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Updated: Jun 27, 2026
A GPC3-targeting Bispecific Antibody, GPC3-S-Fab, with Potent Cytotoxicity
Published on: July 12, 2018
A humanized anti-MSLN×4-1BB bispecific antibody exhibits potent antitumour activity through 4-1BB signaling
Da-Yan Zhang1,2,3, Zhi-Hua Zhang1,3, Wen-Ting Liu2,3
1Department of Medical Oncology, Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China, Anhui Provincial Cancer Hospital, Hefei, 230031, Anhui, China.
Background:
Agonistic monoclonal antibodies targeting 4-1BB/CD137 have shown preclinical promise, but their clinical development has been limited by severe liver toxicity or limited efficacy. Therefore, a safe and efficient immunostimulatory molecule is urgently needed for cancer immunotherapy.
Methods:
A novel anti-MSLN×4-1BB bispecific antibody (bsAb) was generated via antibody engineering, and its affinity and activity were detected via enzyme-linked immunosorbent assay (ELISA), flow cytometry, and T-cell activation and luciferase reporter assays. In vivo antitumour activity was assessed by establishing humanized mice bearing human MSLN-expressing MC38 (MC38/hMSLN) or CT26 (CT26/hMSLN) cells, and safety was further evaluated in cynomolgus monkeys.
Results:
We generated two humanized anti-MSLN×4-1BB bsAbs (HK013-G1/G4) by fusing an anti-4-1BB scFv to the C-terminus of an anti-MSLN VHH with an intact Fc fragment from human IgG1 or IgG4. The two bsAbs were able to block the binding of CA125 to MSLN and stimulate 4-1BB signaling pathway, which was strictly dependent on MSLN expression. In particular, HK013-G1 retained Fc function and induced ADCC effect in tumour cells, whereas HK013-G4 did not. Strikingly, HK013-G1 showed superior antitumour activity to HK013-G4 both in vitro and in vivo and remained effective even in the presence of soluble MSLN. HK013-G1 enhanced antitumour immunity and induced durable antigen-specific immune memory to prevent rechallenged tumour growth, even at a dose as low as 1 mg/kg. Furthermore, HK013-G1 did not induce nonspecific production of proinflammatory cytokines and showed good tolerability up to the highest tested dose (30 mg/kg weekly) for 5 weeks, with no HK013-G1-related adverse effects observed in cynomolgus monkeys. In addition, the mean half-life of HK013-G1 was approximately 61 and 97 h at single doses of 3 and 30 mg/kg, respectively.
Conclusion:
The optimal anti-MSLN×4-1BB bsAb HK013-G1 exhibited synergistic antitumour effects by inducing an ADCC effect (innate immunity) and stimulating the 4-1BB signaling pathway (adaptive immunity) upon cross-bridging with MSLN with no systemic toxicity, which may offer the promise of an improved therapeutic window relative to that of 4-1BB agonists.
