Pirtobrutinib improved progression-free survival (PFS) to 14 months compared to 8 months with Idelalisib/Rituximab or Bendamustine/Rituximab (IdelaR/BR), with a hazard ratio of 0.54, in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) who had previously been treated with covalent BTK inhibitors (cBTKi). It also demonstrated favorable tolerability. With acalabrutinib and venetoclax emerging as preferred first-line therapies, Pirtobrutinib represents a strong second-line option for eligible patients.
Pirtobrutinib, a noncovalent, Bruton tyrosine kinase inhibitor (BTKi), has shown clinical efficacy and a favorable safety profile. BRUIN CLL-321 was an open-label, randomized phase III study conducted exclusively in patients with R/R chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) previously treated with cBTKi, and compared pirtobrutinib with investigator's choice (IC) of idelalisib/rituximab (IdelaR) or bendamustine/rituximab (BR).
Patients were randomly assigned 1:1 to receive pirtobrutinib (200 mg once daily) or IC of IdelaR or BR, and were stratified by previous use of venetoclax and del(17p). The primary end point was independent review committee–assessed progression-free survival (PFS). Secondary end points included time to next treatment or death (TTNT), overall survival (OS), and safety. The primary PFS end point was met at the time of the primary analysis (August 29, 2023), and updated results are reported from the final OS analysis (August 29, 2024).
A total of 238 patients were randomly assigned to receive pirtobrutinib (n = 119) or IC (n = 119; IdelaR [n = 82], BR [n = 37]). The PFS hazard ratio (HR) was 0.54 ([95% CI, 0.39 to 0.75]; P = .0002), with a median PFS of 14 months (95% CI, 11.2 to 16.6) in the pirtobrutinib group and 8.7 months (95% CI, 8.1 to 10.4) with IC. The unadjusted OS HR was 1.09 ([95% CI, 0.68 to 1.75]; P = .7202), and 18-month OS rate was 73.4% (95% CI, 63.9 to 80.7) in the pirtobrutinib group and 70.8% (95% CI, 60.9 to 78.7) with IC. Median TTNT was 24 months (95% CI, 17.8 to 29.7) with pirtobrutinib versus 10.9 months (95% CI, 8.7 to 12.5) with IC (HR, 0.37 [95% CI, 0.25 to 0.52]). At a median follow-up of 17.2 months, grade ≥3 treatment-emergent adverse events (AEs) were lower with pirtobrutinib (57.7%) than IC (73.4%). Treatment discontinuation due to AE occurred in 20 (17.2%) patients receiving pirtobrutinib and 38 (34.9%) patients receiving IC.
Pirtobrutinib improved PFS and TTNT, and demonstrated favorable tolerability, versus IdelaR/BR in exclusively cBTKi pretreated patients with CLL/SLL.
Triple therapy for CLL, AVO, is highly active and has very high MRD-negative rates compared to other studies using Ven+Obi or BTKi therapy alone. The battle between indefinite BTKi therapy vs more intense combination therapy will continue as we don’t know if one paradigm is better from a bigger picture.
It does not seem that all NPM1 mutations are created equally. Type A and B mutations had favorable outcomes and type D mutations do much worse, something to consider when risk stratifying in patients with AML.
The ECHELON-3 study showed BV + Len + R is an active and (relatively) tolerable in the rrDLBCL patient group. Interestingly, patients did not have to be CD30+ to see a benefit.
This study was done with and without obinutuzumab, both arms beat obinutuzumab and chlorambucil. There were more deaths in the obinutuzumab arm even though it was superior because of COVID, so it is immunosuppressive.
Ibrutinib delays disease progression for asymptomatic patients but has no overall survival (OS) benefit; hence, still watch and wait in those patients.