Molecular Insight Pharmaceuticals, Inc. Presents Clinical Oncology Data at Society of Nuclear Medicine 2012 Annual Meeting

CAMBRIDGE, MA--(Marketwire - June 14, 2012) - Molecular Insight Pharmaceuticals, Inc. today announced the presentation of nonclinical and clinical data at the Society of Nuclear Medicine 2012 Annual Meeting held June 9-13 in Miami Beach, Florida. The data were presented in seven oral sessions and five poster presentations and focused on the Company's small molecule approach to targeted radiotherapy and imaging of cancer, with particular emphasis on prostate cancer. These scientific presentations are available on the Company's website: www.molecularinsight.com/MolecularMedicine/ScientificPresentations.aspx

In a presentation titled "Small Molecule Inhibitors of Prostate Specific Membrane Antigen (PSMA) for SPECT: Summary of Phase 1 Studies in Patients with Prostate Cancer (PCa)" (Abstract 179), Dr. John W. Babich, President and Chief Scientific Officer, discussed how 123I and 99mTc-labeled small molecule PSMA inhibitors can rapidly detect metastatic prostate cancer in soft tissue and bone with high specificity and clearly visualize sub-centimeter lymph nodes. In this Phase 1 study, 123I-MIP-1072 planar and SPECT imaging were compared with 111In capromab pendetide images in a group of 24 advanced metastatic prostate cancer patients. Standard clinical endpoints of a prior documented prostate cancer diagnosis including clinical outcome, serial PSA levels, and CT and bone scans were used to define truth; biopsy confirmation of lesions detected radiographically was not included in this Phase 1 study. In 67% of subjects, a greater amount of tumor burden was observed by 123I-MIP-1072 imaging than in the same subjects imaged with 111In capromab pendetide. Additionally, there was agreement in 29% of subjects in which the 111In capromab pendetide and 123I-MIP-1072 estimated the same amount of tumor burden. The study also showed that 123I-MIP-1072 identified 20%-25% more subjects with at least one positive lesion than did 111In capromab pendetide. In addition, at the lesion level, upwards of 50% more lesions were identified as positive by 123I-MIP-1072 as compared to 111In capromab pendetide.

Also presented were the results of a separate study comparing the distribution, kinetics, and prostate cancer targeting of 99mTc-MIP-1404 and 99mTc-MIP-1405 in six patients with metastatic cancer and in six normal men. 99mTc- labeled MIP-1404 and MIP-1405 rapidly localized in bone and lymph node metastases as early as 1 hour post injection and both agents cleared rapidly from blood. Both agents identified a greater number of lesions than bone scans and rapidly detected soft tissue prostate cancer lesions including sub-centimeter lymph nodes. Non-significant uptake was seen in the prostate of normal men, though significantly lower urinary activity was seen with 99mTc-MIP-1404 than with 99mTc-MIP-1405. The lower urinary activity allows enhanced visualization of the prostate and lymph nodes in the lower pelvis making 99mTc-MIP-1404 the preferred agent for further development.

"In patients with metastatic prostate cancer, our clinical studies demonstrated that our technetium-99m-labeled compounds, particularly MIP-1404, rapidly localize to lesions in lymph nodes and bone on whole-body imaging as early as 1 hour post injection," noted Dr. Babich. "The study also showed there is a good correlation with bone scans in most subjects, but, in general, more lesions are visualized with 99mTc-MIP-1404 than with bone scan. With an increasing number of new therapies coming to market for the prostate cancer patient, visualizing disease earlier should help physicians make more rapid and informed decisions regarding the sequencing and use of this expanding group of drugs."

Dr. Babich continued, "Since our studies have demonstrated that 99mTc-MIP-1404 has less urinary excretion, and since better visualization of the prostate and surrounding lymph nodes is crucial in the imaging of prostate cancer, the Company plans to initiate a multi-center international Phase 2 clinical trial in high risk prostate cancer patients undergoing a prostatectomy. The aim of this trial will be to validate 99mTc-MIP-1404 uptake with the presence of prostate cancer in the prostate and lymph nodes as determined by histopathology. The Phase 2 trial is set to begin in the third quarter of 2012."

A second presentation titled, "[131I]MIP-1466, A Small Molecule Prostate-Specific Membrane Antigen (PSMA) Inhibitor for Targeted Radiotherapy of Prostate Cancer (PCa)" (Abstract 170), was delivered by Dr. Shawn M. Hillier, Associate Director, Biology. In this study 123I-MIP-1095, a high affinity ligand for PSMA in prostate cancer, has been shown to localize to radiologically-confirmed metastatic prostate cancer in men. That high expression of PSMA in prostate cancer led to the evaluation of the 131I analog of MIP-1095 (currently identified as MIP-1466) for therapeutic efficacy in a mouse tumor model of human prostate cancer. It was shown that 131 I-MIP-1466 dose dependently inhibited the growth of tumor xenografts in a PSMA specific manner at 131I doses that are clinically relevant. These data support clinical investigation of 131I-MIP-1466 as a targeted radiotherapeutic for the treatment of prostate cancer in men.

From now on, the compound currently identified as MIP-1466 will be known as 131I-MIP-1095. 131 I-MIP-1095 is structurally identical to 123I-MIP-1095 which was previously studied in humans for imaging prostate cancer. It is anticipated that an IND application for 131I-MIP-1095 will be filed with the U.S. Food and Drug Administration in the fourth quarter of this year, and that a Phase 1 dose escalation clinical trial will begin in the first quarter of 2013.

A third presentation titled, "Development of a Simple Kit for Tc-99m-MIP-1404, a Single Amino Acid Chelate (SAACII) Small Molecule Inhibitor of Prostate Specific Membrane Antigen (PSMA) for Imaging Prostate Cancer" (Abstract 523), was given by Director of Radiochemistry and Production, Dr. Kevin P. Maresca. He reported on the development of a simple and efficient radiolabeling kit that could eventually be used to prepare 99mTc-MIP-1404 in radiopharmacies around the world for clinical studies and beyond. Optimization of the radiolabeling reaction conditions (time, temperature and concentration) of the final product was described. Radiochemical yield, radiochemical purity and specific activity were determined by HPLC analysis.

Dr. Maresca reported that the kit preparation method was shown to be robust and tolerant to a broad range of concentrations and volumes. The simple kit also allows the production of 99mTc-MIP-1404 in high radiochemical yield, radiochemical purity and specific activity. 99mTc-MIP-1404 demonstrated excellent radiochemical stability of greater than 90% after more than 24 hours at room temperature. Furthermore, this simple kit procedure has produced sterile, safe and high quality formulations of the 99mTc-MIP-1404 that maintain PSMA binding affinity and allows for vivid diagnostic images of prostate cancer as demonstrated in early clinical experience.

About Molecular Insight Pharmaceuticals, Inc.
Molecular Insight Pharmaceuticals is a clinical-stage biopharmaceutical company focused on critical unmet diagnosis and therapeutic needs of the prostate cancer patient. The Company is targeting the development of a proprietary small molecule platform to improve detection and visualization of primary and metastatic prostate cancer and to provide a novel systemic radiotherapy for relapsed and metastatic prostate cancer. For further information, please visit the Company's website: www.molecularinsight.com.