A new wave of experimental vaccines is the medical community’s latest hope against a powerful staph infection that kills more people in the U.S. than skin cancer and costs as much as $8 billion a year to treat.
Pfizer Inc. (PFE) and GlaxoSmithKline Plc (GSK), two of the world’s biggest drugmakers, and NovaDigm Therapeutics Inc., a closely held biotechnology company, are each testing novel vaccines to halt methicillin-resistant Staphylococcus aureus, or MRSA, long a dangerous infection in hospitals and nursing homes and which is now increasingly finding its way into daycare centers, schools and prisons.
The vaccines are in early studies and years away from possible approval. Two other drug companies have already tried and failed to make an effective vaccine, most recently Merck & Co. (MRK) in 2011. Still, as infections spread, doctors are eager for a vaccine that works.
“It’s very clear we need a vaccine, and we need it soon,” said Robert Daum, a pediatrics professor at the University of Chicago and principal investigator at the school’s MRSA Research Center, in a telephone interview. “The challenge is, we don’t really know what makes people immune to staph infections.”
Mostly benign Staphylococcus aureus bacteria live widely on people’s skin and in their nasal passages. About 1 percent of those with the bacteria carry MRSA, a toxic form of the illness that enters the bloodstream and is resistant to most treatments. MRSA, which kills more than 11,400 Americans a year, can enter the body through a cut, a sore, a catheter or a breathing tube.
Once infected, patients are typically treated with powerful antibiotics. The more these therapies are used, though, the more likely it is that the bacteria will develop resistance to them as well.
Each of the experimental vaccines being developed take a different tack toward their goal of snuffing out the bacteria. Pfizer’s and Glaxo’s products attack on several biological fronts at once, following the model of HIV drug cocktails, while NovaDigm’s sparks an immune system response to kill the bug before it enters the body.
In hospitals, a vaccine would be used for patients going into surgery or those with compromised immune systems, Daum said. Beyond hospitals, people could get routine vaccinations to help protect them against proliferating staph bacteria in places like daycare centers for children and gym locker rooms.
For Jeanine Thomas, a vaccine could have prevented years of suffering. The Chicago-based former marketing executive and avid tennis player slipped on ice and broke her ankle in December 2000. During surgery to repair the joint Thomas was infected with MRSA, leading to months of complications, organ failure and near death, she said in an interview.
“People don’t see this as an immediate threat to them,” Thomas, who founded the advocacy group MRSA Survivors Network in 2003, said in an interview. “But it’s a secret and silent killer.”
Daum, a pediatrician who was one of the first doctors to identify MRSA’s growth in hospitals and the community in a 1998 report in the Journal of the American Medical Association, has said that if such a vaccine could be made to work, it should become part of the regular pediatric vaccine schedule.
Even without a vaccine, better awareness and prevention efforts have helped reduce the amount of invasive MRSA in hospitals and other acute-care facilities in the U.S. by 20 percent, to 67,000 cases in 2010 from 82,000 in 2007-2008, according to the U.S. Centers for Disease Control and Prevention.
The greater problem now is in public places beyond hospital doors. Incidences of staph in the community, which first appear as skin infections, “increased rapidly during the past decade” to about 13,800 cases in 2010 and are likely to keep rising, according to the Atlanta-based agency.
MRSA kills more than 11,400 Americans a year, according to the CDC’s 2010 report, compared with about 9,200 who die annually from melanoma, the most serious form of skin cancer.
The spread of staph infections is a global concern, and thus a potential global market for any successful vaccine. In Europe, for example, infections are spreading, said Carmen Pessoa da Silva, a London-based medical officer with the World Health Organization.
“We are really facing a very rapid increase in these figures, and this is a reason for concern for all of us,” she said in an interview.
The new vaccines from New York-based Pfizer, London-based Glaxo and NovaDigm Therapeutics, in Grand Forks, North Dakota, are in the first phases of a three-step system of research required for U.S. marketing approval. While the earliest testing is primarily designed to check safety, it often provides clues about a treatment’s effectiveness. Typically, it takes years to complete all three test stages, and many fail.
Pfizer has two vaccines in early trials, one an updated version of the original, said Emilio Emini, the drugmaker’s chief scientific officer for vaccine research. The hope is that these treatments will spur action by either three or four separate antigens in the body, substances that activate immune system cells that are part of the body’s natural defenses against outside invaders.
Results from the Phase 1 study of the three-antigen compound will be presented next month at the Infectious Diseases Society of America meeting in San Diego, while a Phase 2 study of the four-antigen vaccine may be reported next year.
The “feeling in the field right now is that a vaccine that’s driven to one specific immunological target is probably going to be insufficient,” Emini, based in Collegeville, Pennsylvania, said in a telephone interview.
While he declined to estimate the potential market size for an approved vaccine, he said the company’s focus now is to target hospital-based infections.
GlaxoSmithKline is also evaluating a four-component vaccine, Melinda Stubbee, a spokeswoman for the company, said in an e-mail. The drugmaker has completed its first-stage trial and is evaluating the results, Stubbee said. She declined to give a time line for further development steps.
The experimental product from NovaDigm Therapeutics, aims to spur patients’ immune systems to recognize MRSA infection on the skin, before it spreads within the body, and send out T cells, Chief Executive Officer Tim Cooke said during an interview. Two Phase 1 trials showed the therapy, dubbed NDV-3, was safe in humans, he said, and earlier studies in mice found it created a protective layer of white blood cells around a skin wound infected with MRSA.
Mice without the vaccine had infections spread deeper into the skin level, he said. “We have had really excellent immune responses.”
Other scientists are working on alternative solutions that wouldn’t require a vaccine. Menachem Shoham, an associate professor of biochemistry at Case Western Reserve University in Cleveland, Ohio, is attempting to outwit the bacteria rather than kill it by ending its ability to create the poisonous toxins it produces.
The research doesn’t seek to “wipe out the bugs, just disarm them of their deadly weapons,” he said.
Resistance occurs when drugs fall short in their drive to eliminate diseases, giving weakened or left-over cells the chance to adapt biologically in ways that allow them to continue their growth. “Since the survival of the bugs isn’t threatened by our approach the likelihood of resistance development is small,” Shoham said.
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