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The risk reduction observed in BRUIN CLL-313 is among the most compelling observed for a single agent BTK inhibitor in a front-line CLL study
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These data will be simultaneously published in the Journal of Clinical Oncology and highlighted in a late-breaking oral presentation at the 2025 American Society of Hematology Annual Meeting and Exposition, and were featured as part of the meeting's press program
INDIANAPOLIS, Dec. 9, 2025 /PRNewswire/ -- Eli Lilly and Company (NYSE: LLY) today announced results from the Phase 3 BRUIN CLL-313 clinical trial of Jaypirca (pirtobrutinib), a non-covalent Bruton tyrosine kinase (BTK) inhibitor, versus bendamustine plus rituximab (BR), in treatment-naïve patients with chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) without 17p deletions. Pirtobrutinib met its primary endpoint demonstrating a reduction in the risk of disease progression or death by 80% (HR=0.20 [95% CI, 0.11-0.37]; p<0.0001).
These data will be highlighted in a late-breaking oral presentation at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition taking place in Orlando, Florida and simultaneously published in the Journal of Clinical Oncology.
"The results from BRUIN CLL-313 show a significant effect size, among the most pronounced ever observed for a single agent BTK inhibitor in a front-line CLL study," said Wojciech Jurczak, MD, PhD, Maria Sklodowska-Curie National Research Institute of Oncology, Krakow, Poland. "The magnitude of the progression-free survival benefit, early overall survival trend and safety profile observed in BRUIN CLL-313 offer highly compelling evidence for the potential role of pirtobrutinib in treatment-naïve CLL."
BRUIN CLL-313 is the first prospective, randomized Phase 3 study examining the efficacy and safety of a non-covalent BTK inhibitor, pirtobrutinib, exclusively in patients with treatment-naïve CLL/SLL. BRUIN CLL-313 enrolled 282 patients with previously untreated CLL/SLL without del(17p), who were randomized 1:1 to receive continuous pirtobrutinib monotherapy (n=141) or BR (n=141). Crossover to the pirtobrutinib arm was allowed after independent review committee (IRC)-confirmed disease progression. The efficacy results are based on a July 11, 2025, data cutoff.
At a median follow-up of 28.1 months, the primary endpoint of IRC-assessed progression-free survival (PFS) was significantly improved with pirtobrutinib compared to BR (HR=0.20 [95% CI, 0.11–0.37]; p<0.0001). PFS results favored pirtobrutinib across all pre‑specified subgroups, including those with high-risk molecular features such as TP53 mutations, complex karyotype, and unmutated IGHV, and was consistently observed among investigator assessments.
Overall survival (OS), a key secondary endpoint, remains immature, but a trend favoring pirtobrutinib was observed (HR=0.257 [95% CI, 0.070–0.934]; p=0.0261) despite over half (52.9%) of patients treated with BR crossing over to receive pirtobrutinib after IRC-confirmed disease progression. Final testing of OS superiority is planned at a future date.
The overall safety profile of patients treated with pirtobrutinib in BRUIN CLL-313 was similar to previously reported trials. Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 40.0% of patients who received pirtobrutinib versus 67.4% with BR. Fewer adverse event-related dose reductions (3.6% versus 31.1%) and TEAE-related discontinuations (4.3% versus 15.2%) were seen with pirtobrutinib versus BR. The incidence of all-grade and high-grade atrial fibrillation/flutter were similar between pirtobrutinib and BR, a notable finding as BR is not a regimen associated with increased risk of this side effect (1.4% versus 1.5% and 0.7% versus 0.8%, respectively).
"These findings support the potential use of pirtobrutinib in certain treatment-naïve patients and underscore its unique position as the only BTK inhibitor to show promise in treating both newly diagnosed patients with CLL or SLL and those who have progressed on a covalent BTK inhibitor," said Jacob Van Naarden, executive vice president and president, Lilly Oncology. "Alongside the recently presented BRUIN-CLL 314 results, we are excited about how collectively these data may advance the therapeutic landscape in treatment-naïve CLL and are hopeful we will receive regulatory approvals for pirtobrutinib in earlier disease settings sometime next year, further expanding treatment options for patients."
