Development of a Commercial-Ready Kit for CTT1403, a Novel PSMA-Targeted Radiotherapy

PROJECT ABSTRACT Prostate-Specific Membrane Antigen (PSMA) is an ideal tumor biomarker with specific expression on rt90% of all prostate cancers that increases with disease progression. Cancer Targeted Technology (CTT) has developed an innovative phosphoramidate-based peptidomimetic that binds irreversibly to PSMA, leading to rt90% internalization and selective accumulation in tumor cells. With previous SBIR grant support, CTT developed and evaluated an 18F-labeled PET diagnostic imaging agent, CTT1057. In a Phase 1 clinical trial, CTT1057 demonstrated significant uptake in PSMA-avid bone and visceral lesions in prostate cancer (PCa) patients with far greater accuracy than standard of care scans. CTT1057 was subsequently licensed to Advanced Accelerator Applications/Novartis. CTT then modified the novel scaffold to develop a specific and potent companion therapeutic, CTT1403, radiolabeled with 177Lu. CTT1403, unlike other PSMA-targeting agents in development, not only binds irreversibly to PSMA but also incorporates an albumin-binding motif to dramatically slow blood clearance, resulting in unprecedented tumor uptake of rt80% that translates to a significant survival advantage in animal models. Manually radiomanufactured CTT1403 is currently in a 40-patient Phase 1 trial in men with castration resistant PCa and to date has demonstrated an excellent safety profile, extended blood circulation time, extended tumor exposure and low uptake in kidney and other dose limiting normal organs. With excellent drug characteristics and a high likelihood of efficacy, the development of a reliable, robust and efficient CTT1403 manufacturing and distribution strategy is critical for subsequent clinical trials with very large patient cohorts. Automated, kit-based radiomanufacture has proven rapid, robust, and reproducible for benchmark agents like 18F-FDG. Development of a novel CTT1403 manufacturing process that facilitates automation will expand access to CTT1403 for radiopharmacies across the United States, increasing availability for pivotal clinical trials and potential for subsequent market and commercialization success. In this SBIR Direct to Phase II grant, we will develop a novel, simplified method for CTT1403 synthesis by developing a new drug precursor, CTT2001, for direct (1-step) 177Lu radiolabeling to be converted to a kit format for use in an automated synthesizer. This process and automation will reduce cost of goods, manufacturing time, and increase distribution efficiency. AIM 1: Demonstrate feasibility of a PSMA-targeted 1-step radiolabeling process. CTT will manufacture the CTT2001 precursor, develop a simple and efficient CTT1403 radiolabeling process, and assess whether the PSMA-targeting function remains intact. AIM 2: Develop an automated kit formulation for CTT1403 synthesis, on the Trasis synthesizer, will include a custom designed, disposable cassette and a custom kit of pre-measured reagents for simple and robust 177Lu labeling. CTT1403 release testing will also be fully developed to rapidly facilitate transition of the kit to large-scale manufacture and clinical use upon completion of this project.