Treatments for chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are moving from traditional chemoimmunotherapy (CIT) to targeted drugs. The BRUIN CLL-313 Phase III study tested pirtobrutinib, a new noncovalent Bruton tyrosine kinase inhibitor (ncBTKi), in patients who had never received treatment before.
The study compared pirtobrutinib alone to bendamustine plus rituximab (BendaR), a common chemo regimen, in 282 patients. Pirtobrutinib showed clear superiority, cutting the risk of disease progression or death by 80%. At 24 months, progression-free survival was 93.4% with pirtobrutinib versus 70.7% for BendaR, and overall response rates were 94.3% vs. 80.9%. Benefits were consistent across age groups and high-risk genetic subgroups, with early signs of better overall survival.
Pirtobrutinib was better tolerated than chemotherapy, even over longer treatment periods. Severe neutropenia and growth factor use were much lower, and serious heart problems were rare. Common side effects included infections and mild bleeding. The study establishes pirtobrutinib as a strong frontline therapy for CLL, signaling a shift away from chemoimmunotherapy and raising questions about how best to sequence it with other targeted treatments.