Cohn, Jeffrey

8011 Background: Maintenance therapy is generally not used in treatment of DLBCL. However, older pts are a unique group in which to study this approach, due to poorer outcome. Methods: As part of intergroup trial E4494/C9793, 415 pts >= 60 years (yr) of age with DLBCL who responded to induction therapy with CHOP or R-CHOP were randomized to MR (rituximab, 375 mg/m2 weekly {wk} X 4 every 6 months for 2 yr) starting 4 wk after the last chemotherapy (n=207) or observation (OBS, n=208) in a prospective 2 × 2 randomized trial design (J Clin Oncol 2006;24:3121). Impact of MR on failure-free survival (FFS) was the primary objective, and impact on time to failure (TTF) and overall survival (OS) were secondary objectives. All p-values are two-sided. Results: Results are presented for 352 centrally reviewed evaluable pts, with a median follow-up after maintenance randomization of 5.5 yr. All results were similar for the intent-to-treat population. Baseline characteristics and response to induction therapy are balanced among the CHOP/R-CHOP pts. At 6 yr, FFS was 46% for those pt who received MR and 36% for the OBS cohort (p=0.005, hazard rate {HR} 0.64); 6-yr OS was 62% for MR and 64% for OBS (p=0.83, HR 0.96). Outcome was also examined in the four treatment subgroups. The 6-yr FFS were: CHOP+MR 44%, CHOP+OBS 35%, R-CHOP+MR 47%, and R- CHOP+OBS 40%. No differences in 6-yr OS were observed according to maintenance randomization following CHOP (57% MR vs 55% OBS) or R-CHOP (67% MR and 72% OBS). Median TTF after maintenance randomization following CHOP+MR was 5.2 yr vs 1.6 yr for CHOP-OBS (p=0.0004), and following R-CHOP+MR was 5.6 yr vs 5.4 yr with R-CHOP-OBS (p=0.50). Proportionately more of the treatment failures occurred within 2 yr after CHOP+OBS (85%) compared to CHOP+MR (61%), p=0.01. In contrast, the proportion of failures within 2 yr was similar for R- CHOP+OBS (47%) and R-CHOP+MR (53%), p=NS. Conclusions: MR after CHOP, but not after R-CHOP, significantly prolongs TTF, but fails to prolong OS, possibly due to a delayed pattern of relapse and/or the efficacy of rituximab in the salvage setting. As 6-yr FFS declined to <50% among R-CHOP responders, with or without MR, there is a need for more effective treatment strategies in older DLBCL pts. No significant financial relationships to disclose.

Purpose To address early and late treatment failures in older patients with diffuse large B-cell lymphoma (DLBCL), we designed a two-stage randomized trial of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) versus rituximab plus CHOP (R-CHOP), with a second random assignment to maintenance rituximab (MR) or observation in responding patients. Patients and Methods Untreated DLBCL patients who were 60 years or older were randomly assigned to R-CHOP (n = 318) or CHOP (n = 314); 415 responders were randomly assigned to MR (n = 207) or observation (n = 208). The primary end point was failure-free survival (FFS). All P values were two sided. Results Three-year FFS rate was 53% for R-CHOP patients and 46% for CHOP patients (P = .04) at a median follow-up time of 3.5 years. Two-year FFS rate from second random assignment was 76% for MR compared with 61% for observation (P = .009). No significant differences in survival were seen according to induction or maintenance therapy. FFS was prolonged with MR after CHOP (P = .0004) but not after R-CHOP (P = .81) with 2-year FFS rates from second random assignment of 77%, 79%, 74%, and 45% for R-CHOP, R-CHOP + MR, CHOP + MR, and CHOP, respectively. In a secondary analysis excluding MR patients, R-CHOP alone reduced the risks of treatment failure (P = .003) and death (P = .05) compared with CHOP alone. Conclusion Rituximab administered as induction or maintenance with CHOP chemotherapy significantly prolonged FFS in older DLBCL patients. After R-CHOP, no benefit was provided by MR. These results, which are consistent with an additive effect of rituximab, suggest that future studies could focus on maintenance strategies with novel agents as well as new induction therapies.