Study Compares Stem Cell Transplants for Myeloma

For younger patients, a transplant from a compatible donor boosts survival.

By Amanda Gardner
HealthDay Reporter

WEDNESDAY, March 14 (HealthDay News) -- Younger patients diagnosed with the blood cancer myeloma survived longer if they received a stem cell transplant from themselves that was followed by one from a matched sibling -- rather than receiving two transplants from themselves, researchers report.

However, while the protocol may be a good treatment alternative for some patients, they represent only a fraction of the total who develop myeloma, outside experts said.

"It's a good study and it gives important perspective, and it will be useful for some patients but it's a small minority of myeloma patients," said Dr. Marshall Lichtman, executive vice president of research and medical programs at the Leukemia & Lymphoma Society.

He was not involved in the study, which was led by Dr. Benedetto Bruno of the University of Turin, Italy, and published in the March 15 issue of the New England Journal of Medicine.

Myeloma (also known as multiple myeloma) is a cancer of the blood's plasma cells, which are a type of white blood cell present in the bone marrow.

According to background information in the study, high-dose chemotherapy followed by a transplant of the patient's own stem cells is the standard of care for newly diagnosed patients under the age of 65.

"The transplant was rescuing the patients after life-threatening chemotherapy. You need that intensity to kill off the tumor, but it also kills off normal blood and immune-forming cells," Lichtman explained. "The patient needs to be replenished."

But sometimes transplanted cells from the patient still don't recognize the cancerous cells as foreign and fail to attack them as they should, allowing the disease a chance to recur.

However, when stem cells come from a compatible outside donor (such as a sibling), it can result in "graft-versus-myeloma" effect, meaning the new immune cells attack and kill off the myeloma cells. Lower relapse rates and longer remissions have been reported in patients receiving stem-cell transplants from other donors compared to transplants using the patients own stem cells.

Transplanted cells from the patient don't recognize the myeloma cells as foreign and don't attack them, allowing the disease to recur more readily.

For this investigation, researchers enrolled 162 patients aged 65 years and younger who had recently been diagnosed with myeloma and had at least one sibling.

All participants were treated with chemotherapy, followed by autologous stem cell rescue (transplants using their own stem cells). Those with a compatible sibling also received radiation and stem cells from that sibling (called an allograft).

Patients without a compatible sibling instead received two consecutive doses of melphalan, a chemotherapy drug, each of which was followed by autologous stem cell rescue.

After a median follow-up of almost four years, median overall survival and survival without a recurrence of the disease were longer in the patients who had received a sibling stem cell transplant. Overall survival was 80 months in those undergoing the two different transplants vs. 54 months for those receiving transplants only from themselves. Event-free survival was 35 months for those in the autologous group and 29 months in the other group.

Deaths resulting from treatment were similar in both groups. Disease-free mortality was higher in the double-autologous group (43 percent vs. 7 percent).

After a median follow-up of 38 months, 36 percent of patients were in complete remission after allografting.

More than half (54 percent) of those receiving two autografts died.

It's important to remember that all participants in the study were under the age of 65, Lichtman said. In "real life," only 40 percent of myeloma patients are in this age group. The proportion with compatible siblings is even less (about 10 percent). And only about half who received the treatment experienced complete remission, or 5 percent of the total.

"For those people who are eligible, this is an interesting and important observation, and it may lead to moving from two auto transplants to an auto and an allo for those people who have a sibling donor," Lichtman said. "For those who are eligible for this sort of treatment this is useful, but it's a minority of patients."

In addition, Lichtman pointed out, this study was started five or more years ago. A whole series of new myeloma drugs has emerged in the intervening years.

"We really don't know what the very best approach would be today for someone of this age," Lichtman said.