A Game Changer for Blood Cancer Treatment

In the procedure, patients begin with chemotherapy that, along with destroying the cancer cells in their bloodstream, also strips away other blood-forming cells. Blood and bone marrow stem cells are then collected from a donor and infused into the patient to jump-start the process of rebuilding the immune system.

The procedures take time, and patients often need to stay in the hospital for several weeks because of their vulnerability to infection. After they are released from the hospital, they still have to stay near the transplant center for several more months to make sure their bodies don’t reject the transplanted stem cells.

“Because of family obligations it would have been a tremendous hardship for our patients to travel out of state,” says Fero. “We were happy to be able to provide this treatment and let our first patient return to his own home immediately after being released from the hospital.”

Until last year, the stem cell transplants performed at the UNM Cancer Center had been autologous transplants.

In autologous transplants, the patient’s own stem cells are coaxed into the bloodstream, harvested and frozen before the chemotherapy treatment. After chemotherapy, the stem cells are carefully thawed and injected back into the patient’s body, where they migrate to the bone marrow and regrow the immune system.

Allogeneic transplants differ from autologous transplants in that stem cells are harvested from a donor. The procedure is used to treat certain blood cancers when an autologous transplant isn’t as helpful.

”Using bone marrow stem cells from a donor ensures that they will not be contaminated with leukemia cells — like they might be if they were harvested from the patient,” says Fero. “But this is not the only benefit. The patient receives an entirely new immune system that can attack the tumor cells and help to eradicate the remaining bits of residual disease. This immune response decreases the risk of the disease coming back.”

In allogeneic transplants, because the stem cells do not come from the patient, the immune system markers must be carefully tested. Donors are matched according to their immune systems’ unique “barcode” in a process called Human Leukocyte Antigen typing, or HLA typing.

HLA typing goes much deeper than evaluating a standard blood type: it identifies the exact HLA markers found on our bodies' cells, from over a million different possible combinations. The immune system relies on these markers to determine which cells belong in the body, and which to fight to stave off infections.

Fero describes another major advance in the field of stem cell transplantation: the ability to use donors whose HLA type is only half-matched.

“The availability of these haploidentical transplants greatly increases the opportunity of New Mexicans to access this therapy,” Fero says. “While there is only a 25% chance that a brother or sister is fully matched, 50% of siblings and 100% of children and parents are haploidentical.” 

Fero explains that haploidentical transplants make treatment possible for many New Mexican patients, who because of their rich and mixed ancestry, might not find matched donors in the registries of unrelated donors.

"We recently completed a haploidentical transplant from a young woman with relapsed leukemia, and are thrilled about how well she has done," Fero says.

Until now, New Mexicans had to travel out of state and live away for months when their treatment plan called for an allogeneic stem cell transplant. With the new allogeneic capability at UNM Cancer Center, they don’t have to.