Preclinical study on the efficacy of CD4/TGF-β bispecific antibody (MR001) and temozolomide combination therapy for the treatment of multiple metastatic melanoma based on MagIC-PDX model.

Abstract

e14504 Background: Advanced melanoma remains therapeutically challenging due to drug resistance, metastasis, and an immunosuppressive tumor microenvironment (TME). Temozolomide (TMZ) has demonstrated antitumor effects in melanoma in combination regimes. MR001 is a CD4/TGF-β bispecific antibody, first-in-class and first-in-human drug (approved by NMPA, 2023LP01942), which simultaneously activates CD4⁺ T cells and inhibits TGF-β signaling, reprogramming TME by limiting Treg-mediated immunosuppression, facilitating antitumor immune response, and increasing drug permeability. Conventional PDX is a powerful translational tool, but it has a low success rate, a lengthy establishment time, and requires high cost. Our previous studies proved that Magnetically-Induced Cell (MagIC) technology can expedite the reconstruction of the TME and the establishment of PDX (MagIC-PDX). This study aims to assess the efficacy of MR001 + TMZ in advanced metastatic melanoma in MagIC-PDX models. Methods: Metastatic melanoma MagIC-PDX models were established using NSG mice (n = 12) from fresh sample donated by a multiple metastatic melanoma patient in our hospital. In parallel, a murine model with humanized CD4⁺ (hCD4) mice (n = 32) were randomized into four groups: control, TMZ, MR001, and MR001 + TMZ; according to the patient all mice were engrafted with magnetized GFP/luciferase-labeled B16F10-GL cells into bone, subcutaneous tissue, and peritoneum using MagIC technology. Treatment was administered for 2 weeks along with bioluminescence imaging. TME remodeling was analyzed by immunofluorescence and qPCR. Concordance between the MagIC-PDX model and the corresponding patient clinical features was assessed. Results: In MagIC murine metastasis models, tumors developed at (3.9 ± 1.79) days. In the MR001 + TMZ group, both metastatic tumor size, qPCR, and bioluminescence signal are significantly decreased compared with both monotherapy groups (P < 0.001) and the control group (P < 0.001). Pathological examination showed that immunofluorescence signals of type III collagen encapsulation and decreased tumoral cell presence in the MR001 + TMZ group (P < 0.001), consistent with an immunoreactive and drug-permeable TME. The MagIC-PDX model behavior corresponds to the patient tumor, and the response to the combination treatment showed similar results compared to the murine model. Conclusions: MR001 synergizes with TMZ to exert potent antitumor activity in the murine multiple metastatic melanoma model and MagIC-PDX model. The MagIC-PDX model accurately reproduced patient-like metastatic dissemination. These findings support further development of MR001 based combination therapies and highlight MagIC-PDX as a rapid, patient-relevant platform for preclinical testing and precision modeling.