Randomized Clinical Trial Representativeness and Outcomes in Real-World Patients: Comparison of 6 Hallmark Randomized Clinical Trials of Relapsed/Refractory Multiple Myeloma

Abstract

Background: Concern has been increasing in oncology regarding randomized clinical trial (RCT) eligibility limiting the generalizability of the findings to real-world populations. Using a large US electronic health record database, we investigated the real-world generalizability of the findings from recent RCTs for relapsed and/or refractory multiple myeloma (RRMM).

Patients and methods: Patients with RRMM initiating second-to fourth-line therapy with the control arm of the following RCTs were retrospectively identified and categorized as "RCT eligible" or "RCT ineligible" according to the eligibility criteria: (1) Rd (lenalidomide, dexamethasone)-ASPIRE, TOURMALINE-MM1, POLLUX, and ELOQUENT-2; and (2) Vd (bortezomib, dexamethasone)-CASTOR and ENDEAVOR. Predictors of RCT ineligibility and overall survival were analyzed using logistic regression and Cox regression analysis.

Results: Variations in the individual trial ineligibility rates were noted, with up to 72.3% (range, 47.9%-72.3%) of patients not meeting the eligibility criteria for 1 of the 6 hallmark RCTs (n = 788 for Rd; n = 477 for Vd). Other malignancies, cardiovascular disease, acute infection, and renal dysfunction were the common reasons for ineligibility. Advanced age, Charlson comorbidity score of ≥ 2, later therapy lines (3-4), and refractory status to the previous line were independently predictive of RCT ineligibility. RCT-ineligible versus RCT-eligible patients had a significantly greater mortality risk (hazard ratio, Rd, 1.46; Vd, 1.51).

Conclusion: Most real-world patients with RRMM were ineligible for the hallmark RCTs. The eligibility rates varied across the RCTs, underlining the flawed nature of cross-study comparisons without RCT validation. Overall survival was significantly affected by the inability to meet the criteria, highlighting the limited generalizability of the RCT results. Greater efforts are required to broaden the eligibility criteria to reflect real-world clinical characteristics and narrow the gap between RCT efficacy and the observed effectiveness in real-world patients with RRMM.

Keywords: Overall survival; Prognostic indicators; RCT; RRMM; Real-world effectiveness.