Abstract 5241: Generation of allogeneic CAR-T circumvents functional deficits in patient-derived autologous product for glioblastoma
Authors: Shaikh Muhammad Vaseem , Salim Sabra K. , Wei Jeffrey , Maich William T. , Anand Alisha A. , Tang Oliver Young , Subapanditha Minomi K. , Suk Yujin , Singh Manoj , Alizada Zahra , Brakel Benjamin , Dimitrov Vassil , Tabunshchyk Zoya , Brown Kevin , Vora Parvez , Binder Zev , Venugopal Chitra , Moffat Jason , Singh Sheila K. 
Published: March 2024

Abstract
Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. Despite an aggressive standard of care that includes maximally safe surgical resection, chemo-radiotherapy, median overall survival remains stagnant at 15 months. However, immunotherapeutic strategies have provided an exciting avenue of exploration to meet clinical need. Chimeric antigen receptor T-cell (CAR-T) therapy has shown promising results in liquid malignancies, but clinical trials in GBM targeting various tumor antigens have not shown durable clinical benefit. While this may be attributable to various tumor-intrinsic immune evasion strategies characteristic of GBM, little work has assessed whether the issue is due to the quality of the CAR-T treatment itself. Currently, CAR-Ts for clinical studies are manufactured in an autologous setting wherein T-cells are extracted from patients, engineered ex-vivo, and subsequently re-infused back. However, peripheral T-cells taken from untreated GBM patients have demonstrated qualitative and functional deficits, which may contribute to suboptimal treatment outcomes. Thus, we aimed to establish whether CAR-Ts generated from GBM patients would show reduced efficacy in comparison to healthy donors using our previously validated CD133 CAR-T. In this work, we show that in-spite of no inherent phenotypic differences, patient derived CAR-Ts shows pre-treatment exhaustion and upon preclinical evaluation using an orthotopic xenograft model of human GBM reduced survival advantage in autologous, patient-derived CD133-targeting CAR-T cell products was observed as compared to the controls. Transcriptomic analysis highlighted a decreased panel-wide enrichment in genes related to T cell and lymphocyte activation, lower prevalence of T cells (including Th1 and CD8+) and higher prevalence of exhausted CD8+ cells in T-cells products derived from GBM donors as compared to healthy donors. To overcome the functional and logistical considerations of autologous therapy, we additionally aimed to generate an “off-the-shelf” allogeneic CD133 CAR-T. Using CRISPR gene editing technology, we generated TCR-knockout CAR-T cells with comparable pre-clinical efficacy to our autologous models. In conclusion, this work highlights the need to reassess autologous CAR-T therapy for GBM and considers allogeneic approaches as promising alternatives. By addressing the inherent deficits in patient-derived CAR-Ts, allogeneic CD133 CAR-Ts may offer a more effective and logistically feasible therapeutic option for treating GBM.
Citation Format: Muhammad Vaseem Shaikh, Sabra K. Salim, Jeffrey Wei, William T. Maich, Alisha A. Anand, Oliver Young Tang, Minomi K. Subapanditha, Yujin Suk, Manoj Singh, Zahra Alizada, Benjamin Brakel, Vassil Dimitrov, Zoya Tabunshchyk, Kevin Brown, Parvez Vora, Zev Binder, Chitra Venugopal, Jason Moffat, Sheila K. Singh. Generation of allogeneic CAR-T circumvents functional deficits in patient-derived autologous product for glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5241.