Research Progress in the Small Molecule Smac Mimetics in Combination Therapy of Cancer

Inhibitors of Apoptosis Proteins (IAP) are inhibitors that can block programmed cell death, are expressed at high levels in various cancers, and are recognized as a therapeutic target for cancer therapy. In the past few years, several small molecule IAP protein inhibitors have been designed to mimic the endogenous IAP antagonist, but no IAP inhibitors have been approved for marketing worldwide. Previously, xevinapant has been awarded a breakthrough therapy designation by the FDA. In addition, a combination of Smac mimetics and chemotherapeutic compounds has been reported to improve anticancer efficacy. According to the phase II clinical data, xevinapant has the potential to significantly enhance the standard therapy for patients with head and neck cancer, which is expected to be approved as an innovative therapy for cancer patients. Therefore, this paper briefly describes the mechanism of IAPs (AT-406, APG-1387, GDC- 0152, TL32711, and LCL161) as single or in combination for cancer treatment, their application status as well as the synthetic pathway, and explores the research prospects and challenges of IAPs antagonists in the tumor combination therapy, with the hope of providing strong insights into the further development of Smac mimics in tumor therapy.