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Antiviral Drugs Advance From the Laboratory to the Patient

Yung-Chi Cheng, PhD

Drugs known as nucleoside analogs that help fight HIV infection have given hope to many patients, but with long-term use they can damage certain organs. In the mid 1980's Yale pharmacologist Yung-Chi “Tommy” Cheng, PhD, was searching for the mechanism that leads to this damage, when he discovered that a mirror form of a known antiviral drug reduced harmful side effects when used in combination with AZT, which is commonly used to treat HIV. His search to find out why this was the case led to the discovery of a new class of compounds called L-configuration nucleosides that paved the way for a new direction in drug development.

One of the drugs discovered by Dr. Cheng and his colleagues in this new class is an HIV drug called Emtriva that has been approved by the FDA and is also showing promise as a treatment for hepatitis B. His continued research has led to the discovery of two additional L-configuration nucleosides: Elvucitabine is longer-acting than Emtriva and is being tested in the treatment of HIV and hepatitis B, and Clevudine, which continues to work even after patients stop taking it, is proving effective against hepatitis B. Dr. Cheng is excited that discoveries he has made in the laboratory are proving beneficial to people who need them. These new medicines would never have found their way to patients without the many volunteers who were willing to participate in clinical trials.