Classic Hodgkin lymphoma: Pathobiological features that impact emerging therapies.

Classic Hodgkin lymphoma (cHL) is defined by distinctive Hodgkin Reed-Sternberg (HRS) cells, which are CD30+/CD15+ multinucleated tumor cells lacking typical B-cell markers. These cells comprise <5 % of tumor mass but orchestrate an extensive immunosuppressive tumor microenvironment (TME). Classic HL was curable with radiation therapy and multi-agent chemotherapy. Despite high cure rates, treatment-related toxicities remain significant. The goals of multimodality therapy are to achieve a cure while minimizing treatment-associated toxicity. Advances in molecular insights into HRS cells have led to transformative therapies, including checkpoint inhibitors, antibody-drug conjugates like brentuximab vedotin, which have shown remarkable efficacy, especially in relapsed or refractory disease. However, challenges persist due to the heterogeneity of cHL, driven by the complex biology of HRS cells and their surrounding tumor microenvironment. Novel approaches such as single-cell RNA sequencing and circulating tumor DNA profiling provide promising strategies to address these challenges. This review examines the origin, morphology, phenotype, and genetic profiles of HRS cells, highlighting key pathobiological features, including biomarkers and Epstein-Barr Virus involvement. It also explores the biological mechanisms underlying HRS cell survival and evaluates standard and emerging therapies, offering insights into the rationale for novel treatment strategies.