A second-generation cancer drug outperformed traditional chemotherapy in a major clinical trial, reducing the risk of disease progression or death by 68% in patients with previously untreated chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL).
The phase 3 trial, published in Signal Transduction and Targeted Therapy, compared orelabrutinib—a Bruton tyrosine kinase (BTK) inhibitor—against a standard chemoimmunotherapy regimen of chlorambucil plus rituximab. This was the first head-to-head phase 3 comparison of orelabrutinib against chemoimmunotherapy in the frontline CLL/SLL setting.
Trial results favor targeted therapy over chemotherapy
A total of 358 patients were screened for study inclusion before being randomly assigned to receive either continuous orelabrutinib (n = 91) or up to six cycles of chemoimmunotherapy (n = 101). After a median follow-up of 21.4 months, median progression-free survival was not reached in the orelabrutinib group, while it stood at 19.4 months in the chemotherapy group.
Related: User account access denied unexpectedly
Response rates also showed an advantage for the newer drug. The duration of response lasted significantly longer, with 84.3% of patients on orelabrutinib maintaining their response at 24 months, compared to 51.7% in the chemotherapy arm. The advantage remained consistent across high-risk subgroups, including those with unmutated IGHV status and complex karyotype.
Safety data revealed fewer severe side effects with orelabrutinib. Only 35.2% of patients experienced grade 3 or higher adverse events, versus 60.2% in the chemotherapy group. The trial reported no cases of treatment-related atrial fibrillation, major bleeding, or second primary malignancies with the BTK inhibitor, though researchers noted that longer follow-up is necessary to confirm these results.
Previous BTK inhibitors, such as ibrutinib, have been associated with cardiovascular risks, including hypertension and atrial fibrillation. Orelabrutinib was developed with greater selectivity, which the investigators say may explain its more favorable off-target safety profile. Patient-reported quality-of-life measures also favored orelabrutinib.
Limitations and broader implications
The trial had an open-label design and did not include a standard-of-care comparator, making it difficult to assess how orelabrutinib compares to other targeted therapies. All participants were Chinese, and those with del(17p)/TP53-mutated disease—a high-risk subgroup—were excluded. The follow-up period was relatively short, leaving overall survival data incomplete.
Related: User Blocked from Social Media Platform
The results contribute to a shift toward continuous oral therapies in CLL/SLL treatment. However, the authors highlighted that first-line therapy must consider individual patient needs, weighing efficacy, safety, cost, and access. Newer fixed-duration regimens are also emerging, adding complexity to treatment decisions.
The findings suggest orelabrutinib could be a strong alternative to chemotherapy, especially for patients who may not tolerate traditional regimens. Its selectivity and sustained target occupancy may make it a safer long-term option, though real-world data will be needed to confirm its effectiveness and broader use.
Access to such treatments remains a challenge for many patients.
