Last week, FDA announced that it had joined EPA and other federal agencies in Tox21, a program to improve, and greatly accelerate, chemical screening of toxicologically active chemicals. The program had been in place for two years, but FDA’s participation signals a new scope and new possibilities.

The Agency brings to the table volumes of data on the impact in chemicals used in past animal and human clinical trials, notes David Jacobson-Kram, Ph.D., D.A.B.T., Associate Director for Pharmacology and Toxicology, speaking recently by phone. FDA gets access to Tox21’s high-throughput screening capabilities that have already screened some 2,000 chemicals, and perhaps as many as 10,000 by the end of the year. Some of the data is already publicly available. (See links at the end of this article.)

“We can test thousands of chemicals in a week,” says Jacobson-Kram. “That has never been the limiting factor. The challenge is designing assays to get the right cell types and trying to elucidate as many of the toxicity pathways as we can.”

It’s extremely valuable to have access to data from in-vitro assays, so that “we hope to ultimately supplant the use of experimental animals” in clinical trials, Jacobson-Kram adds. It’s a more “mechanistic-based toxicology,” he says.

This critical information will be made available to drug companies soon, to help in identifying toxicology issues earlier in the development process. “These tests are really more for industry than they are for FDA,” Jacobson-Kram says. It will provide companies with data to help them reject compounds early that in other instances may have moved through trials before being dismissed.

Will it also provide FDA improved means of assessing the regulatory merit of compounds under review? Not necessarily, says Jacobson-Kram. “It will likely be a pre-regulatory tool,” he says. “We won’t see this data because it will be used so early in development.” He continues, “The real disasters are when drugs fail late in development,” and Tox21 should greatly minimize this possibility.

More information on Tox21 and computational toxicology research program can be found below:
Resources for Publicly Available Data

Press Release on FDA’s Participation in Tox21

ACToR: Aggregated Computational Toxicology Resource

National Center for Computational Toxicology

PubChem Bioassay Summaries

--Paul Thomas