We could switch gears, maybe. If we induce a coma, the disease will progress more slowly, but if we don't come up with something in time, then he loses whatever time he has left now. It's a gamble, but so's Spider-Man.
There's a lot we wish could be different. You know Harry better than me. You could suggest the coma idea. You could tell him about Dr. Connors. Hell, you could tell him Spider-Man is AB+, so they're not even a match.