Abstract
BACKGROUND: Richter syndrome (RS) is an aggressive transformation of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) with poor prognosis. No standard treatment for RS has been established. Epcoritamab, a CD3xCD20 bispecific antibody, may offer clinical benefit. CASE: An 80-year-old woman was diagnosed with SLL in 2017 and remained untreated for nearly 6 years. In 2023, she developed a bulky abdominal tumor. Although the initial biopsy showed SLL progression without transformation, subsequent treatments with acalabrutinib, venetoclax plus rituximab, and bendamustine plus rituximab failed. In 2024, transformation to diffuse large B-cell lymphoma-type RS (DLBCL-RS) was confirmed. Two lines of cytotoxic regimens were ineffective, with rapid tumor growth. Epcoritamab was initiated as third-line therapy. Grade 1-3 cytokine release syndrome occurred but resolved with standard management. No neurotoxicity was observed. Partial response (PR) was achieved by week 12, and the patient has maintained PR for 10 months. Infections including COVID-19 and cytomegalovirus were managed successfully, and immunoglobulin replacement was introduced for hypogammaglobulinemia. CONCLUSION: This case highlights the potential of epcoritamab as an important treatment option for elderly patients with refractory DLBCL-RS.