Cancer patients have been left free of the disease after being treated with a new drug which harnesses the power of their own immune cells.
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Four of 38 patients with non-Hodgkin's lymphoma have seen "complete regressions" following treatment, while five others saw reductions of 50 per cent in their tumours.
Immunotherapy for cancer
While the trials were only carried out on patients with blood cancer, it is hoped the methods can be adapted to tackle other cancers
The drug, which could prove cheaper than other therapies that try to achieve the same effect with cells, works by activating the body's own defences to attack the cancer.
The results have been described as an "exciting" and "significant" development in the use of immunotherapy, the process of using the body's own immune system to fight disease.
While the trials were only carried out on patients with the blood cancer, it is hoped the methods can be adapated to tackle other cancers.
The disease claims the lives of more than 150,000 people in the UK every year and more than one million people are suffering from cancer at any one time.
Earlier this year doctors announced that a patient with advanced skin cancer was free of the disease two years after they injected him with billions of his own immune cells using a different method. However, experts warned at the time that the process could prove extremely expensive.
The development of the drug could prove a much cheaper alternative way of providing immunotherapy treatments.
Professor Peter Johnson, Cancer Research UK's chief clinician, said: "These exciting preliminary results come from using them to harness the body's own immune response in a new way. Although the side effects need to be monitored carefully, we hope that this type of treatment will prove to be active in larger trials in the future"
"This a significant study," said Dr Cassian Yee, Fred Hutchinson Cancer Research Center, Seattle, who has had significant results using the alternative method of treating patients with white blood cells grown in the lab.
"It remains to be seen if most of the responses are longlasting. Certainly the results are very promising."
The drug, which has been developed by Micromet, in Bethesda, Maryland, was trialled by a team led by Dr Ralf Bargou at University of Würzburg in Würzburg, German.
The results, published in the journal Science, are encouraging because they suggest that the bigger the dose, the bigger the effect.
Coauthor of the study Dr Patrick Baeuerle, of Micromet, said all seven who received the highest dose responded to the drug.
"Two of the seven had a complete response, and five a partial regression (greater than 50 per cent reduction of tumour).".
The longest duration of a response was so far seen in a patient who received one quarter of their dose. After 13 months, he remains free of the blood cancer.
There are adverse side effects involved, however, such as fevers and chills, occasionally with confusion and tremor, though all stopped after treatment ceased.
Now a further trial is investigating how the drugs works in patients with another form of blood cancer, called acute lymphoblastic leukaemia.
Trials with a similar drug are also under way on patients with another type of cancer, which affects glandular tissue and can appear in the lungs, prostate, breast, colon and elsewhere in the body.
Micromet targets the body's own white blood cells on the cancer, using a fraction of a millionth of a gram of a specialised protein called a "bispecific antibody".
The company has created antibodies, called BiTE antibodies, which are able to stick to sites with exquisite precision, in this case to activate specialised white blood cells ( T cells) to attack cancer.
The antibodies overcome a key problem with immunotherapy that as tumours become more advanced they become more "invisible" to the T cells because the cancer cells lack molecules for white blood cells to hang on to and stage their attack.
Normal antibodies are designed to latch on to one molecular target but the bispecific antibody developed by Micromet, given the name blinatumomab, binds to two, the cancer cell and the T cell, and bring the two together to target the immune system on the cancer.
The team tried varying doses of blinatumomab in patients, and found that among 38 patients, at doses from 0.0005 to 0.06 milligrams (millionths of a gram) per square metre of body surface per day, 11 of them exhibited major responses and tumour shrinking. The disease was cleared from bone marrow, spleen and liver too.