Monday, December 19, 2011

Drugs double the efficacy of radiation therapy

Radiation therapy is frequently used in the treatment of cancer. It works by irradiating the tumour, which harms the malicious cells. As a side-effect, however, healthy tissue is also affected by the harmful rays. That is why radiation needs to be given in a low dose, which reduces the efficiency. Scientists from Georgia Health Sciences University have discovered that combining a drug therapy with radiation can be beneficial for the patient. In fact, by selectively targeting cancer cells with medicine, the efficacy can be doubled, which is a great improvement for cancer patients.

A patient undergoing radiation therapy.
Breaking the code
Radiation therapy works by damaging the DNA in the cancer cell. By inducing damage, the cell can not function properly anymore, and will die. However, the body has repair mechanisms for DNA damage, and cancers can harness those as well. The drug therapy that was developed at Georgia Health Sciences University works by reducing the repair capabilities of cancer cells, which makes radiation much more effective.

Targeting
Cancer cells can be selectively targeted by aiming for folate receptors on the cellular surface. The folate receptor obviously binds to folate, and the scientists have found a way to attach a drug to the latter. After folate, coupled with the drug, binds to the receptor, and is taken up by the cell. Once inside the cell, the drug is free to target an enzyme that is involved with DNA repair. Inhibiting it leaves the cell vulnerable to DNA damage, and that is exactly what we want. Because folate receptors are predominantly found on cancer cells, they are likely to get the highest dose.

Prospects
So far, the drug therapy seems to be beneficial. However, scientists have only performed tests on cells in the lab, which means the method is yet to be tested on humans. So far, it is unclear when the first clinical trials will start. It is likely that the researchers will want to optimize their method first: maybe it is possible to crank up the specificity and efficacy even more.

Soy beans
At the same time, scientists from Wayne State University found a therapy that is pretty much similar. A compound found in soy beans is also able to inhibit DNA repairing enzymes in cancer cells, and can be used in the same way as the aforementioned drug therapy. The researchers from Wayne State University claim their soy bean-based therapy is safer, because it is based on natural compounds.

Drugs and radiation
It is not the first attempt to combine drugs with radiation to increase efficacy and reduce side-effects. Previously, scientists gave drugs to mice to reduce leaking of the gut, a common side-effect of radiation therapy that leads to bacterial infection. Combined with antibiotics, they managed to reduce the number of infections obtained through radiation. Because of the treatment, mice managed to stay alive when given a normally lethal dose of radiation.


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