MKC8866

MKC8866 is a potent and selective small molecule inhibitor of the RNase domain of Inositol-requiring enzyme 1 alpha (IRE1α), a key sensor of the unfolded protein response (UPR). By inhibiting IRE1α, MKC8866 prevents the unconventional splicing of XBP1 mRNA into its active form, XBP1s, thereby disrupting a major survival pathway used by cancer cells to cope with endoplasmic reticulum (ER) stress. In the context of oncology, particularly non-small cell lung cancer (NSCLC), MKC8866 has been shown to reverse immunosuppression within the tumor microenvironment by reducing the secretion of pro-tumorigenic chemokines like CCL20 and downregulating tumor-intrinsic PD-L1 expression. This dual action enhances CD8+ T-cell infiltration and sensitizes tumors to immune checkpoint inhibitors. It is being investigated for its potential to enhance the efficacy of immunotherapy in various solid tumors.