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January 2, 2007

Two Studies: Speeding Development of Novel Tracer for Prostate Cancer

Two Studies: Speeding Development of Novel Tracer for Prostate Cancer

Research Work on New Tracer Shows Future Possibilities for Use in Diagnosing, Staging Prostate Cancer, Reported in January Journal of Nuclear Medicine

RESTON, Va.—The collaborative work being performed by professionals across medical disciplines in the promising area of molecular imaging—from research scientists to nuclear medicine physicians, urologists, radiochemists and even veterinarians—provides encouraging news in fighting prostate cancer. This type of progressive—or translational—research can be seen in two papers published in the January issue of the Journal of Nuclear Medicine.

Researchers at Emory University in Atlanta, Ga., and at Nihon Medi-Physics’ research center in Chiba, Japan, collaborated closely in examining the potential of using the radiotracer FACBC to better stage or determine prostate cancer spread, said David M. Schuster, an assistant professor and director of the division of nuclear medicine and molecular imaging in Emory’s radiology department. “Our two studies show the progression of molecular imaging in what is called translational research, the process of taking research and finding useful applications for it with patients,” added co-author of “Initial Experience With the Radiotracer Anti 1-Amino-3-[18F]Fluorocyclobutane-1-Carboxylic Acid (Anti-[18F]FACBC) With PET/CT in Prostate Carcinoma.” Together with “A Preliminary Study of Anti 1-Amino-3-[18F] Fluorocyclobutyl-1-Carboxylic Acid for the Detection of Prostate Cancer,” the two papers illustrate the development of a promising radioisotope tracer (a radioactive substance) from in vitro stage (in a test tube) to in vivo (within a live subject) in animals to in vivo in individuals with prostate cancer, explained Schuster. The Emory pilot study with FACBC, performed with only 15 patients, shows that the amino acid analog may hold the potential to provide information to better stage or determine prostate cancer spread, said Schuster. He stressed that FACBC is not available for use with patients, and additional research needs to be done with larger groups of patients.

Other than skin cancer, prostate cancer is the most common type of cancer found in American men. Estimates show that there were more than 230,000 new cases of prostate cancer in this country last year. Schuster’s study is one of many in which researchers are exploring new and “better” radiotracers that could improve a physician’s ability to stage cancer, for example, by providing higher sensitivity. This is very important since treatment and recovery outlook are dependent on the stage of cancer, said Schuster. “FACBC could eventually provide additional anatomical information about cancer location,” he added, indicating that there could also be many “spin-off applications” for the tracer (for example, in patients with brain, breast and lung cancers). “This type of research is not a revolution, rather it’s an evolution; however, these kinds of evolutions can possibly lead to a revolution,” explained Schuster, who is also seeking additional funding for this research.

The two studies used FACBC with positron emission tomography (PET) and PET with computed tomography (PET/CT), both standard imaging tools that can be used to pinpoint diseases in the body. When PET is used to image cancer, a radiotracer is injected into a patient, and it is drawn in higher concentrations to cancerous areas. The highly sensitive PET scan picks up the metabolic signal of actively growing cancer cells. The CT scan generates a detailed picture of internal anatomy, locating and revealing the size and shape of abnormal cancer growths. When these two results are fused together, the functional data from the PET imaging are correlated with anatomy on the CT images to provide a single detailed and informative image.

Tracers—such as 18F-FDG, 11C-choline, 11C-acetate and others—are currently used for diagnosing prostate cancer, said Shuntaro Oka, veterinarian and an assistant research associate at Nihon Medi-Physics. In Oka’s in vitro and in vivo study, FACBC had a high accumulation in cancer cells, small excretion into the bladder and a low accumulation in areas of inflammation, indicating that it could possibly “overcome drawbacks of some traditional PET tracers,” he noted. “It is not unusual that the results of experiments lose touch with the results of clinical study; however, this time, the results of our basic studies correlated well with Dr. Schuster’s findings in patients with prostate cancer,” said Oka. “This is good news for development of our compounds,” he added, indicating clinical PET is not generally accepted in Japan; he hoped that FACBC could become “an agent to enhance the health and quality of life of patients.”

