Final Analysis of the Randomized Phase II/III Study of Standard R-CHOP Versus CHOP Combined with Dose-Dense Weekly Rituximab for DLBCL: JCOG0601

Background: Despite several attempts of randomized phase III trial to overcome R-CHOP in overall survival (OS), R-CHOP has been continued to be a standard of care in previously untreated DLBCL. We conducted a randomized phase II/III study (JCOG0601, jRCTs031180139) that investigated the efficacy of dose-dense weekly rituximab combined with standard CHOP regimen (RW-CHOP) during the early treatment period for previously untreated DLBCL and published the results (Ohmachi K, et al. Blood Adv. 2021). Here in, we report the long-term efficacy and safety of the JCOG 0601 trial after 8 years follow-up from the end of accrual. Methods: Patients aged 20-79 years with previously untreated CD20-positive DLBCL (stage I-IV, performance status 0-2) were randomized to standard R-CHOP (CHOP-21 with eight doses of rituximab, once every 3 weeks) or RW-CHOP (CHOP-21 with eight doses of weekly rituximab). The primary endpoint of phase III part was progression-free survival (PFS). Required sample size was 422 patients, an accrual period of 7 years, and a follow-up period of 3 years with the primary analysis. An additional follow-up period was added to assess long-term outcomes, for a total of 8 years of follow-up. Results: Between December 2007 and December 2014, 422 patients were enrolled, but primary analysis was performed on 421 patients after one patient withdrew consent: 213 in the R-CHOP arm and 208 in the RW-CHOP arm. The baseline characteristics were as follows (R-CHOP arm vs. RW-CHOP arm): median age, 61 vs. 62 years; male sex, 54.5% vs. 55.8%; Ann Arbor stage I/II/III/IV, 14.6/32.9/26.8/25.8% vs. 16.3/42.8/20.2/20.7%; and International Prognostic Index score ≤2, 77.0% vs. 87.5%. At a primary analysis, there was no significant difference in PFS between the arms. At the time of final analysis with a median follow-up of 9.6 years (range: 0.3-14.9) among all patients, meaningful differences were not found in PFS and OS as well as the primary analysist (hazard ratio [HR] in PFS of RW-CHOP against R-CHOP, 0.94; 95% confidence interval [CI], 0.67 to 1.32, one-sided log-rank, P = 0.36 and HR in OS, 0.94; 95% CI, 0.63 to 1.41). Median PFS and OS were not estimable in both arms. Estimated 10 years PFS and OS of all patients was 66.9% (95% CI, 62.1 to 71.3) and 78.0% (95% CI, 73.6 to 81.7). After the first relapse or refractoriness, 126 patients received post-protocol salvage therapy: 66 in the R-CHOP arm and 60 in the RW-CHOP arm. In each arm, 3 patients received high-dose che