Treatment strategy in chronic lymphocytic leukemia with symptomatic central nervous system involvement: A case report

KEY CLINICAL MESSAGE: This case report offers support for treatment approaches in a historically rare and very difficult to treat CLL patient population with no established guidelines. ABSTRACT: Central nervous system involvement of chronic lymphocytic leukemia is a rare condition. Its diagnosis is often challenging, and treatment can be difficult with a lack of established guidelines. We describe a case of a 76‐year‐old male Caucasian with known chronic lymphocytic leukemia for more than 25 years, initially treated with chlorambucil. Upon first clinical relapse, cytogenetic analysis and fluorescence in situ hybridization combined showed three different abnormalities (complex karyotype), suggesting a poor prognosis. He was started on ibrutinib but developed an out‐of‐hospital cardiac arrest due to ventricular fibrillation 2 months later. Ibrutinib treatment was consequently discontinued. Due to the seriousness of the adverse event and the lack of apparent treatment indication after rapid improvement on ibrutinib, a watch‐and‐wait approach was maintained. Four years later, he developed progressive cognitive impairment, a balance disorder, and a peripheral facial nerve palsy. Anamnesis further revealed significant progressive weight loss. Routine blood tests did not show any abnormalities, but brain magnetic resonance imaging showed focal staining of cranial nerves and leptomeningeal staining. Cerebrospinal fluid analysis revealed the same monoclonal B‐cell lymphocytosis as that was already known to be present in the peripheral blood. Further analysis ruled out sample contamination or other conditions. PET‐CT scan revealed an increased uptake in the liver, and biopsy confirmed infiltration of chronic lymphocytic leukemia at the site. The patient was first started on treatment with intrathecal administration of dexamethasone, cytarabine, and methotrexate. This did not result in complete clearance in the cerebrospinal fluid. Next, oral venetoclax was initiated, resulting in rapid clearance and clinical resolution. Venetoclax, administered orally, was able to achieve clearance of the monoclonal B‐cell lymphocytosis from the cerebrospinal fluid as well as clinical response of neurological symptoms. Response was durable with persistent remission at 1 year of treatment.