A newly developed vaccine that researchers hope will prove effective at destroying tumors in cases where all other treatments have failed is currently being trialed in the U.K. The first two participants have already been injected with the medication at Guy’s Hospital in London, and a total of around 30 patients are expected to take part in the study over the next two years.

Similar to how vaccines protect us from certain infections, the treatment attempts to recruit the body’s own immune system to attack and destroy specific entities – in this case cancer cells. Normally, the various components of the immune system – which include white blood cells such as T cells – protect against cancer by killing tumor cells, although some tumors are able to evade these natural defences.

When this occurs and cancer develops to an advanced stage, the immune system is often suppressed. Numerous factors are thought to be responsible for this effect, ranging from tumor cells’ ability to damage immune cells, to a decrease in white blood cell production when cancer spreads to the bone marrow.

Vaccines typically work by injecting a patient with small amounts of antigens, substances that are capable of eliciting an immune response, which stimulate the body to produce antibodies that specialize in the labeling and destruction of that particular entity. The ability to generate these antibodies is retained for a period of time, meaning that the immune system can then fend off future cases of the same illnesses.

Accordingly, the new vaccine currently being tested is comprised of small fragments of an enzyme found in cancer cells. Called human telomerase reverse transcriptase (hTERT), this regulates the length of the protective caps on chromosomes called telomeres, enabling the cells to divide continuously. Scientists are hopeful that this will stimulate patients’ immune systems to produce antibodies that can target this enzyme, thereby facilitating the destruction of cancer cells.

To give the process a kick-start, the vaccine is being combined with low doses of chemotherapy, in order to kill some of the tumor cells and disinhibit the immune system. The investigators behind the trial believe the vaccine could prove effective for all types of solid tumors, and are testing its safety and efficacy on patients whose cancer has been diagnosed as terminal.

Among these is 35-year-old Kelly Potter, who was diagnosed with advanced cervical cancer last summer, but says that taking part in the study has “changed [her] life for the better,” adding that “it’s fantastic to be part of something that could be ground-breaking.”