Research Findings Hold Promise for Leukemia, Blood Cancer Patients

Several studies presented at the 2003 annual meeting of the American Society of Hematology (ASH) described new approaches in stem cell transplantation that may improve the lives of people with leukemia and other genetic or immune system diseases. Some of the most important findings are shared below.

New Treatment Approaches for CML Patients

Since 2001, patients with chronic myeloid leukemia (CML) have had the treatment option of imatinib mesylate (Gleevec®). Gleevec can be a very effective treatment for patients with CML. For many patients, this drug stops the cancerous white blood cells from reproducing; however, for some patients, the drug does not work or stops working over time. Several studies focused on how to identify and help those patients for whom Gleevec alone is not entirely effective. CML patients may want to consider discussing these findings with their physician.

Monitoring Gleevec for Effectiveness

Gleevec effectiveness is determined by hematologic and cytogenetic response rates. The hematologic response refers to a decrease in the number of white blood cells to normal levels. The cytogenetic response refers to eliminating the cells that contain the abnormal Philadelphia chromosome.

Research has shown that CML patients who showed no major decrease in the number of Philadelphia chromosomes within six months of receiving Gleevec had worse outcomes than those who did. Thus, if the drug does not help the patient within three months, other treatment options like stem cell transplantation should be considered.

The review of other research suggested that patients taking Gleevec be monitored every month using a technique called "quantitative RT/PCR" to monitor chromosome changes.¹ This recommendation also was based on NMDP research that shows that transplant outcomes are better when CML patients are transplanted early in their disease.²

Non-myeloablative Transplants Show Encouraging Results

Non-myeloablative transplant is a relatively new blood stem cell transplant option. A non-myeloablative transplant uses lower doses of chemotherapy and radiation to prepare a patient for transplant. This preparation is much less stressful on a patient's immune system and makes transplant possible for patients who would have previously been considered ineligible for transplant. These include patients older than 55 and those who may have other health problems.

The results of these studies are encouraging, but the findings are early. Research about non-myeloablative transplants and new ways to manage post-transplant complications are expected to continue.

One study of 60 patients who received non-myeloablative transplants showed that they experienced less severe graft-versus-host-disease (GVHD) and less serious side effects than patients who received a standard transplant.³ (GVHD is a condition in which the transplanted donor marrow or blood stem cells attack the patient's healthy cells.) These patients were not eligible for a standard transplant.

The same researchers studied 453 high-risk patients who had non-myeloablative transplants. The study showed encouraging patient outcomes two years after transplant, but also found that GVHD was still an issue.⁴

Non-myeloablative allogeneic (cells from a donor, not the patient) stem cell transplants may reduce the size of solid tumors in patients with certain types of cancer, according to research presented at the ASH conference. This may occur because of graft-versus-tumor (GVT) effect. (GVT is when the transplanted donor cells attack the tumor cells.) Because of this research, non-myeloablative allogeneic stem cell transplantation is being considered for patients who have certain solid tumor cancers that have not responded to traditional treatment. These include renal cell carcinoma, metastatic melanoma, colon cancer, ovarian cancer, autoimmune diseases such as scleroderma and lupus, and myelodysplastic syndrome.

¹ Melo JV, Hughes TP, Apperley JF. Chronic myeloid leukemia. Hematology 2003: 132-52. Online: http://www.asheducationbook.org/cgi/content/full/2003/1/132
² Childs R, Chernoff A, Contentin N, et al. Regression of metastatic renal-cell carcinoma after nonmyeloablative allogeneic peripheral-blood stem-cell transplantation. NEJM 2000; 343(11): 750-8.
³ Sorror M, Maris M, Storer B, et al. Transplant-related toxicities (trt) and mortality following hla-matched unrelated donor hematopoietic cell transplantation (urd-hct) using nonmyeloablative (nm) compared to myeloablative (m) conditioning: Influence of pretransplant comorbidities [abstract]. Blood. 2003; 102(11): 262a.
⁴ Sandmaier BM, Maris M, Maloney DG, et al. Low-dose total body irradiation (tbi) conditioning for hematopoietic cell transplants (hct) from hla-matched related (mrd) and unrelated (urd) donors for patients with hematologic malignancies: A five-year experience [abstract]. Blood. 2003; 102(11): 264a.