This study presents a novel dual-targeting strategy for B-cell lymphoma treatment that does not rely on T-cell activation, suggesting that co-targeting CD20 and CD37 may overcome the toxicity limitations of conventional CD3-engaging bispecific antibodies. It provides direct guidance for future antibody design and combination therapy optimization.
Literature Overview
The article titled 'A first-in-class bifunctional antibody targeting CD20 and CD37 remodels the immune microenvironment in relapsed or refractory B-cell malignancies,' published in the Journal of Hematology & Oncology, systematically investigates the safety, efficacy, and immunomodulatory mechanisms of the novel bifunctional antibody PSB202 in patients with relapsed or refractory B-cell malignancies. Through a multicenter Phase Ia clinical trial combined with cutting-edge technologies such as single-cell sequencing, the study reveals its unique mechanism of action and potential biomarkers.Background Knowledge
Currently, although CD20-targeted therapies (e.g., rituximab) have significantly improved outcomes for patients with B-cell non-Hodgkin lymphoma (B-NHL), most patients eventually relapse or develop resistance. Chimeric antigen receptor T-cell (CAR-T) therapy, while effective, is associated with severe adverse events such as cytokine release syndrome (CRS) and neurotoxicity, and its complex manufacturing process and high cost limit accessibility. In recent years, CD3-targeting bispecific antibodies (bsAbs) have shown promising efficacy by recruiting T cells to kill tumor cells, but their clinical utility remains constrained by toxicities arising from excessive T-cell activation. Therefore, developing novel therapeutic strategies independent of T-cell activation has become a research priority.
CD37, an important regulatory molecule on the B-cell surface, participates in lymphocyte adhesion and apoptosis regulation. It is co-expressed with CD20 on mature B cells and B-cell lymphomas, and the two molecules exhibit functional synergy. Previous studies have shown that simultaneously inhibiting CD20 and CD37 enhances complement-dependent cytotoxicity (CDC) and macrophage-mediated clearance. However, no clinical-grade antibody co-targeting CD20 and CD37 has entered human trials, and its safety, pharmacokinetics, and ability to remodel the tumor microenvironment (TME) in humans remain unknown. This study addresses this unmet clinical need by designing and evaluating PSB202, the first-in-class bifunctional antibody targeting CD20/CD37, aiming to achieve T-cell-independent B-cell depletion while avoiding immune-related adverse events (irAEs) such as CRS.
Research Methods and Experiments
The study employed a multicenter, open-label Phase Ia dose-escalation trial (NCT05003141), enrolling 15 patients with relapsed or refractory B-cell non-Hodgkin lymphoma who had failed multiple prior therapies. Participants received intravenous infusions of PSB202 at doses ranging from 12 to 300 mg. The primary endpoints were dose-limiting toxicity (DLT) and maximum tolerated dose (MTD), while secondary endpoints included safety, pharmacokinetics, pharmacodynamics, and overall response rate (ORR). Peripheral blood CD19+ cell dynamics were monitored via flow cytometry, cytokine release was assessed by ELISA, and tumor tissue samples were collected for single-cell RNA sequencing (scRNA-seq) and single-cell T-cell receptor sequencing (scTCR-seq) to systematically analyze changes in the immune microenvironment before and after treatment.
To validate the biological activity of PSB202, the research team evaluated antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) using various human B-cell lymphoma cell lines (e.g., Ramos, Raji) in vitro. Additionally, a Raji cell-derived xenograft model (CDX) was established to assess its in vivo antitumor activity and to explore combination effects with lenalidamide. These preclinical data provided the pharmacological basis for subsequent human trials.Key Conclusions and Perspectives
Research Significance and Prospects
This study marks the first clinical advancement of a CD20/CD37 dual-targeting strategy, demonstrating the feasibility of achieving B-cell depletion without T-cell activation, offering a potential 'off-the-shelf' therapeutic option for patients with B-cell malignancies. Compared to personalized CAR-T therapy, PSB202 offers advantages in scalable manufacturing, potentially reducing treatment costs and improving accessibility.
Mechanistically, PSB202 remodels the TME from an immunosuppressive to an immunostimulatory state, potentially laying the foundation for future combination immunotherapies (e.g., with PD-1 inhibitors). Its ability to induce IFN-γ release without triggering CRS suggests a favorable therapeutic window, maintaining immune surveillance while avoiding excessive inflammatory responses.
Furthermore, the study highlights the value of baseline CD37 expression and TME characteristics as potential predictive biomarkers, indicating that prospective studies are needed to validate their clinical utility. Additionally, PSB202 may still mediate clearance via CD37 in settings of CD20 downregulation or loss, suggesting unique therapeutic potential in anti-CD20-resistant patients, warranting further investigation.
Conclusion
This study establishes the safety and preliminary efficacy of the bifunctional antibody PSB202 targeting CD20 and CD37 in patients with relapsed or refractory B-cell malignancies, revealing its unique mechanism of T-cell-independent B-cell depletion and remodeling of the tumor immune microenvironment. Compared to conventional CD3-engaging bispecific antibodies, PSB202 avoids cytokine release syndrome and neurotoxicity, offering a new treatment option for high-risk or CAR-T-ineligible patients. Its 'off-the-shelf' nature also provides greater clinical accessibility than personalized cell therapies. Single-cell sequencing data further suggest that baseline CD37 expression, T-cell infiltration, and copy number variation status may serve as potential predictive biomarkers, guiding precision medicine approaches. Future studies should expand patient cohorts to confirm efficacy and explore its utility in CD20-resistant settings. Overall, PSB202 represents an innovative antibody engineering strategy that not only expands the therapeutic landscape for B-cell malignancies but also provides important insights for the design of dual-targeting antibodies, potentially becoming a valuable addition to the standard of care for these diseases.
