Age alone no longer a barrier to stem cell transplantation

By Ignacio Lobos, Hutchinson Center external Communications Editor

Age was once considered a defining factor to determine whether an older patient with blood cancer was a candidate for stem cell transplantation.

Many older and medically sicker patients could not tolerate the standard, more toxic, high-dose regimens used to prepare patients for transplantation. For many years after the Hutchinson Center pioneered bone marrow and stem cell transplantation, people over 40 were generally not eligible for either procedure, but thanks to work by Hutchinson Center researchers, that age limit started moving up.

Dr. Rainer Storb

The most dramatic shift came after Center researchers, led by Dr. Rainer Storb, developed what came to be known as the mini-transplant, a “kinder, gentler” form of allogeneic (donor cell) stem cell transplantation.

Today, according to a new study, age alone no longer should be considered a defining factor for older patients seeking stem cell transplantation.

“Age is no longer a barrier to allogeneic transplant,” said Dr. Mohamed Sorror, a lead author of the study.

This is an important finding, the authors said, because more than 20 percent of the U.S. population will be 65 or older by 2030, with an expected 77 percent increase in the number of blood cancers for this population in the next two decades. However, many eligible patients are not being treated with stem cell transplants to treat their blood cancers.

“These statistics clearly highlight the reluctance of providers in offering allogeneic stem cell transplantation to the elderly,” Sorror said. “Little is known about the reasons behind the low referral rate of older patients to transplant or how mini-transplant outcomes compare to those of conventional therapies. We are initiating a multicenter study designed to follow patients from the time of diagnosis to answer both questions.”

Dr. Mohamed Sorror

Sorror and colleagues found that the five-year rates of overall and disease-progression-free survival among mini-transplant patients were 35 percent and 32 percent, respectively.

Patients in three age groups—60 to 64, 65 to 69 and 70 to 75—had comparable survival rates, which suggested that age played a limited role in how patients tolerate the mini-transplant, researchers said.

The mini-transplant, known in medical circles as nonmyeloablative transplantation, relies on the ability of donor immune cells to target and destroy the cancer—without the need for high-dose chemotherapy and radiation. Instead, low-dose radiation and chemotherapy is used to suppress the immune system rather than destroy it. This helps the body accept the donor stem cells, which then go to work to attack cancer cells—called the graft-vs.-leukemia effect—and rebuild the immune system.