Zanubrutinib Improves PFS2, Maintains Sensitivity to Subsequent Therapy in Frontline CLL/SLL

Emerging data from the phase 3 SEQUOIA trial (NCT03336333), presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, demonstrate that frontline zanubrutinib (Brukinsa, BeiGene) not only provides durable disease control compared with bendamustine-rituximab (BR) but also preserves sensitivity to effective subsequent therapies, resulting in superior second progression-free survival (PFS2) in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL).¹

The treatment landscape for CLL/SLL has undergone a dramatic shift with the introduction of Bruton tyrosine kinase inhibitors (BTKis), which have largely replaced chemoimmunotherapy as frontline treatment for many patients. Although zanubrutinib has already demonstrated superiority over bendamustine-rituximab (BR) in frontline CLL/SLL, an increasingly important question is whether early use of a BTK inhibitor affects outcomes after disease progression and influences the effectiveness of subsequent therapies.^2,3

The Evolution of Frontline Therapy in CLL/SLL

Zanubrutinib is a next-generation BTK inhibitor designed to provide potent and sustained BTK inhibition while minimizing off-target effects associated with earlier-generation agents. Prior analyses from the SEQUOIA trial established zanubrutinib as superior to BR for progression-free survival and time to next treatment in treatment-naive patients without del(17p).²

While frontline BTK inhibitor therapy has become increasingly common, questions remain regarding treatment sequencing and outcomes after progression. The current study evaluated subsequent therapies and PFS2 outcomes among patients enrolled in SEQUOIA.¹

Study Design and Long-Term Follow-Up

SEQUOIA investigators randomized 479 treatment-naive patients with CLL/SLL without del(17p) to receive either continuous zanubrutinib (n = 241) or 6 cycles of BR (n = 238). Patients assigned to BR were permitted to cross over to zanubrutinib following disease progression.¹

At a median follow-up of 78.7 months, researchers assessed progression-free survival, time to next treatment (TTNT), time to next treatment or death (TTNT-D), and PFS2, an endpoint increasingly viewed as an important indicator of treatment sequencing because it evaluates outcomes through both frontline and subsequent therapies, helping determine whether an initial treatment strategy preserves future therapeutic options.¹

Durable Disease Control With Zanubrutinib

The updated analysis confirmed the substantial long-term efficacy advantage of zanubrutinib over chemoimmunotherapy. At 78 months, estimated PFS rates were 70.9% with zanubrutinib compared with 28.6% with BR (hazard ratio [HR], 0.28; 95% CI, 0.21-0.38; P < .0001).¹

The majority of patients receiving zanubrutinib remained free from the need for additional treatment. Overall, 87.6% of patients treated with zanubrutinib had not required subsequent therapy at the time of analysis.¹

Similarly, both TTNT and TTNT-D significantly favored zanubrutinib, further supporting the durability of frontline disease control achieved with BTK inhibition.¹

Effective Salvage Therapy Following Zanubrutinib

Beyond frontline disease control, the SEQUOIA data provide insight into treatment sequencing after progression on zanubrutinib. Among the 24 patients who required subsequent therapy, 13 received BCL2 inhibitor–based regimens.¹

Follow-up data indicates that BCL2 inhibitor–based therapy remained highly effective after progression on zanubrutinib. After a median follow-up of 33.5 months from initiation of next-line treatment, 10 of 13 patients remained alive and progression-free, while only 1 patient had experienced disease progression.¹

These findings suggest that frontline zanubrutinib does not appear to compromise the effectiveness of subsequent BCL2 inhibitor–based therapy, supporting its use within modern treatment sequencing strategies for CLL/SLL.^1,3

Improvement in Second Progression-Free Survival

The benefits of frontline zanubrutinib extended beyond initial disease control and into subsequent treatment outcomes. PFS2 significantly favored zanubrutinib over BR (HR, 0.66; 95% CI, 0.45-0.98; P < .05).¹

Despite widespread use of highly effective subsequent therapies—including crossover to zanubrutinib and other novel agents among patients initially assigned to BR—PFS2 continued to favor frontline zanubrutinib (HR, 0.66; 95% CI, 0.45-0.98; P < .05).¹

At 78 months, estimated PFS2 rates were 81.3% for zanubrutinib and 73.8% for BR, demonstrating that the benefits of early BTK inhibition extended beyond first progression and into later treatment outcomes.¹

The SEQUOIA findings collectively demonstrate that the benefits of frontline zanubrutinib extend beyond initial disease control. In addition to significantly improving PFS and delaying the need for subsequent therapy, zanubrutinib maintained superior PFS2 despite widespread crossover and use of novel agents in the BR arm. Together, these findings support zanubrutinib as a frontline treatment strategy that can provide durable disease control while preserving the effectiveness of subsequent therapies, an increasingly important consideration in modern CLL/SLL management.^1,3

REFERENCES

1. Tam CS, Kahl BS, Munir T, et al. Subsequent therapies and time to second progression-free survival events (PFS2) in treatment-naive chronic lymphocytic leukemia/small lymphocytic lymphoma previously treated with zanubrutinib or bendamustine-rituximab in SEQUOIA. Presented at: 2026 American Society of Clinical Oncology Annual Meeting; May 29–June 2, 2026; Chicago, IL. Abstract 7046. Accessed June 15, 2026.

2. Tam CS, Brown JR, Kahl BS, et al. Zanubrutinib versus bendamustine and rituximab in untreated chronic lymphocytic leukaemia and small lymphocytic lymphoma (SEQUOIA): a randomised, controlled, phase 3 trial. Lancet Oncol. 2022;23(8):1031-1043. doi:10.1016/S1470-2045(22)00293-5

3. Wierda W, Brown J, Abramson J, et al. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma. Version 2.2026. JNCCN. 2026;24(3). doi:10.6004/jnccn.2026.0012