> AFAICT there are no approved drugs blocking EPO receptors and no drugs to reduce EPO

Such receptors have a protein structure definitive for them, so a bespoke RNA (mRNA) therapy might be a means of generating receptor blockers?

Edit: looks like this applicable. two interesting articles...

https://pubmed.ncbi.nlm.nih.gov/28629523/

https://www.genengnews.com/topics/cancer/blocking-erythropoi...