This study provides critical evidence for treatment strategies in relapsed/refractory follicular lymphoma, supporting deep complete response as a predictor of long-term survival and highlighting the potential of CD20-targeted bispecific antibodies in high-risk patients, thereby informing the design of future clinical trials.
Literature Overview
The article titled 'Dynamics of complete responses (CRs) in patients with relapsed or refractory follicular lymphoma (R/R FL) treated with odronextamab in the ELM‐2 study,' published in the journal HemaSphere, systematically investigates the dynamics, duration, and association with high-risk factors of complete response (CR) induced by odronextamab in patients with relapsed or refractory follicular lymphoma (R/R FL). Based on an exploratory analysis of the pivotal phase II ELM-2 trial, the study reveals the high efficacy and sustainability of this CD20 × CD3 bispecific antibody in heavily pretreated patients.Background Knowledge
Follicular lymphoma (FL) is an incurable indolent B-cell non-Hodgkin lymphoma, and most patients eventually develop relapsed or refractory disease. As the number of prior therapies increases, the complete response rate declines significantly, particularly in patients with high-risk features such as FLIPI scores of 3–5, progression of disease within 24 months (POD24), or refractoriness to the most recent treatment, who face extremely poor outcomes. Traditional anti-CD20 monoclonal antibodies (e.g., rituximab) combined with chemotherapy have limited efficacy in R/R FL, and low CD20 expression often leads to resistance. In recent years, T-cell-engaging therapies such as bispecific antibodies and CAR-T cells have become research hotspots, but achieving deep and durable responses remains a challenge. Odronextamab, an 'off-the-shelf' CD20 × CD3 bispecific antibody, bridges T cells and malignant B cells to induce T-cell-mediated cytotoxicity, overcoming limitations of CAR-T therapy such as long manufacturing times and high costs. This study focuses on the dynamics of CR, aiming to evaluate its durability and clinical value in real-world settings, providing a basis for optimizing treatment strategies.
Research Methods and Experiments
The study is based on the R/R FL cohort of the phase II ELM-2 trial (NCT03888105), which enrolled 128 patients receiving intravenous odronextamab under a step-up dosing regimen to mitigate cytokine release syndrome (CRS) risk. Efficacy was assessed using Lugano criteria, with best overall response (BOR) determined by independent central review (ICR). The primary endpoint was objective response rate (ORR), with key exploratory endpoints including the dynamics, duration, and biomarker correlations of complete response (CR). Disease assessments were conducted via CT/MRI and PET at baseline, approximately week 12, and every 8–12 weeks thereafter. Circulating tumor DNA (ctDNA) was analyzed using the AVENIO Oncology Assay to evaluate minimal residual disease (MRD). CD20 expression was assessed via immunohistochemistry (IHC) and RNA sequencing (RNAseq), with low expression defined as IHC <10% or mRNA <500 TPM. Statistical analyses used Kaplan-Meier methods to estimate duration of response (DOR), duration of complete response (DOCR), and progression-free survival (PFS).Key Conclusions and Perspectives
Research Significance and Prospects
This study confirms that odronextamab achieves high and durable CR rates in R/R FL, performing particularly well in high-risk patients, offering a new therapeutic option for this poor-prognosis population. Its 'off-the-shelf' nature makes it more accessible than CAR-T therapy and suitable for broad clinical application. Future studies should explore the association between duration of CR and overall survival and validate the clinical utility of ctDNA as a dynamic monitoring tool.
Biomarker analyses show responses even with low CD20 expression, suggesting a need to reevaluate antigen expression thresholds in bispecific antibody therapy. This provides a theoretical basis for developing combination strategies targeting antigen escape mechanisms (e.g., with BTK inhibitors).
Regarding safety, although infections (including COVID-19) were the main adverse events, the treatment discontinuation rate due to adverse events was low (16.0%), supporting the feasibility of long-term therapy. Future studies need to validate the safety and efficacy of reduced-dose maintenance strategies in larger populations to optimize treatment cycles.
Conclusion
This study systematically demonstrates the high efficacy and durability of odronextamab in inducing complete responses in patients with relapsed/refractory follicular lymphoma, achieving deep and long-lasting remissions even in traditionally high-risk populations. Its rapid onset, high CR rate, and manageable safety profile establish CD20 × CD3 bispecific antibodies as a key component in the treatment landscape of R/R FL. The prognostic value of ctDNA-based minimal residual disease status provides a new tool for personalized treatment decisions, while the ability to respond despite low CD20 expression expands the eligible patient population. From bench to bedside, this study not only validates the mechanistic advantages of T-cell-engaging therapies but also advances a paradigm shift from 'response' to 'cure-oriented' treatment. Future adaptive strategies incorporating MRD monitoring are expected to further optimize the use of odronextamab, improve long-term survival, reshape the care system for R/R FL, and deliver meaningful clinical benefits to patients.
