A cancer vaccine that teaches the body to fight tumours has put three lymphoma patients into remission.
The vaccine is injected directly into the tumour and teaches the immune system to destroy it, as well as seek other cancerous cells.
Researchers tested it on 11 patients with lymphoma and said some were in full remission for months and even years.
Trials have been so successful that experts believe it offers hope for many other cancers, including those of the breast, head and neck.
Although the treatment is called a vaccine, it doesn't prevent cancer. Instead, it teaches the person's immune system to fight disease.
Researchers at New York's Mount Sinai Hospital injected tumours with a stimulant that recruits immune cells called dendritic cells.
After treating the tumour with a low dose of radiotherapy, a second stimulant was injected which activated the dendritic cells.
This then instructed T cells, which are a type of white blood cell, to kill cancerous cells throughout the body, while sparing non-cancerous cells, according to the study published in Nature Medicine.
This led to three of the patients to be put into remission as the treatment shrunk both the initial tumours targeted and other ones throughout their body.
People with lymphoma have abnormal lymphocytes - white blood cells that help fight infection - that have divided out of control.
The lymphocytes can collect in any part of the body, most often in the armpits, neck or groin.
Lead author Dr Joshua Brody, director of the Lymphoma Immunotherapy Program at The Tisch Cancer Institute, said: 'The in situ vaccine approach has broad implications for multiple types of cancer.
In lab tests in mice, the vaccine drastically increased the success of checkpoint blockade immunotherapy.
This immunotherapy, which is still being researched, works by blocking points in the body's immune system where cancerous cells can hide and avoid detection.
The results warranted more trials in March - a clinical trial for lymphoma, breast, and head and neck cancer patients opened to test the vaccine with checkpoint blockade drugs.
According to the researchers, the combination was at least three times more powerful than either checkpoint blockade or the vaccine by themselves.
They are “extremely optimistic” about how effective this may be in further trials, and even described the tumour after treatment as a 'cancer vaccine factory.
It is also being tested in the lab in liver and ovarian cancer.
Dr Eric Jacobsen, clinical director of the Dana-Farber Cancer Institute's lymphoma program, told the results are exciting but said more research is needed as this was a small study.
Dr Jacobsen, who was not involved in the study, said: It's definitely proof of concept, but larger studies are definitely needed and additional strategies to try to get more than three out of 11 patients to respond.
Other experts praised the findings of the study.
Dr Silvia Formenti, chairwoman of radiation oncology at Weill Cornell Medicine and NewYork-Presbyterian, who was not involved, said 'it's really promising.
She told CNBC: 'And the fact you get not only responses in treated areas, but areas outside the field [of treatment with radiation] is really significant.
Lymphoma cancer is a cancer of the lymphatic system which is part of the immune system. There are two main types - Hodgkin lymphoma and Non-Hodgkin lymphoma.
Every year around 1,700 people are diagnosed with Hodgkin lymphoma in the UK and 8,110 in the US. And 13,500 British people are told they have Non Hodgkin lymphoma each year, while around 74,200 Americans are given the same news.