2 new trials were added last week to ClinicalTrials.gov that I think may be relevant for us.
The first one is using a drug that has an effect on which genes are turned on of off:
https://clinicaltrials.gov/ct2/show/NCT02423057
The particular agent used in this study has not been tried on synovial sarcoma cells but one similar agent was deemed to have therapeutic potential in synovial sarcoma:
http://www.ncbi.nlm.nih.gov/pubmed/19578875
The 2nd trial is a vaccine:
https://clinicaltrials.gov/ct2/show/NCT02423863
Here is a study that explains the theory behind this vaccine and describes a case report:
http://cancerimmunolres.aacrjournals.org/content/2/8/720.full