Lilly has begun submitting results from BRUIN CLL-313 and BRUIN CLL-314 studies to regulatory authorities with the goal of further expanding Jaypirca's label into earlier lines of therapy.
Lilly is studying Jaypirca in CLL/SLL in multiple Phase 3 studies. Details on the trials can be found by visiting clinicaltrials.gov.
About BRUIN CLL-313
BRUIN CLL-313 is a Phase 3, global, randomized, open-label study of pirtobrutinib versus chemoimmunotherapy (bendamustine plus rituximab) in people with CLL/SLL without 17p deletions who have not been previously treated. The trial enrolled 282 patients who were randomized 1:1 to receive pirtobrutinib (200 mg orally, once daily) or bendamustine plus rituximab (BR) per labeled doses. BR is a chemoimmunotherapy regimen used in the treatment of CLL. The primary endpoint is PFS as assessed by blinded IRC. Secondary endpoints include investigator and IRC assessed overall response rate (ORR), duration of response (DoR), and PFS, OS, time to next treatment (TTNT), safety and tolerability and patient-reported outcomes (PRO).
About Jaypirca (pirtobrutinib)
Jaypirca (pirtobrutinib, formerly known as LOXO-305) (pronounced jay-pihr-kaa) is a highly selective (300 times more selective for BTK versus 98% of other kinases tested in preclinical studies), non-covalent (reversible) inhibitor of the enzyme BTK.1 BTK is a validated molecular target found across numerous B-cell leukemias and lymphomas including mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL).2,3 Jaypirca is a U.S. FDA-approved oral prescription medicine, 100 mg or 50 mg tablets taken as a once-daily 200 mg dose with or without food until disease progression or unacceptable toxicity.
About Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma
Chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are forms of slow-growing non-Hodgkin lymphoma that develop from white blood cells known as lymphocytes.4 CLL is one of the most common types of leukemia in adults.4 In the U.S., CLL accounts for about one-quarter of the new cases of leukemia and there will be approximately 23,690 new cases of CLL diagnosed this year.4,5 SLL is identical to CLL from a pathologic and immunophenotypic standpoint, with the main difference between them being the location of the cancer cells.4 In CLL, the cancer cells are present in the blood, and in SLL, the cancer cells are found in the lymph nodes.4
About Lilly
Lilly is a medicine company turning science into healing to make life better for people around the world. We've been pioneering life-changing discoveries for nearly 150 years, and today our medicines help tens of millions of people across the globe. Harnessing the power of biotechnology, chemistry and genetic medicine, our scientists are urgently advancing new discoveries to solve some of the world's most significant health challenges: redefining diabetes care; treating obesity and curtailing its most devastating long-term effects; advancing the fight against Alzheimer's disease; providing solutions to some of the most debilitating immune system disorders; and transforming the most difficult-to-treat cancers into manageable diseases. With each step toward a healthier world, we're motivated by one thing: making life better for millions more people. That includes delivering innovative clinical trials that reflect the diversity of our world and working to ensure our medicines are accessible and affordable.
Endnotes & References
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Mato AR, Shah NN, Jurczak W, et al. Pirtobrutinib in relapsed or refractory B-cell malignancies (BRUIN): a phase 1/2 study.
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Lancet
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. 2021;397(10277):892-901. doi:10.1016/S0140-6736(21)00224-5
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Hanel W, Epperla N. Emerging therapies in mantle cell lymphoma. J Hematol Oncol. 2020;13(1):79. Published 2020 Jun 17. doi:10.1186/s13045-020-00914-1
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Gu D, Tang H, Wu J, Li J, Miao Y. Targeting Bruton tyrosine kinase using non-covalent inhibitors in B cell malignancies. J Hematol Oncol. 2021;14(1):40. Published 2021 Mar 6. doi:10.1186/s13045-021-01049-7
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Mukkamalla SKR, Taneja A, Malipeddi D, et al. Chronic Lymphocytic Leukemia. [Updated
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]. Cancer Stat Facts: Leukemia—Chronic Lymphocytic Leukemia (CLL). Accessed on September 3, 2025. https://seer.cancer.gov/statfacts/html/clyl.html