New AIDS Therapy Nukes HIV

Radioactive Antibodies Seek and Destroy HIV Infected Cells in Mouse Study

Like guided missiles, radioactive anti-HIV antibodies seek out and destroy HIV-infected cells.

The new approach to AIDS therapy — called radioimmunotherapy — works in mice, report Ekaterina Dadachova, PhD, of New York’s Albert Einstein College of Medicine, and colleagues.

“Radioimmunotherapy is supposed to be curative,” Dadachova tells Todo en Medicamentos. “Current HIV treatments kill the virus, but it will come back because it hides in latently infected cells. Our goal is to go after those cells, so radioimmunotherapy has the potential to cure somebody completely.”

Dadachova’s colleague, Harris Goldstein,tempers his enthusiasm a bit more. Goldstein is director of the Einstein/MMC Center for AIDS Research in New York.

“If we had a nickel for every time HIV was cured we’d all be very wealthy,” Goldstein tells Todo en Medicamentos. “But it is exciting when a new conceptual approach comes along. What makes this treatment unique is that it is designed to target HIV infected cells and kill them. This really has the potential to markedly reduce the viral infection in patients.”

Nuking HIV

What has Dadachova and Goldstein so excited is their finding that the new AIDS therapy concept works not just in the test tube, but in living animals.

The treatment starts with an antibody that homes in on a piece of HIV (called gp41) that sticks out of HIV-infected cells. The antibody is attached to a radioactive isotope. It latches on to cells carrying HIV and irradiates them. Since the antibody doesn’t stick to healthy cells, the treatment doesn’t affect them.

This may sound like the future, but such treatments already exist. The FDA-approved drugs Zevalin and Bexxar are radioimmunotherapies that target cancer cells in people with non-Hodgkin’s lymphoma.

Recently, Dadachova, Goldstein, and others showed that radioimmunotherapy could be used to treat infections as well as cancers. In their new study, they show that the technique can seek out and destroy human HIV infected cells growing in specially bred mice.

“Many things fail in animals that worked in the test tube,” Goldstein says. “So the antibodies being able to hunt out and eliminate HIV infected cells brings this a lot closer to the clinic.”

Indeed, the researchers hope to begin human clinical trials within two years.

It’s an innovative, interesting approach, says HIV researcher Carrie Dykes, PhD, of the University of Rochester, New York. Dykes was not involved in the Dadachova/Goldstein study.

“I think it could play out,” Dykes tells Todo en Medicamentos. “They have a lot of animal studies to do before they get into humans. But it would be interesting to see if it would really work.”

Curing HIV?

Current therapy for HIV — known as highly active antiretroviral therapy or HAART — uses a combination of powerful drugs that keep the AIDS virus from replicating. When treatment is successful, the virus seems to disappear from the blood.

But once treatment stops, the virus eventually comes back. That’s because HIV hides in a few long-lived cells — so-called latent HIV infection.

If a person gets HAART treatment very, very soon after infection, it’s possible to stop the virus before it can establish hideouts. But there is a very narrow window of opportunity to begin this treatment — as little as a day, and certainly within 72 hours of exposure.

That’s because HAART has to work before it starts to replicate within cells. But if radioimmunotherapy were available, the treatment could seek out infected cells and kill them — effectively widening the window of opportunity to eliminate HIV infection.

Moreover, new strategies are being developed to flush HIV out of hiding. Such strategies, combined with radioimmunotherapy and HAART, might conceivably eradicate HIV, even in established infection. But that hope lies far in the future.

Dykes notes that the researchers haven’t yet shown that radioimmunotherapy can track down HIV anywhere in the body. She notes that in the current study, the treatment hit HIV only in liver, spleen, and thymus cells.

“It will be interesting to see whether you could get the radioimmunotherapy to target all the different areas that HIV gets to in the body,” she says. “I have a feeling this treatment probably wouldn’t cross the blood/brain barrier and get to HIV in the brain.”

Dykes agrees with Goldstein that a major benefit of radioimmunotherapy would be to help people for whom HAART simply doesn’t work very well.

“A lot of patients out there don’t have a lot of treatment options left,” Dykes says. “For those patients, this treatment — which, after all, involves radiation — might be something they would be willing to do.”

“While two-thirds of people with HIV respond well to HAART, others don’t,” Goldstein says. “If we treat them with radioimmunotherapy to reduce the number of infected cells, we may be able to take patients who are not responsive and make them responsive to HAART.”

