Matching-Adjusted Indirect Comparisons of Axicabtagene Ciloleucel to Mosunetuzumab for the Treatment of Relapsed/ Refractory Follicular Lymphoma

Axicabtagene ciloleucel (axi-cel) was the first chimeric antigen receptor (CAR) T-cell therapy approved for relapsed/refractory (R/R) follicular lymphoma (FL) patients, while mosunetuzumab was the first bispecific monoclonal antibody approved in this population. In the absence of head-to-head evidence, this study sought to conduct a matchingadjusted indirect comparison (MAIC) to estimate the comparative efficacy and safety of these treatments in 3rd line or higher (3L+) FL. The evidence base consisted of individual patient data (IPD) of all enrolled patients, regardless of infusion status, from the singlearm axi-cel trial, ZUMA-5 (NCT03105336), and aggregate data from the mosunetuzumab FL trial (NCT02500407) from publications identified through a systematic review. Efficacy outcomes were progression-free survival (PFS), duration of response (DoR), objective response rate (ORR), complete response rate (CRR). Analyses used independent central review for both trials, where possible. Safety outcomes were cytokine release syndrome (CRS), neurological events (NE), and treatment-related adverse events (TRAEs). Unanchored MAICs were conducted to align ZUMA-5 to the patient characteristics of the mosunetuzumab trial. For each outcome, prognostic factors were identified a priori through quantitative analysis and clinical experts. For time-to-event outcomes, hazard ratios (HRs) were estimated using Cox regression using IPD from ZUMA-5 and pseudoIPD extracted from Kaplan-Meier plots for mosunetuzumab. Patient characteristics were well-aligned between trials leading to large effective-sample sizes after matching, ranging from 93.4 to 115.5, for ZUMA-5 (n = 127). In comparisons to mosunetuzumab (n = 90), axi-cel was associated with improved PFS (HR: 0.39; 95% confidence interval [CI]: 0.24-0.62) and DoR (HR: 0.45; 95% CI: 0.27-0.76). Similarly, axi-cel led to higher ORR (OR: 3.87; 95% CI: 1.53-9.76) and CRR (OR: 2.80; 95% CI: 1.50-5.26). Although axi-cel was associated with a higher rate of all-grade CRS (OR: 5.54; 95% CI: 2.63-8.94) and NEs (OR: 3.54; 95% CI: 1.28-9.83), differences in grade >= 3 CRS and TRAEs were not statistically