A novel treatment which is a combination of two drugs – one for malaria and the other acquired from frog eggs – may extend survival in mesothelioma patients according to a new study.
Researchers at Shanghai’s Tongji University found that mixing antimalarial drug dihydroartemisinin (DHA) with an enzyme found in early-stage leopard frog embryos – synergistically inhibited progression and angiogenesis of malignant mesothelioma, a deadly cancer associated with asbestos exposure.
The medicine’s ability to fight against tumors were examined by the researchers in 2 ways – in vitro and in vivo. in vitro refers to test done inside a test tube and in vivo refers to test done on a living thing.
DHA considerably improved the antitumor effects of the medicine combination in lab mice inoculated with cancer cells, according to researchers. They also found that those mice tumor tissue density was lower than the mice treated with DHA or Onconase alone.
The results were also found to be consistent with a quick test for analyzing compounds in vivo, known as Matrigel plug assay.
According to the researchers, unlike a combination drug of Onconase and Adriamycin, a medicine tested for mesothelioma, the therapy did not show any obvious adverse effects. The side-effects were weakness, weight loss, drop in temperature, diarrhea and partial or total loss of muscle movement.
Also, biochemical examinations of blood did not show considerable differences between the groups that received treatment and the control group either.
The team says the findings indicate that combination treatment of Onc/DHA can be a safe therapy.
The drug combination was also tested on non–small cell lung cancer.
While early results of testing Onconase in clinical trials reached phase 3 clinical trial after showing promise, findings in the preliminary clinical trial in phase 3b did not show the drug to adequately improve overall mesothelioma survival for the U.S. FDA to allow it orphan drug status. Drug maker Alfacell was forced to halt additional clinical trials in the United States because of the setback.
Onconase was allowed to be used as an orphan drug in treating malignant mesothelioma in Europe and Australia.
Ranpirnase – the generic name for Onconase – helps speed up ability of the body to kill cancer cell or prevent it from dividing. A 2011 showed mesothelioma patients could get slight therapeutic benefit from its low levels of the protein kinase enzyme Akt.
DHA – a derivative of artemisinin – was discovered by Chinese scientists in the 1970s when the extracted it from Quinghao – a traditional Chinese herb, also known as sweet wormwood.
Artemisinin and its derivatives, which are used by doctors as drugs to fight malaria, also have some effects of fighting tumor such as growth inhibition in a few tumors and tumor cells in vitro or in vivo. Studies showed that the drug was used on several types of cancers such as, breast, pancreatic, lung, melanoma, hepatoma and Kaposi sarcoma to suppress growth.
However, the mechanisms behind antitumor effects in artemisinin and onconase are not clear.
Some researchers at the Tongji University are still studying the effectiveness of the combination drug, especially how they work together in destroying mesothelioma tumors.