Cull, Gavin

SummaryThe phase I/II AU‐003 study in patients with treatment‐naïve (TN) or relapsed/refractory (R/R) chronic lymphocytic leukaemia/small lymphocytic lymphoma demonstrated that zanubrutinib therapy results in clinically meaningful and durable responses with acceptable safety and tolerability. We report updated safety and efficacy data for 123 patients with a median follow‐up of 47·2 months. Patients received zanubrutinib 160 mg twice daily (81 patients), 320 mg once daily (40), or 160 mg once daily (two). Discontinuations due to adverse events or disease progression were uncommon. The overall response rate (ORR) was 95·9% (TN, 100%; R/R, 95%) with 18·7% achieving complete response (CR). Ongoing response at 3 years was reported in 85·7%. The ORR in patients with del(17p)/tumour protein p53 mutation was 87·5% (CR 16·7%). The 2‐ and 3‐year progression‐free survival estimates were 90% (TN, 90%; R/R, 91%) and 83% (TN, 81%; R/R, 83%) respectively. The most reported Grade ≥3 adverse events were neutropenia (15·4%), pneumonia (9·8%), hypertension (8·9%) and anaemia (6·5%). The annual incidence of atrial fibrillation, major haemorrhage, Grade ≥3 neutropenia and Grade ≥3 infection decreased over time. With a median follow‐up of ~4 years, responses remain clinically meaningful and durable and long‐term tolerability to zanubrutinib therapy continues.

Abstract Introduction: Ibrutinib (Imbruvica®), an oral, first-in-class covalent BTK inhibitor, is a new treatment option approved by FDA for chronic lymphocytic leukemia (CLL) patients (pts) with ≥1 prior therapy. We previously reported results from the phase III trial, in which ibrutinib (ibr) significantly improved progression-free and overall survival vs ofatumumab (ofa) in pts with relapsed/refractory CLL or small lymphocytic lymphoma (SLL) (Byrd et al. NEJM, 2014). Here, we report measures of patient well-being, including hematologic, immunologic, and quality of-life parameters, at interim analysis (IA). Methods: Pts with CLL/SLL after ≥1 prior therapy were randomized 1:1 to ibr 420 mg/day until progression or unacceptable toxicity, or to ofa for up to 24 weeks. At IA, secondary efficacy endpoints of hematologic improvement (sustained improvement ≥56 days without transfusions or growth factors) and FACiT-Fatigue (FACiT-F) outcomes were analyzed, along with exploratory endpoints assessing disease-related symptoms (DRS), serum immunoglobulin, patient-reported outcomes (PROs) by EORTC QLQ-C30, and medical resource utilization (MRU). Results: Of 391 enrolled pts (ibr n=195; ofa n=196), 63% had cytopenia(s) at baseline: 45% had anemia (hemoglobin ≤11 g/dL), 35% thrombocytopenia (platelets ≤100×109/L), and 20% neutropenia (absolute neutrophil counts [ANC] ≤1.5×109/L). On the ibr arm, 69% of pts with baseline cytopenias experienced sustained improvement in blood counts compared to 43% on ofa (P<0.0001, table). There was no decrement in serum immunoglobulins (IgA, IgG, IgM) during follow-up. IgA levels increased on the ibrutinib arm only (mean change from baseline: 41% at week 24). Immune cells CD4+ and CD8+ T-cell and NK-cell levels remained relatively stable during treatment. Mean change in FACiT-F score from baseline are shown in the figure for ibr and ofa arms. At week 24, clinically meaningful (≥3 points) improvement in FACiT-F occurred in more pts on ibr than ofa (59% vs 46%, P=0.06); clinically meaningful deterioration was reported by 14% vs 24% (P=0.08), respectively. A larger proportion of ibr vs ofa pts showed clinically meaningful improvement on EORTC-QLQ-C30 global health scores (46% vs 40%). Clinically meaningful improvement (≥10 points) from baseline to week 24 in ibr vs ofa pts was observed for fatigue (median 11 vs 0). A 50% reduction in lymph node based on IRC-assessed CT was observed in 93% (177/190 evaluable) of ibr pts compared with 17% (29/174 evaluable) of ofa pts (P< 0.0001). Splenic response based on IRC-assessed CT was reported for 85% (138/163 evaluable) of ibr pts compared with 54% (82/151 evaluable) of ofa pts. Baseline DRS were comparable between groups; however, improvement by at least 1 grade (G) post-baseline was observed in ibr relative to ofa pts for weight loss (100% vs 93%), fatigue (88% vs 72%), night sweats (95% vs 86%), and anorexia (100% vs 64%), respectively. Cumulative MRU was comparable for growth factors and transfusions, with ibr pts having longer median treatment duration: 8.6 months for ibr vs 5.3 for ofa. Hospitalizations in the first 30 days occurred in 2% ibr vs 15% ofa pts. After adjusting for treatment exposure duration, diarrhea, grade 1-2 bleeding events (e.g petechiae), and atrial fibrillation were among those noted to be more frequent on the ibrutinib arm while events such as fatigue, infusion reaction, and peripheral sensory neuropathy were seen more commonly with ofa. Major hemorrhage events were uncommon, observed in 2 patients on the ibr arm vs 3 on ofa arm without adjusting for exposure time. Exposure-adjusted analysis showed no difference in any-grade infection and a 43% relative reduction for grade 3 or higher infections for ibr. Conclusions: Ibr compared to ofa when administered to previously treated CLL/SLL pts led to improvements in hematologic function and disease burden. A survival benefit with ibr, together with sustained improvements in hematologic endpoints and PRO suggest that ibr enhances quality of life while prolonging survival. Table. Sustained hematologic improvement Parameter, n (%) ITT population Pts with cytopenias at baseline Ibr n=195 Ofa n=196 P value Ibr n=195 Ofa n=196 P value Platelets 60 (31) 19 (10) <0.0001 53/74 (72) 14/64 (22) <0.0001 ANC 52 (27) 19 (10) <0.0001 26/41 (63) 12/38 (32) 0.0047 Hemoglobin 42 (22) 32 (16) 0.1883 42/89 (47) 32/86 (37) 0.1815 Figure. Improvement in FACiT-F by treatment arm. Figure. Improvement in FACiT-F by treatment arm. Disclosures Barrientos: Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding. Brown:Sanofi, Onyx, Vertex, Novartis, Boehringer, GSK, Roche/Genentech, Emergent, Morphosys, Celgene, Janssen, Pharmacyclics, Gilead: Consultancy. Kay:Genetech: Research Funding; Pharmacyclics: Research Funding; Hospira: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees. Coutre:Janssen, Pharmacyclics: Honoraria, Research Funding. Tam:Pharmacyclics and Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Mulligan:Roche, Abbvie: Consultancy, Honoraria. Jaeger:Janssen Cilag: Honoraria. Devereux:Pharmacyclics, Janssen: Consultancy, Honoraria. Robak:Janssen: Consultancy, Research Funding. Schuh:Roche, Gilead, GSK, NAPP, Celgene: Honoraria. Bloor:GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Dearden:Roche, GSK, Gilead, Janssen, Napp: Honoraria. Jones:Pharmacyclics: Consultancy, Research Funding. Kierschniak:Pharmacyclics, GmbH: Employment. Eckert:Pharmacyclics: Employment. Suzuki:Pharmacyclics: Employment. Hsu:Pharmacyclics: Employment. James:Pharmacyclics: Employment. Byrd:Pharmacyclics: Research Funding. Hillmen:Pharmacyclics, Janssen, Gilead, Roche: Honoraria, Research Funding.

