FDA Funds Pediatric Trial Testing Genetically Reprogrammed HSV to Treat Cancer

/PRNewswire/ -- A clinical trial testing a genetically reprogrammed herpes simplex virus as treatment for deadly forms of childhood cancer has received a U.S. Food and Drug Administration grant to support the research.

The Phase I trial at Cincinnati Children's Hospital Medical Center currently focuses on testing the safety of the agent HSV1716 in patients. The study includes young patients with solid tumors such as rhabdomyosarcoma or Ewing's sarcoma. These cancers have limited treatment options and survival rates under 30 percent when the cancers recur and spread to other parts of the body.

Survival curves for stubborn, metastatic childhood cancers have leveled off in the last decade, underscoring the need for new therapeutic approaches, says Timothy Cripe, M.D., Ph.D., principal investigator on the trial and a physician/researcher in division of Hematology/Oncology at Cincinnati Children's.

"We've exhausted our ability to improve cure rates with existing conventional therapies, and we need new solutions," he said. "This is why we are testing HSV. It's a potent virus that has been manipulated genetically with the intent of making it safe for the patient. When you're trying to fight fire with fire you need something that is strong."

The $600,000 grant from FDA is part of a program encouraging clinical development of "orphan drugs" as new treatments for rare diseases or conditions. The HSV1716 virus being tested in this trial was developed by Crusade Laboratories of Glasgow, Scotland.

HSV1716 is similar to other viruses now under development by Dr. Cripe and colleagues at Cincinnati Children's in that certain genes are removed so the virus does not infect healthy dormant cells or cause the disease in the recipient. Instead, the genetic manipulation is designed to prompt the virus to target, infect and degrade only rapidly dividing cancer cells.

Genetic information also can be added to HSV that programs the virus to attack cancer cells in other ways – such as activating certain types of chemotherapies in a one-two punch or destroying blood vessels that feed tumors. Research in mouse models of human cancer by Cripe's laboratory has shown oncolytic HSV agents to be effective at shrinking a variety of modeled tumor types, suggesting a possible approach for treating human disease.

"Our goal in the current HSV1716 trial is to light a fire to the cancer so that the virus replicates and spreads to the cancer cells," Dr. Cripe explained. "We have to take this one step at a time, and the initial phase of the trial focuses on making sure the virus doesn't cause adverse side effects. It has been tested in Europe in adults with brain cancer, squamous cell carcinoma and melanoma and shown in those trials to be safe."

HSV1716 has also been tested extensively for safety in animal models at Cincinnati Children's Hospital by Dr. Cripe and in Europe prior to it being tested in people.

The Phase I trial will include up to 18 patients and is expected to last three years. The optimum safe dosing for this virus is unknown, so the study will sequentially increase dosing levels in small groups of patients and observe for side effects as the trial proceeds. This earliest phase tests the lowest dose on older children and young adults with solid tumor cancers who have limited or no standard therapy options available.

The researchers plan to add younger patients with earlier stages of cancer as the trial proceeds. They will not be able to determine if the safety trial is successful until all patients have received treatment and the results analyzed. As with all clinical trials of new anticancer therapies in patients, many factors can influence the risk for severe side effects and anticancer activity. Even though HSV1716 may cause tumor shrinkage in mouse models of pediatric cancer, it may not have antitumor effect in patients.

Initial funding for the trial came from a private foundation, Solving Kids Cancer, of New York. Preclinical research that helped lead to the trial was supported by the American Cancer Society, the National Cancer Institute, the Cincinnati Children's Hospital Medical Center Translational Research Initiative and local foundations, including CancerFree Kids, teeoffagainstcancer.org, the Katie Linz Foundation, The Sarah Zepernick Foundation, the TeamConnor Cancer Foundation and money donated in memory of Katie McKenna Cappel and Zachary Heringer.

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CDC Study Finds U.S. Herpes Rates Remain High

/PRNewswire/ -- About 1 in 6 Americans (16.2 percent) between the ages of 14 and 49 is infected with herpes simplex virus type 2 (HSV-2), according to a national health survey released today by the Centers for Disease Control and Prevention. HSV-2 is a lifelong and incurable infection that can cause recurrent and painful genital sores.

The findings, presented at the 2010 National STD Prevention Conference, indicate that herpes remains one of the most common sexually transmitted diseases (STDs) in the United States.

The new estimate, for 2005-2008, comes from CDC's National Health and Nutrition Examination Survey (NHANES), a nationally representative survey of the U.S. household population that assesses a broad range of health issues.

The findings suggest relatively stable HSV-2 prevalence since CDC's last national estimate (17 percent for 1999-2004), because the slight decline in prevalence between the two time periods is not statistically significant.

The study finds that women and blacks were most likely to be infected. HSV-2 prevalence was nearly twice as high among women (20.9 percent) than men (11.5 percent), and was more than three times higher among blacks (39.2 percent) than whites (12.3 percent). The most affected group was black women, with a prevalence rate of 48 percent.

