Modular assembly and evaluation of a TROP2-targeting immunotoxin for cancer therapy

Area of Science:

• Oncology
• Molecular Biology
• Immunotherapy

Background:

• Trophoblast cell surface antigen 2 (TROP2) is overexpressed in many cancers, correlating with poor prognosis.
• TROP2-targeting antibody-drug conjugates (ADCs) show promise but face challenges like high molecular weight and manufacturing complexity.

Purpose of the Study:

• To develop a novel immunotoxin targeting TROP2 to overcome ADC limitations.
• To evaluate the efficacy and safety of the novel immunotoxin Fab-PE24 in preclinical cancer models.

Main Methods:

• Conjugation of a humanized anti-TROP2 antibody Fab fragment with a truncated Pseudomonas aeruginosa exotoxin A (PE24KDEL) using SpyCatcher-SpyTag technology.
• Assessment of Fab-PE24 binding affinity, internalization, cytotoxicity, and apoptosis induction in TROP2-positive cancer cells.
• Evaluation of in vivo antitumor efficacy in gastric and lung cancer xenograft models and combination therapy with cisplatin.

Main Results:

• Fab-PE24 exhibited high binding affinity to TROP2 and potent cytotoxicity against TROP2-positive cancer cells.
• In vivo studies demonstrated significant tumor growth suppression in xenograft models.
• Fab-PE24 showed synergistic effects with cisplatin, indicating potential to overcome chemotherapy resistance.

Conclusions:

• The modular SpyCatcher-SpyTag approach enables efficient construction of Pseudomonas aeruginosa exotoxin A-based immunotoxins.
• Fab-PE24 is a promising therapeutic candidate for TROP2-positive malignancies, offering an alternative to ADCs.