Researchers at the National Institutes of Health (NIH) have recently reported a high response rate in patients with advanced kidney (renal) cancer following the delivery of donor stem cells infusions. These results are encouraging since patients with this disease are presently left with very limited treatment options. With current treatment methods only 20% are expected to survive beyond one year.
The kidneys are a pair of bean shaped organs located on each side of the spine. The kidneys filter the blood and eliminate waste in the urine through a complex system of filtration tubules. All of the blood in the body passes through the kidneys approximately 20 times an hour. Renal cell cancer is an uncommon form of cancer that is most often characterized by the presence of cancer cells in the lining of the filtration tubules of the kidney. When renal cell cancer spreads beyond the area of the kidney to the main blood vessels, lymph nodes, or other parts of the body, it is referred to as metastatic disease. Through previous studies, it has been found that metastatic renal cell cancer responds well to biologic therapy, which is a treatment strategy utilizing the body’s immune system to fight the cancer. Researchers recently conducted a study in which a type of biologic therapy, called a mini allogeneic stem cell transplantation, was evaluated in patients with metastatic renal cell cancer.
Stem cells are immature cells that are formed in the bone marrow (spongy material inside large bones) but can be found in circulating blood. Stem cells eventually develop into 3 types of blood cells: red blood cells which carry Oxygen to tissues, platelets which aid the blood in clotting, and white blood (immune) cells which aid the body to fight “foreign” cells. During an allogeneic stem cell transplant, stem cells from another person are collected from their circulating blood and later infused into the patient. A few months following the infusion, the donated stem cells develop into blood cells in the patient’s body. Of special interest are the developed immune cells, which recognize the patient’s cancer cells as “foreign” and have the ability to target and kill these cancer cells. This process is called the graft-versus-tumor effect.
National Institutes of Health researchers recently treated 19 patients with metastatic renal cell cancer that was no longer responding to conventional treatment, with a mini allogeneic stem cell transplant. A mini allogeneic stem cell transplant involves the delivery of standard-dose therapy prior to stem cell infusion. In this study, all of the patients received standard-dose chemotherapy followed by an infusion of donor stem cells collected from siblings. If patients did not experience a regression in their cancer, they received additional donor white blood cell infusions to enhance the immune effect against the cancer cells. In this study, 10 patients had a response to this treatment, with 3 being complete responses. Almost 50% of the patients survived beyond one year following treatment. However, a significant number of patients suffered from graft-versus-host disease, which is the attack of donor stem cells on the patient’s healthy tissue.
Researchers are very encouraged by this high response rate, particularly considering the fact that these cancers were no long responding to other treatments. The results of this trial are important because it demonstrates the effectiveness of this treatment approach for persons with advanced renal cell cancer. However, more research needs to be done to improve anti-cancer effects further and reduce side effects of this treatment strategy. Persons with renal cell cancer may wish to talk to their doctors about the risks and benefits of participating in a clinical trial utilizing this biologic approach or other promising new treatment strategies. (The New England Journal of Medicine, Vol 343, No 11, pp 750-758, 2000)