Phase 3 trial published in Signal Transduction and Targeted Therapy showed orelabrutinib reduced progression or death by 68% and improved responses in first-line CLL/SLL.
Written By: Dr. Preethi Putti, PharmD
Reviewed By: Pharmacally Editorial Team
InnoCare Pharma reported that the Phase 3 trial evaluating orelabrutinib in treatment-naïve chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) has been published in Signal Transduction and Targeted Therapy, a Nature Portfolio journal. The peer-reviewed study showed that orelabrutinib significantly prolonged progression-free survival (PFS), reduced the risk of disease progression or death by 68%, and produced deeper, more durable responses than standard chemoimmunotherapy.
The multicenter, randomized Phase 3 trial (NCT04578613) compared continuous oral orelabrutinib with chlorambucil plus rituximab in previously untreated patients with CLL/SLL. The findings support orelabrutinib as an effective first-line treatment option for eligible patients and reinforce the growing role of Bruton tyrosine kinase (BTK) inhibitors in replacing conventional chemoimmunotherapy.
Scientific and Clinical Context
CLL is the most common leukemia in adults, while SLL represents the same disease primarily involving lymph nodes. Historically, frontline treatment relied on chemoimmunotherapy, but targeted BTK inhibitors have transformed disease management by providing durable disease control with improved tolerability.
Orelabrutinib is a potent, irreversible, highly selective BTK inhibitor developed to block B-cell receptor signaling, a key pathway that drives the growth and survival of malignant B cells. Its high kinase selectivity has been associated with fewer off-target toxicities than earlier BTK inhibitors.
Phase 3 Trial Demonstrated Significant Efficacy Advantage
The open-label study enrolled 192 patients across 65 centers in China between February 2021 and July 2024. Participants were randomized 1:1 to receive either orelabrutinib monotherapy or chlorambucil plus rituximab. The primary endpoint was independent review committee (IRC)-assessed progression-free survival, while secondary endpoints included overall response rate (ORR), duration of response (DoR), overall survival, safety, and patient-reported quality of life.
At a median follow-up of 21.4 months, median PFS had not been reached with orelabrutinib compared with 19.4 months for chemoimmunotherapy. Orelabrutinib reduced the risk of progression or death by 68% (HR 0.32; 95% CI 0.18-0.58; p<0.0001).
The benefit remained consistent across prespecified patient subgroups, including older adults, patients with Rai stage III/IV disease, and those with high-risk biological features such as del(11q), unmutated IGHV, or bulky disease.
Treatment with orelabrutinib also produced a significantly higher overall response rate of 90.1%, compared with 79.2% in the control arm. Updated analyses at approximately 30 months showed a complete response rate of 12.1%, while duration of response also favored orelabrutinib (HR 0.30).
Favorable Safety Profile and Improved Quality of Life
Safety outcomes remained favorable despite patients receiving orelabrutinib for substantially longer periods than those receiving chemoimmunotherapy. Median treatment duration reached 19.3 months with orelabrutinib versus 5.2 months in the control group.
Although treatment-related adverse events occurred at similar overall frequencies in both groups, Grade 3 or higher treatment-related adverse events were considerably less common with orelabrutinib. Investigators also reported no treatment-related atrial fibrillation, major bleeding, or second primary malignancies.
Patient-reported outcomes further supported the clinical benefit. Individuals receiving orelabrutinib reported better overall health status and quality of life, with clinically meaningful improvements becoming more pronounced from treatment cycle 16 onward.
Investigator Leadership
The study was co-led by Professor Jianyong Li of Jiangsu Province Hospital and Professor Lugui Qiu of the Chinese Academy of Medical Sciences, Institute of Hematology & Blood Disease Hospital. Co-first authors included Professor Fei Li, Professor Keshu Zhou, and Professor Wei Xu, representing leading hematology centers across China.
Regulatory Path Forward
Orelabrutinib has already received approval in China for first-line treatment of CLL/SLL and was added to the country’s National Reimbursement Drug List in 2025, expanding patient access.
The publication of these Phase 3 results in a high-impact Nature Portfolio journal provides peer-reviewed evidence supporting orelabrutinib as an effective frontline BTK inhibitor for CLL/SLL. The findings add to the growing body of evidence favoring targeted oral therapies over traditional chemoimmunotherapy for newly diagnosed patients and may help inform future treatment strategies in regions where the drug becomes available.
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About the Writer
Dr.Preethi Putti, PharmD (LinkedIn) is a pharmaceutical researcher with experience in healthcare and pharmaceutical market research and competitive intelligence. She specializes in analyzing drug pipelines, clinical data, and industry trends and translating complex scientific data into clear and structured medical content. Strong foundation in clinical research, data interpretation, and evidence-based healthcare analysis. Committed to advancing a global career in clinical research and healthcare innovation.