Indolent B-cell non-Hodgkin lymphomas (iNHLs) comprise a biologically heterogeneous group of hematological malignancies characterized by relatively slow clinical progression and extended overall survival. This category includes follicular lymphoma (FL), marginal zone lymphoma (MZL), Waldenström macroglobulinemia (WM), hairy cell leukemia variant (HCL-v), and unclassified B-cell lymphoproliferative disorder (BCLPD-U). Despite their indolent course, most iNHLs remain incurable, and patients typically experience a relapsing and remitting clinical course with each subsequent remission becoming shorter. The cumulative toxicity from repeated therapies represents a major clinical challenge, particularly in elderly patients. Over the past two decades, anti-CD20 monoclonal antibody-based therapies have transformed the treatment landscape, particularly rituximab in combination with chemotherapy. However, a significant proportion of patients exhibit primary resistance or suboptimal response, highlighting the need for alternative strategies.
Obinutuzumab represents a significant advance as a type II glycoengineered anti-CD20 monoclonal antibody with enhanced antibody-dependent cellular cytotoxicity and direct tumor cell death induction compared with rituximab. Obinutuzumab combined with bendamustine (GB regimen) has shown promising efficacy and acceptable safety in both treatment-naïve and relapsed/refractory settings. Landmark trials such as GALLIUM and GADOLIN have established clinical benefits, with GALLIUM demonstrating superior 3-year progression-free survival of 84% in the obinutuzumab-based group. Despite these advances, important knowledge gaps remain regarding efficacy and safety in Asian populations, where epidemiological profiles and molecular characteristics differ considerably from Western populations. The incidence rates of FL and WM are significantly lower in Japan and Chinese Taiwan, and molecular studies have highlighted ethnic differences such as lower prevalence of BCL2 translocations in Asian patients with FL. These disparities underscore the need for population-specific clinical studies.
This prospective, multicenter study enrolled 220 patients with newly diagnosed indolent B-cell lymphoma across eight centers in China, including 149 patients with FL and 71 with non-FL subtypes. Patients received six induction cycles of obinutuzumab plus bendamustine, followed by two years of obinutuzumab maintenance in those achieving at least partial response. At a median follow-up of 13.1 months, results were remarkably encouraging. Overall response rates were exceptionally high: 96.6% in FL, 100% in MZL and HCL-v, 92.9% in WM, and 88.9% in BCLPD-U. The median duration of response was 16.7 months in the FL group and had not been reached in the non-FL group. Progression-free survival and overall survival had not been reached in any subgroup. Notably, the complete response rate was markedly higher than reported in comparable Western studies, suggesting Chinese patients may derive particular benefit. The FL and non-FL groups showed comparable overall response rates, but FL achieved significantly higher complete response (92.4% vs. 78.5%), while non-FL showed longer progression-free survival.
The safety profile was generally manageable and consistent with previous studies. Treatment-emergent adverse events occurred in 42 patients, with higher frequency in the non-FL group, particularly for infections. This difference highlights the importance of vigilant monitoring and appropriate prophylactic strategies, especially in non-FL patients. Bendamustine contributes substantially to efficacy but is associated with known immunosuppressive effects including profound lymphocytopenia, hypogammaglobulinemia, and elevated infection risk. These considerations are particularly relevant for younger and/or high-risk patients. Multivariate analysis identified elevated beta-2 microglobulin levels and failure to complete all planned treatment cycles as independent predictors of shorter progression-free survival, while advanced age was associated with poorer overall survival. These findings reinforce the prognostic significance of beta-2 microglobulin and underscore the importance of patients receiving the full planned course of GB therapy.
This prospective, multicenter study provides important evidence supporting the GB regimen as a highly effective and well-tolerated first-line treatment for Chinese patients with newly diagnosed indolent B-cell lymphoma. The remarkably high response rates, particularly complete response rates exceeding those in Western studies, suggest the GB regimen may be especially beneficial for Chinese patients. The study also highlights important differences between FL and non-FL subtypes in response depth, progression-free survival, and infection risk, emphasizing the need for subtype-specific approaches. While limitations include the single-arm design, relatively small sample sizes for rare subtypes, and absence of systematic genomic profiling, the findings make a valuable contribution. Future research should focus on validating these findings in larger cohorts, identifying biomarkers predicting response and toxicity, and exploring novel combination strategies. Overall, this study advocates for incorporating the GB regimen into first-line treatment strategies for indolent B-cell lymphoma in the Chinese population.

DOI
10.1007/s11684-026-1200-8