Summary BRUIN CLL‐321 is the first prospective, randomized study conducted in covalent BTK inhibitor (cBTKi) pretreated chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) patients. In this heavily pretreated population, pirtobrutinib significantly improved progression‐free survival (PFS) compared to investigator's choice (IC) of idelalisib/rituximab (IdelaR) or bendamustine/rituximab (BendaR). This report presents results from Chinese patients enrolled in BRUIN CLL‐321, who were randomized 1:1 to pirtobrutinib (200 mg once daily) or IC of BendaR (idelalisib is not approved in China). End‐points included independent review committee (IRC)‐assessed PFS, investigator (INV)‐assessed PFS, overall survival (OS), event‐free survival (EFS), time to next treatment (TTNT) and safety. Among 40 Chinese patients (pirtobrutinib n = 19; BendaR n = 21), IRC‐assessed PFS favoured pirtobrutinib (stratified hazard ratio HR = 0.281; 95% confidence interval CI, 0.070–1.125, nominal p = 0.0554), with median PFS not reached versus 10.6 months with BendaR; INV‐assessed PFS supported these findings. TTNT (HR = 0.150; 95% CI, 0.031–0.728) and EFS (HR = 0.322; 95% CI, 0.094–1.101) were also improved. A trend towards OS benefit was observed (HR = 0.343; 95% CI, 0.031–3.787). Pirtobrutinib showed a favourable safety profile, with fewer grade ≥3 treatment‐emergent adverse events (36.8% vs. 93.3%) and serious adverse events (15.8% vs. 46.7%). These findings support pirtobrutinib as a clinically active and tolerable option for cBTKi‐pretreated Chinese CLL/SLL population.
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