The single-arm phase II AcSè Pembrolizumab study have been demonstrated that the activity of the immunotherapeutic drug is improved in selected rare and ultra-rare sarcoma histotypes, including chordoma and alveolar soft-part (ASPS), rhabdoid tumors, SMARCA4 deficient sarcomas and desmoplastic small round cell tumors (DSRCT). The gene discussed is SMARCA4; the disease is desmoplastic small round cell tumor.