Infectious complications of car T-cell therapy: A longitudinal risk model

Background: CAR T-cell therapy, where a patient's own T cells are re-engineered to express a receptor to a target of interest, is becoming an increasingly utilized cancer-directed therapy. There are significant toxicities that contribute to a novel state of immunocompromise, leading to new patterns of infectious complications that require further detailed study.

Methods: We created a single-center cohort of adult recipients of CD19-directed CAR T-cell therapy and assessed infectious outcomes, supportive care received, toxicities, and markers of immune function up to 2 years following CAR T-cell therapy. Descriptive statistics were used as appropriate for analysis. We additionally conducted time-to-event analysis assessing time-to-first infection with either log-rank testing or Cox regression with univariate analysis, before including significant predictors into a multivariate Cox model of time to infection.

Results: We identified 73 patients who received CD19-directed CAR T-cell therapy who predominantly had diffuse large B-cell lymphoma. Within 30 days of cell infusion, bacterial and Candida infections were the most common, with 64% of infections due to these organisms. Between 30 days and 2 years postinfusion, respiratory viruses and pneumonia were the most frequent infections, with 68% of infections due to these etiologies. Receipt of tocilizumab, development of immune effector cell-associated neurotoxicity syndrome (ICANS), or lower neutrophil count were associated with quicker onset of infection in a multivariate Cox model.

Conclusions: Respiratory viruses remain an important infectious complication of CAR T-cell therapy following the first year. The model may be a useful tool to identify patients at the highest risk of infection.