Novel small molecules used to visualize prostate cancer

March 5, 2013, Society of Nuclear Medicine

Two novel radiolabeled small molecules targeting prostate-specific membrane antigen (PSMA) have excellent potential for further development as diagnostic and therapeutic radiopharmaceuticals, according to research published this month in The Journal of Nuclear Medicine. The imaging agents—123I-MIP-1072 and 123I-MIP-1095—were shown to have a high sensitivity of lesion detection in bone, soft tissue and the prostate gland with minimal retention in non-target tissue.

An estimated 238,500 men will be diagnosed with in 2013, and 29,700 will die from the disease. Accurate diagnosis and staging of prostate cancer is critical to determining appropriate patient management. Patients with localized disease may benefit from a , while those with are typically treated with .

"Current imaging techniques have limitations in diagnosing and staging prostate cancer. New imaging approaches, including the radiolabeled small molecules 123I-MIP-1072 and 123I-MIP-1095, may assess disease status more accurately," said John J. Babich, PhD, lead author of the article "First-in-Man Evaluation of Two High-Affinity PSMA-Avid Small Molecules for Imaging Prostate Cancer." Babich continued, "Improved imaging approaches could better facilitate the selection of optimal treatment and improve patient outcomes."

Separate studies were conducted as part of phase 1 trials under an investigational new drug application to measure the potential effectiveness of the small molecules in diagnosing and staging prostate cancer. In the first study, seven patients with documented prostate cancer were administered doses of 123I-MIP-1072 and 123I-MIP-1095 two weeks apart. In the second study, six healthy volunteers received 123I-MIP-1072 only. Whole body planar imaging and single computed tomography (SPECT)/computed tomography (CT) were performed for each group, and pharmacokinetics, tissue distribution, excretion, safety and organ were analyzed.

Both 123I-MIP-1072 and 123I-MIP-1095 visualized lesions in soft tissue, bone and the prostate gland as early as one to four hours after injection. The imaging agents cleared the blood in a biphasic manner; however, clearance of 123I-MIP-1072 was approximately five times faster, resulting in a higher lesion-to-background ratio as compared to 123I-MIP-1095. The largest organ-absorbed radiation doses for 123I-MIP-1072 were to the urinary bladder, salivary glands, and kidneys; for 123I-MIP-1095 the absorbed doses to the salivary glands, kidneys and thyroid were the largest. Both imaging agents were well tolerated by the study population.

As a result of the phase 1 findings, 123I-MIP-1072 was evaluated as a diagnostic agent in subsequent clinical trials on the basis of its higher lesion-to-background ratios and prolonged tumor retention. 123I-MIP-1095 will be clinically evaluated for radiotherapy for metastatic prostate cancer as the 131I-labeled analog.

"A more accurate method of imaging prostate cancer and prostate cancer metastases would significantly impact the clinical management of men with prostate cancer. This would provide greater certainty as to the presence and extent of disease during the course of the patient's treatment," said Babich. "Data indicate that PSMA is an excellent target for molecular imaging of prostate cancer and that radiolabeled small molecules, which bind PSMA with high affinity, can localize prostate cancer anywhere in the body. The use of SPECT for molecular imaging could represent a significant advance in cancer evaluation."

Explore further: New imaging agent has an appetite for dangerous prostate tumors

More information: "First-in-Man Evaluation of Two High-Affinity PSMA-Avid Small Molecules for Imaging Prostate Cancer" The Journal of Nuclear Medicine.

Related Stories

New imaging agent has an appetite for dangerous prostate tumors

December 8, 2011
Non-invasive imaging detects prostate cancer earlier than ever before, but can't accurately distinguish between malignant and benign disease. According to Lawson Health Research Institute's Drs. John Lewis and Len Luyt, a ...

Advanced imaging pinpoints prostate cancer faster, more accurately

October 5, 2012
It took Wayne Wentzel 14 years, multiple tissue biopsies and travel to four hospitals across multiple states to identify the underlying source of his rising prostate specific antigen (PSA) level. He finally found answers ...

Trio of studies support use of PET/CT scans as prostate cancer staging tool

October 21, 2011
Recent studies have suggested that C-11 choline positron emission tomography/computerized tomography (PET/CT) scans can be utilized as a staging and potentially therapeutic tool in prostate cancer. The results of three studies, ...

Novel technology allows for noninvasive imaging of prostate cancer

April 2, 2012
Use of a novel, noninvasive imaging tool allowed researchers to measure free prostate-specific antigen in prostate cancer models and to visualize bone metastasis in a tumor-specific manner, according to results published ...

Recommended for you

New approach attacks 'undruggable' cancers from the outside in

January 23, 2018
Cancer researchers have made great strides in developing targeted therapies that treat the specific genetic mutations underlying a patient's cancer. However, many of the most common cancer-causing genes are so central to ...

Study: Cells of three advanced cancers die with drug-like compounds that reverse chemo failure

January 23, 2018
Researchers at Southern Methodist University have discovered three drug-like compounds that successfully reverse chemotherapy failure in three of the most commonly aggressive cancers—ovarian, prostate and breast.

'Hijacker' drives cancer in some patients with high-risk neuroblastoma

January 23, 2018
Researchers have identified mechanisms that drive about 10 percent of high-risk neuroblastoma cases and have used a new approach to show how the cancer genome "hijacks" DNA that regulates other genes. The resulting insights ...

Enzyme inhibitor combined with chemotherapy delays glioblastoma growth

January 23, 2018
In animal experiments, a human-derived glioblastoma significantly regressed when treated with the combination of an experimental enzyme inhibitor and the standard glioblastoma chemotherapy drug, temozolomide.

Researchers identify a protein that keeps metastatic breast cancer cells dormant

January 23, 2018
A study headed by ICREA researcher Roger Gomis at the Institute for Research in Biomedicine (IRB Barcelona) has identified the genes involved in the latent asymptomatic state of breast cancer metastases. The work sheds light ...

Boosting cancer therapy with cross-dressed immune cells

January 22, 2018
Researchers at EPFL have created artificial molecules that can help the immune system to recognize and attack cancer tumors. The study is published in Nature Methods.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.