Acusphere, Inc. Announces $20 Million in Private Financing.

Business Editors/Health/Medical Writers

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WATERTOWN, Mass.--(BUSINESS WIRE)--April 21, 2003

Acusphere, Inc., a specialty pharmaceutical company that develops new drugs and improves formulations of existing drugs using its proprietary porous microparticle technology, announced today that it has completed the first closing of a $20 million private financing round. This first closing resulted in Acusphere receiving over $19 million in funding, with additional funding commitments scheduled to close in June 2003. The financing was led by Thomas Weisel Partners, BA Ventures, Burr, Egan, Deleage & Company, Polaris Venture Partners, BancBoston Ventures, HBM Bioventures, Audax Group and Technology Funding.

Proceeds from this financing are intended to fund Acusphere's continued advancement of its products under development and of the broader technology platforms underlying those products. In particular, proceeds from this financing will help fund Acusphere's recently initiated Phase III clinical program to study AI-700(TM), an ultrasound contrast agent designed by Acusphere for use in detecting coronary artery disease in patients with ischemic heart disease.

"This financing allows us to build on the clinical progress that we have been making with our products and we believe it affirms the significant potential of our products and technology towards improving healthcare," said Sherri C. Oberg, President and CEO of Acusphere. "We are very thankful to our investors for their support. We also are appreciative of the dedication of our employees, whose accomplishments and abilities made this financing possible."

About Acusphere, Inc.

Acusphere is a privately held specialty pharmaceutical company that develops new drugs and improved formulations of existing drugs using its proprietary porous microparticle technology. This technology allows the size and porosity of microparticles to be engineered resulting in versatile drug delivery systems for all routes of administration. This porous microparticle technology is broadly applicable as a pulmonary drug delivery system, as a hydrophobic drug delivery system (HDDS(TM)) and as an intravenous gas delivery system for ultrasound contrast. Acusphere has three porous microparticle product candidates: AI-128(TM), an inhaled sustained release asthma formulation; AI-850(TM), an improved formulation of the cancer drug paclitaxel; and AI-700, an ultrasound contrast agent for the detection of coronary artery disease. AI-128 has completed a Phase I clinical trial and AI-850 is currently being evaluated in a Phase I clinical trial. In 2003, AI-700 commenced a Phase III clinical program. Acusphere has focused on therapeutic areas where its drug delivery technology has the potential to provide significant clinical benefits. For more information about Acusphere visit the company's web site at http://www.acusphere.com.