Ng, Wern Lynn

Introduction Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma. The mainstay of frontline therapy remains R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) or R-CHOP-like immunochemotherapy. Patients' responses to R-CHOP therapy vary depending on the stage and/or molecular subtypes of DLBCL. Approximately 40% of advanced-stage DLBCL patients suffer from a refractory or relapsed disease[1]. The outcome for patients with early relapses after rituximab-containing first-line therapy remains poor[2]. DLBCL poses a marked degree of genetic heterogeneity. Here, we compare the expression of genes related to epigenetics and chromatin modifications in DLBCL patients resistant and non-resistant to R-CHOP therapy. Objective The aim of this study is to assess the differences in the expression of genes related to epigenetics and chromatin modification in DLBCL patients that could lead to chemoresistance and failure of R-CHOP treatment. Method The gene expression profile (GEP) was obtained from Gene Expression Omnibus (GEO) database (Accession number: GSE173263) submitted by Dlouhy et al[3]. The GEP was analyzed in DLBCL cases, including 10 early failure cases (defined as refractory to induction treatment or early relapsing (<12 months from diagnosis)) and 29 responding patients, to identify features associated to primary chemoresistance. The comparison was done using the list of genes proposed by Bakhshi, T. et. al[4] , where he selected the genes that were identified to potentially cause epigenetic and chromatin modifications in DLCBL. All the comparisons were done using a T-test. Results There were significant differences in the gene expression related to epigenetics and chromatin modifications between DLBCL patients in the early failure arm versus the remission arm. Patients who had early failure to R-CHOP tended to have higher expression of these genes: SMARCA4 (p=0.010), SETD1B (p=0.018), SETD2 (p=0.024), EP300 (p=0.012), MLL3 (p=0.049), INO80 (p=0.001), CHD8 (p=0.007), NCOR1 (p=0.020), ARID1B (p=0.034), and SETD5 (p=0.007). Compared to the patients who were in remission after R-CHOP therapy, these patients had significantly higher expression of HIST1H1E (p=0.007). Conclusion Gene expression related to epigenetics and chromatin modifications significantly impacts the prognosis of DLBCL patients treated with R-CHOP. Differences in gene expression may lead to chemoresistance, and higher expression levels are associated with a worse prognosis. This study sheds light on the importance of chromatin and epigenetic modifications in DLBCL progression, guiding the development of future therapies.

Abstract An enhanced understanding of the molecular heterogeneity of diffuse large B-cell lymphoma (DLBCL) has opened the door to clinical trials evaluating novel agents with subtype-specific activity. It is an emerging question whether core needle biopsies (CNB) can adequately meet the increasing tissue requirements of these clinical trials. This can potentially lead to selective enrollment of patients who can undergo excisional biopsy (EB). It is also important to know whether patients who can undergo extensive diagnostic work up differ in their disease characteristics and outcomes from those who cannot. In this observational study, we describe the characteristics, outcomes, and adequacy of diagnostic tissue in patients with newly diagnosed DLBCL and primary mediastinal large B-cell lymphoma who underwent EB vs CNB. Of the 1061 patients, 532 (49.8%) underwent EB and 529 (50.1%) underwent CNB. A significantly higher proportion of patients with CNB had advanced stage disease, an international prognostic index of ≥3, and inadequate tissue for molecular analyses. Patients with CNB had significantly worse 5-year event-free survival (67.6% vs 56.9%; hazard ratio [HR], 0.76; confidence interval [CI]95, 0.6-0.9, P < .001) and 5-year overall survival (76.4% vs 69.2%; HR, 0.8; CI95, 0.6-0.9, P < .001). Thus, patients who underwent CNB have poor-risk features and inferior outcomes on frontline chemoimmunotherapy, are more likely to have inadequate tissue for molecular analyses, and might not meet the tissue requirements of biomarker-driven clinical trials. Thus, the increasing tissue requirements of biomarker-driven clinical trials may result in the exclusion of patients with high-risk DLBCL who need novel agents.