WASHINGTON, Dec 7 (Reuters) - Scientists who have reprogrammed the body's own immune cells said on Monday their approach was having surprising effects against cancer, sending six out of eight patients into remission.
Although they stress their findings are very preliminary, they say the new technique is promising enough to try out in bigger groups of cancer patients.
''When you consider that none of these patients had responded to any other therapy, you can begin to understand our enthusiasm,'' Dr. David Liebowitz of the University of Chicago, who presented the study of the weekend to a meeting of the American Society of Hematology, said in a statement.
''We can't claim to have cured anyone,'' he added in a telephone interview on Monday. ''I don't want this to be overhyped because we don't know how long these remissions are going to last. But it is certainly teaching us a lot.''
Liebowitz has been working with a small biotechnology company known as Xcyte Therapies, Inc., based in Seattle. The company has licensed a proprietary process for reprogramming T-cells, known as Xcellerate, from the university.
T-cells are part of the system that attacks foreign invaders such as viruses and which is also supposed to ferret out delinquent cells such as cancer cells and destroy them.
But in patients who develop cancer, the T-cells do not attack as they should.
'This discovery addresses the basic question facing cancer immunotherapy -- why are the T-cells that should attack tumours content to sit idly by?'' Liebowitz said.
The Xcyte and University of Chicago team tried a new system to motivate the T-cells.
They removed stem cells from the blood of eight patients.
Such cells have the potential to grow into any kind of blood cell, including T-cells. They then grew these cells in the laboratory and exposed them to two antibodies, known as CD3 and CD28, which super-activates the T-cells.
These CD3 and CD28 antibodies were attached to magnetic beads that bind them to the receptors, or cellular doorways, they use to prime the T-cells.
This trial was aimed at assessing only whether the therapy was safe. The volunteers were eight patients with severe forms of non-Hodgkin's lymphoma who had not been helped by chemotherapy and who were going to die.
The patients' own bone marrow -- the natural source of T-cells -- was destroyed and each got an injection of the ''souped-up'' T-cells.
A few weeks later some of the patients developed fever and lethargy, which Liebowitz said showed their immune systems were being stimulated. They also had rising numbers of T-cells.
These T-cells evidently went right to work. Very slowly, most of the patients' tumours grew smaller, Liebowitz reported.
Two died, but four of the eight patients have had what appear to be complete remissions -- there is no sign of cancer.
''They are in complete response -- no disease, no drugs,'' Dr. Jeffrey Ledbetter, Xcyte's chief scientific officer, said in a telephone interview.
''One of the patients was playing golf within a month of this therapy.''
But Liebowitz stressed there was no guarantee this would last. Of the six patients who went into remission, two eventually relapsed and one has died, although the cancer seems to have returned in a less-aggressive form in the other.
Xcyte researchers have also experimented with this therapy in patients with the HIV virus that causes AIDS.
Mark Murray, vice-president of business development for Xcyte, said the company was now exploring the possibility of going public or of forming a partnership with a pharmaceutical company.
Xcyte plans to file an application with the U.S. Food and Drug Administration (FDA) to start the process towards eventual approval of the treatment. Murray said more clinical trials would begin next year.
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