Pirtobrutinib in patients with Richter transformation: Results from the phase I/II BRUIN trial

The phase I/II BRUIN trial (NCT03740529) assessed the safety and efficacy of pirtobrutinib, a highly selective, non-covalent, Bruton tyrosine kinase inhibitor (BTKi), in patients with relapsed/refractory (R/R) chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) or non-Hodgkin lymphoma.¹ The Lymphoma Hub previously reported results from this trial for a CLL/SLL cohort, B-cell malignancy cohort, and Waldenstrom’s macroglobulinemia cohort. Results from this trial led to pirtobrutinib approval by the U.S. Food and Drug Administration (FDA) for R/R CLL/SLL and mantle cell lymphoma after ≥2 prior lines of therapy, including a BTKi. Below we summarize results of a subgroup analysis from this trial of 82 patients with Richter transformation, the majority of whom were previously treated with a covalent BTKi, which were published in Lancet Hematology by Wierda, et al.¹

The overall response rate (ORR), complete response rate, partial response rate, and stable disease rate were 50%, 13%, 37%, and 13%, respectively, in patients with Richter transformation, while the ORR was 48.6% in patients treated with previous Richter transformation directed therapy.