PKI-166 is primarily utilized in the field of cancer research and therapy. It functions as a potent inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase, which plays a critical role in the signaling pathways that promote cancer cell growth and survival. By targeting EGFR, PKI-166 helps to inhibit the proliferation of tumor cells, making it a valuable compound in the study of various cancers, including breast, lung, and colorectal cancers. Its application extends to preclinical studies where it is used to understand the mechanisms of EGFR signaling and to evaluate its potential as a therapeutic agent in combination with other cancer treatments. Additionally, PKI-166 is explored for its ability to enhance the efficacy of radiation therapy and chemotherapy by sensitizing cancer cells to these treatments.