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Looking at Genetic Data to Make More Effective Drugs

March 16, 1999

The great advances being achieved in the analysis of human DNA have been giving rise to equally unprecedented developments in medical products and pharmaceutics. Recent studies in Japan and elsewhere have shown that the same medicine can elicit different reactions in different people depending on the individual's genetic constitution, or "genotype." The early twenty-first century is expected to see the appearance of "order-made medicines"--effective pharmaceutics developed to suit each individual's genotype. Not only will such medicines produce fewer side effects and better cures, they will also cut overall medical costs by reducing unnecessary prescriptions.

Varying Effectiveness Depending on Genotypes
Medical personnel may soon carry out tests to determine a patient's genotype, just as they test for blood type today. Routine genetic analysis prior to diagnosis and prescription is expected to become a reality in front-line medical institutions in the near future. Today, patients diagnosed with the same illness and showing the same symptoms are generally treated with the same medicines and methods of administration. This will change, however, once the particular genetic makeup of each patient is taken into consideration before determining treatment.

Recent research has found that the same medication affects different patients in different ways depending on their genetic makeup. One well-known example is a drug to lower blood cholesterol levels designed by a Japanese pharmaceutical company. A Dutch research group recently compiled data on 807 patients suffering from arteriosclerosis to gauge the effect of this widely used drug, which chalks up all of 170 billion yen (1.42 billion U.S. dollars at 120 yen to the dollar) in annual sales in 75 countries throughout the world.

A protein called cholesteryl ester transfer protein (CETP), which carries cholesterol in the blood, comes in two types called B1 and B2. The drug was found to be very effective for people who inherited genes for B1 CETPs from both parents; this group accounted for 35% of the total number surveyed. With people carrying one B1 gene and one B2 gene, who totaled 49% of the patients, the drug was only moderately effective. The medicine had hardly any effect, however, on 16% of the subjects--those who had inherited two B2 genes. For this double-B2 group, the drug was basically useless for their condition. It is common knowledge among medical professionals that this kind of difference in efficacy occurs with many other medications to a greater or lesser extent. Many experts think, in fact, that as many as one in four patients worldwide receive some medication that is ineffective for their genotype.

A Drug for Every Genotype
Even if the disparate efficacy of medications is not solely due to genetic differences, genotype is without a doubt a major factor. There is near consensus throughout the Japanese medical sphere that the current method of developing medicines must be revised and a system established to take into account each patient's genotype.

Once in place, this system will enable patients to receive medications that are more certain to be effective and will improve the treatment provided by medical institutions. More efficient clinical testing, which accounts for much of the expenses involved in developing new drugs, will also save costs for pharmaceutical companies. And reducing the administration of ineffective medication will also help contain rising medical costs, in Japan and throughout the world.

Keeping down side effects is another important aspect of customized medication. The same methods used to find the ideal medicine for a certain genotype can also be used to pinpoint genotypes more susceptible to adverse drug effects. No clear statistics exist on how many people in Japan are hospitalized or lose their lives due to medicinal side effects, but the number is certainly not small. Major pharmaceutical companies now have a chance to reduce this number as they improve their products for individual users. Drug makers around the world have begun clinical studies in preparation for the coming age when order-made medications become the standard.

Trends in JapanEdited by Japan Echo Inc. based on domestic Japanese news sources. Articles presented here are offered for reference purposes and do not necessarily represent the policy or views of the Japanese Government.