Advances in the understanding of molecular genetics and therapy of Richter transformation in chronic lymphocytic leukemia.

Richter's transformation (RT) is defined as the evolution of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma. This complication is rare and aggressive, with poor prognosis and dismal survival. Clonal relationship with the underlying CLL/SLL, observed in ∼80% of cases, represents one of the main factors affecting prognosis. Treatment has been historically based on chemoimmunotherapy, but frequent mutations in genes involved in cell survival and proliferation-such as TP53, NOTCH1, MYC, CDKN2A-confer resistance to standard treatments. During the last years, advances in the knowledge of the biological mechanisms underlying RT allowed to identify genetic and molecular lesions that can potentially be targeted by novel selective agents. Pathway and checkpoint inhibitors, bispecific antibodies and CAR T-cell therapy are currently under investigation and represent promising treatment options. This review summarizes current biological evidence and available data on novel therapeutic agents.