Somebody has to pay for the trial. Drugs are expensive and the amount needed to dose a single person is orders of magnitude more than mice. So who funds the study?

If it's the government or philanthropic fund, you have to put in a grant and show that it's competitive in terms of preliminary results etc.

If it's the drug companies, you have to deal with lots of complicated things with combination therapies. Drug companies don't like their drug paired with other drugs that aren't in their portfolio. They also need to see a way to make a profit on it, which means they need to evaluate whether this is the most likely successful trial, assess bang for buck etc.

If you want to go compassionate use, then you need to get the pharma to donate the drugs or insurance to cover it. This is spain, so I guess insurance is just the government since they have universal healthcare. I have no idea how that works but I am guessing it doesn't move fast.