NEW YORK – Fusion Pharmaceuticals announced Thursday that the US Food and Drug Administration cleared its investigational new drug applications for a radiopharmaceutical targeting solid tumors expressing NTSR1 and a corresponding imaging analogue.
The drug, FPI-2059, comprises actinium-225 and a small molecule domain targeting NTSR1. The FDA's acceptance of Fusion's INDs will allow the firm to study FPI-2059 in a Phase I trial involving patients with NTSR1-expressing tumors. These patients will have head and neck squamous cell, colorectal, pancreatic, gastric, neuroendocrine differentiated prostate, and Ewing sarcoma tumors.
Participants will first receive FPI-2058, an imaging analogue of FPI-2059, to ensure they have NTSR1-expressing tumors. Those who do will then receive FPI-2059.
Fusion engineered a beta-emitting radiopharmaceutical it acquired from Ipsen last year, called IPN-1087, and converted it into the alpha-emitting compound FPI-2059. In a mouse xenograft model of colorectal cancer, FPI-2059 achieved tumor regression at a dose level 1,500 times lower than IPN-1087.
Last year, the FDA cleared another IND from Fusion for its targeted alpha therapy FPI-1966 and corresponding imaging agent FPI-1967, allowing the Hamilton, Ontario-based company to begin a Phase I trial in patients with FGFR3-expressing solid tumors.
The company believes that FPI-2059 can address an unmet need in prostate cancer, where there are several radiopharmaceuticals under development for PSMA-expressing tumors, including a recently approved treatment from Novartis.
"With FPI-2059, we believe there is significant opportunity to address multiple solid tumor types, including neuroendocrine differentiated prostate cancer where PSMA expression is typically low and therefore patients are not adequately treated by existing radioligand therapies," Fusion CEO John Valliant said in a statement. "We look forward to progressing FPI-2059, Fusion's first small molecule-based TAT and third clinical program, into a Phase I study."