Molecular Insight Pharmaceuticals, Inc.’ Trofex Data Published in Journal of Nuclear Medicine

CAMBRIDGE, MA--(Marketwire - July 07, 2011) - Molecular Insight Pharmaceuticals, Inc. today announced that data published in the Journal of Nuclear Medicine demonstrated that Trofex™, [123I]MIP-1072, the Company’s lead molecular imaging candidate for the detection of metastatic prostate cancer, is capable of tracking changes in tumor volume as tumors shrink in response to therapeutic intervention, or continue to grow when no treatment is given or when treatment fails.

Trofex, [123I]MIP-1072, is a radiolabeled small-molecule inhibitor of prostate-specific membrane antigen (PSMA), an enzyme that is highly expressed on the surface of prostate cancer cells. Trofex binds to this enzyme with high affinity and specificity and is internalized by the cancer cell. The high degree of specific uptake and retention of Trofex in prostate cancer cells allows for non-invasive molecular imaging of prostate cancer throughout the body of patients using conventional nuclear medicine cameras. Trofex is in clinical development for imaging metastatic prostate cancer. In this recently published study, the ability of Trofex to track changes in tumor mass in response to chemotherapy was evaluated in an animal model of human prostate cancer using paclitaxel as the chemotherapy and tumors derived from human prostate cancer that express PSMA.

Dr. John W. Babich, President and Chief Scientific Officer of Molecular Insight, noted, “Monitoring the progression of prostate cancer and the success of therapy remains a considerable clinical challenge. Trofex is currently being investigated in clinical trials for the detection of metastatic prostate cancer. In early clinical trials, this compound was shown to detect metastatic lesions in both bone and soft tissue of patients with evidence of metastatic prostate cancer using multiple imaging techniques. The data presented in this paper demonstrate that in a preclinical model, the high specificity of Trofex is capable of monitoring tumor progression or regression in response to chemotherapy both in vivo and in vitro. This is an important nonclinical demonstration of Trofex’s potential utility for monitoring the effects of therapy, an important component of patient management. Future studies will examine whether this benefit may be transferred to the clinic so patients may be monitored before, during, and after therapeutic intervention -- with the ultimate goal of enabling patients to receive the most appropriate therapy.”

Study summary: The data demonstrated a linear correlation between cell number and the magnitude of cellular uptake of [123I]MIP-1072 in vitro using two human tumor prostate cancer cell lines that displayed different levels of PSMA expression. Treatment of PSMA positive human prostate tumor (LNCaP) cells or xenografts with paclitaxel resulted in growth inhibition which was detected with [123I]MIP-1072. Paclitaxel promoted a decrease in tumor volume (-21%) compared to an increase in the untreated xenografts (+205%), without altering PSMA expression. Tumor uptake of [123I]IP-1072 was proportional to changes in tumor mass decreased by paclitaxel treatment and increased in untreated mice, and demonstrated a linear correlation (R2 = 0.7605) between tumor mass and the percent of the injected activity of [123I]MIP-1072 in the tumor. The high specificity of [123I]MIP-1072 for prostate cancer may allow monitoring of tumor regression or progression in patients before, during, and after chemotherapy.

A link to the published manuscript, [123I]MIP-1072, a Small-Molecule Inhibitor of Prostate-Specific Membrane Antigen, Is Effective at Monitoring Tumor Response to Taxane Therapy, is currently available on the Company’s website, www.molecularinsight.com, under the Molecular Medicine tab, Bibliography.

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, development, and commercialization of targeted therapeutic and imaging radiopharmaceuticals for use in oncology. For further information, please visit the Company’s website: www.molecularinsight.com.