HC-5404 is a novel, potent and highly selective PERK (Protein kinase RNA-like Endoplasmic Reticulum Kinase) inhibitor, blocking the activation of the PERK pathway, which in turn inhibits the endoplasmic reticulum stress response signaling pathway, thereby exerting anti-tumor effects, and can be used to treat advanced solid tumors and renal cell Cancer.

In this study, HEK-293 cells were treated with different concentrations of HC-5404 for 30 minutes, followed by treatment with 1 mmol/L tunicamycin for 4 hours. The cells were then lysed using RIPA buffer, and Western blot analysis was performed to detect the phosphorylation level of PERK (p-PERK) and the expression level of ATF4. Specific antibodies were used to recognize p-PERK (T982) and ATF4. The Results showed that HC-5404 inhibited the tunicamycin-induced PERK autophosphorylation (p-PERK) in a concentration-dependent manner, with an IC50 value of 23 nmol/L. Additionally, HC-5404 also inhibited ATF4 expression, with an IC50 value of 88 nmol/L. Overall, HC-5404 effectively inhibited PERK activation and ATF4 expression induced by endoplasmic reticulum stress[1].

In subcutaneous xenograft models using renal cancer cell lines (such as 786-O, A-498, Caki-1, etc.), HC-5404 was administered orally (dose range 3-100 mg/kg, twice daily). Tumor volume was measured regularly, and tumor growth inhibition (TGI) and tumor regression rates were calculated. After a single oral dose, the exposure of HC-5404 in mouse plasma increased in a dose-dependent manner, with the maximum concentration (Cmax) reached within 1 hour post-dose and an average half-life of 2.22 hours. At doses of 30 mg/kg and 100 mg/kg, the free drug concentrations were 186 nmol/L and 839 nmol/L, respectively. In mouse pancreatic tissue, HC-5404 inhibited p-PERK in a time- and dose-dependent manner, with approximately 90% early inhibition of p-PERK after a single oral dose of 30 mg/kg. In the 786-O tumor model, the 30 mg/kg dosing regimen (twice daily) showed the best anti-tumor activity, with a tumor growth inhibition rate of 48%. Furthermore, HC-5404 demonstrated significant synergistic effects when combined with VEGFR-TKI in various renal cancer models [1].