An RNA sequencing-based comparison of adolescent-young adults and adult patients with synovial sarcoma

Synovial sarcoma (SS) is a rare disease accounting for 5%-10% of all soft tissue sarcomas. SS affects younger adults and children with a peak incidence in the fourth decade of life and its molecular hallmark is the SS18::SSX translocation. adolescent and young adults (AYAs) with SS have better 5-year estimated survival rates than adults but the reason behind these differences in outcomes have been hardly investigated. In this retrospective survey, to investigate their potential transcriptomic differences, 14 AYAs and 8 adults SSs samples, were analyzed trough RNA sequencing (RNAseq). The enrichment of recently published transcriptional signatures of specific SSs tumoral and infiltrating cells were also investigated in our data. In terms of both, progression free and overall survival, AYAs patients showed a better clinical outcome but, RNAseq results, underscored that AYAs and adults are characterized by reduced transcriptional variability although a few number of genes (in particular RPL39 and GATA 3 among others), turned out to be differentially expressed. The similarity between AYAs and adults also resulted after the comparison with specific the SSs transcriptional signatures although adults were characterized by the enrichment of cycling cells while half of our AYAs samples showed an enhancement of infiltrating macrophages. Albeit in a context of reduced transcriptional variability, these findings evidenced some biological difference that can potentially contribute to the observed different clinical outcome of AYAs and adults SSs patients.