Radius Health Inc. is the latest to join the ranks of biotech companies with pending initial public offerings (IPOs).

The Cambridge, Mass.-based firm specializes in developing therapeutics for osteoporosis and indications relevant to women's health. Its lead product candidate is a synthetic peptide analogue of human parathyroid hormone-related protein (hPTHrP), designated BA058.

Funds from the potential offering will support the company's goals, including completing a pivotal Phase III study of BA058 injection for osteoporosis in the first half of 2014. It has not yet specified a number of shares or a price range, but the maximum offering price listed was $86.25 million.

Radius' public offering is not a typical IPO. The company started the process of becoming public in early 2011 by merging with MPM Acquisition Corp., an unlisted public reporting shell company. The surviving company was named Radius Health Inc., continuing as a reporting company with the SEC.

The maneuver set Radius up to become a public company upon registration of its private stock for resale with the SEC.

The order of events was reversed from a standard IPO. According to Radius, a traditional IPO would bring significant uncertainty in terms of proceeds as it entered Phase III trials with its lead product. Instead, it raised $91 million in equity and debt financing, followed by a shift to public status about nine months later. (See BioWorld Today, May 25, 2011.)

Radius has generated more than $197 million in funding since its founding in 2003.

Its prospects for success on the public markets are uncertain. On one hand, Boston-based Verastem Inc. had a very successful recent offering, and even surged 10 percent above its offering price on its first day of trading. Verastem's IPO raised hopes that the chilly IPO market was warming up. (See BioWorld Today, Jan. 30, 2012.)

But shortly after Verastem's debut, Cempra Inc. took a huge cut below its $11 to $13 target range to make its IPO. Cempra sold 8.4 million shares for $6 apiece, raising a total of $50.4 million. And, unfortunately, Cempra's experience is more representative of recent IPOs than Verastem's. (See BioWorld Today, Feb. 6, 2012.)

Radius began dosing patients in a Phase III trial of BA058 in April 2011. The trial will enroll 2,400 patients in Europe, Latin America and Asia. Therapy with BA058 injection 80 mcg will last for 18 months, with data anticipated in 2013.

The primary endpoints of the study are safety and efficacy compared to placebo for prevention of vertebral fractions in otherwise healthy postmenopausal women ages 50 to 85 who have severe osteoporosis.

The trial also will compare BA058 to Forteo (terparatide, Eli Lilly and Co.) with regard to secondary efficacy outcomes like bone mineral density of the spine, hip and femoral neck and hypercalcemia.

Forteo had worldwide sales of $830 million in 2010, but Radius believes that BA058 may show greater efficacy, faster benefit and offer a shorter therapy course.

Radius completed its Phase II trial of BA058 in 2009. Data from that trial showed that the drug significantly increased bone mineral density of the lumbar spine and femoral neck after six months.

Improvements were even greater in a subgroup treated for 12 months, and at both time points BA058 outperformed Forteo.

However, Radius's partner, Novartis AG, passed on an option attached to its 2007 partnership deal. That deal was worth up to $500 million, but the Swiss big pharma decided not to exercise an option that would have given it exclusive, worldwide rights to the drug outside of Japan. (See BioWorld Today, Sept. 18, 2007.)

Radius also is developing BA058 in the form of a microneedle patch in partnership with 3M Drug Delivery Systems, of St. Paul, Minn., for osteoporosis.

In December 2011, Radius reported that transdermal BA058 microneedle patch showed positive results in a Phase Ib trial, showing rapid release of drug and increase of bone formation marker P1NP in serum after seven days. The drug was tested in a group of 74 healthy postmenopausal women.

In addition to BA058 injection and BA058 microneedle patch, Radius's pipeline includes RAD1901, licensed from Eisai Co. in 2006, for hot flashes associated with menopause.

UBS Investment Bank and Leerink Swann LLC are acting as joint book-running managers and underwriters for the offering. Cowen and Co. LLC and Rodman and Renshaw LLC are named as co-managers.

Upon pricing, Radius' stock will trade under the symbol "RDUS" on NASDAQ.