Zanubrutinib Monotherapy for Relapsed or Refractory Non-Germinal Center Diffuse Large B-Cell Lymphoma

Modest responses and antitumor activity were observed with zanubrutinib monotherapy in patients with non-GCB DLBCL.

Potential antitumor activity was observed in DLBCL with mutations in both CD79B and MYD88 genes.

The non-germinal center B-cell like (non-GCB) subtype of diffuse large B-cell lymphoma (DLBCL) has poor clinical outcomes. Bruton tyrosine kinase (BTK) inhibitors have established therapeutic activity in B-cell malignancies, with modest activity in DLBCL. Zanubrutinib, a potent and selective BTK inhibitor, was evaluated in patients with relapsed or refractory (R/R) non-GCB DLBCL. The BGB-3111-207 study (NCT03145064) was a multicenter single-arm phase 2 study. Patients received twice-daily oral zanubrutinib, 160 mg, until disease progression or unacceptable toxicity. The primary end point was the overall response rate (ORR). Secondary end points included progression-free survival (PFS) and duration of response (DOR). Overall survival (OS) was an exploratory end point. Forty-one patients were enrolled in China after having progressed or not responded to prior therapy. At data cutoff, 4 patients continued treatment with 37 discontinuations. The median follow-up was 6.8 months, the ORR was 29.3%, and the complete response rate was 17.1%. Median DOR, PFS, and OS were 4.5, 2.8, and 8.4 months, respectively. Adverse events (AEs) leading to treatment discontinuation were reported in 4 patients, and grade ≥ 3 AEs were reported in 48.8% of patients. Major hemorrhage, atrial fibrillation, and/or flutter were not observed. Zanubrutinib demonstrated modest antitumor activity in non-GCB DLBCL, like other BTK inhibitors, as well as a safety profile consistent with previous studies. Through retrospective biomarker testing, potential antitumor activity was observed in patients with both CD79B and MYD88 mutations, who have inferior outcomes to immunochemotherapy. Future studies of zanubrutinib in R/R non-GCB DLBCL will focus on developing mechanism-based treatment combinations and biomarker-driven patient selection.

Zanubrutinib for the treatment of Waldenström Macroglobulinemia

Introduction: Waldenström Macroglobulinaemia (WM) is a heterogeneous, incurable condition which often relapses after chemoimmunotherapy. Novel therapies such as Bruton tyrosine-kinase (BTK) inhibitors have shown to be efficacious in treating WM but with an established, significant toxicity profile seen in the first-generation inhibitor Ibrutinib. Zanubrutinib is a selective, potent BTK inhibitor with the potential to reduce toxicity and improve efficacy. Areas covered: This review examines the activity of Zanubrutinib in treating treatment-naïve and relapsed refractory WM and it's toxicity profile when compared to Ibrutinib. Outcomes from the AU003 and ASPEN studies will be examined in detail including a particular focus on MYD88^WT and CXCR4^WHIM disease. Strengths and weaknesses of this treatment approach will be highlighted and future directions for research will be identified. Expert opinion: Zanubrutinib induces deeper responses and have greater activity in MYD88^WT and CXCR4^WHIM WM. Zanubrutinib also has a favorable toxicity profile when compared to Ibrutinib. This may potentially translate to lower discontinuation rates, improved quality of life and ultimately longer progression-free survival in patients with WM.

An evaluation of zanubrutinib, a BTK inhibitor, for the treatment of chronic lymphocytic leukemia

INTRODUCTION

Recent years have seen a tremendous increase in the availability of therapeutic options for the management of patients with chronic lymphocytic leukemia (CLL). Notable among those are Bruton's tyrosine kinase (BTK) and b-cell lymphoma-2 (bcl-2) inhibitors.

AREAS COVERED

The authors provide a brief overview of the BTK signaling pathway as well as available, approved BTK inhibitors for CLL. In addition, they review pre-clinical and clinical data related to zanubrutinib and its use and CLL and other lymphoid malignancies.

EXPERT OPINION

Two BTK inhibitors are currently Food and Drug Administration (FDA) approved for use in CLL, and multiple additional agents are in development. Zanubrutinib is currently approved for the treatment of patients with relapsed mantle cell lymphoma and has demonstrated an impressive safety and efficacy profile. The choice of a specific BTK inhibitor for clinical use is dependent on its efficacy and relative toxicity profile. In addition, drug interactions also influence this decision. Zanubrutinib therefore provides an exciting option to utilize a specific BTK inhibitor with potentially limited toxicities. Additional comparative studies are currently underway to establish its advantage over currently available BTK inhibitors. Combination strategies are also being pursued to increase the depth and durability of remissions.