Acusphere's Unique Paclitaxel Formulation To Begin Phase I Clinical Trials In Cancer Patients; AI-850 Utilizes Platform Technology, HDDS, to Formulate Poorly Soluble Drugs.

Business/Technology Editors & Health/Medical Writers

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WATERTOWN, Mass.--(BW HealthWire)--May 29, 2002

Acusphere, Inc. announced today that it has begun Phase I clinical trials of AI-850(TM), a unique formulation of paclitaxel, the active compound in the widely used oncology drug Taxol(R). Acusphere is developing the proprietary formulation to enhance the tolerability of paclitaxel and thus enable use of higher, potentially more effective doses of the drug. AI-850 is the first product candidate to enter clinical trials that has been formulated using Acusphere's hydrophobic drug delivery system (HDDS(TM)), a technology for improving the dissolution of drugs having poor water solubility.

Sherri Oberg, President and CEO, will discuss this program and other recent company highlights at 10:00 a.m. on Wednesday, June 5th, 2002 at the UBS Warburg Global Specialty Pharmaceuticals Conference to be held at the Grand Hyatt New York, Park Avenue at Grand Central Station, New York City, New York.

Dr. Eric K. Rowinsky, a Principal Investigator in the AI-850 clinical trial, Director of Clinical Research at the Institute for Drug Development, and Clinical Professor, Medical Oncology, University of Texas Health Science Center, San Antonio, Texas commented that, "Based upon the preclinical data, it appears that this novel formulation has the potential for improved efficacy as compared to the current-approved formulation of paclitaxel, yet with reduced toxicity and no premedications."

Sherri C. Oberg, President and CEO of Acusphere said, "With the introduction of AI-850 into the clinic, our second product to begin human studies this month, Acusphere continues to achieve key milestones and demonstrate significant progress. The application of our HDDS technology in the cancer arena further demonstrates the versatility of our core technology to address significant challenges in drug development and the company's ability to develop improved products that address significant medical problems." She added that Acusphere now has three products in clinical development that employ its proprietary porous microparticle technology.

Taxol is marketed by Bristol-Myers Squibb Company (NYSE:BMY) for the treatment of ovarian, breast and non-small cell lung cancer. Taxol is formulated with Cremophor(R)EL to increase paclitaxel's solubility, however, Cremophor EL is an agent that is associated with hypersensitivity reactions in some patients. As a result, patients are given premedications to reduce these hypersensitivity reactions associated with Cremophor EL. AI-850 is a rapidly dissolving formulation of paclitaxel that is free of Cremophor EL. In preclinical animal studies, AI-850, administered without premedication, had a maximum tolerated dose that was up to eight-fold that of Taxol. This superior tolerance compared to Taxol resulted in the ability to administer higher doses of paclitaxel with AI-850 and demonstrated superior efficacy in animals implanted with human tumors.

Acusphere's HDDS system is a technology that converts drugs with poor water solubility into tiny drug microparticles embedded in a porous, water soluble, sponge-like matrix. When mixed with water, the pores in the sponge-like matrix absorb the water to wet the drug microparticles and dissolve the matrix leaving a suspension of drug microparticles that dissolves rapidly upon intravenous injection. In addition to paclitaxel, the active compound in Taxol, Acusphere has applied this technology to other drugs including celecoxib, the active agent in Celebrex(R) and nifedipine, the active agent in Procardia(R).

The Phase I clinical study will be conducted at up to 3 sites in the United States and will enroll cancer patients who have solid tumors. The primary objectives of the clinical study are to determine the maximum tolerated dose of AI-850 and to select doses for subsequent efficacy studies. Other study objectives include evaluation of the pharmacokinetic profiles and determination of the need for premedications for hypersensitivity. Patients will receive a bolus intravenous injection of AI-850 (lasting only a few minutes) instead of the longer 3 to 24 hour infusion required with the marketed paclitaxel formulations.

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 a versatile drug delivery system 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. In addition to the rapidly dissolving formulation of paclitaxel, Acusphere is developing two other porous microparticle product candidates; an inhaled sustained release asthma formulation and AI-700TM, an ultrasound contrast agent. The inhaled sustained release asthma formulation is being developed as part of Acusphere's joint venture with Elan Corporation, plc. The asthma product candidate entered Phase I clinical trials in May 2002. AI-700 is an ultrasound contrast agent for the detection of coronary artery disease that has completed Phase II clinical trials. Acusphere has focused on therapeutic areas where its drug delivery technology has the potential to provide significant clinical benefits. The company is financed by a leading group of venture capital investors including Polaris Venture Partners, Thomas Weisel Capital Partners and BA Venture Partners. For more information about Acusphere visit the company's Web Site at http://www.acusphere.com.