In a post to FDA Voice – the US Food and Drug Administration's blog – recently appointed Deputy Commissioner for Medical Products and Tobacco Robert Califf says progress toward curing some diseases, such as Alzheimer's, is being slowed by a lack of understanding of disease biology.

Why are There Effective Treatments for Some Diseases and not Others?

Califf raises this question, and points to some diseases like HIV/AIDS, where advances in scientific understanding have led to "critical insight on how to develop effective treatments." Califf says the discovery of biomarkers, measurable characteristics of the body's response to a disease or treatment, has "resulted in important breakthroughs, rapid drug development and speedy FDA approvals."

The problem, Califf says, is that "the paucity of reliable biomarkers in some diseases highlights the critical need for more research … [For] Alzheimer's and many rare diseases … the scientific community still lacks basic information about what causes these diseases."

Don't Point at Us

Early in the article, Califf calls FDA the world's fastest regulator, and reminds his audience that most new drugs are approved in the US ahead of other markets. So when "viable cures are not in the pipeline," Califf says, pointing the finger at FDA is not the solution.

Califf goes on to say that FDA can help "reduce the length and cost of initial clinical trials for drug approval … by developing tools such as biomarkers and surrogate endpoints." However, while biomarkers and endpoints can help drugmakers target specific mechanisms to treat disease, observational studies are still the gold standard for determining a drug's "cumulative effects."

Alzheimer's Versus Hepatitis C

In a report released alongside Califf's post titled Targeted Drug Development: Why Are Many Diseases Lagging Behind? FDA compares progress in several disease areas, including Alzheimer's, diabetes, rare diseases and hepatitis C (HCV), to scientists' understanding of the causes of those diseases.

For Alzheimer's, FDA points to the fact that, "Scientists have not yet confirmed that any potential biomarkers … [can] predict clinical improvement," except for some rare genetic versions of the disease. Likewise, treatment options for Alzheimer's are poor.

In contrast, drugmakers have made massive leaps in treating HCV, after technologies developed in the 1990s to better understand AIDS were applied to other viral infections, including HCV. These technologies helped scientists better understand HCV and fostered the development of so-called "direct-acting" drugs, such as Gilead Sciences' massively successful Sovaldi and Harvoni.

FDA Voice, Targeted Drug Development: Why Are Many Diseases Lagging Behind?