Abstract 305: ELU001, a targeted C'Dot drug conjugate (CDC) for the treatment of folate receptor alpha (FRα) overexpressing cancers

Abstract CDCs are novel ultra-small (6-7 nm) nanoparticle drug conjugates that have been demonstrated to be capable of faster tumor targeting and deeper tumor penetration than antibody drug conjugates in animal models. CDCs are capable of targeting tumors in the brain and pancreas that are difficult to access, while exhibiting limited exposure to normal tissues due their efficient renal elimination. CDCs are composed of a silica core, in which Cy5, a far red dye is covalently encapsulated. The silica core is covalently coated with a layer of polyethylene glycol which is then functionalized with targeting moieties and payloads. ELU001 is a CDC functionalized with ~20 molecules of the topoisomerase-1 inhibitor exatecan linked via a proteolytic cleavable linker as a payload and ~15 folic acids to provide targeting to FRα overexpressing cancers. ELU001 is rapidly internalized into FRα expressing cells and is trafficked to the lysosome where the payload is released from the CDC. ELU001 exhibits potency in the low single digit nanomolar to sub-nanomolar range against cancer cells that express 3+ (KB, IGROV-1) and 2+ (SK-OV-3, HCC827 and OVCAR-3) levels of FRα after a 6-hr exposure in a 7-day viability study. In contrast, an anti-FRα ADC based ADC mirvetuximab soravtansine exhibits lower potency (>100 nM IC50) against SK-OV-3 and HCC827 cells and 40 nM IC50 against OVCAR-3 cells. ELU001 exhibits potent efficacy against established s.c. KB human cervical tumor xenografts in immunodeficient mice with significantly better efficacy and safety than free exatecan payload. It is also effective in treating established SK-OV-3 tumors with lower (2+) FRα expression, a setting where the ADC is again less effective. IND-enabling nonclinical studies are currently underway to prepare for initiation of a first-in-human phase 1 clinical trial in subjects with FRα overexpressing cancers in the second half of 2021. Citation Format: Gregory Paul Adams, Kai Ma, Aranapakam Venkatesan, Feng Chen, Fei Wu, Melik Turker, Thomas Gardinier, Peiming Chen, Vaibhav Patel, Eliel Bayever, Paul Rudick, Geno Germano. ELU001, a targeted C'Dot drug conjugate (CDC) for the treatment of folate receptor alpha (FRα) overexpressing cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 305.