The HapMap helped reveal an environmental as well as an inheritable component to genetics. That, plus our new understanding of the complex interplay between the genomics of a disease and the unique minor genetic differences among individuals, has led to custom-tailored therapies based on the individual patient’s unique genetic situation.

2006 was the year when the swallows (therapies) amassed in sufficient numbers to show that the Summertime of gene therapy had truly arrived. Acne drug Aczone, which targets patients with a particular enzyme deficiency, was added to the pharmacogenomic formulary. Two gene therapies — one for chronic granulomatous disease, one for advanced melanoma — were still working to protect patients after 18 and 24 months of trial respectively. Re-analysis of trial data for the “failed” experimental heart-failure drug bucindolol showed that it actually worked for patients who carried a particular version of a heart-related gene. There may be many more shelved drugs that will turn out to work for patients with a specific genetic makeup.

Bucindolol and breast cancer drugs tamoxifen (which blocks the effect of estrogen) and Herceptin (which blocks the effect of the HER2 gene in cancer cells) were only the early harbingers of gene therapy. In 2006, gene therapies cured more than two dozen patients in Europe suffering from three rare immune disorders, new techniques made gene therapy safer and more effective, and more than 300 gene therapy trials were underway around the world. They included:

• A trial amongst Parkinson’s patients, in which genetic material was encased in a viral vector attracted to nerve cells in the brain. The virus was then injected into a discrete region of the patient’s brain that governs movement. 

   

• A similar trial to normalize the overactive nerve cells of 12 Parkinson’s patients resulted in a 27 percent improvement in stability and ability to walk, and less stiffness and tremors on the treated side of the body. 

   

• A trial targeting angina, in which a gene was injected into the hearts of 400 patients to spark the growth of tiny blood vessels and increase blood flow to oxygen-starved cells. 

   

• 300 patients with peripheral arterial disease were being given injections of a gene that controls the body’s response to low oxygen, to grow new blood vessels and improve blood flow in the legs. 

   

• A preliminary trial for arthritis showed a 20 to 30 percent reduction in swelling among 14 patients treated with a gene to interfere with an inflammation-causing chemical. 

   

• Animal studies were underway for gene therapies to treat hearing loss and to clear clogged arteries. 

   

• A disabled HIV virus engineered with genes to block HIV reproductioncaused HIV levels in phase I trial patients’ blood to either stabilise or decrease. 

   

• Human testing began of a mouthwash containing a tumor-suppressor gene to treat leukoplakia, a precancerous condition characterized by lesions on the cheeks, gums, or tongue, and thereby prevent oral cancers. 

   

• Acne drug Aczone was approved in July 2005 for patients who test negative for an enzyme deficiency that could put them at risk of developing anemia from the drug. 

   

• Two men afflicted by chronic granulomatous disease (CGD)were in good shape and no longer had to take round-the-clock antibiotics, and neither patient was suffering negative side effects, after 18 months of gene therapy. 

   

• A gene therapy has completely prevented the onset of Type 1 diabetes in mice by attaching a gene that makes interleukin-4, a cytokine than inhibits inflammation, to a harmless adeno-associated virus. 

   

• In what the US National Cancer Institute (NCI) hailed as the first real success in cancer gene therapy, researchers cured two patients (out of 17 treated) of advanced melanoma that had already spread through the body. Both patients were cancer-free for two years following the therapy. The NCI plans to try the same gene therapy (but with genes coding for the appropriate receptors) in patients with common cancers such as breast or colon cancer.