Preparing to start Phase III trials in the detection of acute cardiac ischemia, Molecular Insight Pharmaceuticals Inc. raised more than $28 million in its Series C financing round to advance a pipeline of imaging agents and radiotherapeutics.

That figure "exceeded the initial target by about 50 percent," said David Barlow, chairman and CEO of the Cambridge, Mass.-based company, due to oversubscription by investors.

New investors Siemens Venture Capital GmbH Corp., a venture organization for Erlangen, Germany-based Siemens AG; along with MedCap Management & Research LLC, of San Francisco; and Emigrant Capital Corp., of New York; joined existing institutional and individual investors. New York-based SG Cowen & Co. served as the placement agent. In connection with the financing, Andrew Jay, of Siemens Venture Capital, is joining Molecular Insight's board.

To date, Molecular Insights has raised more than $51 million. The company also has been awarded 26 grants totaling about $4 million from the National Institutes of Health during the past five years, which Barlow called "a very strong endorsement of our underlying technology platforms."

The recent financing is expected to take the company through Phase III development of its lead compound, BMIPP, a molecular imaging pharmaceutical designed to detect cardiac ischemia based on changes in cardiac cell metabolism. Studies are expected to begin around the end of the year, with a new drug application expected to be filed toward the end of 2006 and possible marketing approval in 2007.

Existing diagnostic procedures are based on blood flow imaging agents, meaning that their efficacy is limited to only a few hours after chest pain symptoms have gone away. But, since a healthy heart muscle relies on fat and fatty acids as its primary source of energy, Molecular Insights decided to develop a method of detecting the heart's use of fatty acids to determine risks for ischemia.

By injecting BMIPP, a fatty-acid compound, "doctors can get an image of the heart and see how the heart is using fatty acid," said John Babich, president and chief scientific officer of Molecular Insights. A reduction in the use of fatty acids indicates cardiac ischemia that would have to be medically or surgically treated.

The big difference between BMIPP and existing diagnostics is the time. BMIPP has a "window of about 30 hours after symptoms have gone away," Babich added.

Of an estimated 6 million patients every year who enter the emergency room with chest pains, about 3.5 million of those will have to undergo a prolonged period of assessment to determine if they are suffering from a cardiac disease or a less-serious, unrelated problem with a similar symptom, such as indigestion. That assessment can take up to four days and include hospital admission.

"So this is a huge medical and economic opportunity," Barlow told BioWorld Today.

Molecular Insights initially will seek approval for BMIPP in emergency room settings, though the company is considering additional indications in the stress test market, heart failure and diabetes. Barlow added the company also would like to look at cardiac assessment in women, who often do not suffer some of the traditional symptoms associated with cardiac ischemia.

BMIPP, if approved, would be marketed by Molecular Insights, Barlow said, since it is a market "we feel we can access with our own sales force."

In addition to BMIPP, Molecular Insights also has second- and third-generation compounds in preclinical development. BMIPP is sold in Japan as Cardiodine by Nihon-Medi-Physics.

While its lead program makes its way through Phase III development, the company also intends to use funds from the financing to advance its first radiotherapeutic, MIP-120T, for the treatment of neuroendocrine tumors in children and adults. Phase I studies are expected to begin next year.

The company's targeted radiotherapeutic program is based on the same technology used to create its molecular imaging pharmaceuticals, and there is "a lot of synergy and overlap," Barlow said. "We saw a significant opportunity to apply this platform technology."

Like the imaging pharmaceuticals, the targeted radiotherapeutics have a built-in radioactive isotope that selectively binds to a protein on specific disease tissues. But, instead of giving off radioactivity to be visualized in an imaging procedure, the isotope is designed to give off radiation to attack the tumor, thereby delivering "a therapeutic payload to that cancer," Babich said.