Evolution of eligibility criteria for diffuse large B-cell lymphoma randomised controlled trials over 30 years

Eligibility criteria for randomised control trials (RCT) in diffuse large B-cell lymphoma (DLBCL) may be becoming increasingly strict. In this analysis, 42 first-line phase III RCTs enrolling DLBCL patients since 1990 were identified from PubMed and clinicaltrials.gov. Changes in 31 individual eligibility criteria were assessed using three pre-defined eras [(1) 1993-2005; (2) 2006-2013; and (3) 2014-2020]. The presence of 15/31 criteria increased significantly over time, and the total number of criteria per study also increased over time [median Era 1: 14·5, interquartile range (IQR) 12·6-16·4; Era 2: 21, 18·8-23·3; Era 3: 23, 21-25; P < 0·001]. When each trial's eligibility criteria were applied to 215 consecutive patients from an institutional database treated between 2010 and 2020, a median of 57% (IQR 47-70) of patients were hypothetically eligible for trial enrolment. The median percentage of patients eligible was 68% (56-91), 54% (37-81) and 47% (38-82) for Era 1, 2 and 3 respectively (P = 0·004). Phase III front-line DLBCL trial criteria have become increasingly restrictive over the last three decades, resulting in a diminishing proportion of trial-eligible patients, with less than 50% of our patients eligible for modern-era studies. This potentially impacts generalisability of recent trial results and will likely limit recruitment to ongoing studies.