Efficacy of Zanubrutinib in Chronic Lymphocytic Leukaemia with High-Risk Genetic Features

Background: Why Genetic Risk Stratification Matters in CLL

Chronic lymphocytic leukaemia (CLL) is a clinically heterogeneous malignancy. While some patients follow an indolent course for years without requiring intervention, others present with or develop features that predict more aggressive disease behaviour and historically shorter survival. Among the most clinically significant of these features are deletion of chromosome 17p [del(17p)], mutation of the TP53 tumour suppressor gene, deletion of chromosome 11q [del(11q)], unmutated immunoglobulin heavy-chain variable region gene (IGHV), and complex karyotype defined by three or more chromosomal abnormalities.

These genomic markers are routinely assessed at diagnosis and before initiating therapy because they directly influence prognosis and treatment selection. Patients carrying del(17p) and/or TP53 mutations, in particular, have historically derived limited and short-lived benefit from conventional chemoimmunotherapy, which made them among the most challenging populations to manage in the era preceding targeted therapies.

The emergence of Bruton's tyrosine kinase (BTK) inhibitors has contributed to improved clinical outcomes in patients with high-risk CLL in clinical studies. Among these agents, zanubrutinib, a next-generation covalent BTK inhibitor developed by BeOne Medicines, has been evaluated for its selectivity profile and its accumulating evidence across high-risk CLL subgroups.

Mechanism and Pharmacological Rationale

Zanubrutinib was designed to achieve more complete and sustained BTK occupancy than first-generation inhibitors, with reduced off-target kinase activity. By minimising activity against off-target kinases such as ITK, TEC, and EGFR, zanubrutinib's selectivity profile was intended to improve both tolerability and depth of BTK inhibition. This characteristic is considered relevant to its performance in high-risk CLL, where sustained pathway suppression may be particularly important given the greater likelihood of disease progression under suboptimal inhibition.

Clinical Evidence in del(17p) and TP53-Mutated CLL

SEQUOIA Trial: Treatment-Naive del(17p) Cohort

The phase 3 SEQUOIA trial (NCT03336333) enrolled a dedicated cohort of treatment-naive patients with del(17p), given that this population is generally excluded from randomised comparisons due to known resistance to standard chemoimmunotherapy. At a median follow-up of 5.5 years in this cohort, the median progression-free survival (PFS) was not reached. The estimated 60-month PFS rate was 72.2%, and the estimated 60-month overall survival rate was 85.1%. The overall response rate was 97.3%.

Among the 111 patients in this cohort, 42.3% had TP53 mutations, and 27.9% had a complex karyotype with three or more abnormalities, representing a particularly high-risk group within the already high-risk del(17p) population. More than 62% of patients remained on zanubrutinib monotherapy at five years, and no new safety signals emerged beyond those observed in earlier follow-up.

Commenting on these results, Dr Constantine Tam of Alfred Hospital and Monash University noted that the findings were reassuring for current clinical practice and suggests evolving perspectives on risk classification in the context of targeted therapies.

SEQUOIA Arm D: Zanubrutinib Plus Venetoclax in High-Risk Disease

Arm D of the SEQUOIA trial examined the all-oral combination of zanubrutinib and venetoclax in treatment-naive patients, including a substantial proportion with high-risk features. A total of 114 patients in this non-randomised cohort received zanubrutinib 160 mg and venetoclax 400 mg, with 66 patients carrying del(17p) and/or TP53 mutation and 47 without these features.

With a median study follow-up of 31.2 months, the median PFS was not reached for the full population, and the 24-month PFS rate was 92% (95% CI, 85% to 96%). The overall response rate across all patients was 97.4%, including a complete response or complete response with incomplete hematologic recovery rate of 48.3%.

The regimen's activity appeared consistent across genomic subgroups. As of April 2025, 78 patients (68%) remained on zanubrutinib, and all patients had completed or discontinued venetoclax per protocol. These results were presented at the 2025 American Society of Clinical Oncology Annual Meeting and have informed the regimen's recognition as a preferred first-line option in relevant clinical guidelines.

ALPINE Trial: Relapsed/Refractory CLL Including High-Risk Subgroups

The ALPINE trial (NCT03734016) was a randomised, head-to-head phase 3 study comparing zanubrutinib with ibrutinib in patients with relapsed or refractory CLL. The study enrolled over 600 patients, with baseline characteristics including TP53 mutation without del(17p) in approximately 8 to 9% of patients and unmutated IGHV in approximately 73% of the zanubrutinib arm.

In clinical trials, zanubrutinib was associated with longer progression-free survival at 24 months compared with ibrutinib (78.4% versus 65.9%; hazard ratio 0.65), with consistent benefit observed in the TP53/del(17p) high-risk subgroup specifically (72.6% versus 54.6%; hazard ratio 0.53). The overall response rate in the zanubrutinib group was 83.5% compared with 74.2% in the ibrutinib group, with a hazard ratio for disease progression or death of 0.65 at a median follow-up of 29.6 months.