Oka said the two research studies were definite examples of molecular imaging, a technique to visualize the activity of molecules in the body. PET showed the activity of amino acid transporters that “mediate” FACBC, the radiotracer that was developed in Mark M. Goodman’s lab at Emory University, into prostate cancer. “ ‘Hot spots’ on FACBC PET indicate the location of the amino acid transporters in target tissue and the site’s increased activity of the amino acid transporters,” said Oka. Schuster indicated that the research was conducted with individuals representing “a panoply of clinical knowledge” from Emory Healthcare and Winship Cancer Institute of Emory University, Emory University, the Atlanta VA Hospital and Nihon.

The American and Japanese collaborative research appears in the January issue of the Journal of Nuclear Medicine, which is published by SNM, the largest molecular imaging and nuclear medicine association. Authors of “Initial Experience With the Radiotracer Anti 1-Amino-3-[18F]Fluorocyclobutane-1-Carboxylic Acid (Anti-[18F]FACBC) With PET/CT in Prostate Carcinoma” are David M Schuster, John R Votaw, Weiping Yu, Jonathon A Nye and Mark M. Goodman, Radiology Department, Division of Nuclear Medicine; Peter T Nieh, Viraj Master and Muta M. Issa, Urology Department; and F. DuBois Bowman, Biostatistics Department, all at Emory University in Atlanta, Ga.

“A Preliminary Study of Anti 1-Amino-3-[18F]Fluorocyclobutyl-1-Carboxylic Acid for the Detection of Prostate Cancer” was written by Shuntaro Oka, Ryota Hattori, Fumie Kurosaki, Masahito Toyama, Yasunori Yoshida and Osamu Ito, all with the Research Center, Nihon Medi-Physics Co. Ltd., in Sodegaura, Chiba, Japan; and Larry A. Williams, Weiping Yu, John R. Votaw and Mark M. Goodman, all with the PET Center and the Radiology Department at Emory University, in Atlanta, Ga.

Media representatives: To obtain a copy of this article, please contact Maryann Verrillo by phone at (703) 652-6773 or send an e-mail to mverrillo@snm.org. Current and past issues of the Journal of Nuclear Medicine can be found online at http://jnm.snmjournals.org. Print copies can be obtained by contacting the SNM Service Center, 1850 Samuel Morse Drive, Reston, VA 20190-5316; phone (800) 513-6853; e-mail servicecenter@snm.org; fax (703) 708-9015. A subscription to the journal is an SNM member benefit.


About SNM—Advancing Molecular Imaging and Therapy
SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular and nuclear imaging to diagnose, manage and treat diseases in women, men and children. Founded more than 50 years ago, SNM continues to provide essential resources for health care practitioners and patients; publish the most prominent peer-reviewed journal in the field (the Journal of Nuclear Medicine); host the premier annual meeting for medical imaging; sponsor research grants, fellowships and awards; and train physicians, technologists, scientists, physicists, chemists and radiopharmacists in state-of-the-art imaging procedures and advances. SNM members have introduced—and continue to explore—biological and technological innovations in medicine that noninvasively investigate the molecular basis of diseases, benefiting countless generations of patients. SNM is based in Reston, Va.; additional information can be found online at http://www.snm.org.

Related Items
Adobe Portable Document Format JNM article: "Initial Experience With the Radiotracer Anti 1-Amino-3-[18F]Fluorocyclobutane-1-Carboxylic Acid (Anti-[18F]FACBC) With PET/CT in Prostate Carcinoma"
Figure 1: Coronal PET and CT fused images
Figure 2: Maximum-intensity-projection image
Figure 3: Time-activity curves for initial staging data
Figure 4: Coronal PET and CT-fused images
Figure 5: Axial PET an d fused images
Figure 6: Time-activity curve for restaging patient
Adobe Portable Document Format JNM article: "A Preliminary Study of Anti 1-Amino-3-[18F]Fluorocyclobutyl-1-Carboxylic Acid for the Detection of Prostate Cancer"
Figure 1: Time course of uptake
Figure 2: Autoradiographs and corresponding sections
Figure 3: Dynamic transverse images
Figure 4: Time-activity curves for PCa, muscle, pancreas, blood and urinary bladder
Figure 5: Comparison of uptake into normal popliteal lymph node
Figure 6: Comparison of uptake into prostate lobes