The present invention relates to 1,2,4- oxadiazoles and 1,2,4- thiadiazole compounds, these compounds are as the therapeutic agent for being able to suppress apoptosis 1 (PD1) signal transduction pathway. The invention further relates to the derivatives of the therapeutic agent. The invention also includes the therapeutic agents and 5 kinds of derivative whats via including inhibiting by the purposes of the immunological enhancement treatment illness of PD-1, PD-L1 or PD-L2 immunosupress signal induced, and the therapy using them.本發明涉及1,2,4‑噁二唑和1,2,4‑噻二唑化合物,這些化合物作爲能够抑制程序性細胞死亡1(PD1)信號傳導通路的治療劑。本發明還涉及所述治療劑的衍生物。本發明還包括所述治療劑和5種衍生物用於經由包括抑制由PD‑1、PD‑L1、或PD‑L2誘導的免疫抑制信號的免疫增强作用治療病症的用途,以及使用它們的療法。