BACKGROUND AND OBJECTIVE: Registrational trials for ciltacabtagene autoleucel 
[cilta-cel]) and idecabtagene vicleucel [ide-cel] chimeric antigen receptor 
T-cell (CAR-T) therapies were single-arm studies conducted with relapse 
refractory multiple myeloma (MM) patients who were triple-class-exposed (TCE) or 
triple-class-refractory (TCR). It is critical for researchers conducting 
comparative effectiveness research (CER) to carefully consider the most 
appropriate data sources and comparable patient populations. The aim of this 
study was to identify potential data sources and populations for comparing to 
single-arm CAR-T trials CARTITUDE-1 (cilta-cel) and KarMMa (ide-cel).
METHODS: A 2-part global systematic literature search produced a review of (1) 
clinical trials of National Comprehensive Cancer Network (NCCN) guideline 
preferred regimens in previously treated MM, and (2) real-world data cohorts of 
TCE or TCR populations, published between 1/1/2015 and 12/10/2020, with sample 
sizes of > 50 patients and reporting survival-related outcomes. Implications on 
CER and accepted best practices are discussed.
RESULTS: Nine clinical trials of NCCN preferred regimens were identified along 
with five real-world data-based publications. No clinical trials evaluated 
patients with TCE or TCR MM. Among the real-world data-based publications, two 
evaluated patients exclusively with TCR MM, two analyzed a mixed population of 
patients with TCE or TCR MM, and one publication assessed patients exclusively 
with TCE MM. Real-world data treatment patterns were heterogeneous.
CONCLUSION: Current NCCN preferred regimens were not specifically studied in TCE 
or TCR MM patients, although some studies do include a proportion of these types 
of patients. Therefore, appropriate matching of populations using either 
real-world data or patient level clinical trial data is critical to putting 
trials of novel CAR-Ts (i.e., CARTITUDE-1 or KarMMa) into appropriate 
comparative context.