All these things are open research questions; there's no roadmap to curing these things, there's a bunch of promising experiments that may or may not pan out. IIRC getting a new drug candidate through the full trial process costs maybe $1B for those that get as far as stage 3 trials (the final stage; most candidates will fail out earlier; conversely if a drug passes earlier trials there will probably be people willing to invest in return for a share of future profits, so you don't necessarily have to fund the full $1B yourself), but there's simply no way to know how many candidates you're gonna have to try to get one that works.