According to the following paper LSD1 is overexpressed in synovial sarcoma:
http://www.ncbi.nlm.nih.gov/pubmed/22245111
This is just an abstract. It mentions a FDA approved drug inhibiting a few sarcoma cell lines growth in vitro although none were synovial sarcoma (may be they didn't have a synovial sarcoma cell line available?). The LSD1 inhibitor used is not named. A quick search on the web gave me the name of 2 anti-depressants known to inhibit LSD1, tranylcypromine and phenelzine:
http://en.wikipedia.org/wiki/Tranylcypromine
http://en.wikipedia.org/wiki/Phenelzine
http://www.jhttonline.jhu.edu/TechnologyDetail.aspx?TechID=D5BBB46A-C2F1-4F24-BADA-2CA7C1CC1263