SCL-1

SCL-1 is a novel, orally bioavailable small molecule inhibitor of the programmed cell death 1 (PD-1) and programmed death-ligand 1 (PD-L1) immune checkpoint interaction. Developed as a potent immunotherapy candidate, SCL-1 has demonstrated significant anti-tumor activity in various preclinical models, including triple-negative breast cancer, colon cancer, bladder cancer, and melanoma. Its mechanism of action involves blocking the PD-1/PD-L1 axis to enhance CD8+ T-cell infiltration and activation within the tumor microenvironment. Uniquely, SCL-1 treatment has been shown to upregulate the expression of tumor-specific long non-coding RNAs (lncRNAs) that may serve as neoantigens, further stimulating cytotoxic T lymphocyte (CTL) activity. In comparative preclinical studies, SCL-1 has exhibited tumor growth inhibition rates exceeding 50%, often outperforming established monoclonal antibodies such as nivolumab and atezolizumab. Separately, the name SCL-1 is also used as a code for a stapled antimicrobial peptide derived from chemerin and is a widely recognized cell line for cutaneous squamous cell carcinoma research.