Drisapersen

Drisapersen
Systematic (IUPAC) name
RNA, (P-thio)(Um-Cm-Am-Am-Gm-Gm-Am-Am-Gm-Am-Um-Gm-Gm-Cm-Am-Um-Um-Um-Cm-Um)
Clinical data
Trade names Kyndrisa (proposed)
Legal status
  • Never marketed
Identifiers
CAS Number 1251830-50-8
ATC code M09AX04 (WHO)
ChemSpider none
Synonyms PRO051; GSK2402968

Drisapersen (also known as Kyndrisa, PRO051 and GSK2402968[1]) is an experimental drug that is under development by BioMarin, after acquisition of Prosensa,[2] for the treatment of Duchenne muscular dystrophy. The drug is a 2'-O-methyl phosphorothioate oligonucleotide that alters the splicing of the dystrophin RNA transcript, eliminating exon 51 from the mature dystrophin mRNA.

Mechanism of action

Duchenne muscular dystrophy (DMD) is caused when a mutation in the dystrophin gene changes the RNA so that it no longer codes for functional dystrophin protein. This usually happens due to a mutation that alters the reading frame of the RNA downstream of the mutation, so-called frameshift mutation. If an exon with an appropriate number of bases lies near the mutation, removing that exon can correct the downstream reading frame, restoring the production of partially functional dystrophin. This is the general strategy used in the design of exon-skipping oligonucleotides for DMD. As there are 79 exons in the longest splice form of the dystrophin transcript, many different oligonucleotides are needed to address the range of mutations present in the population of people with DMD.

Clinical studies

The compound has completed Phase III trials and did not meet its primary endpoint.[3][4] In January 2016, the FDA rejected drisapersen (Kyndrisa) largely on the basis of toxicity which limits dosing, and so efficacy.[5] This effectively shifted focus of exon skipping therapy to a competing drug, eteplirsen.[6] Eteplirsen is another exon skipping drug, but has a different backbone chemistry (it is a Morpholino antisense oligomer) which gives it different pharmacology while still targeting the same site on the dystrophin gene, exon 51. The hope is that lower toxicity of that backbone chemistry will allow higher dosing and greater efficacy.

An long term open-label extension study (DEMAND IV) suggests that giving the drug at an earlier age and treating the boys for longer may delay progression of the disease. This corresponds with the earlier Phase III trials (DEMAND III) data that shows a potentially clinically meaningful difference in a subgroup of patients age 7 or younger.[7]

Current status

The Phase III trials were sponsored by GlaxoSmithKline but GSK terminated the collaboration agreement between GSK and Prosensa and Prosensa has regained all rights from GSK to drisapersen. Prosensa was then acquired by BioMarin Pharmaceutical,[8] which is continuing the development of drisapersen[9] and is concurrently working with similar exon skipping therapies for other exons.[10]

Both drisapersen and the similar drug eteplirsen have filed a New Drug Application (NDA) for review with the US Food and Drug Administration (FDA).[11] In January 2016, the FDA rejected drisapersen (Kyndrisa) after it concluded that the standard of substantial evidence of effectiveness had not been met, effectively shifting focus to rival Sarepta's eteplirsen.[12] The Prescription Drug User Fee Act (PDUFA) goal dates for these are December 27, 2015 for drisapersen and February 26, 2016 for eteplirsen.

References

  1. ↑ "PRO051/GSK2402968". Prosensa. Archived from the original on July 29, 2012. Retrieved 29 October 2012.
  2. ↑ "BioMarin to Pay Up to $840 Million for Prosensa". Wall Street Journal. 24 November 2014. Retrieved 2015-11-05.
  3. ↑ "A Clinical Study to Assess the Efficacy and Safety of GSK2402968 in Subjects With Duchenne Muscular Dystrophy (DMD114044)". ClinicalTrials.gov. Retrieved 29 October 2012.
  4. ↑ "Setback for Drug Made by Glaxo, Prosensa". Wall Street Journal. 20 September 2013. Retrieved 2013-09-20.
  5. ↑ finance.yahoo.com/news/fda-rejects-biomarins-dmd-drug-135156448.html
  6. ↑ finance.yahoo.com/news/fda-rejects-biomarins-dmd-drug-135156448.html
  7. ↑ "Positive New Results for Eteplirsen, Drisapersen in DMD". Medscape. May 15, 2014. Retrieved 2014-06-13.
  8. ↑ Walker, Joseph (Nov 24, 2014). "BioMarin to Pay Up to $840 Million for Prosensa". Wall Street Journal.
  9. ↑ "Prosensa regains rights to drisapersen from GSK and retains rights to all other programmes for the treatment of Duchenne muscular dystrophy (DMD)" (Press release). GlaxoSmithKline. 13 January 2014. Retrieved 2014-06-13.
  10. ↑ "Pipeline" (Press release). Retrieved 2014-06-13.
  11. ↑ "FDA Accepts Sarepta's NDA for Eteplirsen". Rare Disease Report.
  12. ↑ finance.yahoo.com/news/fda-rejects-biomarins-dmd-drug-135156448.html
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