(NYTimes Health) In a small, preliminary study, an experimental vaccine provoked a strong immune response against precancerous cells in women treated for cervical lesions that can progress to cancer.
Most cases of cervical cancer are caused by infection with two types of human papillomavirus, or HPV. Some women who have precancerous cervical lesions associated with the Type 16 and Type 18 strains of HPV are able to fight them off without medical intervention. They do so by producing high levels of immune cells called killer T-cells.
The experimental drug, called VGX-3100, is a therapeutic vaccine using synthetic DNA that is intended to work in patients who have abnormal precancerous changes in the cervix. It is not related to preventive vaccines meant to protect against infection with HPV. The experimental vaccine attempts to harness the human immune system to fight disease: Similar to gene therapy, the drug inserts a piece of DNA into a patient’s cells to produce a protein that primes the immune system to attack HPV-altered cells.
“Our immune system is capable of protecting us from millions of pathogens,” said J. Joseph Kim, president and chief executive of Inovio Pharmaceuticals, maker of the experimental vaccine. “We want to use the existing hardware in our immune system, but use better software to train our immune system to fight off disease.”
The new study, published online on Wednesday by the journal Science Translational Medicine, was very small, involving only 18 women, all of whom had already been treated with standard therapies for precancerous conditions associated with infection with Type 16 and Type 18 HPV. All 18 participants received three doses of the DNA vaccine by electroporation, in which an electric pulse accompanies the injection.
Administration of the experimental vaccine increased production of killer T-cells, which were aimed at the abnormal cervical cells altered by HPV. Whether the vaccine can actually eliminate or control precancerous cervical lesions in untreated patients will be tested in the next phase of research, the scientists said. Results are expected by the end of next year.
Other vaccines that mobilize the immune system, priming it to attack cancers likemelanoma and multiple myeloma, have met with varying degrees of success. Some scientists who were not involved in the research urged caution in interpreting the findings of the new study, an early so-called Phase 1 clinical trial.
Similar cancer vaccines have been under development for about 20 years, but over all the results have been disappointing so far, said William C. Phelps, program director for preclinical and translational cancer research with the American Cancer Society. Two years ago, he noted, the Food and Drug Administration approved a cancer vaccine, Provenge, for treatment of advanced prostate cancer. Trials showed it extended life by just four months on average.
Original article can be found at: http://nyti.ms/STlvRZ