Is that your idea? Is it speculation? Did the contract text state that the improved version is also covered?FX-345 is not up for grabs as Astellas is already entitled to the rights on it since it is simply an improved version of FX-322 with just a more potent GSK3 inhibitor.
Astellas does not have a patent. They signed a contract with Frequency Therapeutics when several people saw a 10 dB improvement at 8 kHz from FX-322. $545 million would be too cheap if the FX-345 provided a more substantial hearing recovery. I think FX-345 is a different drug than FX-322, even if it is an improved version.