Real-world analyses largely provide confirmatory data that complement what is already known from prospective trials. That said, clinical trials of MCL may enroll patients who are younger and fitter than those encountered in the real world, so there is a role for both types of study. MCL is typically a disease of older and frailer people, unlike Hodgkin lymphoma, which usually affects younger and fitter individuals. Clinical trials might not entirely reflect the actual MCL patient population, and MCL is a disease state in which real-world data, if they are robust and include older patients, could be particularly helpful. 

Now, sometimes we are limited by the nature of the data set that is available to work with, and such is the case in the analysis by Kabadi et al, which was conducted using a commercially insured population with younger individuals (aged <65 years) with MCL. The median age was 57 years in this study, compared with 68 years in the general MCL population. The majority of patients (63%) experienced 1 or more incident adverse event(s), and an increasing number of incident adverse events was linked to increased hospitalization risk. Among the treatments that fit the working definition of frontline therapy for MCL, R-CHOP was the most common, followed by rituximab monotherapy, then bendamustine-rituximab, and then, lastly, ibrutinib. The authors noted that the high frequency of first‐line rituximab monotherapy should be interpreted with caution and may reflect limitations of the claims‐based analysis. Further, the analysis spanned from November 2012 to January 2018, and my sense is that patterns had been changing during that period, to the extent that there would be less R-CHOP use and more bendamustine-rituximab use as frontline therapy in more recent years. 

Further, Kabadi and colleagues noted that the stem cell transplantation rate of just 10% among patients receiving the 4 most common regimens was likely low due to underreporting in the database. Indeed, data from the Center for International Blood & Marrow Transplant Research (CIBMTR) indicate that, over a 10-year period between 2007 and 2017, there were 7144 autologous/allogeneic stem cell transplantations for MCL. If one were to extrapolate the annual incidence of MCL reported by Kabadi et al over 10 years, there would be some 33,000 incident MCL cases in the United States, and, with the 7144 transplants reported for MCL by the CIBMTR over the 10-year period, the rate of transplant in this younger population studied by Kabadi et al does seem low. Thus, real-world data have inherent limitations; one would not conclude, for instance, that a low rate of transplantation observed in the claims database reflected the true rate of transplantation. However, to the extent that these studies may shed light on patients not typically enrolled in clinical trials, they might have a role in confirming or extending what is known.