Abstract Zanubrutinib is a potent and highly selective inhibitor of Bruton tyrosine kinase (BTK). In this first-in-human, open-label, multicenter, phase 1 study, patients in part 1 (3 + 3 dose escalation) had relapsed/refractory B-cell malignancies and received zanubrutinib 40, 80, 160, or 320 mg once daily or 160 mg twice daily. Part 2 (expansion) consisted of disease-specific cohorts, including treatment-naive or relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). The primary end points were safety and tolerability, and definition of the maximum tolerated dose (part 1). Additional end points included pharmacokinetics/pharmacodynamics and preliminary efficacy. Reported herein are results from 144 patients enrolled in the dose-finding and CLL/SLL cohorts. No dose-limiting toxicities occurred in dose escalation. Median BTK occupancy in peripheral blood mononuclear cells was &gt;95% at all doses. Sustained complete (&gt;95%) BTK occupancy in lymph node biopsy specimens was more frequent with 160 mg twice daily than 320 mg once daily (89% vs 50%; P = .0342). Consequently, 160 mg twice daily was selected for further investigation. With median follow-up of 13.7 months (range, 0.4-30.5 months), 89 CLL/SLL patients (94.7%) remain on study. Most toxicities were grade 1/2; neutropenia was the only grade 3/4 toxicity observed in &gt;2 patients. One patient experienced a grade 3 subcutaneous hemorrhage. Among 78 efficacy-evaluable CLL/SLL patients, the overall response rate was 96.2% (95% confidence interval, 89.2-99.2). Estimated progression-free survival at 12 months was 100%. Zanubrutinib demonstrated encouraging activity in CLL/SLL patients, with a low incidence of major toxicities. This trial was registered at www.clinicaltrials.gov as #NCT02343120.