- (GROUP B) Recurrent high-risk diffuse large B cell lymphoma defined as relapsing within one year of completion of rituximab and anthracycline based multi-agent chemotherapy or a sAAIPI (second-line age-adjusted International Prognostic Index) intermediate or high at relapse or acquisition of double/triple hit features upon relapse (as defined in group A) and at least stable disease after salvage chemotherapy. Patients with an initial diagnosis of low-grade/indolent non-Hodgkin lymphoma (i.e. follicular, marginal zone) who present relapse with histologic transformation to diffuse large B cell lymphoma (confirmed by biopsy) and meet the definition for high-risk as presented above, are also eligible.