After many setbacks, Acusphere (NASDAQ:ACUS) is having a big day. The specialty pharmaceutical company remains a fairly risky investment, but seems to have at least one important feature going for it.

This morning, the small firm announced that it sealed a $70 million partnership for AI-700, its experimental ultrasound contrast agent, with privately held European pharmaceutical concern Nycomed. Shares of Acusphere soared 20% on news of the pact.

The revelation was welcome after several bumps in the road. The company first attempted to go public on Sept. 4, 2001, only to withdraw three months later due to deteriorating market conditions. Then, in late 2002, Elan (NYSE:ELN) bailed out of a partnership to develop an asthma treatment. At the end of 2003, Acusphere helped break the multiyear drought in biotech and pharmaceutical initial public offerings when it sold 3.75 million shares at $14 apiece; in short order, the stock slid well below that price, where it has remained ever since.

The Nycomed transaction shows Acusphere's resilience, although the company is far from easy street. AI-700 is in phase 3 testing for assessment of blood flow to the heart muscle. Unfortunately, privately held POINT Biomedical, backed by General Electric's (NYSE:GE) General Electric Capital and others, has completed trials for a similar product and plans to file for U.S. approval later this year. As a result, AI-700 probably will enter the market behind this competitor.

In addition, Acusphere has no marketed products, and in the first quarter it burned through almost $8 million, leaving it with $47 million in cash and equivalents. Nycomed will only add $12 million to its coffers before AI-700 receives approval, which means Acusphere may be running on or near empty by the time it files AI-700's new drug application with the Food and Drug Administration in the first half of 2006.

Finally, AI-850, the company's most promising candidate behind AI-700, only recently completed phase 1 trials. It seems unlikely that Acusphere will be able to advance AI-850, a unique formulation of the active ingredient behind Bristol-Myers Squibb's (NYSE:BMY) cancer drug, Taxol, into later-stage studies without a significant investment or a willing partner.

Nevertheless, Acusphere has shown an uncanny ability to survive. After its first failed IPO attempt, it limped along by raising venture capital dollars in an incredibly difficult environment. If it can continue to find cash and develop more partnerships, it may yet thrive.

Fool contributor Brian Gorman is a freelance writer living in Chicago, Ill. He does not own shares of any companies mentioned here.