Longitudinal real-world surveillance of infection outcomes in CAR-T and bispecific therapy recipients: the CLARITY...

Infections are a leading cause of non-relapse mortality following chimeric antigen receptor T-cell therapy (CAR-T) and bispecific antibody (BsAb) therapies. However, infection data from clinical trials are often incomplete, lack pathogen-level detail and rarely capture late infectious complications. This CAR-T treatment in Lymphoma: Analysis of Risk of Infection following Therapy (CLARITY) study aims to generate real-world, longitudinal infection data with extended follow-up to characterise infection timing, including late events and inform risk prediction in patients with lymphoma and myeloma receiving novel immunotherapies.

CLARITY is a multicentre observational cohort study across six Australian centres enrolling adults treated with CAR-T or BsAb therapies. A co-designed REDCap (Research Electronic Data Capture) instrument captures infections classified as microbiologically defined, clinically defined or fever of unknown origin, using internationally standardised definitions. Patients were enrolled between 2019 and 2023, with at least 2 years follow-up per patient, allowing time-updated data on immunosuppressive exposures, haematological recovery and prophylaxis. Multivariable regression and landmark analyses will estimate infection incidence and identify dynamic risk factors over time. Incidence rate ratios will assess prophylaxis effectiveness. Data integrity is supported by central adjudication and site-level audits.

The study has received a waiver of consent (HREC/PMCC/89002) and was co-designed by haematology and infectious diseases investigators. Findings will be disseminated through peer-reviewed publications, scientific meetings and national guideline committees to inform infection prevention and late effects surveillance in immunotherapy-treated populations.