The pronounced separation in the high-risk subgroup compared to the overall population suggests that the clinical differentiation between these agents may be more meaningful, particularly in patients where sustained, complete BTK inhibition is most critical.

Six-Year Data: Maturing Evidence in del(17p) Disease

At the 2025 American Society of Haematology Annual Meeting, Dr Tam and colleagues presented six-year data on zanubrutinib versus bendamustine-rituximab in patients with del(17p). Zanubrutinib had already demonstrated superiority over the chemoimmunotherapy combination at 60 months, and the six-year analysis continued to show maturing PFS benefit, particularly among this high-risk del(17p) population receiving first-line therapy.

Long-term safety findings were consistent with prior experience. Atrial fibrillation and hypertension rates were low, and no new safety signals were identified, reinforcing zanubrutinib as a has demonstrated a safety profile consistent with prior studies in frontline settings across risk groups, including those with high-risk disease features.

Evidence in del(11q) and Unmutated IGHV

High-risk CLL is not defined exclusively by del(17p) and TP53 status. Deletion of 11q and unmutated IGHV are independently associated with more aggressive disease behaviour and shorter time to treatment.

Patients classified as high-risk in clinical analyses of zanubrutinib have included those with detectable deletion of chromosomes 17p or 11q, mutations in the TP53 gene, or an unmutated immunoglobulin heavy-chain variable region gene. Across these subgroups, the available evidence from ALPINE and SEQUOIA suggests that zanubrutinib's clinical activity is not confined to the del(17p)/TP53 subset but extends to other genomically defined high-risk groups.

A Bayesian network meta-analysis involving 12 trials and 4,437 patients across 13 treatment options identified zanubrutinib among the most effective agents for relapsed/refractory CLL, with a hazard ratio of 0.65 (95% CI, 0.49 to 0.86) versus ibrutinib and a surface under the cumulative ranking curve value of 90%.

Systematic Review Findings

A recently published systematic review and single-arm meta-analysis evaluated efficacy data for zanubrutinib in CLL across multiple clinical trials. The analysis included both treatment-naive and relapsed/refractory patients and was performed in accordance with PRISMA guidelines, searching PubMed, Medline, Scopus, and Web of Science up to August 2025. The conclusions noted that zanubrutinib demonstrates favourable efficacy in CLL, achieving high overall response rates in both treatment-naive and relapsed/refractory patients, with particularly durable responses in treatment-naive populations.

The authors also noted that complete response rates remain modest, particularly in relapsed/refractory patients, a finding consistent with the known mechanistic behaviour of covalent BTK inhibitors and reflective of the expectation that many patients will require continued therapy to maintain disease control.

Clinical Context and Ongoing Questions

The accumulating data across SEQUOIA and ALPINE confirm that zanubrutinib produces responses observed in clinical studies, including longer-term follow-up in patients with high-risk CLL features, including del(17p), TP53 mutation, del(11q), and unmutated IGHV. Long-term outcomes with zanubrutinib appear robust across risk groups, and atrial fibrillation rates remain low, reflecting the agent's selectivity profile relative to earlier-generation BTK inhibitors.

Several questions relevant to high-risk populations remain under active investigation. The optimal duration of fixed-duration combination regimens in high-risk patients, the role of measurable residual disease-guided therapy, and the management of patients who progress after BTK inhibition are all areas where additional data are anticipated. Novel strategies to address resistance, including BTK degraders and cellular immunotherapy approaches, are being evaluated but remain in earlier stages of development.

For clinicians and researchers seeking detailed molecular and clinical data supporting zanubrutinib's profile in CLL, including trial summaries, congress presentations, and educational resources, zanubrutinib chronic lymphocytic leukaemia resources are available through the BeOne Medical Affairs platform, covering the full scope of published and presented evidence.

Summary

Zanubrutinib has established a meaningful and growing evidence base in CLL characterised by high-risk genetic features. Five and six-year follow-up data from the SEQUOIA trial demonstrate durable disease control in treatment-naive del(17p) patients, a population with historically poor outcomes on standard approaches. The ALPINE trial demonstrates consistent benefit in relapsed/refractory high-risk subgroups, with a more pronounced PFS advantage in patients carrying del(17p) or TP53 mutations compared to the overall study population. Combination data from SEQUOIA Arm D suggest that the pairing of zanubrutinib with venetoclax produces deep and durable remissions across genomic risk categories, including in patients with TP53-aberrant disease. Together, these findings support zanubrutinib as a indicates zanubrutinib has been studied across multiple high-risk CLL subgroups.