Defining Primary Refractory Large B-cell lymphoma

Patients with large B-cell lymphoma (LBCL) that fail to achieve a complete response (CR) or relapse early after anthracycline-containing immunochemotherapy (IC) have a poor prognosis and are commonly considered “primary refractory disease”. However, different definitions of primary refractory disease are used in the literature and clinical practice. In this study, we examined variation in the time to relapse used to define refractory status and association with survival outcomes in patients with primary refractory LBCL in a single-center prospective cohort with a validation in an independent multi-center cohort. Newly diagnosed LBCL patients were enrolled in the Molecular Epidemiological Resource cohort (MER; N=949) or the Lymphoma Epidemiology of Outcomes cohort (LEO; N=2,755) from 9/2002 to 5/2021. Primary refractory LBCL was defined as no response (SD) or progressive disease (PD) during or by the end of frontline (1L) IC (primary PD; PPD), partial response at end of treatment (EOT PR), or relapse within 3-12 months after achieving CR at EOT to 1L IC (early relapse). In the MER cohort, patients with PPD had inferior OS (2-year OS rate 15% MER, 31% LEO) when compared to other subgroups considered in defining primary refractory disease, EOT PR (2-year OS rate 38% MER, 50% LEO) and early relapse (2-year OS rate 44% MER, 58% LEO). Among patients receiving frontline IC with curative intent, we identified that patients with PPD are the key subgroup with poor outcomes. We propose a definition of primary refractory LBCL as SD or PD during or by the end of 1L treatment.