Sickle Cell Anemia Gets a New Ray of Hope

Sickle cell disease (SCD) is a blood disorder caused by a mutation in the β-globin gene responsible for normal hemoglobin production. This genetic mutation produces abnormal hemoglobin in the form of sickle-shaped cells, which clump together and can cause fatal strokes and embolisms. The only available cure till now is a bone marrow transplant (BMT) involving a matched donor. This is not used frequently due to the many risks including rejection.

Facts and Statistics about Sickle Cell Disease (SCD)

• Around 100,000 people in the U.S are estimated to suffer from SCD
• Globally, around 300,000 children and adults have this condition
• SCD is one of the most common genetic disorders in the world with debilitating symptoms often leading to disability and death
• Treating the disease and its complications are expensive to costs amounting to nearly $30,000 annually for adults.
• A one-time cure may work better, in the long run, both economically and for the health of patients.

SCD has long been a neglected disease owing to the fact that many of the patients are from marginalized communities. This has been an underserved sector for too long.

Experimental Gene Therapy to Cure Sickle Cell Disease (SCD)

Several groups of researchers are currently working on one-time curative gene therapy for SCD. SCD was one of the first single-gene disorders considered amenable to corrective gene therapy.

One of the key researchers is Dr. David Williams, president of the Dana Farber and Boston Children’s Cancer and Blood Disorders Center. Dr. Williams is the Chief scientific officer and senior vice-president of Boston Children’s hospital and also a professor at Harvard Medical School. He has been working on SCD since the last 30 years and has recently been involved in experimental gene therapy to cure SCD.

Other researchers include Dr. Alexis Thompson, an SCD specialist at Northwestern University who was involved in this therapy. One of the first patients to receive a functional beta-globin gene via gene therapy from Bluebird bio is Brandon Williams.

Williams no longer suffers from painful symptoms or requires regular blood transfusions. These pioneering trials have greatly benefited suffering patients. Carmen Duncan (20) was also one such patient who received the Bluebird bio gene therapy. She is now free of SCD.

Currently, scientists are testing three approaches to curing SCD. The approches include:

• First is traditional gene therapy using a viral vector to insert a functional copy of the missing/mutated gene
• Second is turning on the gene responsible for fetal hemoglobin production. This gene is active in the fetus but turns off after birth so that adult hemoglobin kicks in. However, turning on this gene can increase the total hemoglobin in the body

According to Dr. Stuart Orkin, the researcher at Harvard University who found the fetal hemoglobin switch, fetal hemoglobin works just as well as adult hemoglobin without sickling. Manny Hernandez (20) is one of the first patients to have received the fetal hemoglobin switch at the Boston Children’s Hospital. He is under observation and the therapy has worked which means he no longer has the disease.

• Third approach to curing SCD is gene editing using CRISPR to cut out parts of the gene and insert functional sections

Several research groups are working on this approach too. The National Institutes of Health has recently launched an initiative called Cure Sickle Cell to encourage further research.

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All these steps herald new hope for SCD sufferers who can look forward to better approaches to treat and cure this painful disorder.

References:

1. Gene Therapy Advances Offer Hope For Sickle-Cell Disease Cure - (https://www.wbur.org/onpoint/2019/01/28/sickle-cell-disease-gene-therapy)
2. New gene therapy strategy for sickle cell disease shows early promise in humans - (https://www.dana-farber.org/newsroom/news-releases/2018/new-gene-therapy-strategy-for-sickle-cell-disease-shows-early-promise-in-humans/)

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Source-Medindia