Hi Steve,
I couldn't find any evidence-based mentions of serrapeptase being used to help treat myelofibrosis. I found no mention of it in the National Center for Complementary and Integrative Health (NCCIH) database. A few members like @steve1948 @hishamhussain and @marzz have mentioned using it for lung conditions with varying success (or lack thereof).

Have you spoken to your wife's doctor about it?

Hello, I took serrapeptase for a while. I really had no idea if it was working and, as it was rather expensive I stopped in favour of several other supplements (which, combined appear to have contained my myelofibrosis without medication since diagnosis in early 2011). I recently added broccoli sprouts powder and quercetin to my liposomal vitamin C mixture which I take daily having been told they might reduce the fibrin. However, I had a sound scan yesterday and my spleen is bigger even though my blood counts are good and my consultant recently said I was 'unusually' stable. I am looking now at Serra Enzyme® 250,000IU Maximum Strength Serrapeptase. It is £50 for 80 ... gulp! I do not have savings of any quantity but have never stinted on experimenting with otherwise harmless options so would count myself reckless not to try it! I say throw caution to the winds and dare to spend where the results 'may' be positive!!