Assuming he's doing it under medical advice, probably just fine. Congratulations to him.
I haven't reduced the frequency but have reduced the quantity of Abraxane per infusion. Under advice. So far, it's working with potential for further reductions if scans and the CA19-9 continue to look good.
My doctor had said that science knows the maximum safe dose. But doesn't necessarily know the minimum effective dose for an individual. It's trial and error. Obviously, you want the lowest dose that does the job.
Good luck.