MIPI Molecular Insight Pharmaceuticals (MM)

Molecular Insight Pharmaceuticals, Inc. (NASDAQ: MIPI), this week presented data from a preclinical study that indicate Trofex™ ((123)I-MIP-1072), its lead molecular imaging candidate for the detection of metastatic prostate cancer, may also be used to visualize changes in tumor volume in response to treatment of the disease. These data were presented at the American Society of Clinical Oncology (ASCO) Annual Molecular Markers in Cancer Conference in Hollywood, Florida, on October 18, 2010.

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.

In addition to the ability to rapidly visualize and monitor prostate cancer activity, there is a growing interest in improved methods to measure response to treatment of the disease. Traditional endpoints used to measure disease response in most oncology clinical trials are not adequate to evaluate metastatic prostate cancer.

Currently, paclitaxel is commonly used to treat advanced and recurrent prostate cancer. In the ASCO poster presentation, titled "Monitoring prostate cancer response to paclitaxel by molecular imaging of PSMA," Molecular Insight reported that the uptake of Trofex in animal models of human prostate cancer was shown to be proportional to tumor mass, suggesting that Trofex may visualize changes in tumor volume and therefore response to treatment or progression.

"The ability to assess tumor burden in prostate cancer is important for optimizing disease management, said John W. Babich, Ph.D., Executive Vice President, Chief Scientific Officer and President of Research and Development, and senior author. "With recent and pending approvals of therapies for hormone refractory prostate cancer, the ability to objectively track tumor response will help determine whether treatments are working and when new treatments need to be introduced. This type of measurement will also be important for more rapidly assessing the effectiveness of new therapies being developed for prostate cancer."

Study summary: It was demonstrated that paclitaxel inhibited the growth of human prostate tumor (LNCaP) cells in culture, and binding of Trofex was proportional to the density of live cells. Paclitaxel did not alter PSMA expression in these cells. Treatment of human prostate tumors in mice with paclitaxel resulted in a decrease in tumor volume (-19%) compared to an increase in tumor volume in the untreated control mice (+217%). Tumor uptake of Trofex was proportional to changes in tumor mass: decreased in paclitaxel treated tumors and increased in tumors of untreated mice.

The authors concluded that treatment of LNCaP cells or xenograft tumors with paclitaxel resulted in growth inhibition which was detected with Trofex. The high specificity of Trofex for prostate cancer may allow monitoring of changes in tumor burden in response to chemotherapy.

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 potential of Trofex in visualizing changes in tumor volume and monitoring response to treatment or progression. 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