Intratumoral injection of mouse tumors with an antagonistic anti-PD-L1 mAb-encoding self-amplifying (sa)RNA, which is derived from alpha- or flaviviruses and encodes both the protein of interest and a replicase for RNA amplification, resulted in superior anti-tumor efficacy compared to the intraperitoneally or intratumorally administered recombinant protein counterpart. The gene discussed is CD274; the disease is neoplasm.