P035 | OUTCOME COMPARISON BETWEEN R-CHOP AND R-DA-EPOCH IN ADVANCED-STAGE DOUBLE EXPRESSOR DIFFUSE LARGE B-CELL LYMPHOMA: A SINGLE-CENTER RETROSPECTIVE ANALYSIS

Background: Double expressor lymphomas account for ~30% of DLBCLs and are associated with poor prognosis, including higher CNS relapse risk with R-CHOP. More intensive regimens such as R-DA-EPOCH have shown controversial results. Since 2016, advanced-stage DEL patients ≤75 years at our center have been treated with R-DA-EPOCH. We retrospectively compared outcomes in two consecutive cohorts treated with R-CHOP or R-DA-EPOCH. Methods: Among 93 advanced-stage DLBCL cases treated with R-CHOP (2010–2015), 32 DEL were identified after histological review and FISH to exclude double-hit lymphomas. The R-DA-EPOCH cohort (2016–2023) included 34 DEL cases. Clinical and pathological features were compared using Chi-square/Fisher’s exact tests. Survival was estimated using the Kaplan-Meier method and compared by log-rank test. Cumulative incidence in the presence of competing events was assessed using Gray’s test. All analyses were performed with SAS. Results: Sixty-six patients were analyzed: 32 treated with R-CHOP and 34 with R-DA-EPOCH. Although median age was significantly higher in the R-CHOP group (68 vs 62 years, p=0.046), other major baseline characteristics (including IPI ≥2 in >85%, CNS-IPI, ECOG PS, LDH, and Ki-67) were comparable. Complete response rates were 68.8% for R-CHOP and 76.5% for R-DA-EPOCH (p=0.724). Median follow-up was longer in the R-CHOP group (119.3 vs 50.7 months, p<0.001). The cumulative incidence of relapse/progression was 28% for R-CHOP and 29% for R-DA-EPOCH at 1 year, and 38% and 29%, respectively, at 2 years (p=0.415). Two-year progression-free survival (PFS) was 56.3% for R-CHOP and 70.6% for R-DA-EPOCH (p=0.124). Three R-CHOP patients died within 2 years from causes unrelated to lymphoma or treatment. Two-year overall survival (OS) was 77% (65% R-CHOP vs 88% R-DA-EPOCH, p=0.013), with median OS not reached in the R-DA-EPOCH group. Conclusions: In this retrospective single-center study, although a statistically significant difference in OS was observed between the two groups, this did not translate into a benefit in terms of PFS or cumulative incidence of relapse/progression. The OS advantage is likely influenced by the availability of more effective salvage therapies since 2017. Despite sample size limitations, our analysis suggests that R-DA-EPOCH has a limited impact on disease control in DEL.