A phase 2 expanded access study of zanubrutinib (ZANU) in patients (pts) with Waldenström Macroglobulinemia (WM)

• Published in: Journal of clinical oncology Vol. 40; no. 16_suppl; p. e19522
• Main Authors: Castillo, Jorge J., Kingsley, Ed, Narang, Mohit, Yimer, Habte Aragaw, Dasanu, Constantin A, Melear, Jason M., Coleman, Morton, Farber, Charles Michael, Gupta, Mukul, Shulman, Jonah, Mantovani, Emily H., Zhang, Xiaowei, Cohen, Aileen, Huang, Jane
• Format: Journal Article
• Language: English
• Published: 01.06.2022
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/JCO.2022.40.16_suppl.e19522

e19522 Background: Bruton tyrosine kinase (BTK) inhibition is an emerging standard of care for WM. The next-generation BTK inhibitor ZANU (BGB-3111), designed to maximize BTK occupancy and minimize off-target inhibition of other kinases, is approved by the United States (US) Food and Drug Administration, Health Canada, and the European Union at a dose of 320 mg once daily (QD) or 160 mg twice daily (BID) for adult pts with WM. BGB-3111-216 is a single-arm expanded access study of ZANU in treatment-naïve (TN) pts who were unsuitable for standard chemoimmunotherapy or pts with relapsed refractory (R/R) WM. This study provides real-world experience with ZANU in pts with WM. Methods: Eligible pts with TN or R/R WM received ZANU 320 mg QD or 160 mg BID orally. Primary endpoint was the number of pts enrolled/treated and enrolling sites. Secondary endpoints included treatment-emergent adverse events (TEAEs) of special interest, disease response rate, progression-free survival (PFS), and overall survival (OS). Response was evaluated by investigator assessment according to the 6th International Workshop on WM ( Br J Haematol. 2013;160(2):171-6) every 6 mo at minimum. The study was closed by the sponsor in July 2021 and active pts were transitioned to commercial ZANU via a patient assistance program. Results: Fifty pts with WM (17, TN; 33, R/R) were enrolled between December 2019 and June 2021 across 10 academic and community medical centers in the US. Median age was 72 years, 54% had intermediate-, 40% had high-risk disease, and the median number of prior therapies for R/R pts was 2. Median treatment exposure was 9.2 mo (range, 1.4-20.0). Thirty-eight (76%) pts had ≥1 TEAE, and 36 (72%) had ≥1 TEAE of special interest. Grade ≥3 TEAEs of special interest were hypertension (8%), infection (8%), atrial fibrillation/flutter (2%), neutropenia (2%), and second primary malignancy (2%). No new safety signals were observed. In pts with ≥1 response evaluation, 39% achieved a best overall response (BOR) of very good partial response. Overall response rate was 85.4% and major response rate was 73.2% (Table). Of the 4 pts with BOR of progressive disease, 3 had IgM values that met partial response criteria before the 6-mo response assessment. PFS and OS were immature due to short follow-up, and the median was not met. Conclusions: These real-world expanded access study results were consistent with the established ZANU profile in WM or other B-cell malignancies when administered as oral monotherapy at 160 mg BID or 320 mg QD in pts with intermediate or high-risk R/R or TN WM. Clinical trial information: NCT04052854. [Table: see text]