ROR1 and neoplasm: Preclinical studies using PRGN-3007 UltraCAR-T have so far shown a significant reduction in PD-1 expression, increased ROR-specific tumor cell cytotoxicity, and inflammatory cytokine production upon co-culture with ROR1 + PD-L1 + tumors, effectively reducing tumor burden in xenograft models with long-term persistence of PRGN-3007 UltraCAR-T in tumor-bearing mice [178].