Factors Affecting the Clinical Course of Follicular Lymphoma: A Multistate Survival Analysis Using Individual Patient Data from Eight Multicenter Randomized Clinical Trials

Introduction/Background: Leveraging the Follicular Lymphoma Analysis of Surrogacy Hypothesis database of individual patient data from first-line clinical trials, we studied the clinical course of follicular lymphoma (FL) and investigated clinical factors associated with FL outcomes. Patients and Methods: We examined 2428 patients from 8 randomized trials using multistate survival models with 4 states: induction treatment, progression, death from FL, and death from other causes. We utilized Aalen-Johansen estimator and Cox models to assess the likelihood of FL outcomes and quantify predictors’ effects. Results: Two-year progression, FL-related death, and death from other causes estimates were 26.5%, 3.4% and 1.4%, respectively. FL-associated deaths were the primary cause of mortality within 10 years of follow-up. Male sex (hazard ratio: 1.25; 95% confidence interval: 1.05-1.47), > 4 involved nodal areas (1.51; 1.23-1.86), elevated LDH (1.20; 1.01-1.43), low hemoglobin (1.44; 1.15-1.81), and elevated β-2 levels (1.23; 1.02-1.47) increased risk of progression. CD20-targeting agents reduced risks for progression (0.29; 0.22-0.39), death from FL (0.05; 0.01-0.20), and death from other causes without progression (0.13; 0.05-0.33) and following progression (0.52; 0.30-0.92). Estimated 2-year progression rates were 22.3% and 43.5% with or without CD20-targeting agents, respectively. Two-year FL-associated mortality rate was 8.3% among patients without CD20-targeting agents, 5.4% with B-symptoms, 4.9% with elevated LDH, and 9.1% with low hemoglobin. Conclusion: This study identified independent contributions of baseline clinical factors to distinct outcomes for patients with FL following first-line therapy on a clinical trial. Similar analytical approaches are needed to increase understanding of factors that influence FL outcomes in other settings.