A phase 2 study of zanubrutinib in combination with rituximab and lenalidomide in de novo diffuse large B-cell lymphoma

Older patients with diffuse large B cell lymphoma (DLBCL) present unfavorable genetic and microenvironmental alterations. In this phase 2 trial, we assessed the efficacy and safety of zanubrutinib in combination with rituximab and lenalidomide (ZR2) in patients with de novo DLBCL aged ≥75 years (NCT04460248). Forty patients were enrolled, and the primary endpoint was complete response rate, which was 65.0% (95% confidence interval CI: 48.3-78.9) at the end of induction treatment. The 2-year progression-free and overall survival rates were 67.1% (95% CI: 50.1-79.4) and 82.4% (95% CI: 66.5-91.2). The most common grades 3 and 4 hematologic adverse event (AE) was neutropenia (n = 14; 35.0%). The most common grades 3 and 4 non-hematologic AEs were increased alanine transaminase (n = 5; 12.5%) and aspartate transaminase level (n = 5; 12.5%), and pulmonary infection (n = 5; 12.5%). No events of atrial fibrillation were observed. Importantly, the efficacy of ZR2 was more dependent on tumor microenvironmental than genetic alterations, in association with up-regulation of Class I and II human leukocyte antigen, increased number and function of conventional type 1 dendritic cells. Pre-existing expansion of intra-tumoral CD8+T cells and treatment-induced clonal T-cell receptor (TCR) repertoire contributed to better clinical outcome. TCR sequencing of the peripheral blood mononuclear cell samples from patients with durable remission detected the expanded T cell clones 3 years post-treatment. These findings thus provided better understanding of T-cell immunological memory effect on immunotherapy as ZR2, and a paradigm shift in the era of mechanism-based targeted therapy of aggressive lymphoma.