2497 - IKS01, a next generation antibody drug conjugate (ADC) designed to be efficacious in tumors with low and moderate levels of folate receptor expression

Background

Frequent over-expression of FRA in ovarian and non-small-cell lung cancer (NSCLC), and relative lack of expression in normal tissue, make it an attractive therapeutic target. Ovarian cancer is the ninth most common cancer in women and the leading cause of death in gynaecological cancer. Lung cancer remains a leading cause of cancer-related death with NSCLC accounting for 80 % of cases. ADCs are the focus of intense interest as a means to provide selective tumor killing with increased efficacy and less off-target toxicity than standard of care chemotherapies. Clinical evaluation of mirvetuximab soravtansine in solid tumor indications demonstrated that FRA can be successfully targeted by an ADC. However, anti-tumor activity appears to be generally limited to patients whose tumors express high levels of FRA. IKS01 is an ADC comprised of an FRA-targeting antibody conjugated via Iksuda’s PermaLink conjugation technology to Femtogenix’s highly potent FGX2-62 payload. FGX2-62 is a pyrridinobenzodiazepine DNA mono-alkylating agent with pM potency in a range of tumor cell lines. IKS01 has been designed to be sufficiently potent to have target-dependent efficacy even in tumors with low or moderate expression of the target antigen.

Methods

IKS01 was generated with a drug to antibody ratio of 2. Efficacy was evaluated in human cell line derived xenograft models with a range of FRA expression, including the choriocarcinoma Jeg-3 model (high expression), the ovarian adenocarcinoma OV-90 model (low expression) and the lung adenocarcinoma NCI-H2110 model (moderate expression). An FRA-targeting benchmark ADC with a format that has shown clinical efficacy was included for comparison.

Results

IKS01 is highly effective in causing tumor regressions in FRA-expressing tumor models at doses that are well tolerated. IKS01 was significantly more active than benchmark ADC in the high FRA-expressing Jeg-3 model and caused complete or near complete regressions in low/moderate FRA-expressing xenograft models where the benchmark ADC showed limited or no activity.

Conclusions

IKS01 shows marked anti-tumor efficacy in pre-clinical models of ovarian and lung cancer, even in models with low or moderate FRA expression.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Iksuda Therapeutics Ltd.

Funding

Iksuda Therapeutics Ltd.

Disclosure

J. Thirlway: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd. A. Lodge: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd. A. Pelava: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd. D.J. Williamson: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd. D. Carta: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd. M. Al Nakeeb: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd. J. Mysliwy: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd. P.J.M. Jackson: Shareholder/Stockholder/Stock options: Femtogenix Ltd. D.E. Thurston: Shareholder/Stockholder/Stock options: Femtogenix Ltd. R.J. Lutz: Shareholder/Stockholder/Stock options: Iksuda Therapeutics Ltd.