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The potential use of CRISPR to treat disease is gaining momentum

13 January 2020
Appeared in BioNews 1030

Promising results from clinical trials give hope for using CRISPR/Cas9 genome editing to treat various heritable diseases and cancer in humans.

It has been seven years since the discovery that the CRISPR/Cas9 defence system, used by microbes to destroy viruses, could be re-engineered to edit the human genome. Since then researchers have carried out an array of experiments to explore potential applications.

Biophysist Dr He Jiankui sparked global controversy concerning the ethics of genome editing when he used CRISPR to genetically modify embryos, resulting in the birth of the first genome-edited babies (see BioNews 977).

Yet researchers worldwide have at the same time been investigating the use of CRISPR for non-heritable changes, modifying the genes in non-embryonic cells to treat a wide range of diseases. 

'There's been a lot of appropriate caution in applying this to treating people, but I think we're starting to see some of the results of that work,' said Dr Edward Stadtmauer, a haematologist at the University of Pennsylvania, Philadelphia. 

Over a dozen new clinical trials testing CRISPR therapy on diseases such as cancer, HIV and sickle cell anaemia were listed on the clinicaltrials.gov database last year. One trial in its early stages used CRISPR to treat sickle cell anaemia and beta-thalassaemia, both genetic blood disorders that result in the production of an abnormal form of the oxygen-carrying protein, haemoglobin. 

Two patients with these disorders were treated by CRISPR Therapeutics in Cambridge, Massachusetts, and Vertex Pharmaceuticals in Boston, Massachusetts, using CRISPR to inactivate a gene that switches off the production of an alternative form of haemoglobin. Preliminary results of the study suggest that this therapy improved some of the symptoms but the participants will need to be followed for a longer period to be sure.

Results from two other trials, one in which genome-edited blood cells were transplanted into a man to treat HIV infection, and the other in which they were transplanted into three people to treat some forms of cancer, were less successful. In both cases, the transplanted cells flourished in the bone marrow of recipients, without any serious safety concerns, but did not produce a clear medical benefit. The study has been placed on hold while researchers explore ways to boost that percentage, says Hongkui Deng, a stem-cell researcher at Peking University, Beijing, China and a lead author of the work.

Other researchers are trying to move beyond editing cells in vitro. In July 2019 a clinical trial was launched to treat Leber congenital amaurosis 10 (LCA10), a rare genetic disease that causes blindness. The trial, launched by two pharmaceutical companies, Editas Medicine in Cambridge, Massachusetts, and Allergan in Dublin, Ireland, will be the first trial that uses CRISPR to edit cells inside of the body. The researchers are testing AGN-151587 (EDIT-101), which is a novel CRISPR treatment delivered via adeno-associated virus (AAV) directly to the eye's light-sensing photoreceptor cells to remove the mutation that causes LCA10. 

There are some encouraging results so far from these trials. However the sample sizes are so small that it is difficult to draw a firm conclusion about their safety and efficacy in humans. Moving forward, larger groups of patients need to be studied over a substantial period of time.
Overview: CRISPR Technology Headed to Clinical Trials
BioSpace |  7 January 2020
Quest to use CRISPR against disease gains ground
Nature |  6 January 2020
The first clinical trials of CRISPR gene editing have shown promising results
News Medical Life Sciences |  7 January 2020
16 August 2021 - by Dr Charlotte Douglas 
A genome-editing-based gene therapy for blood diseases sickle cell disease and beta-thalassaemia continues to be effective more than two years after treatment...
12 April 2021 - by Dr Molly Godfrey 
A clinical trial for a new gene therapy approach to treat sickle cell disease has been approved to proceed by the US Food and Drug Administration...
11 January 2021 - by Anna Wernick 
A type of genome editing had been used in mice to treat the symptoms of progeria, a fatal premature ageing disease in children...
9 November 2020 - by Dr Laura Riggall 
A new screening technique using human tissue has identified previously unknown genes that cause microcephaly...
23 March 2020 - by Dr Jay Stone 
A new CRISPR-based technology can target RNA in human cells, including the RNA-based genome of the coronavirus...
18 November 2019 - by Dr Laura Riggall 
Researchers claim that the genome-editing tool CRISPR could be used to detect dangerous viruses in a drop of blood within an hour...
11 November 2019 - by Shaoni Bhattacharya 
Early results from the first clinical trial to use CRISPR/Cas9 genome editing in three cancer patients in the USA suggest the approach is safe...
28 October 2019 - by Dr Jennifer Frosch 
An improved genome editing method could potentially correct 89 percent of known genetic defects causing disease, US scientists say.
19 August 2019 - by Rachel Siden 
California has passed the first-ever bill regulating genome editing technology that targets do-it-yourself CRISPR kits...
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