Guide to News at ASCO Meeting - 06/08/2010
Guide to News at ASCO Meeting
June 8, 2010 -- These news tips are based on abstracts and presentations by Johns Hopkins Kimmel Cancer Center scientists at the annual meeting of the American Society of Clinical Oncology, June 4-8, in Chicago.
DRUG THAT RESTRICTS BLOOD SUPPLY TO PROSTATE TUMORS DELAYS DISEASE PROGRESSION
A blood vessel-blocking drug called tasquinimod slowed the rate of disease progression in a clinical trial of 200 prostate cancer patients, according to experts at Johns Hopkins, Roswell Park Cancer Institute and Duke University.
Tasquinimod is a so-called "anti-angiogenesis" drug that squeezes off blood supply to prostate tumors by blocking new blood vessel development. Tumors require these vast networks of blood vessels to supply nutrients.
The multicenter trial at seven institutions, including Johns Hopkins, enrolled prostate cancer patients whose disease had spread to take a once-daily pill for four weeks. At six months, 57 percent of men taking tasquinimod had no disease progression as compared with 33 percent taking a placebo. Overall, the drug added approximately 12 weeks of time that the disease did not worsen (progression-free survival).
The most common side effects included gastrointestinal problems, fatigue and bone pain, and some rare occurrences of heart attack, stroke and deep vein thrombosis.
"Given these results, we feel it is reasonable to move forward with Phase III studies," says Michael Carducci, M.D., professor at the Johns Hopkins Kimmel Cancer Center, who will lead the next phase of an international study of the drug. "After exploring the drug as a single agent, we may study it in combination approaches with other prostate cancer drugs."
Research leading to tasquinimod began in the early 1990s when John Isaacs, Ph.D., a professor at the Johns Hopkins Kimmel Cancer Center, found that a drug called linomide, which had been tested in multiple sclerosis, restricted blood supply to prostate tumors. However, the drug's cardiac side effects were too toxic for humans, so Isaacs in collaboration with the pharmaceutical company Active Biotech identified tasquinimod for clinical testing after searching for drugs similar to linomide with the same blood vessel action but with less toxicity.
Isaacs says that tasquinimod works by stopping new blood vessel development around the tumor, but does not make existing vasculature disappear. "The idea for anti-angiogenesis drugs is not to prevent tumors from developing; rather, it is to stabilize disease," says Isaacs, who is conducting additional laboratory studies to identify the drug's precise cellular target.
Funding for the study was provided by Active Biotech, manufacturer of tasquinimod, and the U.S. Department of Defense.
Carducci is a paid consultant to Active Biotech and the terms of this arrangement are being managed in accordance with policies set by The Johns Hopkins University.
DELAY IN SURGERY NOT LIKELY TO WORSEN TUMORS IN MEN WITH LOW-RISK PROSTATE CANCER
Johns Hopkins experts have found that men enrolled in an active surveillance program for prostate cancer that eventually needed surgery to remove their prostates fared just as well as men who opted to remove the gland immediately, except if a follow-up biopsy during surveillance showed high-grade cancer.
Active surveillance, or "watchful waiting," is an option open to men whose tumors are considered small, low-grade and at low risk of being lethal. Given the potential complications of prostate surgery and likelihood that certain low-risk tumors do not require treatment, some men opt to enroll in active surveillance programs to monitor PSA levels and receive annual biopsies to detect cellular changes that signal a higher grade, more aggressive cancer for which treatment is recommended. Yet, according to the Johns Hopkins experts, there is concern that delaying surgery in this group until biopsy results worsen may result in cancers that are more lethal and difficult to cure.
Bruce Trock, Ph.D., associate professor at the Johns Hopkins Brady Urological Institute, and his colleagues compared the pathology results of men in an active surveillance group at Johns Hopkins who later had surgery with those who also had low-risk tumors and opted for immediate surgery.
Results initially showed that 116 active surveillance participants who had surgery were more likely to have high-grade, larger tumors than 348 men who had immediate surgery. But Trock says that these results were found only in 43 (37 percent) men in the surveillance group who were recommended for surgery because a follow-up biopsy during surveillance worsened to indicate a high-grade tumor.
"We think that these men had high-grade tumors to begin with that their initial biopsy missed, and this group may be over-represented in men who are recommended for treatment after an initial period of active surveillance," says Trock. He adds that, in general, 15 to 25 percent of men whose initial biopsy shows a low-risk prostate tumor will actually have a high-grade cancer upon further review of the entire prostate once it is removed.
Apart from the 43 men whose pathology results worsened during surveillance, the remaining men in the surveillance group had similar pathology results at surgery to those in the immediate surgery group.
"This means that most tumors are not likely to worsen during the period of active surveillance," says Trock.
The researchers calculate that the risk of finding high-grade tumors in the entire group of 801 active surveillance patients is low -- about 4.5 percent per year.
Trock is leading a National Cancer Institute-funded study with four other cancer centers to identify biomarkers that may identify men who have worse tumors than their initial biopsy indicates.
The Johns Hopkins Active Surveillance program, led by H. Ballentine Carter, M.D., of Johns Hopkins, has enrolled 801 men since 1995 and is believed to be the largest such program in the U.S. Fourteen men in the program who later had radiation and four who had radical prostatectomy developed recurrences, but no participants have developed distant metastases and none have died from prostate cancer.
Fourteen men in the program died from other causes unrelated to prostate cancer.
The current study was funded by the Johns Hopkins Prostate Cancer Specialized Program of Research Excellence (SPORE) grant awarded by the National Cancer Institute and by Dr. and Mrs. Peter S. Bing. The research also was presented at the American Urological Association Annual Meeting (Abstract #1062).
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