Innovative Research Advances Stem Cell and Bone Marrow Transplantation

www.earthtimes.org ^ | Mon, 10 Dec 2007 | American Society of Hematology

[Coleus]

ATLANTA, Dec. 10  /PRNewswire-USNewswire/ -- New data being presented at the 49th Annual Meeting of the American Society of Hematology in Atlanta, GA, suggest innovative strategies to improve the success of stem cell and bone marrow transplantation. These studies demonstrate improved outcomes using a new treatment regimen for children with a specific form of leukemia; new ways to increase the number of specialized stem cells harvested from the bone marrow prior to transplantation; efforts to effectively expand stem cell transplantation among patients older than 55; and preclinical research that re-examines the way physicians prepare a patient's immune system to accept a stem cell transplant. A press conference revealing this new research will take place Monday, December 10, from 8:00 to 9:00 a.m.

"The data and discussion highlighted today give a glimpse into the great strides and promises of stem cell transplantation," said Armand Keating, MD, Princess Margaret Hospital, Toronto, Canada, and moderator of the transplantation press conference. "Stem cell transplantation is certainly not new, but advanced techniques and new ways of applying older technologies have the potential to change clinical practice and dramatically improve survival rates and quality of life for our patients whether young, old, or in the prime of their lives."   Stem cells are the body's "parent" cells and can produce specialized cells that differentiate and become various tissues in the body, such as those found in the blood, immune system, heart, brain, and liver. Treatments used to fight cancer cells in the body often also devastate healthy cells and tissues, including stem cells, and the ability to extract, purify, and then reintroduce -- or transplant -- stem cells to patients following cell-destroying cancer treatments can help "rescue" a patient's compromised immune and hematologic system and speed his or her recovery.

-- Children with a certain type of acute lymphoblastic leukemia who receive imatinib along with high-dose chemotherapy experienced improvements in survival [Abstract #4]  Kirk R. Schultz, MD, Child and Family Research Institute and the University of British Columbia, Vancouver, British Columbia, Canada

A Children's Oncology Group study examined whether increasing the number of days of imatinib (Gleevec (R)) therapy in combination with high-dose maintenance chemotherapy would improve early event-free survival in children with Philadelphia chromosome-positive acute lymphoblastic leukemia. A total of 93 children were enrolled in one of five cohorts, receiving imatinib for 42 days, 63 days, 84 days, 126 days, or 280 days, respectively, prior to maintenance chemotherapy.  A bone marrow transplant was performed after two cycles of imatinib therapy only if a sibling donor was available; otherwise chemotherapy was continued.  Patients who received a bone marrow transplant started imatinib four to six months following the transplant for six months.   Increasing imatinib exposure resulted in improved early event-free survival at one year of 70.6 percent for the first and second cohorts, 90.9 percent for the third and fourth cohorts, and 95.3 percent for the fifth cohort. The one-year event-free survival in cohort five, 65.7 percent, was significantly higher than had been seen in previous Children's Oncology Group studies.

In conclusion, the study found that imatinib given in combination with intensive chemotherapy resulted in a significant improvement in early event-free survival. Imatinib given following a bone marrow transplant also improved early outcomes in related-donor bone marrow transplants. Intensive imatinib with intensive chemotherapy results in equivalent early event-free survival among patients treated with allogeneic-related or alternative-donor bone marrow transplants. Longer observation will be needed to see if these results produce a clinically significant difference in long-term event-free survival.

-- Umbilical cord blood may be good source of stem cells for cancer patients older than 55  [Abstract #331]  Navneet S. Majhail, MD, University of Minnesota, Minneapolis, MN

The aging of the Baby Boomer generation - every hour another 330 Americans turn 60 - will have a tremendous impact on the prevalence of blood cancers and other disorders of the hematologic system in the years to come. Many older people with blood disorders may not be candidates for life-saving stem cell transplants because they cannot tolerate the steps needed to transplant stem cells harvested from their own bone marrow or cannot find donors who share their same genetic make-up. For these patients, stem cells from umbilical cord blood (UCB) may be a good alternative stem cell source.  This study of 90 patients found that UCB was a viable source for stem cells for older patients who needed a transplant but did not have a matched related donor. The use of UCB and reduced- intensity immune system conditioning extended the availability of transplant therapy to older people previously excluded on the basis of age and lack of a suitable matched donor.

-- Production of specialized stem cells increases when new compound is added to standard pre-transplantation routine for multiple myeloma patients [Abstract #445]
John DiPersio, MD, PhD, Washington University School of Medicine, St. Louis, MO

In order for a stem cell transplant to be successful, physicians must be able to extract -- or harvest -- an adequate number of specialized cells called CD34+ cells via a procedure known as apheresis. The CD34+ cells are purified following their extraction and re-introduced, or transplanted, back into the body following high-dose radiation or chemotherapies designed to kill the cancer cells in the body.  Various medicines are given to patients to accelerate the production of CD34+ cells, and physicians continue to look for new ways to improve how quickly and how many of these cells can be produced.

Interim results of a phase III, randomized, placebo-controlled trial concluded that the addition of the drug plerixafor to G-CSF therapy in patients with multiple myeloma results in a statistically significant increase in number of harvested CD34+ cells, and that transplants using these cells were durable at three months of follow-up. Patients receiving plerixafor +G-CSF were more than twice as likely to achieve target CD34+ cell apheresis amounts compared with patients receiving G-CSF alone (72 percent vs. 34 percent). These gains were seen without additional side effects for patients receiving the add-on drug treatment.

-- Targeting a new antibody may lead to more tolerable transplantation procedures, according to early animal research [Late-Breaking Abstract #LB2] Agnieszka Czechowicz, Stanford University School of Medicine, Stanford, CA

While stem cell transplants use the body's own immune system to repair the damage done by cancers or blood disorders and their treatments, the body's own remaining stem and immune cells often fight against a transplant and limit its effectiveness in helping a patient recover.  In this animal study, a new model eliminated the myeloablative -- or cell-killing -- conditioning regimens used in traditional stem cell transplants by targeting a special protein on the surface of cells - the C-kit antigen.  To achieve these positive results, the researchers cultivated stem cells with a special antibody called ACK2, administering the antibody to mice.  The ACK2-treated animals saw the rapid removal of more than 98 percent of their own stem cells, and subsequent stem cell transplants in the mice were highly successful.  This study could eventually define a new way of approaching bone marrow transplantation/hematopoietic stem cell transplantation (BMT/HSCT). Extrapolation of these methods to humans may enable efficient conditioning regimens for transplantation, thus expanding the potential applications of BMT/HSCT to include treatment of many non-malignant hematologic disorders and a wide variety of autoimmune disorders, such as diabetes and multiple sclerosis, as well as the facilitation of organ transplantation.

The study authors and press program moderator will be available for interviews after the press program or by telephone. In addition to the press conference on transplantation, four additional press briefings will take place at the annual meeting focusing on blood clotting and bleeding disorders, leukemias, sickle cell disease and thalassemia, and hematologic malignancies. For the complete annual meeting schedule and additional information, please visit http://www.hematology.org/meetings/2007.

The American Society of Hematology (http://www.hematology.org/) is the world's largest professional society concerned with the causes and treatment of blood disorders. Its mission is to further the understanding, diagnosis, treatment, and prevention of disorders affecting blood, bone marrow, and the immunologic, hemostatic, and vascular systems, by promoting research, clinical care, education, training, and advocacy in hematology.   American Society of Hematology