Multiple myeloma clinical trials exclude patients with the highest-risk disease: a systematic review of trial exclusion criteria

Patients with certain subsets of multiple myeloma continue to have poor outcomes and are in need of novel treatment approaches. Strict eligibility criteria for randomized controlled trials (RCTs) limit access to clinical trials and limit the external validity of trial results for these patients. We systematically reviewed RCTs in newly diagnosed myeloma from 2006 to 2023 to ascertain the prevalence of 12 key exclusion criteria and trends over time. 80 RCTs were included. Exclusion criteria included: age in 43 (51%) trials; projected life expectancy in 20 (24%); performance status in 74 (87%); non-secretory and/or oligosecretory disease in 47 (55%), hepatic function in 64 (79%), renal function in 63 (74%), hematological thresholds in 50 (59%), prior malignancy in 68 (80%), and neuropathy in 50 (59%). For 53 trials which had detailed exclusion criteria available, plasma cell leukemia was excluded in 21 (40%), extramedullary disease in 5 (9%) and CNS disease in 13 (25%). The percentage of studies invoking each of these exclusion criteria did not significantly improve over time on univariate regression analysis, and exclusion criteria relating to neuropathy have worsened. The restrictive eligibility criteria of most myeloma RCTs perpetuate a cycle where limited data exists to treat challenging myeloma subtypes.