November 20, 2019

Two patients with different blood diseases who were treated with CRISPR in the summer are showing significant improvements, according to new data released Tuesday.

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Encouraging results following treatment

The trials that generated the data were conducted jointly by Vertex Pharmaceuticals and CRISPR Therapeutics.

For the research, doctors tested whether they could use CRISPR to treat two patients suffering from different conditions stemming from inherited blood disorders. One patient, Victoria Gray, has sickle cell disease and another patient, who has remained anonymous, has beta thalassemia.

For the trials, doctors extracted bone marrow cells from the patients and edited a gene in the cells to make them produce fetal hemoglobin, a protein produced by fetuses in the womb to provide oxygen.

The patients then underwent chemotherapy to kill the defective bone marrow cells. After that, they were injected with the CRISPR-modified bone marrow cells. The doctors' hope was that fetal hemoglobin would help compensate for the genetic defect that causes both sickle cell and beta thalassemia.

Four months after Gray received the modified cells, blood tests showed that her hemoglobin levels were normal, as about 47% were fetal hemoglobin, STAT News reports. The level that exceeds the fetal hemoglobin level of between 25% and 30% that, according to STAT News, scientists believe is enough to "cure" a patient who has sickle cell disease. The doctors also discovered that 94.7% of Gray's red blood cells contain fetal hemoglobin.

The beta thalassemia patient has seen her total hemoglobin reach almost-normal levels, STAT News reports. She has also not needed a blood transfusions for nine months, a significant change from the more than 16 blood transfusions the patient previously needed each year, the trial data showed.

'This is definitely a huge deal'

Haydar Frangoul, from HCA's Sarah Cannon Research Institute, who is treating Gray, said the data so far "shows for the first time that gene editing has actually helped a patient with sickle cell disease. This is definitely a huge deal."

However, Frangoul cautioned that the results are preliminary and that it's "still too early to celebrate."

Jeffrey Leiden, chair, president, and CEO of Vertex Pharmaceuticals, said the study is "a very important scientific and medical milestone. We have potentially cured [Gray] with a single treatment. We are very hopeful."

David Altshuler, chief science officer at Vertex, said the results of this study are "the first evidence that in people the new CRISPR technology has the potential to be curative for serious genetic diseases."

He added that this study "is just the beginning" for CRISPR. "Its applications can go beyond sickle cell disease and beta thalassemia to other genetic diseases."

Francis Collins, director of NIH, said he thinks it's "enormously exciting that we've reached a point where gene editing using CRISPR is being applied to sickle cell disease." He added, "To be able to take this new technology and give those people a chance for a new life, which it really would be, is a dream come true."

For Gray, the treatment has been "a miracle," she said. "When you pray for something for so long, all you can have it hope. It's amazing" (Stein, "Shots," NPR, 11/19; Begley/Feuerstein, STAT News, 11/19; Rosenbaum, Forbes, 11/19).

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