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An Experimental Vaccine to Treat Malaria

Scientists hope to get a better grasp on the system these vaccines employ, known as cellular immunity. Harnessing this system could help tackle hepatitis and HIV infection.

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Vaccines
A doctor assists people looking for treatment for malaria at a health center in San Felix, Venezuela. VOA
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After decades of disappointment in efforts to develop a malaria vaccine, researchers are starting to see promise in a new approach.

While most vaccines trigger the body’s defenses to produce antibodies against a disease-causing germ, the new approach recruits an entirely different branch of the immune system.

If it works, it could open up a new route to attack other diseases, including hepatitis and possibly HIV, the virus that causes AIDS.

Nearly 450,000 people die of malaria each year, according to the World Health Organization. The parasites that cause the disease are increasingly becoming drug-resistant.

One successful vaccine has been developed so far, but it prevented only about a third of cases in a clinical study.

Experts have decided that’s better than nothing. The vaccine is being piloted in Ghana, Kenya and Malawi.

Vaccine
Defensive cells killed liver cells that were infected with malaria parasites. (VOA)

New angle

Other scientists are trying a different angle of attack.

There are basically two ways to prevent germs from causing infections. “You either prevent them from getting into cells with antibodies, or you kill them inside the cells with T-cells,” said Stephen Hoffman, chief executive officer of Sanaria, a company working on one vaccine.

Most vaccines target the infection by building up antibodies. “If you need to kill them inside the cells with T-cells, we haven’t been overwhelmingly successful,” Hoffman said.

But Sanaria is one group seeing success by targeting malaria parasites inside infected liver cells, the first stop in the complex life cycle of the disease.

One key difference is how the vaccine is delivered. Hoffman’s group tried a typical route: injecting radiation-weakened parasites into patients’ skin or muscle. That didn’t work.

But it did work when injected directly into veins.

Vaccine
A public health worker takes a blood sample from a woman to be tested for malaria in Bo Rai district, Trat province, Thailand. VOA

The weakened parasites traveled to the liver, where they set off an immune reaction. Defensive cells killed liver cells that were infected with malaria parasites.

And the liver’s defenses were ready when faced with the real thing months later.

Most of that early work has been done in mice and macaques. When Hoffman and colleagues did something similar with a handful of human patients, most were protected against infection.

No waiting

Recruiting immune cells in the liver is especially effective because “we don’t need to wait until the immune system figures out that the parasite is in the liver and starts mounting an immune response, which can take days and sometimes weeks,” said Adrian Hill, director of the Jenner Institute at Oxford University.

“By then, the malaria’s gone. It only spends a week in the liver, and then it’s out in your blood causing disease.”

Vaccine
FILE – A worker of the Ministry of Public Health and Population fumigates in the street against mosquito breeding to prevent diseases such as malaria, dengue and Zika in Port-au-Prince, Haiti, Feb. 15, 2016. VOA

Hill’s group just published a study in the journal Science Translational Medicinein which immune cells in the liver were triggered by using a protein from the parasite, rather than the entire organism.

Scientists hope to get a better grasp on the system these vaccines employ, known as cellular immunity. Harnessing this system could help tackle hepatitis and HIV infection.

Also Read: Alcohol Kills More People Than AIDS, Violence Combines: WHO

Drugs can control HIV infection but can’t eliminate it from the body.

“If somebody could get cellular immunity to work really well for vaccination, that would be transformative for a whole range of diseases,” Hill said. “Not just for infectious diseases that we want to prevent, but ones that we want to treat and we can’t treat today.” (VOA)

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Immunotherapy Drugs Show Significant Improvement Against Breast Cancer: Study

Side effects need a close look, both doctors said. Nearly all study participants had typical chemo side effects such as nausea or low blood cell counts.

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Breast Cancer
This undated fluorescence-colored microscope image made available by the National Institutes of Health in September 2016 shows a culture of human breast cancer cells. For the first time, one of the new immunotherapy drugs has shown promise against breast cancer in a large study that combined it with chemotherapy to treat an aggressive form of the disease. VOA

For the first time, one of the new immunotherapy drugs has shown promise against breast cancer in a large study that combined it with chemotherapy to treat an aggressive form of the disease. But the benefit for most women was small, raising questions about whether the treatment is worth its high cost and side effects.

Results were discussed Saturday at a cancer conference in Munich and published by the New England Journal of Medicine.

Drugs called checkpoint inhibitors have transformed treatment of many types of cancer by removing a chemical brake that keeps the immune system from killing tumor cells. Their discovery recently earned scientists a Nobel Prize. Until now, though, they haven’t proved valuable against breast cancer.

Breast Cancer
Weight loss may lower breast cancer risk for post-menopausal women. Pixabay

In the study

The new study tested one from Roche called Tecentriq plus chemo versus chemo alone in 902 women with advanced triple-negative breast cancer. About 15 percent of cases are this type, their growth is not fueled by the hormones estrogen or progesterone, or the gene that Herceptin targets, making them hard to treat.

Women in the study who received Tecentriq plus chemo went two months longer on average without their cancer worsening compared with those on chemo alone, a modest benefit. The combo did not significantly improve survival in an early look before long-term follow-up is complete.

Failed protein test

Previous studies found that immunotherapies work best in patients with high levels of a protein that the drugs target, and the plan for the breast cancer study called for analyzing how women fared according to that factor if Tecentriq improved survival overall.

breast cancer
FILE – A patient receives chemotherapy treatment for breast cancer at the Antoine-Lacassagne Cancer Center in Nice, July 26, 2012. VOA

The drug failed that test, but researchers still looked at protein-level results and saw encouraging signs. Women with high levels who received the combo treatment lived roughly 25 months on average versus about 15 months for women given chemo alone.

That’s a big difference, but it will take more time to see if there’s a reliable way to predict benefit, said Dr. Jennifer Litton of the MD Anderson Cancer Center in Houston. She had no role in running the study but enrolled some patients in it and oversees 14 others testing immunotherapies.

“We’re really hopeful that we can identify a group of women who can get a much bigger and longer response,” she said.

Another breast cancer specialist with no role in the study, Dr. Michael Hassett at Dana-Farber Cancer Institute in Boston, said he felt “cautious excitement” that immunotherapy may prove helpful for certain breast cancer patients.

Breast Cancer
Breast cancer cell, Wikimedia Commons

Side effects and cost

Side effects need a close look, both doctors said. Nearly all study participants had typical chemo side effects such as nausea or low blood cell counts, but serious ones were more common with the combo treatment and twice as many women on it stopped treatment for that reason.

Three of the six deaths from side effects in the combo group were blamed on the treatment itself; only one of three such deaths in the chemo group was.

Also Read: New DNA Tool To Predict People’s Height And Risk For Cancer

Cost is another concern. Tecentriq is $12,500 a month. The chemo in this study was Celgene’s Abraxane, which costs about $3,000 per dose plus doctor fees for the IV treatments. Older chemo drugs cost less but require patients to use a steroid to prevent allergic reactions that might interfere with the immunotherapy. Abraxane was chosen because it avoids the need for a steroid, said one study leader, Dr. Sylvia Adams of NYU Langone Health.

The study was sponsored by Roche and many study leaders consult or work for the company or own stock in it. (VOA)