Extended Follow-up of ALPINE Randomized Phase 3 Study Confirms Sustained Superior Progression-Free Survival of Zanubrutinib Versus Ibrutinib for Treatment of Relapsed/Refractory Chronic Lymphocytic Leukemia and Small Lymphocytic Lymphoma (R/R CLL/SLL)

• Published in: BLOOD Vol. 142; no. Supplement 1; p. 202
• Main Authors: Brown, Jennifer R., Eichhorst, Barbara F., Lamanna, Nicole, O'Brien, Susan M., Tam, Constantine S., Qiu, Luqui, Kaźmierczak, Maciej, Jurczak, Wojciech, Zhou, Keshu, Simkovic, Martin, Mayer, Jiri, Gillespie-Twardy, Amanda L., Ferrajoli, Alessandra, Ganly, Peter S., Weinkove, Robert, Grosicki, Sebastian, Mital, Andrzej, Robak, Tadeusz, Osterborg, Anders, Yimer, Habte A., Wang, Megan (Der Yu), Salmi, Tommi, Wang, Liping, Li, Jessica, Wu, Kenneth, Cohen, Aileen Cleary, Shadman, Mazyar
• Format: Journal Article Conference Proceeding
• Language: English
• Published: 02.11.2023
• Subjects: Medicin och hälsovetenskap
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-174289

Introduction: ALPINE, a randomized, multinational phase 3 study (NCT03734016) in patients with R/R CLL/SLL, established the statistical and clinically meaningful superiority of zanubrutinib over ibrutinib on progression-free survival (PFS) and overall response rate (ORR) and confirmed the favorable safety/tolerability profile of zanubrutinib (Brown et al. NEJM; 2022). Now, with 3 years of overall study follow-up, we report the results of an extended follow-up analysis. Methods: As previously published, patients with R/R CLL/SLL who had received ≥1 prior therapy and had measurable disease were randomized 1:1 to receive zanubrutinib or ibrutinib. Efficacy assessments, including PFS and ORR, were evaluated by the investigator based on 2008 iwCLL criteria; sensitivity analyses to confirm PFS results were also conducted. Updated safety analyses were performed. All reported P-values are descriptive. Results: Overall, 652 patients were randomized to receive zanubrutinib (n=327) or ibrutinib (n=325). As of 15 May 2023, 63.3% (n=207/327) of patients remain on zanubrutinib and 52.3% (n=170/325) remain on ibrutinib. At a median study follow-up of 36.3 months, benefit of zanubrutinib over ibrutinib was sustained (HR: 0.67 [95% CI, 0.52-0.86]; 2-sided P=.002; Fig 1). At 36 months, the PFS rates were 65.8% with zanubrutinib and 54.3% with ibrutinib. Benefits in PFS with zanubrutinib were also observed across major subgroups, including in patients with del(17p)/ TP53 mutations (HR: 0.52 [95% CI, 0.32-0.83] 2-sided P=.005) where 36-month PFS rates were 60.1% and 43.6%, respectively. Additionally, the zanubrutinib PFS benefit was confirmed in a sensitivity analysis that included only progression and death events that occurred on active treatment (HR: 0.69 [95% CI, 0.49-0.97]; 2-sided P=.031). ORR remained higher with zanubrutinib compared with ibrutinib (85.0% vs 74.8%; 2-sided P=.001). Responses deepened in both arms with CR/CRi rates of 10.1% (zanubrutinib) and 7.4% (ibrutinib); therate of PR-L or better was 90.2% vs 82.8%, respectively. Fifty-nine (18.0%) patients treated with zanubrutinib and 71 (21.8%) treated with ibrutinib had died (OS HR: 0.76 [95% CI, 0.54-1.08]); 36-month OS rates were 82.6% (zanubrutinib) and 79.7% (ibrutinib). In this extended follow-up, median treatment duration was 34.7 months (zanubrutinib) and 31.5 months (ibrutinib). Across both arms, the most common reasons for treatment discontinuation were AEs (20.2%, zanubrutinib; 24.9%, ibrutinib) and progressive disease (12.2%, zanubrutinib; 16.3%, ibrutinib). Dose interruption and dose reduction due to AEs were 59.6% vs 61.1% and 14.2% vs 17.6% with zanubrutinib vs ibrutinib, respectively. The most common AEs of any grade with zanubrutinib and ibrutinib were COVID-19 (37.3% vs 25.6%), diarrhea (17.9% vs 25.6%), and upper respiratory tract infection (25.9% vs 17.3%). Rates of any grade ≥3 AEs and serious AEs were 72.2% vs 75.6% and 49.7% vs 57.4% with zanubrutinib vs ibrutinib, respectively. Most commonly reported grade ≥3 AEs were neutropenia (17.3% vs 16.4%) and hypertension (15.1% vs 12.0%). Rates of serious infections were 30.6% in each treatment arm. Discontinuation rates due to cardiac disorders were lower with zanubrutinib (0.6% [n=2]) vs ibrutinib (4.6% [n=15]). Overall cardiac events remain lower with zanubrutinib, including atrial fibrillation/flutter (6.2% vs 16.0%; 2-sided P<.0001). Across this study, no grade 5 AEs due to cardiac disorders were observed with zanubrutinib but were reported in 6 patients (1.9%) with ibrutinib ( Table 1). Conclusions: ALPINE was the first study to demonstrate PFS superiority in a head-to-head comparison of BTK inhibitors. At a median follow-up of 3 years, the study showed sustained PFS benefits of zanubrutinib over ibrutinib. The durable PFS benefits with zanubrutinib were observed across major subgroups, including multiple sensitivity analyses. The overall safety/tolerability profiles were consistent with previous reports for both treatments. The cardiac safety profile remained favorable for zanubrutinib compared with ibrutinib, with no new safety signals emerging with longer follow-up. With over 3 years of treatment, zanubrutinib continues to be a more efficacious and better tolerated treatment than ibrutinib for patients with R/R CLL/SLL. At time of presentation, data with further follow-up will be presented.