, Muhammad A. Al-Hajj. AUTO6NG overcomes immune suppressive mechanisms in the TME and demonstrate preclinical anti-tumor activity in GD2-expressing solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2661.