Efficacy and Safety of a NOVEL ANTI-CD20 Agent (SCT400) in CD20-Positive B-NHL: A Retrospective, Realworld Study in Chongqing, China

Introduction

Developed by Sinocelltech Ltd., SCT400 is a cutting-edge recombinant human-mouse chimeric anti-CD20 monoclonal antibody. Diverging from Rituximab (Mabthera®), SCT400 integrates the commonly occurring IgG1 allotype, G1m (1,17), prevalent among the Chinese population. It further differentiates in its amino acid structure, specifically at position 219 of the CH1 domain, where SCT400 substitutes valine for the alanine present in Rituximab (Mabthera®). A pivotal Chinese multi-center phase 3 clinical trial has demonstrated that the SCT400-CHOP regimen matches the R-CHOP regimen in terms of efficacy and safety for the initial treatment of ND-DLBCL (Yuankai Shi, et al. 2022). Additionally, SCT400 offers a more cost-effective solution, positioning it as a strong alternative to Rituximab (Mabthera®) within the Chinese healthcare landscape. Nevertheless, as of its approval in China in August 2022, comprehensive evaluations of SCT400's real-world effectiveness and safety in B-NHL treatments are yet to be reported.

Methods

This retrospective analysis encompassed patient data from three Chinese centers, spanning August 2022 to December 2023. The study included patients diagnosed with CD20-positive B-NHL who had received at least two cycles of SCT400 therapy and underwent at least one post-treatment efficacy assessment. We gathered baseline data prior to the initiation of SCT400 therapy, which included sociodemographic details, diagnostic information, disease status, and prior chemotherapy treatments. Data collected on SCT400 therapy encompassed dosage, treatment cycles, and adverse events. Efficacy was assessed every two cycles using imaging techniques such as CT and PET/CT, alongside routine follow-ups. The primary endpoint was the Overall Response Rate (ORR), with secondary endpoints including Complete Response (CR) rate, Partial Response (PR) rate, Duration of Response (DOR), and 6-month Progression-Free Survival (PFS). Safety was evaluated by the incidence of adverse events.

Results

This investigation incorporated 47 patients, with a median age of 60 years, of which 66% were male. The distribution of B-NHL subtypes was as follows: Burkitt lymphoma (BL) 7 cases (14.9%), Diffuse large B-cell lymphoma (DLBCL) 19 cases (40.4%), Follicular lymphoma (FL) 3 cases (6.4%), Mantle cell lymphoma (MCL) 8 cases (17.0%), Marginal zone lymphoma (MZL) 9 cases (19.1%), and Small lymphocytic lymphoma (SLL) 1 case (2.1%). Among them, 30 patients (63.8%) were newly diagnosed and had not received prior chemotherapy. A total of 34 patients (72.3%) presented with advanced disease stages (Ann Arbor III-IV), and 39 patients (83.0%) exhibited an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-1. Three patients (6.4%) had a history of autologous hematopoietic stem cell transplantation (auto-HSCT).

Patients underwent a median of 5 SCT400 treatment cycles (range: 3-10 cycles), with a median follow-up duration of 6 months (range: 2-15 months). The overall response rate (ORR) was 93.6%, including a complete response (CR) rate of 29.8% (14 patients), a partial response (PR) rate of 63.8% (30 patients), and a non-response rate of 6.4% (3 patients). Detailed subgroup analyses indicated ORRs for BL, DLBCL, FL, MCL, MZL, and SLL as 100%, 94.7%, 66.7%, 100%, 88.9%, and 100% respectively, as outlined in Table 2.

The median duration of response (DOR) was reported as 8 months (interquartile range: 5-10 months), and the 6-month progression-free survival (6m-PFS) rate stood at 70.2%. Adverse events (AEs) included both hematological and non-hematological side effects. Notable grade 3/4 hematological AEs comprised neutropenia (25.5%) and thrombocytopenia (17%), with occurrences of febrile neutropenia and anemia each at 6.4%. The predominant grade 3/4 non-hematological AEs were nausea/vomiting (8.5%), fatigue (6.4%), and infections (6.4%). Mild allergic reactions were noted in 3 cases (6.4%), with no severe allergic reactions reported.

Conclusions

Our real-world study provides initial proof supporting the effectiveness and safety of SCT400 as an alternative to rituximab in treating B-NHL within the Chinese demographic. The outcomes indicate that SCT400 could potentially replace rituximab in medical practice. Nonetheless, to solidify these findings, additional research with an expanded patient group is essential.

No relevant conflicts of interest to declare.