Progression-Free Survival at 24 Months (PFS24) and Subsequent Outcome For Patients With Diffuse Large B-Cell Lymphoma (DLBCL) Enrolled On Randomized Clinical Trials

Abstract

Background

Patients with diffuse large B-cell lymphoma treated with first-line anthracycline based immunochemotherapy and remaining in remission at two years have excellent outcomes. This study assessed overall survival (OS) stratified by progression-free survival at 24 months (PFS24) using individual patient data from patients with DLBCL enrolled in multi-center, international randomized clinical trials as part of the SEAL collaboration.

Patients and Methods

PFS24 was defined as being alive and progression-free 24 months after study entry. OS from PFS24 was defined as time from identified PFS24 status until death due to any cause. OS was compared to each patient's age-, sex-, and country-matched general population using expected survival and standardized mortality ratios (SMRs).

Results

5853 patients enrolled in trials in the SEAL database received rituximab as part of induction therapy and were included in this analysis. The median age was 62 years (range 18-92), and 56% were greater than 60 years of age. At a median follow-up of 4.4 years, 1337 patients (23%) had disease progression, 1489 (25%) had died, and 5101 had sufficient follow-up to evaluate PFS24. 1423 evaluable patients failed to achieve PFS24 with a median OS of 7.2 months (95% CI 6.8-8.1) after progression; 5-year OS after progression was 19% and SMR was 32.1 (95% CI: 30.0-34.4). 3678 patients achieved PFS24; SMR after achieving PFS24 was 1.22 (95% CI: 1.09-1.37). The observed OS versus expected OS at 3, 5, and 7 years after achieving PFS24 was 93.1% vs. 94.4%, 87.6% vs. 89.5%, and 80.0% vs. 83.7%, respectively.

Conclusion

Patients treated with rituximab containing anthracycline-based immunochemotherapy on clinical trials who are alive without progression at 24 months from the onset of initial therapy have excellent outcomes with survival that is marginally lower but clinically indistinguishable from the age-, sex-, and country-matched background population for seven years after achieving PFS24.