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Axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) are autologous anti-CD19 chimeric antigen receptor T (CAR T) cell therapies for the treatment of patients with relapsed/refractory large B cell lymphoma (RR-LBCL). Both can induce durable responses; however, cross-trial comparisons are difficult due to differences in study design. In this study, the registration trials of axi-cel and tisa-cel were compared using a matching adjusted indirect comparison (MAIC). A MAIC was performed to adjust for differences in patient characteristics between trials. The estimates for the ZUMA-1 (axi-cel) trial were adjusted using patient-level data to match the study population in JULIET (tisa-cel) for key variables: International Prognostic Index), Eastern Cooperative Oncology Group score, stage, refractoriness or relapsed disease, double/triple hit status, cell of origin, and number of prior lines of therapy. The endpoints analyzed were response, overall survival (OS), and adverse events. After adjusting for differences in patient characteristics between trials, axi-cel was associated with a greater objective response rate (relative risk [RR]=1.61; 95% confidence interval [CI], 1.29 to 2.01) and complete response (RR = 1.62; 95% CI, 1.16 to 2.27) than tisa-cel among patients who underwent infusion. The OS from infusion onward comparing axi-cel to tisa-cel had a hazard ratio of 0.51 (95% CI, 0.31 to 0.83). The indirect comparison showed a higher rate of grade 1 to 2 cytokine release syndrome (CRS) in ZUMA-1 compared with JULIET (RR = 2.03; 95% CI, 1.55 to 2.65) and similar rates of grade ≥3 CRS and neurologic events. In the absence of a direct head-to-head study, the MAIC statistical technique suggests axi-cel may have superior efficacy but a greater risk of grade 1 to 2 CRS. Future real-world studies can further inform the relative efficacy and safety of CAR T therapies in RR-LBCL.

Patients treated with anti-CD19 chimeric antigen receptor (CAR) T-cell therapies have shown either sustained remission or rapid progression. Traditional survival modeling may underestimate outcomes in these situations, by assuming the same mortality rate for all patients. To illustrate this issue, we compare standard parametric models to mixture cure models for estimating long-term overall survival in patients with relapsed or refractory large B-cell lymphoma treated with axicabtagene ciloleucel (axi-cel). Compared to standard models without cure proportions, mixture cure models have similar fit, but substantially different extrapolated survival. Standard models (Weibull and generalized gamma) estimate mean survival of 2.0 years (95% CI (1.5, 3.0)) and 3.0 years (95% CI (1.7, 5.6)), respectively, compared to 15.7 years (95% CI (9.3, 21.1)) and 17.5 yrs (12.0, 22.8) from mixture cure models (using Weibull and generalized gamme distributions). For cancer therapies where substantial fractions achieve long term remission, our results suggest that assumptions of the modeling approach should be considered. Given sufficient follow-up, mixture cure models may provide a more accurate estimate of long-term overall survival compared with standard models.