Researchers Discontinue Promising Sickle Cell Treatment Trials

Just as a new gene therapy for sickle cell disease seemed to be on the way to success, a company developing a cure discovered that two patients now have cancer and is testing it. Was canceled.

Patients treated five and a half years ago developed myelodysplastic syndrome, a type of cancer that often signals leukemia. Reported by Bluebird BioMeanwhile, another person developed acute myeloid leukemia.

It is not clear whether cancer is associated with experimental gene therapy. However, the sudden retreat is disappointing for many patients with sickle cell disease, primarily African Americans. I was hoping that a cure was imminent..

Dr. Melissa J. Fly Jones, a researcher at the University of Texas School of Medicine in San Antonio, said:

“My other concern is that the black community will once again lose confidence and confidence in research after it takes a long time for the medical community to regain some trust,” she added.

It is not yet clear what caused the cancer. One possibility is that the impaired virus used to provide gene therapy therapy damaged important DNA in the hematopoietic cells of the patient’s bone marrow. That would be the worst scenario, said Dr. John F. Tisdale, head of cell and molecular therapy at the National Institute of Cardiopulmonary Blood.

However, it is possible that both cancers were caused by the powerful drug busulfan. Busulfan is used to clean the bone marrow to make room for new cells that have been modified by gene therapy. Busulfan is known to pose a risk of blood cancer, Dr. Tizdale said. “We’re back to what we know,” he said, when he was found to be the culprit in the Bluebird Bio trial.

The disabled wrench virus that Bluebird uses to provide gene therapy was designed with safety features. It is believed to be at much lower risk than the virus that caused cancer in immunocompromised children, which was used in gene therapy a few years ago. The wrench virus is also used in gene therapy trials for sickle cell disease at Boston Children’s Hospital.

The first patient in the Bluebird trial also developed myelodysplastic syndrome about three years after receiving gene therapy, Dr. Tizdale said. Examination revealed that busulfan was the cause.

The new case is “very similar to what we saw in the first patient,” said Dr. Tisdale. But at this point, he said, more tests need to be done to confirm that the new patient actually has the syndrome.

Bluebird has completed an analysis to determine if a gene inserted into a patient’s DNA has landed near a gene associated with a new cancer. If not, it may be due to busulfan.

Complicating the matter is the fact that people with sickle cell disease are known to be at increased risk of leukemia without treatment. Still, no one expects two patients to get the disease in a small trial.

It’s not clear what the Food and Drug Administration will do if it turns out that there is a problem with gene therapy.

Dr. David A. Williams, a hematologist at Boston Children’s Hospital, said that sickle cell disease itself degenerates and weakens, causing episodes of severe pain, damaging tissues and organs, incapacitating patients and prolonging their lives. Remarkably shorten.

The risk of gene therapy may be offset by the benefits of treatment that may alleviate this terrible burden, he and other experts said.

Researchers must be careful when guessing what cancer means for Bluebird’s gene therapy, says Dr. Michael R. Devawn, director of the Vanderbilt-Mehary-Matthewwalker Sickle Cell Center. Said. But he sees cancer diagnosis as “a warning story about a strange combination of cutting-edge science, low-participation clinical trials, and hope for a population that has been largely ignored by the medical community.” He said he was.

However, he is optimistic that there will ultimately be sufficient evidence for patients to make informed choices about treatments, including gene therapy and bone marrow transplantation.

“After all, families want the option of curing their illness,” Dr. Debaun said. “They may not discuss treatments, but they want to know that they have options.”

Researchers Discontinue Promising Sickle Cell Treatment Trials

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