Abstract 1693: ASN004, a novel 5T4-targeted Dolaflexin™ antibody drug conjugate, causes complete regression in multiple solid tumor models

ASN004 is an Antibody Drug Conjugate (ADC) that targets the 5T4 oncofetal antigen (trophoblast glycoprotein), which is highly expressed in a wide range of malignant tumors, while having very limited expression in normal tissues. ASN004 incorporates a novel single-chain homo-dimer antibody, Fleximer® linker technology (Mersana Therapeutics), and several cytotoxic dolastatin (auristatin) analog warheads per ADC molecule (drug/antibody ratio ∼15). ASN004 shows high affinity for the 5T4 antigen and for 5T4-expressing tumor cells. As well, ASN004 shows potent cytotoxicity that is selective for 5T4-expressing tumor cells. ASN004 provides strong tumor regression and tumor-free survivors in multiple tumor xenograft models, at well-tolerated doses as low as 0.3 mg/kg iv. Furthermore, ASN004 causes tumor regression when administered to xenografts bearing more advanced (500 mm3) tumors. Robust, potent efficacy for ASN004 has also been demonstrated in head-to-head comparison studies with relevant reference ADCs. A favorable pharmacokinetics profile was observed in rodents and primates. Dose-range finding exploratory toxicology studies have been completed in both pharmacological and non-pharmacological non-clinical species. Efforts toward IND-enabling safety studies with this promising new agent are in progress. Citation Format: Roger A. Smith, Nitin K. Damle, Sanjeeva P. Reddy, Alex Yurkovetskiy, Natalya Bodyak, Mao Yin, Dmitry Gumerov, Elena Ter-Ovanesyan, Liu Qin, Peter U. Park, Timothy B. Lowinger, Sandeep Gupta. ASN004, a novel 5T4-targeted Dolaflexin™ antibody drug conjugate, causes complete regression in multiple solid tumor models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1693. doi:10.1158/1538-7445.AM2015-1693