Cancer That Kills the Young May Have Met Its Match
Surgery, radiation, and/or chemotherapy have been the standard treatment for neuroblastoma. But because so many of cases are at an advanced stage of disease at diagnosis, the success rate is low. In addition, radiation and chemotherapy badly damage normal cells. One of the reasons researchers are testing the MIBG compound is the ability to deliver the radiation directly to the tumor without affecting the other cells.
"About 10 or 12 years ago, we realized that if we attached a higher amount of radiation to the MIBG, we might be able to kill the tumors," Yanik says. His team has now treated 11 children aged two to 14 years with a protocol of MIBG with high radiation followed two weeks later by a high dose of chemotherapy. "It's a double knockout punch."
However, the knockout punch damages the bone marrow that produces both red blood cells that transport oxygen and white blood cells that fight infection. So one week after the chemotherapy, doctors transplant bone marrow stem cells which had been previously harvested from the child.
"Think of it as using a chemical to take out the weeds but in killing the weeds we kill the whole lawn. Then we need to put down new seed," he says in explaining why bone marrow cells must be transplanted.
Robert Seeger and Patrick Reynolds, doctors at the Children's Hospital of Los Angeles, have developed a process to purge the patients' bone marrow of any neuroblastoma cells that might be present. In this way, physicians know that they are not reintroducing the disease.
Yanik says that the use of the MIBG radioactive compound improves treatment outcome because shrinking of the tumors in all of the children occurred before the chemotherapy dosage was administered.
"The current study is for those who would have less than a 10% cure rate; we have selected the most severe cases," he says. "The tumor shrink rates showed promise; all [the patients] have achieved some response and eight achieved remission within three months of therapy."
However he cautions that it's too early to know how much this treatment will improve cure rates because none of the patients have been followed long term. The researchers are still trying to discover the optimal dosages of MIBG and of the chemotherapy.