Scientists say they have ‘completely’ cured bowel cancer using a pioneering form of immunotherapy.
They report they have achieved a ‘100-percent cure rate’ in mice without any treatment-related toxic effects.
A US team developed a new type of radioimmunotherapy (RIT), which combines traditional radiation treatment and immunotherapy.
They believe it has the potential to eradicate ‘virtually all’ types of tumors.
Immunotherapy has been hailed as a potential ‘game-changer’ in cancer treatment that could replace chemotherapy within a few years’ time.
It works by ‘waking up’ a patient’s own immune system and teaching the body to attack tumors.
Experts say they have used a new tyoe of radioimmunotherapy – which combines traditional radiation treatment and immunotherapy – to ‘cure’ bowel cancer in mice (stock photo)
Until now, RIT has had limited success combating solid tumors, say the researchers from Memorial Sloan Kettering Cancer Center (MSKCC) in New York and Massachusetts Institute of Technology in Boston.
But they have devised a new type of the therapy which, they say, has worked because it delivers the correct amount of radiation.
Study authors Steven Larson and Sarah Cheal from MSKCC wrote: ‘If clinically successful, our approach will expand the repertoire of effective treatments for oncologic patients.
‘The system is designed as a “plug and play” system, which allows for the use of many fine antibodies targeting human tumor antigens and is applicable, in principle, to virtually all solid and liquid tumors in man.’
Bowel cancer, also known as colorectal cancer, is one of the most common forms of cancer in men and women, causing 50,000 deaths in the US and in the UK every year.
Patients with an advanced form of the disease have a five-year-survival of only 11 percent.
What is radioimmunotherapy?
In immunotherapy, a laboratory-produced molecule called a monoclonal antibody is engineered to recognize and bind to the surface of cancer cells.
Drugs known called monoclonal antibodies have been devised to mimic the antibodies naturally produced by the body’s immune system that attack invading foreign substances, such as bacteria and viruses.
In RIT, a monoclonal antibody is paired with a radioactive material, or radiotracer.
When injected into the patient’s bloodstream, the radiation-linked monoclonal antibody travels to and binds to malignant cells, allowing a high dose of radiation to be delivered directly to the tumor.
It is a highly targeted method of killing cancer cells without killing health cells too, like standard chemotherapy and radiotherapy does.
The authors of the new study explain the main ‘hurdle’ why radioimmunotherapy has yielded limited impact up until now is because of problems calculating the appropriate amount of radiation to be delivered that will match an individual’s body tolerance.
Key findings of the study
The team carried out their experiment on 10 mice, which are biologically very similar to humans.
They aimed to target an antigen – which help cancer cells grow – called glycoprotein A33 (GPA33). This is found in more than 95 percent of primary and metastatic colorectal cancers in humans.
The did this using an antibody to specifically target this harmful antigen. They also used a second antibody to work as a radioactive hapten, which are molecules that prompt an immune response when attached to antibodies – to boost the effect.
This then found the cancer cells in the mice, destroyed them, leaving healthy cells unharmed.
All the treated animals tolerated the treatment well, and all had no trace of cancer remaining upon microscopic examination.
Furthermore, there was also no detectable radiation damage to critical organs, including bone marrow and kidneys.
‘This research is novel because of the benchmarks reached by the treatment regimen, in terms of curative tumor doses, with non-toxic secondary radiation to the body’s normal tissues,’ wrote the researchers.
‘The success in murine tumor models comes from the unique quality of the reagents developed by our group, and the reduction to practice methodology, including a theranostic approach that can be readily transferred, we believe, to patients.’
Essentially, they believe their approach overcame previous problems calculating the correct amount of radiation to deliver by using a mathematic model to calculate how much of the hapten-binding antibody to use.
Study limitations
The researchers, whose paper was published in in The Journal of Nuclear Medicine, hope their finding can be replicated in other cancers.
Dr Larson and Dr Cheal wrote: ‘There is a huge unmet need in oncology, especially for the solid tumors, for curative treatments for advanced disease.
‘This includes, colon, breast, pancreas, melanoma, lung, and esophageal, to name a few.’
However, experts said because of the small study size the findings should be treated with caution.
Dr Áine McCarthy from Cancer Research UK, said: ‘These scientists have carried out a small study in only 10 mice looking at improving radiotherapy treatment for bowel cancer.
‘It’s very early stage research and we’re a long way from knowing if this new approach works, and is safe to use, in people with bowel cancer.’