FDA approval of zanubrutinib for adult patients with Waldenström’s macroglobulinemia

On September 1, 2021, it was announced that the U.S. Food and Drug Administration (FDA) approved the use of zanubrutinib, a small molecule Bruton’s tyrosine kinase inhibitor, for the treatment of adult patients with Waldenström’s macroglobulinemia (WM).¹ WM is a rare type of indolent lymphoma with limited therapeutic options; zanubrutinib is the second therapy approved specifically for the treatment of this orphan disease. The approval was based on results from the multicenter, open-label, randomized phase III ASPEN trial (NCT03053440) investigating the efficacy of zanubrutinib versus ibrutinib in patients with WM who have the myeloid differentiation primary response gene 88 (MYD88) mutation.

This constitutes the second indication for zanubrutinib, as in 2019 the drug was also approved by the FDA for the treatment of patients with relapsed/refractory mantle cell lymphoma. This latest approval follows 10 regulatory approvals in the last 2 years, including one by China’s National Medical Products Administration, as well as a National Comprehensive Cancer Network recommendation.

The recommended dose of zanubrutinib is either 160 mg twice daily or 320 mg once daily, taken orally with or without food.² Although the primary efficacy endpoint of patients achieving a partial response or better as assessed by independent review committee was not met, zanubrutinib demonstrated clinically meaningful antitumor activity with improved tolerability. Detailed results of the ASPEN trial have previously been reported by the Lymphoma Hub, which you can read here for more information on study design, patient characteristics, reported adverse events, and key outcomes.