Feasibility and Safety of RNA-transfected CD20-specific Chimeric Antigen Receptor T Cells in Dogs with Spontaneous B Cell Lymphoma

Abstract

Preclinical murine models of chimeric antigen receptor (CAR) T cell therapy are widely applied, but are greatly limited by their inability to model the complex human tumor microenvironment and adequately predict safety and efficacy in patients. We therefore sought to develop a system that would enable us to evaluate CAR T cell therapies in dogs with spontaneous cancers. We developed an expansion methodology that yields large numbers of canine T cells from normal or lymphoma-diseased dogs. mRNA electroporation was utilized to express a first-generation canine CD20-specific CAR in expanded T cells. The canine CD20 (cCD20) CAR expression was efficient and transient, and electroporated T cells exhibited antigen-specific interferon-gamma (IFN-γ) secretion and lysed cCD20+ targets. In a first-in-canine study, autologous cCD20-ζ CAR T cells were administered to a dog with relapsed B cell lymphoma. Treatment was well tolerated and led to a modest, but transient, antitumor activity, suggesting that stable CAR expression will be necessary for durable clinical remissions. Our study establishes the methodologies necessary to evaluate CAR T cell therapy in dogs with spontaneous malignancies and lays the foundation for use of outbred canine cancer patients to evaluate the safety and efficacy of next-generation CAR therapies and their optimization prior to translation into humans.

Mechanisms of resistance to CAR T cell therapy

“…RNA transfection has also been used to deliver the CAR gene construct, resulting in transient CAR expression (because the CAR gene is not inserted into the genome of the T cells 50 ). Such transient CAR-expressing T cell products have only short-lived benefits in preclinical models, with no durable responses observed 51 . Finally, non-viral vector-based introduction of the CAR gene into the T cell genome has been successfully achieved using a transposon-transposase system 52,53 , and clinical trials using such products have been reported, with the data demonstrating the safety and feasibility of this approach and providing preliminary evidence of CAR T cell activity 54 .…”

CAR-T cell therapy in gastrointestinal tumors and hepatic carcinoma: From bench to bedside

“…transiently expressed the mRNA for the T cell receptor CD3ζ and for the tumor necrosis factor receptor superfamily member TNFRSF9 (4-1BB) into autologous T cells; the authors observed the antitumor effects of mesothelin-specific CAR-T cells but observed no corresponding toxicity in patients with metastatic pancreatic cancer and malignant papillary mesothelioma. Furthermore, data from completed preclinical 81 and clinical 82 trials at the University of Pennsylvania confirmed the feasibility, safety, and preliminary effectiveness of this method.…”

CAR T Cell Immunotherapy in Human and Veterinary Oncology: Changing the Odds Against Hematological Malignancies

“…In a first-ever canine study, Panjwani and colleagues (58) have reported successful mRNA electroporation of primary canine T cells to generate CAR T cells. In brief, a novel expansion methodology was developed that yields large numbers of canine T cells from normal or lymphomadiseased dogs.…”