AC Immune, which filed to go public in May, said it would offer 4.55 million common shares at an estimated price range of $11 to $13 per share to raise between $50 million and $59 million.

Finding an effective therapy for the memory-robbing disease of Alzheimer's is a "holy grail" of the pharmaceuticals industry, since any successful product is likely to become a multibillion-dollar-a-year seller.

Scientists, however, are still struggling to understand the biology of the condition, even as global cases of dementia are expected to treble by 2050.

AC Immune's work in the field is more advanced than many, thanks to its tie-up with Roche. The Lausanne-based biotech licensed its experimental drug crenezumab to Roche's Genentech division in 2006 and the product last year entered pivotal Phase III trials.

Crenezumab works by targeting protein plaques found in brains of patients with Alzheimer's.

Another Alzheimer's drug company, Axovant, stunned many analysts in June 2015 when it came to market with a valuation of nearly $3 billion, although its value has since fallen to around $1.6 billion.

AC Immune, which is backed by German billionaire Dietmar Hopp, plans to use the proceeds from its U.S. share sale to develop separate products targeting Alzheimer's disease.

The company is the latest among a growing list of European biotech firms, including Britain's Adaptimmune Therapeutics and French allergy drugmaker DBV Technologies, to opt for a U.S. listing.

AC Immune is led by Andrea Pfeifer, who formerly headed Nestle's (>> Nestle SA) global research.

With money from Roche largely financing crenezumab, AC Immune plans to use proceeds from its U.S. share sale to develop separate products targeting Alzheimer's disease.

The group also raised $43.5 million in May in a private financing backed by certain institutional and existing shareholders.

Pfeifer had told Reuters last year the company was considering an IPO.

Credit Suisse, Jefferies and Leerink Partners are joint book-running managers for the IPO. AC Immune aims to list its common stock on the Nasdaq under the symbol "ACIU".

(Reporting by Ankur Banerjee and Ben Hirschler; Editing by Anil D'Silva and Louise Heavens)

Stocks treated in this article : Roche Holding Ltd., Nestle SA, Axovant Sciences Ltd