Long-term Tumor Regression Induced by an Antibody-Drug Conjugate That Targets 5T4, an Oncofetal Antigen Expressed on Tumor-Initiating Cells

作者：Sapra Puja^*; Damelin Marc; DiJoseph John; Marquette Kimberly; Geles Kenneth G; Golas Jonathon; Dougher Maureen; Narayanan Bitha; Giannakou Andreas; Khandke Kiran; Dushin Russell; Ernstoff Elana; Lucas Judy; Leal Mauricio; Hu George; O'Donnell Christopher J; Tchistiakova Lioudmila; Abraham Robert T; Gerber Hans Peter

来源：Molecular Cancer Therapeutics, 2013, 12(1): 38-47.

DOI：10.1158/1535-7163.MCT-12-0603

Antibody-drug conjugates (ADC) represent a promising therapeutic modality for the clinical management of cancer. We sought to develop a novel ADC that targets 5T4, an oncofetal antigen expressed on tumor-initiating cells (TIC), which comprise the most aggressive cell population in the tumor. We optimized an anti-5T4ADC (A1mcMMAF) by sulfydryl-based conjugation of the humanized A1 antibody to the tubulin inhibitor monomethylauristatin F (MMAF) via a maleimidocaproyl linker. A1mcMMAF exhibited potent in vivo antitumor activity in a variety of tumor models and induced long-term regressions for up to 100 days after the last dose. Strikingly, animals showed pathologic complete response in each model with doses as low as 3 mg antibody/kg dosed every 4 days. In a non-small cell lung cancer patient-derived xenograft model, in which 5T4 is preferentially expressed on the less differentiated tumor cells, A1mcMMAF treatment resulted in sustained tumor regressions and reduced TIC frequency. These results highlight the potential of ADCs that target the most aggressive cell populations within tumors, such as TICs. In exploratory safety studies, A1mcMMAF exhibited no overt toxicities when administered to cynomolgus monkeys at doses up to 10 mg antibody/kg/cycle x 2 and displayed a half-life of 5 days. The preclinical efficacy and safety data established a promising therapeutic index that supports clinical testing of A1mcMMAF. Mol Cancer Ther; 12(1); 38-47.

• 出版日期2013-1