The results showed that SUMO family members were significantly coexpressed with a variety of immune checkpoint genes, including CD44, HHLA2, and HAVCR2, that play a tumor-promoting role in malignant tumors such as PAAD, lymphoma and malignant pleural mesothelioma (https://www.genecards.org/). The gene discussed is HHLA2; the disease is pancreatic adenocarcinoma.