Hi Ita,
You don't write how many months your father has been treated with Thalidomide. After about 9 months many patients loose the response but there are patients who respond much longer time. Here is a review about Thalidomide:
http://forums.marrowforums.org/showthread.php?t=1041
If he not is responding any longer the doctor should try another drug for example Revlimid if your father still has low risk MDS otherwise Vidaza that is the first drug for high risk MDS according to many doctors.
Both Thalidomide and Revlimid are often combined with Prednisone or a similar drug.
June 2010 I started with Thalidomide 50 mg/day + Prednisone 20 mg/day (it should have been 30 mg/day but that dose gives me sleep problems). My WBCs decreased and I can only tolerate Thalidomide 50 mg four times a week. Then I continue with Prednisone 5 mg/day. After 4 weeks my platelets increased from 22 to 43. After 3 months I didn't need txs though I had been tx dependent since dx 2006. My counts are still OK after 23 months.
Kind regards
Birgitta-A
73 yo, dx MDS Interm-1 2006