Proteostasis Therapeutics Closes in on IPO

Proteostasis Therapeutics has filed an amended S-1 form with the U.S. Securities and Exchange Commission (SEC) for its initial public offering (IPO). This company expects to price its 3.85 million shares in the range of $12 to $14 per share, with an overallotment for an additional 577,500 shares. At the maximum price, the entire offering is valued up to $61.99 million. Proteostasis intends to list its shares on the Nasdaq Global Market under the symbol PTI.

The underwriters for this offering are Leerink Partners, RBC Capital Markets, Baird and H.C. Wainright.

This innovative biopharmaceutical company is committed to the discovery and development of novel therapeutics that treat diseases caused by an imbalance in the proteostasis network, a set of pathways that control protein biosynthesis, folding, trafficking and clearance. The initial therapeutic focus is on cystic fibrosis (CF), which is caused by defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein and insufficient CFTR protein function.

CF is an orphan disease that affects an estimated 70,000 to 100,000 patients worldwide, with the vast majority of affected individuals in the United States, Canada, Europe and Australia. CF is the most common fatal inherited disease in Caucasians, and there is presently no cure.
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In the filing the company said:

Our lead product candidate PTI-428 is an orally bioavailable CFTR modulator belonging to the amplifier class. CFTR modulators are compounds that affect the folding, trafficking and clearance of CFTR protein and can be classified according to the ways in which they affect CFTR protein. Amplifiers are CFTR modulators that selectively increase the amount of an immature form of CFTR protein, thereby providing additional substrate for other CFTR modulators, such as correctors or potentiators, to act upon. Correctors, such as lumacaftor or VX-661, are CFTR modulators that are believed to improve protein folding and trafficking to enable abnormally folded CFTR protein to achieve some level of activity without repairing the actual protein. Potentiators, such as ivacaftor, are CFTR modulators that increase the opening time of the CFTR protein channel resulting in higher ion flow across the cell membrane.

The company intends to use the net proceeds from this offering to develop and advance PTI-428, expand research and development of products in CF, and for working capital and other general corporate purposes.