T-cell/histiocyte-rich large B-cell lymphoma in the era of novel immunotherapy: A focused review.

T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) is an uncommon aggressive large B-cell lymphoma variant which can develop synchronously or following a diagnosis of nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). There is morphological, immunophenotypic and molecular overlap between THRLBCL and NLPHL suggesting that these two entities may lie on the same spectrum. Due to the rarity of THRLBCL, accurate diagnosis can be challenging and there is a paucity of data on which to base treatment decisions. The management has largely followed diffuse large B-cell lymphoma (DLBCL) with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone established as the standard of care in the first line, with outcomes comparable to international prognostic index matched DLBCL. In the relapsed/refractory (R/R) setting, there is no standard of care. There is a move towards inclusion of THRLBCL patients in clinical trials evaluating novel agents, although historically they were commonly excluded. Due to the small numbers included in clinical trials, it has been difficult to discern the effect of novel agents in this cohort. Thus, we are reliant on larger real-world datasets to inform our understanding. This review will examine the data available in the first line and R/R setting with a focus on immunotherapeutic approaches.