Here is a new article which looks at the state of basic research in synovial sarcoma so far:
http://www.hindawi.com/journals/srcm/2012/249219/
Note that the article suggests that appropriate targeted therapy may depend on the specific fusion gene, for example SS18-SSX1 or SS18-SSX2. These two fusion genes seem to influence pathways differently... In other words it may be necessary to divide synovial sarcoma patients in more subgroups depending on their fusion gene.