CRISPR is among the most promising and exciting treatment options scientists have been exploring in recent years. The theory for CRISPR was laid out by Francisco Mojica in 1993.
Data from an experimental study published in the European Hematology Association congress (which was held virtually) details the treatment of two blood-transfusion dependent beta-thalassemia patients and a severe sickle cell disease (SCC) patient experiencing vaso-occlusive crises.
The mechanism of the disease
Worldwide, there are millions of beta-thalassemia and SCC patients. These diseases are inherited so there had been no previous long-lasting treatment options, only management therapies. They affect hemoglobin, a protein found in our bodies’ oxygen-vessel red-blood cells. Patients require regular blood-transfusions which take up to four hours per session.
In this ongoing study, researchers edited the genes of patients’ bone-marrow stem-cells with CRISPR. Dr. Haydar Frangoul said in the congress, “...The preliminary results... demonstrate a functional cure for patients with beta-thalassemia and sickle cell disease.”
The mechanism of the treatment
Numerous people with the disease live through their lives without even knowing. The reason for this is that they keep producing fetal hemoglobin in adulthood. Normally, the production of fetal hemoglobin is halted soon after birth.
This property found in some people was the source of inspiration behind this treatment. With the help of CRISPR, scientists aimed to up the production of fetal hemoglobin in patients to eliminate the need for continuous treatment.
The method of treatment
Bone-marrow stem-cells were extracted from the patients, then, the genetic sequence responsible for stopping fetal hemoglobin production is disabled with CRISPR.
Then, as for perhaps the most drastic part of the treatment, patients are put in chemotherapy treatment. Patients' own bone-marrow stem-cells have to be killed beforehand so as to make sure the new modified cells will handle new blood cell production.
While the CRISPR itself doesn’t seem to pose many risks in terms of side-effects according to the data we have, we cannot say the same about chemotherapy. To name a few, risks include loss-of-appetite, infertility, vomiting, hair loss, and infection.
While CRISPR appears safe, patients have still experienced side-effects from chemotherapy to a degree. Due to the experimental status of CRISPR, subjects will require life-long monitoring to ensure their safety.
The outcome of the treatment
Beta-thalassemia patients became transfusion-independent at 5 and 15 months after the treatment. The SCC patient was free of vaso-occlusive crises after 9 months. The study had been on hold these last few months due to the COVID-19 outbreak but has since resumed.