[Efficacy and safety analysis of the OR-CHOP regimen for the treatment of MCD subtype diffuse large B cell lymphoma in the real-world setting].

<b>Objective:</b> To investigate the efficacy and safety of orelabrutinib combined with R-CHOP in the treatment of MCD subtype diffuse large B cell lymphoma (DLBCL) . <b>Methods:</b> Twenty-three MCD subtype patients whose gene-subtype classification was based on baseline tumor tissue and/or baseline plasma using the LymphGen algorithm from June 2022 to June 2023 in the First Affiliated Hospital of Nanjing Medical University were retrospectively enrolled in the analysis. All patients were treated with R-CHOP or R-miniCHOP in Course 1, OR-CHOP or OR-miniCHOP (21 days for one course) in Courses 2-6, and R-monotherapy in Courses 7-8. <b>Results:</b> Of the 23 patients, the median age was 58 years (range: 30-81 years), and 11 (47.8% ) aged >60 years. Fifteen cases (65.2% ) had international prognostic index (IPI) scores of 3 to 5. The top 10 mutated genes in the gDNA tissues were PIM1 (78.3% ), MYD88 (69.6% ), ETV6 (43.5% ), BTG1 (39.1% ), CD79B (43.5% ), HIST1H1E (39.1% ), BTG2 (34.8% ), KMT2D (30.4% ), CD58 (26.1% ), and CDKN2B (21.7% ). The consistency rate of the tissue and plasma mutations was 80%, while the baseline plasma ctDNA burden was closely correlated with the LDH levels and IPI scores (<i>P</i><0.05). All patients received 5 courses of OR-CHOP regimens. The mid-term (after 3 courses) evaluation showed that the overall response rate (ORR) was 100% (23/23), with 22 patients (95.65% ) achieving complete remission (CR), and 1 patient (4.35% ) achieving partial remission (PR). The ORR after the end of treatment (EOT) was 95.65% (22/23). Moreover, 21 patients (91.30% ) obtained CR, 1 patient (4.35% ) obtained PR, and 1 patient (4.35% ) obtained progression disease (PD). Of the 21 patients who had the dynamic EOT-ctDNA burden, only four patients (19.0% ) did not achieve EOT-ctDNA clearance, while the other 17 patients (81.0% ) achieved EOT-ctDNA clearance. The median follow-up time was 20.8 (15.3-30.0) months, while the median progression-free survival (PFS) and overall survival (OS) were not reached. The 2-year PFS rate was 71.8% (95% <i>CI</i> 54.7% -94.2% ), while the 2-year OS rate was 91.3% (95% <i>CI</i> 80.5% -100.0% ). Furthermore, the OR-CHOP regimen was generally well tolerated during clinical use, with hematological toxicity being the main adverse effect. <b>Conclusion:</b> This study revealed that the OR-CHOP regimen can be used as an effective and safe first-line treatment for MCD subtype DLBCL.