David Fisher, 60, has his own dramatic story to tell. A retired military man living in North Highlands, Fisher was diagnosed in September 1997 with inoperable, metastatic lung cancer. His prognosis was grim.

But rather than give up, Fisher enrolled in a clinical trial at UC Davis Cancer Center of an investigational drug called tirapazamine. Two years later, his lungs are clear and he is enjoying retirement, restoring a ’64 Comet, puttering in his yard and re-reading the classics.

Iressa and tirapazamine represent a new generation of anti-cancer agents, drugs that work at the molecular level. Unlike radiation or chemotherapy, which indiscriminately kill malignant and healthy cells alike, these smart drugs destroy just cancer cells.

For a cancer to grow, hundreds of biochemical signals, traveling by hundreds of different pathways, must reach their proper destinations. Capitalizing on decades of research into the molecular biology of cancer, the new targeted therapies defeat cancer by interrupting these signals.

Iressa, for example, is an epidermal growth factor receptor blocker, designed to jam a key signal that enables cancer cells to proliferate. Tirapazamine takes advantage of the fact that solid tumors have low levels of oxygen, while healthy tissues are well-oxygenated. Engineered to be harmless in oxygen-rich cells, the drug is deadly to poorly oxygenated cells.

Targeted therapies, because they don’t harm healthy cells, cause fewer side effects than radiation or traditional chemotherapy. But the smart drugs’ selectivity is also their chief drawback: Targeted therapies work only when a target is present. To date, even the most successful smart drugs work only in small subgroups of select cancers.

The hope is that researchers will either discover a target common to most cancers, making possible the development of a smart drug that can defeat a broad range of cancers, or that medicine will accumulate an arsenal of targeted therapies varied enough to take out any cancer.

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David Fisher

Diagnosis:

Lung Cancer

Treatment:

Tirapazomine clinical trial

Status:

In remission