Cancer Research UK's phase I trial results of CHT25 published in Clinical Cancer Research

Dec 16 2009

New radioactive drug shows impressive results in early Hodgkin's lymphoma

TWO THIRDS of Hodgkin's lymphoma patients treated with an experimental radioactive cancer therapy responded well to the treatment, reveal the results of a Cancer Research UK phase I trial published in Clinical Cancer Research, today (Tuesday).

Researchers at Cancer Research UK's Experimental Cancer Medicine Centre at UCL Cancer Institute and the Royal Free Hospital in London tested an experimental drug therapy called CHT25 in 15 lymphoma patients who were no longer responding to standard treatments, in order to determine a safe dose and effectiveness.

Results from the trial showed that two thirds of the patients receiving a clinically relevant dose of CHT25 showed clinical benefit, by responding completely or partially to the treatment. One patient remains disease free two and half years later. In addition, there was evidence to suggest that CHT25 may also benefit people with T-cell lymphoma.

CHT25 is based on an antibody treatment given to people who have received kidney transplants to prevent them from rejecting their new organ. In the late 1990s Professor Richard Begent, a Cancer Research UK clinical scientist and Dr Peter Amlot, both at UCL, modified the antibody by linking it to a radioactive isotope. The antibody delivers the radioactive isotope to tumour sites in the body where it selectively kills lymphoma cells. This clinical trial was then set up by the charity and managed by its drug development office.

The antibody part of CHT25 is very similar to a human antibody and can be administered in repeated treatments with a minimal risk of immune reaction.

The trial showed that radioactivity was targeted selectively to cancer cells reducing damage to healthy cells. The radioactivity was also shown to remain at the tumour site for at least four days giving maximum therapeutic effect.

Professor Richard Begent, head of Cancer Research UK's Experimental Cancer Medicine Centre at UCL Cancer Institute, said: "These initial results are very encouraging and we are now developing a Phase II trial to test the drug's efficiency in a larger number of patients.

"There is an urgent need for new treatments for Hodgkin's lymphoma and T-cell lymphoma because a number of patients develop drug resistance to the therapy options already out there."

The Phase II trial will be conducted at Cancer Research UK's Experimental Cancer Medicine Centres at UCL, Manchester and Southampton, which are jointly funded by the National Institute for Health Research.

Hodgkin's lymphoma is the third most common cancer in the UK in people aged 15-29 but also occurs in older people. More than 300 people died from the disease in the UK in 2007.

Dr Christopher McNamara, consultant haematologist at the Royal Free Hospital, said: "Hodgkin's lymphoma is radiosensitive and CHT25 delivers radiation in small doses right to the tumour while avoiding harm to healthy tissue which results in a better response and fewer side effects."

"This is a very different way of delivering radiotherapy - traditionally Hodgkin's lymphoma patients receive external beam radiotherapy and this drug is delivered intravenously targeting the drug right to the lymphoma."

Lara Smrtnik, 30, from Swansea, was diagnosed with Hodgkin's lymphoma in 2007 and underwent months of chemotherapy treatment. She said: "Fortunately my body responded well to the chemotherapy, however I know this is not always the case. It is great to hear that today there are such sophisticated developments in the treatment of Hodgkin's lymphoma. Not only does this provide more options for treatment of the illness, which is a step forward in cancer care, but it also gives more hope to patients and their families."

Dr Nigel Blackburn, Cancer Research UK's director of drug development said: "This clever new drug delivers radiotherapy to the tumour in a targeted fashion, maximising the damage to the tumour while reducing harm to healthy cells.

"We are delighted to have been involved with the early development of this drug and with the positive response seen in these patients. Cancer Research UK's doctors and scientists have contributed to 19 of the top 20 drugs used to treat people with cancer in the UK today. We hope the next trial of this new drug to treat Hodgkin's lymphoma will lead to a new success story, helping more people to survive the disease."