Chimeric antigen receptor (CAR) T-cell therapy is a type of immunotherapy that uses altered T cells to fight cancers such as lymphoma, leukemia, and multiple myeloma when other treatments have not been successful.1 In April 2024, the U.S. Food and Drug Administration (FDA) required a boxed warning for the risk of T-cell malignancies following CAR T-cell therapy and recommended lifelong monitoring for secondary cancers.2 However, others have reported that secondary cancers after CAR T-cell therapy are rare.3,4
To understand the rate of secondary cancer among patients who received CAR T-cell therapy, we studied 3,296 patients treated with CAR T-cell therapy between January 1, 2017, and August 1, 2023. Secondary cancers included both metastatic cancers and second primary cancers. Overall, we found that 5.2% of treated patients had a new cancer diagnoses three weeks to one year after the start of CAR T-cell therapy, as seen in Figure 1. When we stratified the data by the specific CAR T-cell therapy, we found small variations in the rate of secondary cancer, though no specific treatment was significantly different from the overall rate.
Skin, respiratory organ, and digestive organ cancers were the most diagnosed types of secondary cancers for patients who had received CAR T-cell therapy, as seen in Figure 2.