LITTLE ROCK"For the first time, we have shown that with increasing age, the number of stem cells mobilized decreases," said Guido J. Tricot, MD, PhD, reporting the results of a multiple myeloma study (ASCO abstract 1055). Clinicians can compensate for the decrease, however, by using chemotherapy early in the disease course to mobilize stem cells, he advised.
Dr. Tricot is head of the Academic Division of Myeloma Transplant, Myeloma Institute for Research and Therapy, University of Arkansas for Medical Sciences in Little Rock. As part of a study of 984 multiple myeloma patients, the team led by Dr. Tricot looked at peripheral blood stem cell mobilization in 106 elderly patients at least 70 years of age.
"Most clinicians reserve mobilization followed by transplantation for the younger patients and treat the older ones with conventional therapies first, using transplantation only as a last resort. This is the wrong approach because by the time older patients go through conventional therapy, their own resources are depleted," Dr. Tricot said. "They have a much better chance if it’s done earlier. If we can collect stem cells early in the course of multiple myeloma, chances of having a higher platelet count and good outcome are much better, even in older patients."
Standard therapy of less than 12 months and platelet count at least 200,000/µL before mobilization were identified by multivariate analysis as favorable variables predicting better outcome. Among patients who had both favorable variables, 85% had adequate collections of at least 4 × 106 CD34+ cells/kg after a median of one collection. Among all 106 elderly patients, 70% had successful collections of at least 4 × 106 CD34+ cells/kg after a median of three collections.
Chemotherapy-based mobilization significantly increased the yield of CD34+ cells compared to growth factors alone, but only in patients who had both favorable variables. "Using growth factors and other agents, we can manipulate the outcome, but one thing we can’t change is the patient’s age," Dr. Tricot said. "The number of stem cells decreases with age, but we can compensate by mobilization with chemotherapy very early in the disease."
Incremental Effect of Age