Cholera vaccine deployed to control African outbreakSCIENTISTS have made major breakthroughs in developing preventive and therapeutic cancer vaccines and drugs, as well as deploying the newly developed cholera vaccine during an epidemic.Researchers at Moffitt Cancer Center, United States, have developed and tested in mice a synthetic vaccine and found it effective in killing human papillomavirus-derived cancer, a virus linked to cervical cancers among others.The research was published in a recent issue of Cancer Immunology, Immunotherapy. Also, a trial drug has outperformed earlier efforts to marshall the body's defences to combat tumours.Researchers working in the burgeoning field of cancer immunotherapy last week announced that a way of arming the body's natural defences to fight tumour cells has proved effective against three different types of cancer.An antibody-based treatment developed by Suzanne Topalian, an oncologist at the Johns Hopkins University in Baltimore, Maryland, United States, and her colleagues either eliminated or shrank tumours in 49 of 236 patients with certain types of advanced skin, kidney and lung cancer.Previous cancer immunotherapies have worked in smaller percentages of patients. The results of the phase I clinical trial were published in June 2 issue of the New England Journal of Medicine.Also, patients in Guinea are first in Africa to be given oral vaccination during an epidemic. For the first time, health officials in West Africa have begun a vaccination campaign to try to control cholera during an active epidemic.According to a report in Nature, the charity Mdecins Sans Frontires (MSF; also known as Doctors Without Borders) in collaboration with the Ministry of Health in Guinea has been administering the cholera vaccine Shanchol in the region of Boffa, 150km northwest of the country's capital, Conakry.The programme began in late April, with patients receiving a two-dose oral vaccine. In total, almost 150,000 people received at least one dose of vaccine and just over 110,000 people received a second dose.Iza Ciglenecki, project manager for diarrhoeal diseases at MSF, ran the campaign in Guinea. She hopes that the results will lead to more widespread use of the vaccine in epidemics. 'Until very recently, no one was using this as an extra tool to control cholera,' she says. 'We hope to add to the evidence base regarding this vaccine to help develop an intervention criteria for the control of cholera in outbreaks.'The programme follows on the heels of two modelling studies, published in the journal PLoS Neglected Tropical Diseases last year, which suggested that cholera vaccines were beneficial after outbreaks occurred in Vietnam and Zimbabwe. But more information is needed on how and when to administer the vaccine, explains Ciglenecki.Senior member and professor in Moffitt's Immunology Programme, Prof. Esteban Celis said, 'vaccines for cancer can be good alternatives to conventional therapies that result in serious side-effects and are rarely effective against advanced disease. The human papillomavirus, or HPV, is known to cause 99 per cent of cervical cancers and annually causes more than 250,000 deaths worldwide.' In addition, HPV is the causative agent of a large proportion of head and neck and genital cancers.Although two approved prophylactic vaccines against strains of HPV that cause cervical cancer are now in wide use as a measure to prevent HPV infections, these vaccines cannot be used to treat HPV-induced cancers. Thus, there is a need to develop therapeutic vaccines for HPV-related tumors.In an effort to find an effective HPV-cancer vaccine that would eliminate existing HPV-induced cancer, Celis and Kelly Barrios-Marrugo, Ph.D., of the University of South Florida College of Medicine's Molecular Medicine programme, designed a peptide vaccination strategy called TriVax-HPV.The TriVax vaccine strategy was designed to generate large numbers of cytotoxic T-cells that would seek out the proteins preferentially expressed in the tumors. The HPV16-E6 and E7 proteins function as oncogenic proteins inducing cancer. Thus, according to Celis and Barrios-Marrugo, a vaccine targeting these viral proteins is an 'ideal candidate' to create strong immune responses, with the additional benefit of not generating autoimmune-related pathologies.When they tested their vaccine in mice with HPV16-induced tumors, they found that TriVax containing a small synthetic fragment (peptide) of the E7 protein 'induced tumor clearance in 100 percent of the treated mice' while the unvaccinated mice with HPV-induced tumors had their tumors grow 'at a fast rate.' 'Although the magnitude of the T-cell responses achieved with TriVax in mice is impressive,' Barrios-Marrugo said,' we do not know whether similar effects can be accomplished in humans.'Celis and Barrios-Marrugo point out that current therapies for cervical cancer can be devastating, highly toxic and associated with a 10 per cent chance of recurrence. Additionally, a significant proportion of women in the Third World will not receive the approved prophylactic vaccine to prevent HPV infection and, thus, will continue at high risk for cervical and other cancers related to HPV.
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