Emerging Drug Developer: Presidio Pharmaceuticals

Presidio anticipates bright future for HCV cocktail therapies

When Presidio Pharmaceuticals first opened its doors in 2006, the developer was concentrating on new antivirals for the HIV market, which had been wowed by the arrival of new cocktail therapies that were able to stop the lethal virus in its tracks.

That combination approach still dominates HIV treatment, but while Presidio remains tightly focused on antivirals, its development effort has shifted to hepatitis C--where cocktail therapies have yet to arrive.

"I believe that antivirals in general and that (HCV) market in particular is a very strong market," says Presidio CEO Omar Haffar, PhD. "It's underserved."

A large group of venture backers agree. The San Francisco-based developer raised $27 million in a Series B last July, bringing its total VC haul to $54.5 million to date. New Leaf Ventures came on board as a new investor, a serendipitous plus for the developer after its contact at Panorama Capital, Srinivas Akkaraju, jumped to the fund. Panorama also agreed to invest more, alongside Baker Brothers Investments, Ventures West Capital, Bay City Capital, Nexus Medical Partners and Sagamore BioVentures. And the VC groups are clearly intrigued by the market potential of a new hepatitis C development program. 

"The market dictates where you get funding," says the CEO. "At present, the HCV market has catapulted ahead of HIV."

Presidio is focusing on an NS5A inhibitor, a niche in HCV development that has also attracted both Bristol-Myers Squibb as well as Eiger BioPharmaceuticals, which raised a $7 million Series A at the beginning of this year. An NS4B inhibitor as well as another NS5A inhibitor are also in the works, but Presidio's focus is clearly on getting its lead therapy--PPI-461--into the clinic and pointed to clinical proof-of-concept.

"What we've done over the past year is accelerated the program to identify small molecule inhibitors of a new target, NS5A," says the CEO. "The target was validated in the clinic, and the data was presented by Bristol-Myers Squibb at a liver meeting last fall. We had been working on it before then."

"We selected our first clinical candidate in June," adds Haffar. "It is a small molecule direct antiviral, which should be used in combination with other classes of antivirals. The future of hepatitis C is going to be a cocktail of small molecule antivirals, direct antivirals, which could be in used in combination" with new drugs now in late-stage development at companies like Vertex, Roche and Intermune.

The FDA has clearly mapped out the approach that developers have to follow for an approval. A new hepatitis C therapy is combined with the standard of care and then compared in clinical trials with the standard. Eventually, he says, that will change as new combination therapies become the norm.

"When that will change the clinical treatment paradigm is several years in the future," says the CEO. For now, "we cannot abandon the classic development path."

That classic path will take Presidio's lead program into the clinic in 2010, and Haffar hopes to see clinical proof-of-concept data by the end of 2010. After that, it's likely that developers in the field will also start winning approvals for new therapies like telaprevir, setting the stage for future combination trials.

"We really believe that the market is going to be driven by the strongest combination therapy that is going to make it to market," says Haffar. "We have spoken to other companies that have other small molecules to see how we can arrange an agreement, see how our compound works in combination with theirs.

"We're not looking to out-license, we believe we have the management experience" to handle the clinical development work. Dr. Nathanial Brown was just hired as the head of clinical development at Presidio. He had worked at Idenix Pharmaceuticals, where he handled development programs for hepatitis C and B.

"We're considering more of a collaboration," says Haffar. "We're a small company with limited resources. A relationship with a bigger player will help accelerate our program and a combination therapy."

Presidio has remained "somewhat virtual," says Haffar, with about 20 people on the payroll right now. That number is likely to grow by two or three as the developer heads into the clinic.

Emerging Drug Developer: Presidio Pharmaceuticals
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