Increasing tissue requirements in lymphoma trials may exclude patients with high risk disease or worse prognosis.

Enhanced understanding of molecular heterogeneity of diffuse large B cell lymphoma (DLBCL) has opened doors to clinical trials evaluating novel agents with subtype-specific activity. It is an emerging question whether core needle biopsies (CNB) can adequately meet increasing tissue requirements of these clinical trials. This can potentially lead to selective enrollment of patients who can undergo excisional biopsy. It is also important to know whether patients who can undergo extensive diagnostic work up differ in their disease characteristics and outcomes from patients who can't. In this observational study, we describe characteristics, outcomes and adequacy of diagnostic tissue in patients with newly diagnosed DLBCL and primary mediastinal large B cell lymphoma who undergo EB versus CNB. Out of 1061 patients, 532 (49.8%) underwent EB and 529 (50.1%) underwent CNB. Significantly higher proportion of patients with CNB had advanced stage, IPI>=3 and inadequate tissue for molecular analyses. Patients with CNB had significantly worse 5-year event free survival (EFS, 67.6% vs 56.9%, HR 0.76 (CI95: 0.6-0.9, p<0.001) and 5-year overall survival (OS, 76.4% vs 69.2%, HR 0.8 (CI95: 0.6-0.9), p<0.001). Thus, patients who undergo CNB have poor risk features, have inferior outcomes on frontline chemoimmunotherapy, are more likely to have inadequate tissue for molecular analyses and might not be able to meet tissue requirements of biomarker-driven clinical trials. Thus, increasing tissue requirements of biomarker driven clinical trials may result in exclusion of high risk DLBCL pts who need novel agents.