Good morning, Elizabeth. The results your husband is having with the Vidaza is pretty encouraging in reducing the cancer cells.
As for the continued transfusions, that is out of my area of personal experience. But your husband still has bone marrow. Otherwise he wouldn’t be making red or white cells. His other blood numbers rebound during chemo cycles so it shows his marrow is still functioning. However it isn’t able to produce enough platelets because it’s compromised.

In healthy bone marrow, there’s a fine network of fiber on which the stem cells can divide and grow. Specialized cells in the bone marrow known as fibroblasts make these fibers.
Chemicals released by the cancerous cells over-stimulate the fibroblasts so instead of a fine network of webbing, they create thick coarse fibers in the bone marrow, which gradually replace normal bone marrow tissue. Over time this destroys the normal bone marrow environment, preventing the production of adequate numbers of red cells, white cells and platelets…in your husband’s case, it’s platelets. Doing a little research this morning, there have been trials of drugs for reducing fibrotic tissue to help with the treatment of MF and other conditions. Not sure if they are on the market yet.
But this is a good question for your husband’s oncologist as to whether he can expect to see a reduction in his transfusions once the inflammation caused by excess cancer cells is reduced. Could this potentially make a difference in his platelet production?