Safety and Feasibility of Third-Party Cytotoxic T Lymphocytes for High-Risk Patients with Covid-19.

Cytotoxic T lymphocytes (CTLs) destroy virally infected cells and are critical for the elimination of viral infections such as those caused by the SARS-CoV-2 virus. Delayed and dysfunctional adaptive immune responses to SARS-CoV-2 are associated with poor outcomes. Treatment with allogeneic SARS-CoV-2-specific CTLs may enhance cellular immunity in high-risk patients and provide a safe, direct mechanism of treatment. Thirty high-risk ambulatory patients with COVID-19 were enrolled on a phase I trial to assess the safety of 3rd party, SARS-CoV-2-specific CTLs. Twelve Interventional patients, 6 of whom were immunocompromised, matched the human leukocyte antigen (HLA)-A*02:01 restriction of the CTLs and received a single infusion of one of four escalating doses of a product containing 68.5% SARS-CoV-2-specific CD8+ CTLs/total cells. Symptom improvement and resolution in these patients was compared to an Observational group of eighteen patients lacking HLA-A*02:01 who could receive standard of care. No dose-limiting toxicities were observed at any dosing level. Nasal swab PCR data showed ≥ 88% and >99% viral elimination from baseline in all patients at 4- and 14-days post-infusion. The CTLs did not interfere with the development of endogenous anti-SARS-CoV-2 humoral or cellular responses. T-cell receptor beta (TCR) analysis comparing SARS-CoV-2-specific T-cell responses derived from the CTL donor versus recipients showed persistence of donor-derived CTLs through the end of the 6-month follow-up period. Interventional patients consistently reported symptomatic improvement 2-3 days after infusion, whereas improvement was more variable in Observational patients. This study shows that SARS-CoV-2-specific CTLs are a potentially feasible cellular therapy for COVID-19 illness. (Clinicaltrials.gov #NCT04765449).