MIPI Molecular Insight Pharmaceuticals (MM)

Molecular Insight Pharmaceuticals, Inc. (NASDAQ: MIPI), this week presented positive data from Phase 1 clinical studies comparing Trofex™ (123I-MIP-1072), its lead molecular imaging candidate for the diagnosis and monitoring of metastatic prostate cancer, and ProstaScint® (111In-capromab pendetide), an imaging radiopharmaceutical for the visualization of metastatic prostate cancer. Data presented at the Annual Congress of the European Association of Nuclear Medicine in Vienna demonstrated that Trofex rapidly detected prostate cancer localized in the prostate bed, soft tissues and bone within four hours post injection. In contrast, ProstaScint required five days before imaging and was unable to detect metastatic disease in bone.

Trofex is a radiolabeled, small-molecule that binds prostate specific membrane antigen (PSMA), a protein highly expressed by prostate cancer cells, with high affinity and specificity. The high degree of uptake and retention of Trofex in prostate cancer cells allows for non-invasive molecular imaging of prostate cancer.

Data from two completed Phase 1 studies and preliminary data from one ongoing Phase 1 study were presented in an abstract titled: Detection of Metastatic Prostate Cancer (PCa) in Soft Tissue, Bone, and Prostate with 123I-MIP-1072: A Comparison with 111In-Capromab Pendetide. John W. Babich, Ph.D., Molecular Insight Executive Vice President, Chief Scientific Officer and President of Research and Development, senior author of the study, presented the data from these studies.

Study Methodology The two completed Phase 1 studies enrolled a total of 13 subjects (7 prostate cancer patients and 6 healthy volunteers) while in the ongoing study 12 patients have been enrolled. In the first two studies, patients with confirmed metastatic prostate cancer and normal subjects received Trofex (370 MBq), followed by serial whole-body planar imaging, SPECT/CT scanning, and blood and urine analysis. Image analysis from the Trofex scans was used to estimate organ pharmacokinetics and to calculate radiation dosimetry. In the ongoing study, Trofex and ProstaScint images as well as bone scans were compared in the same patient. All images were compared visually and by quantitative image analysis for assessing relative tumor detectability.

Conclusions Molecular Insight reported that in this limited group of patients Trofex visualized lesions in the prostate, lymph nodes and bone at four hours after injection, confirming that targeting the extracellular domain of PSMA with small molecules is a viable approach for imaging metastatic prostate cancer. In comparison to Trofex, which is rapidly cleared from the blood and can detect tumors within a few hours, ProstaScint requires five days for optimal imaging. In this study, ProstaScint was unable to detect bone metastases and required supplementary blood pool imaging for confirmation of lymph node metastases along the normal vasculature.

In the second presentation at the EANM Annual Congress, Molecular Insight reported new preclinical data from its prostate cancer therapy program. Molecular Insight scientists have developed an analog of Trofex that carries the therapeutic iodine radionuclide, I-131, creating a molecularly targeted radiotherapeutic that specifically binds PSMA on prostate cancer cells and offers the potential for treatment of metastatic prostate cancer. In an abstract titled Inhibition of Human Prostate Cancer Growth by Targeting Prostate Specific Membrane Antigen (PSMA) using an I-131 labeled small molecule inhibitor, researchers reported that a Molecular Insight compound, 131I-MIP-1375, was effective at inhibiting, in a dose-related manner, the growth of human PSMA-expressing prostate tumors in a mouse model. The Company said that these preclinical data provide a basis for advancing the development of 131I-MIP-1375 as a targeted radiotherapeutic option in the treatment of prostate cancer.

About Prostate Cancer According to the American Cancer Society, more than 2.5 million men are currently affected by prostate cancer and approximately 200,000 new cases are diagnosed annually. While early diagnosis has improved overall survival rates, prostate cancer is the second leading cause of cancer death among men in the United States. Most prostate cancer mortalities occur when the disease has spread and therefore staging and monitoring the disease accurately is critically important in improving patient outcomes.

About Molecular Insight Pharmaceuticals, Inc. Molecular Insight Pharmaceuticals is a clinical-stage biopharmaceutical company and pioneer in molecular medicine. The Company is focused on the discovery and development of targeted therapeutic and imaging radiopharmaceuticals for use in oncology. Molecular Insight has five clinical-stage candidates in development. For further information on Molecular Insight Pharmaceuticals, please visit www.molecularinsight.com.

Forward-Looking Statements Statements in this release that are not strictly historical in nature constitute "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, statements about the ongoing study of Trofex and the potential of (131)I-MIP-1375 to treat metastatic prostate cancer. 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; difficulties or delays in obtaining financing and generating the revenue as anticipated; competition from other pharmaceutical or biotechnology companies; and the additional risks discussed in filings with the Securities and Exchange Commission (SEC). The Company's SEC filings are available through the SEC's Electronic Data Gathering Analysis and Retrieval system (EDGAR) at http://www.sec.gov/. Press releases for Molecular Insight Pharmaceuticals, Inc. are available on our website: http://www.molecularinsight.com/. All forward-looking statements are qualified in their entirety by this cautionary statement, and Molecular Insight undertakes no obligation to revise or update this release to reflect events or circumstances after the date hereof.

Contacts: Investors Charles H. Abdalian Senior Vice President of Finance Chief Financial Officer (617) 871-6618 cabdalian@molecularinsight.com Media Martin A. Reynolds Manager Corporate Communications (617) 871-6734 mreynolds@molecularinsight.com Susan Pietropaolo BCC Partners (201) 923-2049 spietropaolo@bccpartners.com