Are you interested in studying cancer in Italy? AIRC is the foundation that could sponsor your postdoc in Italy!
https://www.direzionescientifica.airc.it/funding-for-research/fellowship/italy-post-doc/
This is is one of the most updated postdoctoral funding opportunity open source repository
made by Johns Hopkins University:
https://research.jhu.edu/rdt/funding-opportunities/postdoctoral/
Le borse dell'American-Italian Cancer Foundation, fondata da Montezemolo e Veronesi, potrebbero fare al caso tuo: https://www.americanitaliancancer.org/research-fellowships.html
Here you can find a useful website to write your K99/R00. Later I will give you my personal advice.