Infections following chimeric antigen receptor T cell therapy: 2018-2022.

Background: Chimeric antigen receptor (CAR) T-cell therapy is an emerging therapeutic modality for relapsed and refractory hematological malignancies. Infectious complications following CAR T-cell therapy are not well defined.

Methods: This is a retrospective analysis of data on patients who received CAR T-cell therapy between April 2018 and December 2022 at the Karmanos Cancer Center, Detroit. Patients' data were collected up to their last known clinic or inpatient follow-up visit. An infectious episode was defined as any microbiologically proven or clinically documented infection.

Results: Seventy-six patients received therapy with FDA-approved CAR T-cell products. Thirty-three patients (43.4%) had at least one infectious episode. There were 61 infectious episodes during a median follow-up of 184 (96-340) days. Median duration for the onset of infection was 59 (22-209) days. Bacterial and viral infections occurred in 42.6% and 41% of the infectious episodes, respectively. COVID-19 was the most common infectious complication (14.8%). Time-to-event analysis showed that most infections occurred within the first 100 days. Empirical antibiotic use during Cytokine Release Syndrome/Immune effector Cell-Associated Neurotoxicity Syndrome (CRS/ICANS) in the absence of documented bacterial infection was reported in 85.7% of patients. Clostridioides difficile accounted for 11.5% of all infectious episodes. Five of six patients with C. difficile infection had CRS/ICANS and received antibiotics.

Conclusion: COVID-19 and C. difficile infection were the most common infections following CAR T-cell therapy. Most infections occurred within the first 100 days. Empiric antibiotic use and C. difficile infection were common in patients with CRS/ICANS, in the absence of documented bacterial infection, thus providing an excellent opportunity for antimicrobial stewardship in this population.