Wednesday, December 13

Developing Vaccines to Combat Cancer Are Beginning to Bear Positive Results

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Worldwide, multiply the studies in search of cancer vaccines. And it is not today. The first studies date back to the late nineteenth century, with the emergence of immunology, the discovery of antibodies and in the middle of last century, the structure of DNA. In recent decades, knowledge about genetics and disease progressed very well as the forms of treatment, including immunotherapy, which stimulates the immune system reaction to inhibit tumor. But when it comes to vaccine, the results are still in their infancy. 

Meanwhile, the vaccines of proven cancer fighting not already established, but injury-causing virus that can cause malignant tumors. This is the case of vaccination against hepatitis B, related to the occurrence of liver cancer, available and incorporated into routine vaccination in Brazil since 1998. It is also the case of a vaccine against human papillomavirus (HPV), which protects against four subtypes responsible for 70% of lesions that may progress to cervical cancer. The HPV vaccine was released commercially in the country in 2006, but still is not offered by the public health system, although cervical cancer is the second most prevalent among the female population, according to the National Cancer Institute ( INCA). While the monitoring of vaccinated patients is not yet sufficient to obtain definitive data, it is believed that the vaccine will decrease by more than 90% cases of cervical cancer. For maximum effectiveness, it should preferably be conducted before the body has contact with the virus – so before a woman begins her sexual life. The ages between 9 and 25 years of age is the main target for immunization. The HPV vaccine is also effective in preventing penile cancer.However, it is more rare – although a certain occurrence in regions of extreme poverty – no country established as a guideline to HPV vaccination for males. 

The development of vaccines to combat malignant tumors established based on principles different from the classic vaccine, which aims to prevent disease. The aim is to stimulate the body’s defenses to attack the established disease. One of the fronts in the study involves the dendritic cells that induce the body’s immune response. They are taken from blood and cultured in the laboratory with the patient’s cancer cells or proteins typical of the tumor. Are then reinjected into the patient, to stimulate the immune response that fights disease. 

Ongoing studies point towards more individualized vaccines, which target specific types growing tumors. 
In this line of vaccines, in April this year the Food and Drug Administration – FDA, drug control agency of the United States, released the T-Sipuleucel vaccine for treating prostate cancer that has already metastasized – when the disease spreads to other parts of the body – and is resistant to conventional hormone therapy. The clinical study, published in the New England Journal of Medicine, shows that, although it has not prevented the progression of the disease, the group of patients who received the vaccine had a survival rate four months longer than the group not receiving. For now, the product is only available in dozens of U.S. hospitals, the cost of treatment, which consists of three injections of the vaccine, is more than $ 90 000. 

What complicates the development of cancer vaccines is the immense diversity of malignant cells. Therefore, the dream of a single vaccine that can cure all types of cancer is considered unlikely. The ongoing studies, especially for the most prevalent tumors such as breast, lung, prostate and melanoma (skin cancer), pointing toward more individualized vaccines, ie, which target specific types of growing tumors, and thus benefiting specific profiles of patients. It is therefore possible that some day there are vaccines effective for a subtype of these tumors, or even customized vaccines only for a patient. In the context of many other advances in cancer treatment, vaccines are a promising development that should help reduce cancer mortality in the coming decades.

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