Gene therapy tested to protect bone marrow during chemotherapy
Researchers at the Center for Stem Cell and Regenerative Medicine and the Case Comprehensive Cancer Center at Case Western Reserve University and the Ireland Cancer Center at University Hospitals of Cleveland report progress toward the goal of employing gene therapy to help protect the bone marrow cells of cancer patients undergoing chemotherapy.
Stanton Gerson, M.D., professor of medicine, has been leading the effort to introduce a gene into bone marrow cells that would protect the cells against the debilitating effects of chemo, thereby helping the patients maintain greater strength following chemotherapy.
June 6, at the American Society of Gene Therapy meeting in Minneapolis, Gerson and colleagues will present preliminary results of a Phase I clinical trial to test the safety of the method in humans. The study found no complications in five patients who were tested thus far, and found up to 41 percent transfer of the protective gene to the bone marrow, or blood stem cells.
Gerson, who also directs the Center for Stem Cell and Regenerative Medicine, said, "The results are encouraging and will help move this novel approach into new therapies."
Gersons group, which includes Jane Reese and Omer Koc, M.D., has studied the gene mutant MGMT, that is able to protect stem cells from chemotherapy. In animal studies, they have found that this gene can provide stem cells with very high levels of survival advantage [more than 500 fold] compared to normal stem cells not carrying the gene.
Based on those preclinical animal results, they have begun this clinical trial in patients with advanced cancer. Blood stem cells are collected from patients and exposed to a retrovirus containing the gene, which inserts the gene into the cells. Patients are then infused with their own genetically-modified cells. Patients are then treated with combination chemotherapy. Because stem cells have the new gene, they are resistant to these chemotherapy agents.
This trial is unique because the patients do not undergo treatment to empty the bone marrow prior to cell infusion, which is the standard procedure. Instead, the intent is to "select" for the genetically altered cells with intermittent outpatient chemotherapy treatments, said Gerson.
So far, five patients have entered the trial at the Ireland Cancer Center at University Hospitals of Cleveland, all with advanced malignancies. Only one patient has been able to receive more than one dose of chemotherapy because the others had evidence of tumor growth and were switched to other therapies. In one patient, evidence of genetically altered cells was documented by molecular analysis in both the blood and marrow six weeks after the infusion.
Accrual for this study continues so that different levels of cell infusion and the impact of more doses of chemotherapy on the ability to select for the genetically altered stem cells can be assessed.
Future clinical trails with this stem cell gene may be used to improve treatments for patients with specific cancers and with inherited stem cell diseases.
George Stamatis | EurekAlert!