Xue Zhi Zhao, Ph.D.
Dr. Zhao has been a pioneer in the field of anti-AIDS agents, with a particular focus on developing inhibitors of HIV-1 integrase (IN). His recent studies have concentrated on the discovery of inhibitors that retain efficacy against virus harboring mutant forms of IN integrase, which are resistant to current FDA-approved drugs. These efforts are being done in collaboration with the NCI laboratories of Drs. Yves Pommier (Developmental Therapeutics Branch) and Stephen Hughes (HIV Drug Resistance Program). His compounds offer potential leads for further structural variation that may ultimately yield clinical agents capable of overcoming problems associated with the development of resistance.
The main focus of my research is to develop HIV-1 integrase (IN) as potential AIDS therapeutics. Raltegravir (RAL) (Merck, October 2007), Elvitegravir (EVG) (Gilead, August 2012) and Dolutegravir (DTG) (GSK, August 2013) are currently the only IN strand transfer inhibitors (INSTIs) approved by the FDA for the treatment of AIDS. However the ability of mutant forms of IN to exhibit drug resistance emphasizes the need to develop additional agents that retain efficacy against resistant mutants. My work is being done in collaboration with the NCI laboratories of Dr. Yves Pommier and Stephen Hughes. Through an extensive synthetic effort, I examined 2,3-dihdroxybenzoylhydrazides and amides as new classes of diketoacid (DKA) mimetics. These agents utilized methylene and oxomethylene bridges to form bicyclic variants of these 2,3-dihdroxybenzoylhydrazides and amides in which key metal-chelating heteroatoms are conformationally constrained to coplanarity. This work resulted in the discovery of structurally simple 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-ones and 4,5-dihydroxy-1H-isoindole-1,3(2H)-diones that exhibit potent integrase inhibition at low nanomolar concentrations and display good antiviral potencies in HIV-1-infected cells. Based on these integarse inhibitors, I further developed 6,7-dihydroxy-1-oxoisoindoline-4-sulfonamide-containing HIV-1 integrase inhibitors. Co-crystal structures of these inhibitors in complex with the Prototype Foamy Virus (PFV) intasome disclosed their binding mode. I also examined tricyclic and bicyclic hydroxy-1H-pyrrolopyridine-trione containing INSTIs in an effort to overcome cytotoxicity of our earlier series of catechol-containing inhibitors. Most recently, I have developed 1-hydroxy-2-oxo-1,2-dihydro-1,8-naphthyridine-3-carboxamides IN inhibitors. Members of this series show single-digit nanomolar antiviral potencies against cells transfected with wild-type (WT) IN, while having improved antiviral efficacies against a panel of cells transfected with viral constructs carrying the major forms of resistant mutant IN. Low cytotoxicity in many cases results in selectivity indices (CC50/EC50) of greater than 50,000. These compounds offer potential leads for further structural variation that may ultimately yield clinical agents capable of overcoming problems associated with the development of resistance.
Selected Key Publications
4-Amino-1-hydroxy-2-oxo-1,8-naphthyridine-containing compounds having high potency against raltegravir-resistant integrase mutants of HIV-1.J. Med. Chem. 57: 5190-202, 2014. [ Journal Article ]
Bicyclic 1-hydroxy-2-oxo-1,2-dihydropyridine-3-carboxamide-containing HIV-1 integrase inhibitors having high antiviral potency against cells harboring raltegravir-resistant integrase mutants.J. Med. Chem. 57: 1573-82, 2014. [ Journal Article ]
- Chem Biol Drug Des. 79: 157-65, 2012. [ Journal Article ]
- Bioorg. Med. Chem. Lett. 22: 7309-13, 2012. [ Journal Article ]
- Bioorg. Med. Chem. 21: 2986-90, 2011. [ Journal Article ]
Dr. Zhao received his Ph.D. degree in organic chemistry from Lanzhou University, China under the direction of Professor Yongqiang Tu. In 2005, he joined Dr. Terrence Burke's laboratory as a visiting fellow and was appointed as a staff scientist in 2010. His efforts have been focused on developing HIV-1 integrase inhibitors as potential anti-AIDS agents.