Learning and memory defects (“chemo brain”) caused by drugs used for cancer treatment are rapidly emerging as a major clinical problem, with 1.5 million people being diagnosed with cancer every year in the U.S., of which more than 60% now survive for 20 years or more. There is no current treatment for these cognitive problems. Our research suggests that chemotherapy drugs affect the brain by reducing the number of synapses, which are the major means of communication among brain cells underlying learning and memory. Chemotherapy also damages and kills neural stem cells, the renewable resource that can generate new neurons to replace those damaged by chemotherapy.
The long-term goal of our research is to develop a stem cell-based therapy that will replace the damaged synapses and repair the learning and memory deficits in our cancer patients. Our preliminary data in animal models of chemotherapy-induced impairment are very promising and suggest that this goal is possible. Research efforts will concentrate on defining the best strategy for treatment: using clinically compatible, transplantable neural stem cells generated from high-quality human pluripotent stem cell lines, or by means of a drug already in clinical use [Redacted], or a combination of these two approaches. The most active treatment found by our research will ultimately be chosen to test in patients diagnosed with chemotherapy-induced cognitive impairments.
The California Department of Public Health states that over 1.2 million Californians who are alive today have a history of cancer. In 2012, about 150,000 Californians will be diagnosed with cancer. With the recent and significant progress made in cancer treatments, two out of three Californians who get cancer this year will be alive five years after diagnosis. Because the overwhelming majority of these patients are treated with chemotherapy, the potential risk of surviving the cancer but being disabled by learning and memory impairments is looming, both over our patients and their quality of life but also over our health care system. The majority of these patients will not be able to return to work, and will need expensive medical and social support. Consequently, the economic, social and medical costs associated with care for cancer survivors are significant. Estimates place the annual cost of cancer survivorship care in the United States in the billions of dollars. The development of a stem cell therapy for treatment of patients affected by severe chemotherapy-induced cognitive impairments will not only alleviate ongoing suffering, but also allow our patients (and their families) to return to work and contribute to California’s economy. Moreover, a stem cell-based therapy that will provide sustained recovery will reduce the ever-growing cost burden to the California cancer care system.