KZR-261 is the first candidate developed using Kezar’s novel discovery Protein Secretion Inhibition Platform. This candidate is a first-in-class, small molecule inhibitor of the Sec61 translocon – a previously undruggable target at the beginning of the protein secretion pathway – for the treatment of advanced/metastatic solid tumors. Many cellular proteins require Sec61 to enter the endoplasmic reticulum (ER) of the cell, the first step of the protein secretion pathway. Selectively inhibiting Sec61 blocks the expression of key secreted proteins that are responsible for proliferation, metastasis and immune evasion of cancer cells. By simultaneously inhibiting multiple protein drivers of cancer, KZR-261, as a single drug, can elicit a broad anti-tumor immune response – both on the tumor cells and in the tumor microenvironment – a response that usually takes combination therapies to achieve.