(471) CAR T-Associated Bacteremia: A Single-Center, Five-Year Retrospective

Introduction: Chimeric antigen receptor (CAR) T cell therapy, as with other forms of cancer-directed immune effector cell (IEC) therapy, is a promising form of immunotherapy for a rising number of malignancies. CAR T and other IEC therapies are associated with infection in the post-infusion period owing to lymphodepleting chemotherapy, B-cell aplasia (in CD19-targeting IECs), and immunosuppressants used to curb inflammatory toxicities.

Methods: A single-center retrospective chart review identified adult patients who received cancer-directed IEC therapy between 02/2018 and 02/2023. We reviewed these cases, collecting clinical and laboratory data, noting the presence bacterial or fungal isolates from blood cultures as well as other microbiological assays in the period between conditioning (D-14) and 30 days following infusion (D+30).

Results: Of 585 cancer-directed IEC patients, 246 (42%) had positive microbiological assays. 168 of these patients (68%) received CD19-targerting IECs, while 26 (11%) received BCMA-targeting IECs, 16 (7%) solid tumor antigen-targeting IECs, and 36 (15%) another IEC, such as tumor-infiltrating lymphocytes. 87 patients grew bacteria from ≥1 blood cultures. The most represented Gram-negative species were 9 E. coli, 8 Pseudomonas spp., 7 Klebsiella spp., 3 Stenotrophomonas spp., and 3 E. cloacae. Gram-positives included 11 Enterococcus spp., 4 Streptococcus spp., 2 Staphylococcus aureus, and 49 coagulase-negative Staphylococcus spp (CoNS). There were 7 patients with ≥2 non-CoNS bacteria in blood cultures (polymicrobial infections), while there was only 1 Candida case. Of note, mean (and standard error [SE]) methylprednisolone equivalents used between infusion (D+0) and first positive culture was higher in non-CoNS bacteremic patients at 691 mg (SE 283, range 0 to 9,127 mg) than the mean total (D+0 to D+30) equivalents used in remaining patients at 323 mg (SE 49, range 0 to 12,647 mg).

Conclusions: Our findings reflect the burden of infection in IEC patients, with bacteremia occurring in 15% of cases. Mean corticosteroid usage was greater in the lead-up to non-CoNS bacteremia than the total usage in other IEC patients, highlighting the contribution of immunosuppressants to the cost of this increasingly effective oncological therapy.