A few years ago, there was a study from Germany suggesting dasatinib as a promising treatment for synovial sarcoma:
http://cancerres.aacrjournals.org/content/73/8/2518.long
A phase 2 trial of dasatinib in advanced sarcoma did not show promising results but it didn't have any patient with synovial sarcoma:
http://meetinglibrary.asco.org/content/41263-74
Has anybody tried one of the following trials:
Dasatinib + ipilimumab (in New York):
https://clinicaltrials.gov/ct2/show/NCT01643278
AZD0424, another Src inhibitor (in the UK):