A53-Adapted Decitabine-Containing R-CHOP in Newly Diagnosed Diffuse Large B-Cell Lymphoma Defined by LymphGen: Preliminary Results of a Prospective Proof-of-Concept Study.

Background: Diffuse large B-cell lymphoma (DLBCL) with TP53 abnormalities, corresponding to the LymphGen A53 molecular subtype, represents a biologically high-risk group associated with primary resistance to standard R-CHOP therapy. Epigenetic sensitization using hypomethylating agents may enhance chemosensitivity in this setting. We prospectively evaluated the clinical activity and safety of a molecularly adapted DAC-R-CHOP regimen in newly diagnosed A53-DLBCL. Methods: In this single-center prospective pilot cohort study, 70 consecutive patients with newly diagnosed DLBCL underwent targeted next-generation sequencing using a 60-gene panel with integrated copy number variation analysis. Six patients (8.5%) were classified as the A53 subtype. All patients received one cycle of standard R-CHOP. From cycle 2 onward, A53 patients received decitabine (10 mg/m2 IV, days 1-5) prior to R-CHOP (DAC-R-CHOP), for a total of six cycles. The primary endpoint was complete metabolic response (CMR) according to Lugano 2014 criteria. Exact 95% confidence intervals (CI) were calculated. Results: The median age of the A53 cohort was 65 years. CMR was achieved in all six patients (100%; 95% CI, 54-100%). At a median follow-up of 6 months, all patients remained alive in confirmed CMR. Grade III-IV hematologic toxicity occurred in all cases. Febrile neutropenia developed in 100% of patients, requiring mandatory G-CSF support and anti-infective therapy; no treatment-related mortality or permanent dose reductions were observed. Two patients (33%) experienced gastrointestinal bleeding related to local tumor lysis, which was managed conservatively without protocol discontinuation. Conclusions: In this prospective molecularly stratified pilot cohort, integration of decitabine into front-line immunochemotherapy showed promising clinical activity in A53-DLBCL, albeit at the cost of substantial hematologic toxicity requiring intensive supportive care. Given the small sample size, short follow-up, and absence of a comparator arm, these findings should be considered hypothesis-generating and warrant validation in larger multicenter phase II studies with integrated translational biomarker analyses.