A Real-World Data-Based Analysis of Prognostic Indices as Part of Trial Eligibility Criteria in Diffuse Large B-Cell Lymphoma Patients

OBJECTIVES: Recent front-line clinical trials used the International Prognostic Index (IPI) to identify trial-eligible patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL). However, many IPI-like variants with improved accuracy have been developed over the years for rituximab-treated patients.

METHODS: We assessed the impact of International Prognostic Indices on patient enrolment in clinical trials, aiming to exclude low-risk IPI patients based on POLARIX/EPCORE DLBCL-2 trial criteria.

RESULTS: We identified 2877 patients in the Danish Lymphoma Registry who would have been eligible for the POLARIX trial if patients with IPI 0-1 scores were included. IPI and NCCN-IPI assigned 33.3% and 11.9% of patients to the low-risk group, respectively. Shorter 5-year overall survival (91.4% vs. 97.5%), higher relapse rate (9.9% vs. 4.4%), and more deaths (16.1% vs. 4.4%) occurred in the low-risk IPI group compared with low-risk NCCN-IPI group. Analyzed models failed to identify true high-risk patients with poor prognosis. Similar results were found in the confirmatory cohort developed based on EPCORE DLBCL-2 trial eligibility criteria.

CONCLUSION: True low-risk patients are more optimal identified by NCCN-IPI and should be excluded from front-line clinical trials due to their excellent prognosis. However, additional high-risk factors besides clinical prognostic models need to be considered when selecting trial-eligible patients.