The value of immune checkpoint blockade in PD-L1 negative gastric cancer patients has been questioned due to lower objective response rate (ORR).<h4>Case presentation</h4>We report an unusual case of a PD-L1 negative, proficient mismatch repair (pMMR)/microsatellite stability (MSS), tumor mutational burden-low (TMB-L) gastric cancer patient who achieved good response to immune checkpoint blockade after failure of systematic treatment. The gene discussed is CD274; the disease is gastric cancer.