Expecting to begin pivotal testing of its lead compound, Fx-1006A, in familial amyloid polyneuropathy (FAP) later this year, FoldRx Pharmaceuticals Inc. brought in $43 million through a Series B round.

"We will use the money to continue to expand our clinical program," featuring Fx-1006A, a disease-modifying, oral small molecule aimed at treating rare genetic diseases caused by a misfolding of the transthyretin (TTR) protein, said Richard Labaudiniere, FoldRx's president and CEO.

Mutation in the TTR protein results in amyloid deposits. In the case of FAP, a disease affecting 5,000 to 10,000 people worldwide, those amyloid deposits build up in the peripheral nerve tissue.

Patients begin by suffering sensory neuropathy, usually starting in the lower extremities, before progressing to a loss of motor function, and usually die within seven to 10 years, Labaudiniere said.

No therapies exist on the market for FAP patients, and the only treatment alternative is a liver transplant, "and that's a drastic option," he added.

FoldRx's compound is designed to stop the progression of the disease by binding to the mutated TTR protein and stabilizing it to prevent misfolding. Once the protein is stabilized, "you don't form the amyloid deposits, which is really the cause of the disease," Labaudiniere told BioWorld Today.

The Cambridge, Mass.-based company is finishing up a Phase I study of Fx-1006A and expects to be able to start a pivotal trial in FAP by the end of the year.

Funds from the Series B are anticipated to get the company through pivotal testing in FAP.

To date, FoldRx has raised $59 million. The company brought in $16 million in its Series A round at the end of 2004. (See BioWorld Today, Dec. 14, 2004.)

The Series B was led by Texas Pacific Group Ventures, of Menlo Park, Calif., and Alta Partners, of San Francisco, with participation from existing investors HealthCare Ventures and Fidelity Biosciences, both of Boston.

"The fact that we were able to raise that amount of money really indicates that [targeting protein misfolding] is considered by investors to be an avenue of the future," Labaudiniere said.

Though a relatively new approach, there are a few other companies advancing programs to treat diseases by stabilizing and preventing proteins from misfolding. One is Cranbury, N.J.-based Amicus Therapeutics Inc., which recently filed for its initial public offering. Amicus is in Phase II with its lead product, Amiga (migalastat hydrochloride), in Fabry's disease, a genetic disorder caused by mutations in the alpha-galactosidase protein, and is investigating compounds to treat Gaucher's disease and Pompe disease.

Dallas-based Reata Pharmaceuticals Inc. licensed a drug discovery assay, RPM (Rescuing Proteins from Misfolding), to screen potential compounds that target misfolding proteins in neurodegenerative diseases and cancer, including a molecule that can prevent the misfolding of tumor-suppressor protein p53.

After investigating Fx-1006A in FAP, FoldRx plans to expand the program into familial amyloid cardiomyopathy (FAC), a disease also stemming from a TTR mutation.

"It's the same concept as FAP, except that the amyloid deposition ends up in cardiac tissues," Labaudiniere said, and as a result, "the heart is not able to pump blood efficiently."

In the U.S. about 125,000 people suffer from FAC, and the specific mutation is found in about 4 percent of the African-American population. At this time, there are no treatment options.

Since both FAP and FAC comprise small patient populations, FoldRx anticipates taking Fx-1006A to the market itself, reserving partnerships for other programs coming up through its early stage pipeline.

Following Fx-1006A, FoldRx is developing a molecule to treat Parkinson's disease by preventing the misfolding of the alpha-synuclein protein. Like Fx-1006A, this program also aims at stopping disease progression.

"There are only symptomatic treatments" available now, Labaudiniere said. "Ours would be a disease-modifying compound."

For the Parkinson's product, FoldRx likely will look for partners once the product has achieved proof-of-principle in animal studies, set to be completed this year.

FoldRx has 14 employees, though that number is anticipated to grow to 20 by the end of 2006 to accommodate the company's clinical progress.

In other financings news:

• Profectus BioSciences Inc., of Baltimore, completed an additional $3 million private equity placement with the sale of securities to private investors led by Cross Atlanta Capital Partners. Under the terms, investors purchased shares of newly issued convertible Series A preferred stock and exchanged previously issued convertible notes. Proceeds are expected to fund work on cell-cycle agent technologies to enhance the clinical efficacy of existing drugs and formulate new viral entry inhibitors. Money also will go toward investigating other enabling technologies that support the production of antiviral vaccines and therapeutics, and to generate revenue from licensing agreements.

• Sirna Therapeutics Inc., of San Francisco, said underwriters exercised in full their overallotment option to purchase 1.4 million shares of common stock in connection with its follow-on stock offering, for a total of 10.4 million shares priced at $5 each. Net proceeds from the offering are estimated at $47 million and are expected to be used for general corporate purposes, including research and development and clinical trial expenses and potential in-licensing of intellectual property and technology. (See BioWorld Today, May 25, 2006.)