APL-045

APL-045 is a selective, ATP-competitive small molecule inhibitor of protein kinase RNA-like ER kinase (PERK), also known as Eukaryotic translation initiation factor 2-alpha kinase 3 (EIF2AK3). Developed by Apollo Therapeutics in collaboration with Sandexis, APL-045 targets the unfolded protein response (UPR) and integrated stress response (ISR) pathways. Cancer cells often utilize PERK signaling to adapt to endoplasmic reticulum (ER) stress caused by hypoxia or nutrient deprivation within the tumor microenvironment. By inhibiting PERK, APL-045 prevents the phosphorylation of eIF2α and suppresses downstream effectors such as ATF4 and CHOP, leading to impaired tumor cell survival. Preclinical data demonstrate potent inhibition of PERK (Ki 4.6 nM) and significant tumor growth inhibition in renal cell carcinoma (RCC) xenograft models. The compound exhibits a favorable pharmacokinetic profile with high bioavailability and selectivity across the kinome.