Antibiotic development is an ideal FDA "Critical Path" opportunity due to the lack of antitrust concerns surrounding the therapeutic category, Lilly VP-Scientific Affairs Gail Cassell, PhD, told the FDA Science Board Advisory Committee April 22.

FDA should designate "maybe just two therapeutic areas initially" for Critical Path opportunities "and dissect them in terms of trying to set priorities and lay out the roadmaps," Cassell suggested.

"Infectious diseases would be a natural because...you don't run into a lot of the antitrust issues that you might in such highly competitive other arenas like neurosciences or cardiovascular" agents, Cassell said.

The agency plans to identify and publish Critical Path opportunities this fall (see ¹ Also see "FDA Will Publish “Critical Path” Opportunities List By Fall, Woodcock Says" - Pink Sheet, 3 May, 2004. ). Documents outlining the opportunities will include details on available funding for particular projects (² Also see "FDA On “Critical Path” To Secure Support For Drug Development Project" - Pink Sheet, 19 April, 2004., p. 3).

Antibiotic development under the Critical Path initiative would be free of antitrust concerns because "so many large companies having gotten out of the development of antibiotics," Cassell said.

"There's an obvious difference between what we see in the pipeline now compared to what we would have seen 10 years ago, and that is that most of the antibiotics are being developed by biotech companies and companies outside the U.S., as opposed to typical large pharma," Cassell said.

The lack of a sufficiently sized antibiotic market to recoup the R&D investment "is just one of many reasons that most companies have chosen to invest resources in other areas," Cassell maintained.

In addition, "there are still significant challenges in antibiotic drug discovery," which have contributed to big pharma's exit from the antibiotic market.

"It's not due to lack of targets. We have a plethora of targets," Cassell said. "Where there is a need is an increase in chemical diversity and a better understanding of the interactions of the different targets that we currently are trying to develop inhibitors for."

Cassell told FDA earlier this year that converting validated targets into a clinical candidates was a major hurdle in antibiotic development (³ Also see "Antibiotic Research Stalling In Conversion Of Target Into New Drug" - Pink Sheet, 19 January, 2004., p. 42).

One development barrier that manufacturers face is the expense associated with evaluating antibiotics in large trials, Cassell noted. "The large number of patients required for the different number of indications that one would want to develop are very important considerations when you look at that cost."

As a result, the pipeline "is currently bare with respect to new antibiotics in clinical development," Cassell said, noting that only two new classes of antibiotics have been discovered in the past 40 years.

Aventis' Ketek is the first agent in the class of ketolide antibiotics. Ketek (telithromycin) cleared FDA April 1 for the treatment of respiratory infections (⁴ Also see "Aventis Ketek July Launch Will Highlight Targeted Antibacterial Activity" - Pink Sheet, 5 April, 2004., p. 30).

The "thinness" of the antibiotic pipeline, coupled with "the fact that we have several pathogens for which now strains have been identified for which there are no remaining antibiotics left," has created a "crisis" in terms of antibiotic development, Cassell declared.

The Critical Path initiative could be used not only "to develop new diagnostics and the use of them to promote more judicious use of the agents that we do have, but also to identify...new agents," Cassell said.

Other Critical Path priorities include "improved manufacturing, particularly as it might relate to use of natural products for development of new antibiotics."

Antibiotics are a particularly strong candidate for an FDA Critical Path opportunity because "there's already this new investment of $1.7 bil." in the National Institute of Allergy & Infectious Diseases "for the development of anti-infectives," Cassell said.

"The thing I like best about the Critical Path initiative is the realization that there is a lot of synergy between research in the public and private sectors that's relevant... to drug discovery and development," the Lilly exec said.

"We should admit that - all of us, as well as the public and Congress - and figure out how we can better have these two sectors working together in the area of drug discovery and development."

Antibiotics Should Be One Step On FDA’s “Critical Path,” Lilly VP Says

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