A Review of Current and Emerging Therapeutic Options for Hemophagocytic Lymphohistiocytosis

To provide an overview of clinical sequelae and emerging treatment options for hemophagocytic lymphohistiocytosis (HLH).

A literature search was conducted using the search terms "hemophagocytic lymphohistiocytosis," "hemophagocytic syndrome," "macrophage activation syndrome," and "treatment" on Ovid and PubMed from January 1, 2017, through September 28, 2022.

Relevant clinical trials, meta-analyses, case reports, review articles, package inserts, and guidelines to identify current and emerging therapeutic options for the management of HLH.

Genetic disorders and secondary causes may trigger HLH in both children and adults. Notable improvements in the diagnosis of HLH were seen with implementation of the HLH-2004 standard diagnostic criteria; however, timely and accurate identification of HLH remain significant barriers to optimal management. Multiagent immunochemotherapy are the backbone of aggressive therapy for acutely ill patients with HLH.

The global coronavirus 2019 (COVID-19) pandemic and emerging immune effector cell therapies have served to highlight the concerns with immune dysregulation and subsequent HLH precipitation. Without prompt identification and treatment, HLH can be fatal. Historically, the clinician's armamentarium for managing HLH was sparse, with etoposide-based protocols serving as the standard of care. Relapsed or refractory disease portends a poor prognosis and requires additional treatment options. Second- or subsequent-line options now include hematopoietic stem cell transplantation, emapalumab, alemtuzumab, anakinra, ruxolitinib, and tocilizumab.

Improvements in diagnostic methods and novel immunosuppressive treatment strategies, including noncytotoxic immunochemotherapy, have transformed the therapeutic landscape. Unfortunately, many unanswered questions remain. Additional studies are required to optimize dosing, schedules, treatment sequences, and indications for novel treatment options.