20 February 2019 - - The first patient was dosed in a Phase 1, first-in-human clinical trial of lead product candidate [225Ac]-FPI-1434 in patients with advanced solid tumors, Canada- and US-based biopharmaceutical company Fusion Pharmaceuticals said.

The Phase 1 clinical study (FPX-01-01) is a dose-escalation study that will characterize the safety and tolerability of a single dose [225Ac]-FPI-1434 Injection in patients with advanced solid tumors. [225Ac]-FPI-1434 is a targeted alpha radioimmunoconjugate that consists of a humanized monoclonal antibody targeting the insulin-like growth factor-1 receptor 1 (IGF-1R), Fusion's Fast-ClearTM Linker, a bifunctional chelate, and actinium-225.

Patients will be screened for target expression with the imaging agent [111In]-FPI-1547. [111In]-FPI-1547 contains the same targeting antibody, Linker, and bifunctional chelate as the [225Ac]-FPI-1434 therapeutic form, however it will contain indium-111 in place of actinium-225.

Only those patients who have IGF-1R expression will be receiving the [225Ac]-FPI-1434 therapeutic radioimmunoconjugate. Investigators will evaluate the safety and tolerability of a targeted alpha-emitting radiotherapeutic. Up to 30 patients will be treated and followed for safety and for signs of efficacy.

Fusion uses its proprietary Fast-ClearTM Technology Platform to convert molecules into radiopharmaceuticals. Fast-ClearTMlinkers promote increased clearance of radoisotopes the linkers are engineered to improve the safety of radiopharmaceuticals without impacting efficacy.

The predecessor [225Ac]-FPI-1434 antibody (AVE1642) is a humanized antibody against IGF-1R (insulin-like growth factor receptor) that had previously been in Phase I and II clinical trials. Fusion has an exclusive license to AVE1642 from ImmunoGen, Inc. Fusion applied its Fast-ClearTM linker to convert AVE1642 into a potent radiopharmaceutical, [225Ac]-FPI-1434.

Fusion Pharmaceuticals is a biopharmaceutical company located in Hamilton, Ontario, Canada and Boston, MA, focused on becoming a leader in the targeted alpha therapy field.

Fusion will exploit its unique expertise in linking medical isotopes to targeting molecules to create highly effective therapeutics. In addition to its lead programme, [225Ac]-FPI-1434, Fusion is expanding its pipeline of products through a proprietary protein discovery platform, in-licensing targeting molecules, and forming new strategic partnerships.