Molecular Insight Pharmaceuticals, Inc. Announces Positive Results of Azedra(TM) Phase 1 Dosimetry Trial for Neuroendocrine Tumors.

- Ultratrace Technology Demonstrated Increased Efficacy and Improved Side Effect Profile in Data Presented at European Association of Nuclear Medicine Meeting -

CAMBRIDGE, Mass. -- Molecular Insight Pharmaceuticals, Inc. (NASDAQ: MIPI) announced today positive results of the Phase 1 dosimetry trial of its lead oncology molecular radiotherapeutic candidate, Azedra(TM) (Ultratrace(TM) iobenguane I 131, or Ultratrace MIBG) and further preclinical studies. The trial was designed to evaluate the safety, tolerability and distribution of Azedra in adult patients with either carcinoid or pheochromocytoma neuroendocrine cancers. Results from the trial were part of an oral presentation at the European Association of Nuclear Medicine 2007 Annual Congress in Copenhagen, Denmark. The presentation also highlighted that the ultrapurity resulting from Ultratrace technology used in Azedra produced no change in overall patient safety and that Azedra demonstrated increased efficacy and safety over currently available MIBG in preclinical animal models.

Azedra has Fast Track and Orphan Drug designations from the U.S. Food and Drug Administration. Developed using Molecular Insight's proprietary Ultratrace technology, Azedra, which is free of unnecessary cold contaminants, is designed to maximize the radiotherapy delivered to neuroendocrine tumors while minimizing side effects. Cold contaminants are biologically active, non-radiolabeled MIBG molecules present in currently available MIBG therapy that, when administered to patients, may sub-optimize efficacy and cause unnecessary side effects.

"Azedra exemplifies Molecular Insight's strategy to apply its radiochemistry expertise to improve an existing therapy. Current targeted radiotherapies for cancer suffer from sub-optimal radiochemistry, which leads to an excess of non-therapeutic, cold contaminant molecules administered to patients. These cold contaminants compete for tumor binding and reduce the amount of therapeutic radiopharmaceutical that can bind the cancer cells. Our proprietary Ultratrace technology eliminates the presence of cold contaminants, creating a product that contains only radiolabeled molecules," said John W. Babich, President and CSO of Molecular Insight and an author on the study. "We believe that this ultrapurity, or lack of cold contaminants, produces optimal tumor uptake and efficacy. Additionally, the animal data in this study demonstrated that Azedra's ultrapurity resulted in a more favorable cardiovascular side effect profile than is available with current MIBG."

"There are no currently approved treatments in the United States for patients with metastatic neuroendocrine tumors, so a targeted radiotherapeutic such as Azedra that might provide a more potent, effective therapy would be a significant therapeutic advancement for the treatment of these diseases," commented Dr. R. Edward Coleman of Duke University Medical Center and an author on the study.

Dr. Norman LaFrance, Senior Vice President of Clinical Development and CMO of Molecular Insight added, "As we anticipated and demonstrated in this dosimetry trial, Ultratrace technology did not alter the tissue distribution or pharmacokinetics of Azedra in neuroendocrine tumor patients with pheochromocytoma or carcinoid, enabling us to progress the product into the therapeutic dose-ranging trial that is currently underway. We are very pleased that the current trial is confirming that Azedra is well tolerated with impressive preliminary efficacy, and we expect that after we determine the maximum tolerated dose for Azedra, we will initiate a planned pivotal Phase 2 efficacy trial in the first half of 2008."

Study Design and Outcomes

The study, "Radiation Dosimetry and Clearance of No Carrier-added 131I-MIBG (Ultratrace) in Seven Carcinoid and Four Pheochromocytoma Patients," was designed to evaluate Ultratrace technology and its application in cancer therapy, the impact of cold-carrier MIBG on efficacy and toxicity and the Phase 1 dosimetry of Azedra, which was designed to evaluate the safety, tolerability and distribution of Azedra in adult patients with one of two forms of neuroendocrine cancer, carcinoid or pheochromocytoma. Overall, Azedra was well tolerated and the pharmacodynamics observed were consistent with results previously observed with cold-carrier 131I-MIBG.

In the dosimetry study, seven patients with carcinoid disease and four patients with pheochromocytoma received a single intravenous administration of Azedra. Patients were then scanned with serial anterior/posterior scintigraphic images, and blood and urine samples were collected during a five day follow-up period. Analysis of the scans in the region of interest analysis was then used to compute radioactive uptake for several organs. Distribution of the radioisotopes was as expected in internal organs. From a pharmacokinetic standpoint, Azedra blood levels rapidly declined after i.v. injection.

Authors on the study were: J.A. Barrett, N. Borys, J.F. Kronauge, H. Mok, J. Qi and J.W. Babich, from Molecular Insight Pharmaceuticals, Inc.; R.E. Coleman, M.A. Morse, N. Petry and G. Vaidyanathan, from Duke University; and J.B. Stubbs, from Radiation Dosimetry Systems, Inc.

About Molecular Insight Pharmaceuticals, Inc.

Molecular Insight Pharmaceuticals (NASDAQ: MIPI) is a biopharmaceutical company specializing in the emerging field of molecular medicine, applying innovations in the identification and targeting of disease at the molecular level to improve healthcare for patients with life-threatening diseases. The company is focused on discovering, developing and commercializing innovative and targeted radiotherapeutics and molecular imaging pharmaceuticals with initial applications in the areas of oncology and cardiology. Its lead targeted molecular radiotherapeutic product candidates, Azedra and Onalta, are being developed for detection and treatment of cancer. The company's lead molecular imaging pharmaceutical product candidate, Zemiva, is being developed for the diagnosis of cardiac ischemia, or insufficient blood flow to the heart. In addition, the company has a growing pipeline of product candidates resulting from application of its proprietary platform technologies to new and existing compounds. Molecular Insight Pharmaceuticals is based in Cambridge, Massachusetts and its website address is: www.molecularinsight.com.

Forward-Looking Statements

Statements in this release that are not strictly historical in nature constitute "forward-looking statements." Such statements may include, without limitation, statements with respect to the Company's plans, objectives, expectations and intentions and other statements identified by words such as "may," "could," "would," "should," "believes," "expects," "anticipates," "estimates," "intends," "plans" or similar expressions. Examples of such statements include, but are not limited to, statements regarding potential uses of Azedra or Ultratrace, other statements regarding product candidates, product development programs, the U.S. FDA, or the clinical trial process or its outcomes. Such forward-looking statements involve known and unknown risks, uncertainties, and other factors that may cause the actual results of Molecular Insight to be materially different from historical results or from any results expressed or implied by such forward-looking statements. These factors include, but are not limited to, risks and uncertainties related to the progress, timing, cost, and results of clinical trials and product development programs; difficulties or delays in obtaining regulatory approval for product candidates; competition from other pharmaceutical or biotechnology companies; and the additional risks discussed in filings with the Securities and Exchange Commission. All forward-looking statements are qualified in their entirety by this cautionary statement, and Molecular Insight undertakes no obligation to revise or update this news release to reflect events or circumstances after the date hereof.