Impact of Progression-Free Survival at 24 Months on Subsequent Survival in Patients with Diffuse Large B-Cell Lymphoma Treated with R-CHOP Therapy: A Supplementary Analysis of JCOG0601

Introduction The impact of progression-free survival status at 24 months (PFS24) or event-free survival status at 24 months (EFS24) on subsequent survival has been evaluated in patients with various lymphoma subtypes. Patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) who achieve PFS24 or EFS24 generally have excellent outcomes. It has been observed that the overall survival (OS) after achieving EFS24 was not significantly different from that of the general population (M.J. Maurer. J Clin Oncol, 2014). However, the OS after achieving PFS24 was significantly worse than that of the general population (M.J. Maurer. Ann Oncol, 2018). Consequently, the impact of achieving PFS24 for DLBCL patients remains controversial. In this supplementary analysis, we evaluated the impact of achieving PFS24 on the subsequent survival of untreated DLBCL patients by using data from JCOG0601, a randomized phase2/3 study assessing the schedule of rituximab administration in combination with tri-weekly CHOP (Ohmachi K. Blood Adv, 2021). Methods Among 422 patients enrolled between Dec 2007 and Dec 2014 in JCOG0601, 409 patients were eligible for this analysis (Data cutoff date: Dec 19, 2017). PFS24 was defined as being alive without progression or relapse for 24 months from randomization. The protocol treatment was initiated within 7 days after randomization. OS from PFS24 was defined as the time from achieving PFS24 or the date of progression or relapse to death from any cause. We compared OS from PFS24 with that of age-, sex-, and calendar period-matched Japanese general population using standardized mortality ratios (SMRs). Similarly, PFS12 and PFS60, as well as OS from PFS12 and PFS60, were defined in the same manner as PFS24 and OS from PFS24. The log-rank P-values for OS were calculated. Results The baseline characteristics of the 409 patients were as follows: a median age of 62 years (range, 20-79), with males accounting for 56% (n=227) of the patients. At diagnosis, 46% (n=188) of the patients were Ann Arbor stage III or IV. The majority of patients (82%; n=335) were classified as international prognostic index low or low-intermediate risk. Based on the Hans algorithm for cell-of-origin, 51% (n=210) of the patients were categorized as non-germinal center B-cell type (non-GCB). At a median follow-up of 5.3 years among all patients, a total of 334 patients (82%) achieved PFS24, while 66 patients (16%) failed to achieve PFS24. Five patients died without progre