Highlights 

  • Lilly’s Jaypirca outperformed Imbruvica on the overall response rate in a first-of-its-kind Phase 3 comparison study. 
  • Pirtobrutinib delivered an 87% ORR vs. 78.5% for ibrutinib in treatment-naïve and BTK inhibitor-naïve CLL/SLL patients. 
  • Early progression-free survival (PFS) findings leaned in favor of pirtobrutinib, including a 76% risk reduction in treatment-naïve patients. 
  • Safety data indicated fewer heart-related and hypertension-related adverse events with pirtobrutinib. 
  • Results were featured at the 2025 ASH Annual Meeting and published in the Journal of Clinical Oncology. 

Eli Lilly and Company (NYSE:LLY) has released pivotal data from the Phase 3 BRUIN CLL-314 trial, marking the first randomized head-to-head comparison between covalent and non-covalent BTK inhibitors in chronic lymphocytic leukemia and small lymphocytic lymphoma. Jaypirca (pirtobrutinib), Lilly’s highly selective, reversible BTK inhibitor, surpassed its primary goal by achieving non-inferiority on overall response rate — and delivered a higher numerical ORR than Imbruvica (ibrutinib), AbbVie’s long-established therapy. 

In the intent-to-treat population of 662 patients, pirtobrutinib achieved an ORR of 87% compared with 78.5% for ibrutinib. These results included patients who were treatment-naïve or had relapsed/refractory disease but were BTK inhibitor-naïve. The findings were simultaneously showcased at the 67th American Society of Hematology Annual Meeting. 

Efficacy Trends Suggest a Potential Shift in First-Line Treatment 

While progression-free survival data is still developing, early trends favored Jaypirca across all major patient groups. The most notable benefit was seen in the treatment-naïve cohort, where pirtobrutinib was associated with a 76% reduction in the risk of disease progression or death. 

In the broader ITT group, the hazard ratio for PFS was 0.569, indicating a meaningful tilt toward pirtobrutinib even at this interim stage. A formal test for superiority on PFS is planned once more mature data becomes available. Importantly, overall survival showed no disadvantage for pirtobrutinib compared to ibrutinib. 

These early advantages may signal a future shift in clinical preference, as pirtobrutinib’s mechanism allows inhibition of BTK even in the presence of resistance mutations that can limit covalent BTK inhibitors. 

Improved Safety Profile Adds to the Treatment Appeal 

Safety outcomes were in line with prior studies of Jaypirca, with several notable declines in adverse events compared with Imbruvica. Rates of atrial fibrillation/flutter were lower (2.4% vs. 13.5%), and fewer patients required dose reductions or discontinuation due to side effects. Hypertension events were also less frequent in the Jaypirca arm. 

Lilly highlighted that these tolerability benefits, paired with clinical performance, underline the potential of pirtobrutinib for earlier use in the CLL/SLL treatment journey. More data from the ongoing BRUIN clinical program—including results from the Phase 3 BRUIN CLL-313 trial—will continue to shape the therapy’s position in treatment guidelines. 

Conclusion 

The BRUIN CLL-314 findings represent a potential turning point in BTK inhibitor therapy, offering evidence that a reversible inhibitor can deliver better tolerability and enhanced clinical activity compared to a covalent standard of care. With additional Phase 3 studies underway, Lilly is positioning Jaypirca as a candidate for broader use across CLL/SLL treatment lines. 

Eli Lillys’ shares closed at USD1010.31,markinga0.41% decrease from the prior session.