"In a bid to make cancer immunotherapy more effective researchers report they have succeeded in halting the progress of aggressive melanoma in its tracks  at least briefly  in seven patients treated with an army of cloned cancerfighting immune cells. In one of those patients the treatment resulted in complete remission of his metastatic melanoma and evidence that his immune system stands ready to fight any return of the cancer after three years. The study published Monday in the Proceedings of the National Academies of Science contributes to hopes that a tumorfighting strategy called immunotherapy can slow halt or even reverse the growth of a range of cancers  and do so with fewer dangerous side effects. Immunotherapy is one of medicines most promising  and most problematic  approaches to cancer treatment. It aims to charge up the patients immune system to attack cancer cells and halt their outofcontrol growth. The approach outlined in the new study by researchers from the Fred Hutchinson Cancer Research Center in Seattle identifies several ways to make it better said Dr. Cassian Yee the studys senior author. The key is to identify specific cancerfighting cells already circulating in the blood of patients and make thousands of copies of them in the lab.   This type of adoptive immunotherapy could be effective against a wide range of cancers Yee said. His research group is making plans to try the technique on patients with advanced ovarian cancer and sarcomas  rare tumors that arise from connective tissue in bones and muscle. Several independent researchers said the study results were promising. But they also noted that the trial involved only  patients and said the therapy was less effective than in other published trials. Someday cellbased therapy will be mainstream in cancer therapy said Dr. Jeff Miller of the University of Minnesotas cell therapy core laboratory. Each article that shows clinical activity is giving us a piece of the puzzle that will make it safer and more effective he said. Immunotherapy usually starts with clinicians harvesting immune system cells called T cells that have attached themselves to a tumor in an effort to attack. They then coax the cells to multiply either in the lab or in the body and let them loose in the bloodstream so they can attack cancer wherever they find it. Yees team tried to do this more precisely. The researchers hoped that by choosing T cells more selectively and cloning only those judged most likely to vanquish their foe the treatment would be more effective. Sorting through the bodys vast and diverse population of T cells to select just the right ones is a painstaking process. But Yee bet that the extra effort would pay off with better results and fewer side effects. Researchers drew blood from patients and scoured it to find the rare type of immune cell  a melanomaspecific cytotoxic T lymphocyte cell  that specifically homes in on proteins expressed by the cancer. Then they put their harvest  as few as a few hundred cells  into a test tube and cloned them creating millions. The last step was to infuse the resulting army of cancerfighting clones back into the patient. In six of the  patients in the trial the melanoma stopped progressing for  to  weeks. Another patient was declared in remission because his cancer ceased to spread and after several months disappeared altogether. Three years later researchers continue to detect the presence of the cloned cells they infused into the patient yearold high school history teacher Gardiner Vinnedge of North Bend Wash. For six years Vinnedge endured painful rounds of chemotherapy only to have his melanoma return. The immunotherapy allowed him to return to work three weeks after treatments began. The only side effect he said was a raging rash that lasted for three days. My back my legs were just covered with a hot red rash Vinnedge said. It meant the treatment was working  the war was on between my T cells and the melanin in my skin. Now he says he is optimistic he may live to see retirement age though hes not sure hell ever stop teaching.   For immunotherapy to work the manufactured T cells must survive for the months it takes to reach a tumor and dismantle it as well as to round up migrating cancer cells and kill them. Currently the T cells have limited staying power and often die off before their work is done. Doctors give them a boost by administering a growth factor called interleukin. But at high doses it can cause dangerously low blood pressure breathing problems kidney failure and heart arrhythmias. Yees group showed that by choosing T cells more selectively patients can get by with much lower doses of interleukin making the treatment less toxic. The researchers also discovered another way to reduce their dependence on interleukin  by selecting the most youthful T cells which survived the longest when infused into patients. Dr. Patrick Hwu of the MD Anderson Cancer Center in Houston said the study adds to the wealth of what we know about using the bodys immune system to fight cancer. But immunotherapy pioneer Dr. Steven A. Rosenberg was highly critical of the methods and results. Cloned cells dont work said Rosenberg who heads the National Cancer Institutes tumor immunology section. In larger immunotherapy trials that used cultured cancerfighting immune cells taken from patients tumors Rosenberg and his colleagues achieved durable and complete regression in as many as  as patients with advanced metastatic melanoma. These results he said are inferior."