Spark nails a $161M IPO to fund its 'breakthrough' gene therapy

Spark Therapeutics ($ONCE), at work on one-time treatments for rare diseases, pulled off a $161 million IPO, pricing above its range and keeping biotech's Wall Street hot streak rolling.

The company, headquartered in Philadelphia, sold 7 million shares at $23 apiece, a price roughly 35% above the high end of its initial range. Spark has set aside another 1 million shares for its underwriters, putting it in line to gross about $185 million if they exercise their options.

Spark has earmarked most of its potential proceeds for SPK-RPE65, an FDA-designated "breakthrough" therapy now in Phase III development to treat a group of vision-destroying ailments called inherited retinal dystrophies. Spark's pipeline also includes SPK-CHM, a treatment for the retinal disease choroideremia; and SPK-FIX, a Pfizer ($PFE)-partnered hemophilia B therapy.

Spark's approach to gene therapy involves targeting diseases that result from genetic malfunctions and using a modified version the harmless adeno-associated virus (AAV) to deliver corrective genes. The company, a 2014 Fierce 15 honoree, raised more than $100 million in venture cash and collaboration revenue in about a year. That money, combined with its IPO haul, should fund its work through 2017, Spark said, paying the way for its clinical candidates and helping get some early-stage assets into Phase I.

And gene therapy as a whole is in the midst of a second honeymoon among investors and researchers. Serious safety issues and deliverability woes long hampered R&D in the field, but, after years of work, a new generation of academics and investigators believes it has hammered out the right viral vectors to safely and predictably get the right genes to their target tissues, spurring renewed hope for widespread clinical success. And that's drawn the attention of heavyweights including Pfizer, Biogen Idec ($BIIB), Celgene ($CELG) and Bayer.

Meanwhile, 2014's record-setting pace of biotech IPOs has hardly slowed in the new year, as this week alone has seen Ascendis Pharma ($ASND) raise $108 million, Flex Pharma ($FLKS) bank $86 million and Zosano Pharma ($ZSAN) pull in $50 million. Last year, biotech debutantes raised a record $6.3 billion in IPO cash, a figure buoyed by increasing high valuations and investor fervor over new technologies.

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Special Report: FierceBiotech's 2014 Fierce 15 - Spark Therapeutics

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