As with other STDs, biological factors may make women more susceptible to HSV-2 infection. Additionally, racial disparities in HSV-2 infection are likely perpetuated because of the higher prevalence of infection within African-American communities, placing African-Americans at greater risk of being exposed to herpes with any given sexual encounter.

"This study serves as a stark reminder that herpes remains a common and serious health threat in the United States. Everyone should be aware of the symptoms, risk factors, and steps that can be taken to prevent the spread of this lifelong and incurable infection," said Kevin Fenton, M.D., director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention. "We are particularly concerned about persistent high rates of herpes among African-Americans, which is likely contributing to disproportionate rates of HIV in the black community."

Research shows that people with herpes are two to three times more likely to acquire HIV, and that herpes can also make HIV-infected individuals more likely to transmit HIV to others. CDC estimates that over 80 percent of those with HSV-2 are unaware of their infection. Symptoms may be absent, mild, or mistaken for another condition. And people with HSV-2 can transmit the virus even when they have no visible sores or other symptoms.

"Many individuals are transmitting herpes to others without even knowing it," said John M. Douglas, Jr., M.D., director of CDC's Division of STD Prevention. "We can't afford to be complacent about this disease. It is important that persons with symptoms suggestive of herpes -- especially recurrent sores in the genital area -- seek clinical care to determine if these symptoms may be due to herpes and might benefit from treatment."

Combination of Prevention Approaches Needed to Reduce National Herpes Rates

Although HSV-2 infection is not curable, there are effective medications available to treat symptoms and prevent outbreaks. Those with known herpes infection should avoid sex when herpes symptoms or sores are present and understand that HSV-2 can still be transmitted when sores are not present. Effective strategies to reduce the risk of HSV-2 infection include abstaining from sexual contact, using condoms consistently and correctly, and limiting the number of sex partners.

CDC does not recommend HSV-2 screening for the general population. However, such testing may be useful for individuals who are unsure of their status and at high risk for the disease, including those with multiple sex partners, those who are HIV-positive, and gay and bisexual men.

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Discovery Explains How Cold Sore Virus Hides During Inactive Phase

Now that Duke University Medical Center scientists have figured out how the virus that causes cold sores hides out, they may have a way to wake it up and kill it.

Cold sores, painful, unsightly blemishes around the mouth, have so far evaded a cure or even prevention. They're known to be caused by the herpes simplex virus 1 (HSV1), which lies dormant in the trigeminal nerve of the face until triggered to reawaken by excessive sunlight, fever, or other stresses.

"We have provided a molecular understanding of how HSV1 hides and then switches back and forth between the latent (hidden) and active phases," said Bryan Cullen, Duke professor of molecular genetics and microbiology.

His group's findings, published in Nature, also provide a framework for studying other latent viruses, such as the chicken pox virus, which can return later in life as a case of shingles, and herpes simplex 2 virus, a genitally transmitted virus that also causes painful sores, Cullen said.

Most of the time, HSV1 lives quietly for years, out of reach of any therapy we have against it. It does not replicate itself during this time and only produces one molecular product, called latency associated transcript RNA or LAT RNA.

"It has always been a mystery what this product, LAT RNA, does," Cullen said. "Usually viral RNAs exist to make proteins that are of use to the virus, but this LAT RNA is extremely unstable and does not make any proteins."

In studies of mice, the team showed that the LAT RNA is processed into smaller strands, called microRNAs, that block production of the proteins that make the virus turn on active replication. As long as the supply of microRNAs is sufficient, the virus stays dormant.

After a larger stress, however, the virus starts making more messenger RNA than the supply of microRNAs can block, and protein manufacturing begins again. This tips the balance, and the virus ultimately makes proteins that begin active viral replication.

The new supply of viruses then travels back down the trigeminal nerve, to the site of the initial infection at the mouth. A cold sore always erupts in the same place and is the source of viruses that might infect another person, either from direct contact, or sharing eating utensils or towels, Cullen said.

The approach to curing this nuisance would be a combination therapy, Cullen said. "Inactive virus is completely untouchable by any treatment we have. Unless you activate the virus, you can't kill it," he said.

Cullen and his team are testing a new drug designed to very precisely bind to the microRNAs that keep the virus dormant. If it works, the virus would become activated and start replicating.

Once the virus is active, a patient would then take acyclovir, a drug that effectively kills replicating HSV1.

"In principle, you could activate and then kill all of the virus in a patient," Cullen said. "This would completely cure a person, and you would never get another cold sore."

He and the team are working with drug development companies in animal trials to begin to answer questions about how to deliver this drug most effectively.

Co-authors included Jennifer Lin Umbach, Ph.D., and Heather W. Karnowski, B.S., of the Duke Department of Molecular Genetics and Microbiology and Center for Virology, and Martha F. Kramer, Igor Jurak, and Prof. Donald M. Coen of the Department of Biological Chemistry and Molecular Pharmacology at Harvard Medical School. This work was supported by two NIH grants.