In addition to the usual details about user fees, the latest reauthorization of the PDUFA package passed by the House and Senate also includes special incentives for antibiotic drugs. (See BioWorld Today, May 31, 2012.)

Drugmakers could certainly use them. Between 2008 and 2010, there were only two new antibiotics approved, down from 16 approved in a four-year span from 1983 to 1987.

In the latter half of the previous decade, as the FDA's guidance for endpoints shifted, pharma abandoned the space. Large drugmaker's migration from acute to chronic treatments also contributed to the pull out. (See BioWorld Insight, Sept. 21, 2009.)

Since then, the FDA's guidance became clearer, and pharma has inched back into the antibiotic waters. While there are some signs of life for the field, it's still hard for companies to find funding for antibiotic drug development. "There is a challenge in acquiring capital for early stage companies to advance early discoveries into the clinic," Jeffery Stein, president and CEO of antibiotic specialist Trius Therapeutics Inc., told BioWorld Insight.

Trius completed a successful Phase III trial of its antibiotic tedizolid phosphate for acute bacterial skin and skin structure infections last December and is currently testing the drug in another Phase III trial. The company's preclinical programs are being funded under contracts from the National Institute of Allergy and Infectious Diseases and the U.S. Department of Defense. (See BioWorld Today, Dec. 20, 2011.)

Even big pharma has accepted financial help. Five pharmas, including GlaxoSmithKline plc and AstraZeneca plc, are part of a 50-50 public-private European cooperative effort called "New Drugs for Bad Bugs," aimed at speeding up development of new antibiotics. (See BioWorld Today, May 30, 2012.)

"The discovery stage for antibiotics is the most difficult of any therapeutic area," Stein said. Rather than simply finding a protein in a pathway and an appropriate drug to target it, developers of antibiotics have to hit a bacterial target in a human, where there are typically multiple variants of the protein target in different species of bacteria.

There's also the challenge of getting the drug across the cell wall of a bacteria in an animal. Although, at least one group is targeting adhesion proteins on the outside of bacteria that allow them to infect human cells. (See BioWorld Today, Nov. 18, 2011.)

And once a drug candidate is discovered and proven to work in the clinic, there's limited prospects from a sales perspectives. Stein pegs the peak sales potential of a hospital-based antibiotic at about $1 billion to $2 billion worldwide because the drug is self limiting. "The better your drug works, the faster the infection is treated, and the less drug you have to take," he said.

The incentives in the new PDUFA legislation will help drugs as they head toward FDA approval. There's potential for priority and fast-track review, which has typically not been awarded to antibiotics. But the provision is only in the Senate version of the bill and not the House version, so companies will have to wait and see if it survives the reconciliation process. Leadership from both chambers said they'd like to complete the reconciliation of the bills by July 4.

Both bills also contain language to give antibiotics an additional five years of exclusivity. But the Senate version limits the incentive to new antibiotics that target serious or life-threatening diseases, while the House version allows a broader range of antibiotics to qualify for the incentive.

The new incentives might add some value to late-stage assets like Trius' tedizolid phosphate in Phase III trials, but Stein doesn't see it changing the funding landscape all that much.

"The priority review might decrease by three to six months the amount of capital required by a company in late-stage clinical development, but it's not going to be a deciding factor in whether an investor chooses to fund a company," Stein said.