We haven't found anything better to replace animal trials yet, but they aren't close enough to deliver good results.
Animal trials precede the first (Phase I) clinical trials in people.
93% of drugs that make it past animal trials and into Phase I clinical trials fail to make it all the way to final approval:
https://blogs.sciencemag.org/pipeline/archives/2019/05/09/th...
It's also not clear how many drug candiates we're missing out on because animal models give false positives for toxicity in humans. Compounds that are extremely poisonous to experimental animals may be tolerated much better in humans.
Humans survive exposure to TCDD at levels that would be more than 50 times higher than the lethal dose in guinea pigs:
https://en.wikipedia.org/wiki/2,3,7,8-Tetrachlorodibenzodiox...
Acetaminophen is a deadly poison to cats even at modest doses.
It's impractical and unethical to try novel druglike compounds in humans right away, so we may not know how many premature rejections come from animal models until/unless we're able to grow whole human organs for drug testing.