Homoharringtonine, BCL-2 Inhibitor, Rituximab, and Prednisone in Relapsed/Refractory Diffuse Large B-Cell Lymphoma

This study is a prospective, multicenter, single-arm, Phase Ib/II clinical trial designed to evaluate the safety, tolerability, and efficacy of homoharringtonine (HHT), a B-cell lymphoma 2 (BCL-2) inhibitor, rituximab, and prednisone in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL). Despite the curative potential of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), approximately 30-40% of patients experience relapse or refractory disease, and outcomes remain poor, especially in those not eligible for transplantation or those relapsing after multiple prior therapies. Homoharringtonine is a cephalotaxine alkaloid approved in China for myeloid malignancies. It inhibits protein synthesis and downregulates Myeloid Cell Leukemia 1 (MCL-1), an important resistance factor to BCL-2 inhibition. Venetoclax (or Lisaftoclax, depending on study drug) is a selective oral BCL-2 inhibitor that restores apoptosis in tumor cells. Preclinical data demonstrate synergistic cytotoxicity when combining HHT with BCL-2 inhibition through complementary apoptotic mechanisms. Rituximab, an anti-CD20 monoclonal antibody, and prednisone, a glucocorticoid, further enhance anti-lymphoma activity and are established components of immunochemotherapy. Phase Ib will use a 3+3 dose-escalation design to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), and the recommended Phase II dose (RP2D) of HHT. Phase II will subsequently treat patients at the RP2D to assess overall response rate (ORR) as the primary efficacy endpoint, evaluated after 3 and 6 cycles according to Lugano 2014 criteria. Secondary endpoints include complete remission (CR), partial remission (PR), progression-free survival (PFS), overall survival (OS), and safety outcomes. Exploratory biomarker analyses will be performed to investigate predictors of treatment response. These include targeted gene sequencing, monitoring of circulating tumor DNA (ctDNA), and spatial transcriptomic profiling in selected patients. The findings are expected to provide important insights into the clinical potential of HHT combined with BCL-2 inhibition in relapsed/refractory DLBCL, and may inform the design of biomarker-guided treatment strategies in the future.