More information at Todo en Medicamentos.

CDC: Routine HIV Testing for All

Recommendation Opens Way to HIV Test as Regular Part of Medical Checkup

The CDC now officially advises all health care providers to test everyone aged 13 to 64 for HIV infection.

The next time you see a doctor, you’ll be told that your routine lab tests will include an HIV test. You’ll have the opportunity to refuse the test. But if you don’t opt out, your lab results will come back "HIV negative" or "HIV positive."

Why? The CDC estimates that at least a quarter of a million Americans carry HIV without knowing they’re infected. And by the time 40% of Americans learn they’re HIV positive, they’ve carried the virus for about 10 years. This means they can’t get the full benefit of treatment — and that they’ve unwittingly infected others.

"No child in the U.S. should be infected from birth. No person in the U.S. should lack access to HIV treatment or diagnosis. And nobody should get HIV. We should be able to eliminate HIV transmission in the future," CDC director Julie L. Gerberding, MPH, said in a news conference announcing the new recommendations.

HIV Testing: What Will Change

Current recommendations call for doctors to offer people HIV tests if they are at high risk of infection. They also demand that a person receive detailed HIV prevention counseling before testing, and that they sign a consent form.

This approach hasn’t worked. Health providers often fail to find time to assess a patient’s HIV risk, provide counseling, and obtain written consent — even in patients who have other sexually transmitted diseases. And patients with high-risk behaviors, feeling stigmatized by being singled out, may refuse HIV tests.

The new recommendations remove these "barriers" to testing, says Kevin Fenton, PhD, director of the CDC’s National Center for HIV, STD, and TB Prevention.

"The purpose is to make sure everyone has lifesaving information on whether they are infected," Fenton said at the news conference.

The lives that would be saved aren’t just those of the people who are infected. CDC data suggest that people who don’t know they carry HIV are 3.5 times more likely to infect another person than people who are aware of their HIV infection.

The CDC estimates that if everyone with HIV infection knew it, there would be about a third fewer new sexual HIV transmissions.

Fenton stressed that the recommendations apply only to health care settings. HIV/AIDS outreach programs, community-based organizations, or mobile testing vans will still have to provide pretest counseling and obtain signed consent.

The lifting of the counseling and consent requirement isn’t getting universal approval. The National Association of People With AIDS — which has for years called for universal HIV testing – says that counseling and consent are crucial aspects of HIV testing.

"Testing without consent is a violation of ethical medical standards, pure and simple, and the removal of counseling and informed consent will heighten chances these abuses will occur," NAPWA board chair Judith Billings, said in a news release.

HIV in Pregnant Women

There’s already universal HIV testing of pregnant women in the U.S. That’s because simple anti-HIV treatment during pregnancy greatly reduces the risk that a mother will pass HIV to her child.

This has reduced the flood of mother-to-child HIV transmission to a trickle: from a peak of about 1,650 cases in 1991 to about 240 cases in recent years.

The new recommendations seek to staunch even this trickle of cases. They call for repeat HIV testing during the third trimester of pregnancy for all women living in areas where there’s at least one HIV diagnosis per 1,000 pregnant women screened.

There’s also a recommendation to give a rapid HIV test during labor when a woman’s HIV status is unknown.

Linking Testing to Treatment ‘Critical’

The sad reality in the U.S. is that not everyone who needs HIV treatment gets it.

Federal and state programs that pay for HIV treatment already are overburdened, says Harvard researcher Daniel R. Kuritzkes, chair of the HIV Medicine Association and director of AIDS research at Brigham and Women’s Hospital in Boston.

"The big question mark is where the resources will come from to pay for the care of all these people," Kuritzkes tells Todo en Medicamentos. "If we find all those 250,000 new cases of HIV, that is a really big bolus of people entering the treatment system. It will be a real disservice to find them and not offer them care."

"Linkage of testing to care is critical — treatment is the other side of the testing coin," Timothy Mastro, acting director of the CDC’s Division of HIV/AIDS Prevention, said at the news conference. "There certainly is much more work to be done. We are working with the HHS Health Resources and Services Administration to make sure individuals do have access to care."

Kuritzkes says that federal legislation will be needed to expand access to treatment for those who cannot afford it.

More information at Todo en Medicamentos.