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 ß-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.

End of induction positron emission tomography complete response (PET-CR) as a surrogate for progression-free survival in previously untreated follicular lymphoma.

Progression-free survival (PFS) has been the regulatory primary end-point for recent phase III trials in first-line follicular lymphoma (FL), but requires prolonged follow-up. Complete response (CR) at 30 months after initiation of induction treatment was validated as surrogate end-point for PFS. Our objective was to further evaluate surrogacy of CR measured by [18 F] fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging at the end of induction (EoI). Individual patient data were analysed from 1505 patients from five randomized trials. Trial-level surrogacy examining the association between treatment effects on EoI-PET-CR and PFS was evaluated using linear regression ( RWLS2 ) and bivariate Copula ( RCopula2 ) models. Although EoI-PET-CR strongly predicted PFS at a prognostic level, the trial-level assessment did not show strong correlation ( RWLS2=0.56 , confidence interval [CI]: 0.20-0.88; RCopula2=0.35 , CI: 0.0-0.82). The high uncertainty in estimation was possibly due to the small number of trials and the population of patients with available PET data. Maintenance therapy affecting PFS beyond induction treatment, but not EoI-PET-CR end-point, may have distorted the association between treatment effects. However, there will probably be a number of additional trials approaching completion with available PET response data. Refined evaluation of PET-CR based surrogate end-points is still warranted.