"Race in a Bottle"


By Jonathan Kahn J. カーン
English 日本語 日本語
Two years ago, on June 23, 2005, the U.S. Food and Drug Administration approved the first “ethnic” drug. Called BiDil (pronounced “bye-dill”), it was intended to treat congestive heart failure―the progressive weakening of the heart muscle to the point where it can no longer pump blood efficiently―in African-Americans only. The approval was widely declared to be a significant step toward a new era of personalized medicine, an era in which pharmaceuticals would be specifically designed to work with an individual's particular genetic makeup. Known as pharmacogenomics, this approach to drug development promises to reduce the cost and increase the safety and efficacy of new therapies. BiDil was also hailed as a means to improve the health of African-Americans, a community woefully underserved by the U.S. medical establishment. Organizations such as the Association of Black Cardiologists and the Congressional Black Caucus strongly supported the drug's approval. 2005年6月23日,米国食品医薬品局(FDA)は初の“特定人種用医薬”バイディル(BiDil)を承認した。この薬は,心筋が徐々に弱まって血液をうまく送れなくなる慢性心不全(うっ血性心不全)の治療薬だが,処方はアフリカ系アメリカ人(黒人)に限定された。患者個人の特定遺伝子に働くようデザインされた医薬を目指すオーダーメード医療時代に向けた第一歩として,FDAはこの承認を広くアピールした。こうした新薬開発の方法は薬理ゲノム学(ファーマコゲノミクス)と呼ばれ,開発コストや治療費を下げるとともに,薬の安全性と有効性を高めると見込まれている。
A close inspection of BiDil's history, however, shows that the drug is ethnic in name only. First, BiDil is not a new medicine―it is merely a combination into a single pill of two generic drugs, hydralazine and isosorbide dinitrate, both of which have been used for more than a decade to treat heart failure in people of all races. Second, BiDil is not a pharmacogenomic drug. Although studies have shown that the hydralazine/isosorbide dinitrate (H/I) combination can delay hospitalization and death for patients suffering from heart failure, the underlying mechanism for the drug's efficacy is not fully understood and has not been directly connected to any specific genes. Third, and most important, no firm evidence exists that BiDil actually works better or differently in African-Americans than in anyone else. The FDA's approval of BiDil was based primarily on a clinical trial that enrolled only self-identified African-Americans and did not compare their health outcomes with those of other ethnic or racial groups. しかし,バイディル誕生の経緯を詳しく見ていくと,特定人種用というのが名ばかりであることがわかる。
So how did BiDil become tagged as an ethnic drug and the harbinger of a new age of medicine? The story of the drug's development is a tangled tale of inconclusive studies, regulatory hurdles and commercial motives. BiDil has had a relatively small impact on the marketplace―over the past two years, only a few million dollars' worth of prescriptions have been sold―but the drug has demonstrated the perils of using racial categories to win approval for new pharmaceuticals. Although African-Americans are dying from heart disease and other illnesses at younger ages than whites, most researchers believe the premature deaths result from a complex array of social and economic forces [see “Sick of Poverty,” by Robert Sapolsky; Scientific American, December 2005]. Some medical professionals and policy experts, however, have pointed to BiDil as proof that genetic differences can explain the health disparity. Worse, some pharmaceutical companies are now using this unfounded argument to pursue other treatments targeted at various ethnic groups, a trend that may segregate medicine and fatten the profits of drugmakers without addressing the underlying causes that are killing so many African-Americans before their time. では,バイディルはどのようにして特定人種用医薬,新時代の薬のさきがけと呼ばれるようになったのか。この薬の開発ストーリーは複雑で,決め手に欠ける複数の試験や規制上のハードル,営利的な思惑が絡み合っている。これまでのところ,バイディルは市場ではあまり目立たない存在で,この2年間の売上げは数百万ドル程度だった。しかしこの薬は,新薬の承認を勝ち取るために人種というカテゴリーを持ち込むことの危うさをはっきりと示す実例だ。
アフリカ系アメリカ人は白人に比べて心臓病その他の病気で若くして死亡する。多くの研究者はその原因は社会的側面と経済的側面が複雑に絡んだものと捉えている(R. サポルスキー「貧しい人はなぜ不健康なのか」日経サイエンス2006年3月号参照)。しかし,医学および政策の専門家の一部は,バイディルの存在こそが健康格差を遺伝子の違いで示しうる証拠だとしている。さらにまずいことに,製薬会社の中には,この根拠のない主張をよりどころにして,特定の民族グループに的を絞った治療薬をあれこれと模索しているところもある。この状況が進めば,若くして命を落とすアフリカ系アメリカ人がなぜこんなに多いのか,その根本原因を明らかにすることなく,“人種別新薬”の乱発によって製薬会社の儲けを増やすことになりかねない。