Diagnosis and Treatment of Chronic Lymphocytic Leukemia

Importance: Chronic lymphocytic leukemia (CLL), defined by a minimum of 5 × 109/L monoclonal B cells in the blood, affects more than 200 000 people and is associated with approximately 4410 deaths in the US annually. CLL is associated with an immunocompromised state and an increased rate of complications from infections. Observations: At the time of diagnosis, the median age of patients with CLL is 70 years, and an estimated 95% of patients have at least 1 medical comorbidity. Approximately 70% to 80% of patients with CLL are asymptomatic at the time of diagnosis, and one-third will never require treatment for CLL. Prognostic models have been developed to estimate the time to first treatment and the overall survival, but for patients who are asymptomatic, irrespective of disease risk category, clinical observation is the standard of care. Patients with symptomatic disease who have bulky or progressive lymphadenopathy or hepatosplenomegaly and those with a low neutrophil count, anemia, or thrombocytopenia and/or symptoms of fever, drenching night sweats, and weight loss (B symptoms) should be offered treatment. For these patients, first-line treatment consists of a regimen containing either a covalent Bruton tyrosine kinase (BTK) inhibitor (acalabrutinib, zanubrutinib, or ibrutinib) or a B-cell leukemia/lymphoma 2 (BCL2) inhibitor (venetoclax). There is no evidence that starting either class before the other improves outcomes. The covalent BTK inhibitors are typically used indefinitely. Survival rates are approximately 88% at 4 years for acalabrutinib, 94% at 2 years for zanubrutinib, and 78% at 7 years for ibrutinib. Venetoclax is prescribed in combination with obinutuzumab, a monoclonal anti-CD20 antibody, in first-line treatment for 1 year (overall survival, 82% at 5-year follow-up). A noncovalent BTK inhibitor, pitobrutinib, has shown an overall response rate of more than 70% after failure of covalent BTK inhibitors and venetoclax. Phosphoinositide 3'-kinase (PI3K) inhibitors (idelalisib and duvelisib) can be prescribed for disease that progresses with BTK inhibitors and venetoclax, but patients require close monitoring for adverse events such as autoimmune conditions and infections. In patients with multiple relapses, chimeric antigen receptor T-cell (CAR-T) therapy with lisocabtagene maraleucel was associated with a 45% complete response rate. The only potential cure for CLL is allogeneic hematopoietic cell transplant, which remains an option after use of targeted agents. Conclusions and Relevance: More than 200 000 people in the US are living with a CLL diagnosis, and CLL causes approximately 4410 deaths each year in the US. Approximately two-thirds of patients eventually need treatment. Highly effective novel targeted agents include BTK inhibitors such as acalabrutinib, zanubrutinib, ibrutinib, and pirtobrutinib or BCL2 inhibitors such as venetoclax.