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Home » Phase3 drugs » Phase 3-Gilead’s newly-acquired Sofosbuvir, GS-7977 shines in Hepatitis C trial

Phase 3-Gilead’s newly-acquired Sofosbuvir, GS-7977 shines in Hepatitis C trial



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Isopropyl (2S)-2-[[[(2R,3R,4R,5R)-5-(2,4-dioxopyrimidin-1-yl)-4-fluoro-3-hydroxy-4-methyl-tetrahydrofuran-2-yl]methoxy-phenoxy-phosphoryl]amino]propanoate

hepatitis c

The Foster City, CA-based Gilead said that its experimental drug GS-7977, originally known as PSI-7977 before the acquisition, when combined with ribavirin, cured a group of genotype 1 hepatitis C patients after four weeks of treatment. The clinical study involved hepatitis C patients who either failed to respond to previous therapies or had not been treated before. The genotype 1 is the most common form of HCV in the United States. It affects 70 to 90 percent of the people in this country who have hepatitis C.

Norbert Bischofberger, chief scientific officer at Gilead said patients with genotype 1 hepatitis C had no detectable signs of the virus after treated with GS-7977 combination therapy for a course of close to a month. Previous study showed the drug candidate could also cure patients with genotype 2 and 3 HCV.

Gilead gained rights to GS-7977 through the $11 billion Pharmasset acquisition deal, which enable the company to be in an advanced position to compete with a few pharma companies seeking to develop an all-oral regimen for hepatitis C. The 100 percent cure rate data suggested that GS-7977 may be one of the most promising therapies for hepatitis C.

Last year, GS-7977, an oral uridine nucleotide analog polymerase inhibitor of HCV, received fast track designation from the U.S. FDA for the treatment of HCV infection.

The World Health Organization estimated that 3–4 million people are infected with HCV each year. Some 130–170 million people are chronically infected with HCV and at risk of developing liver cirrhosis and/or liver cancer,  and more than 350,000 people die yearly from hepatitis C-related diseases.

Sofosbuvir (formerly PSI-7977 or GS-7977) is an experimental drug candidate for the treatment of hepatitis C.[1] It was discovered at Pharmasset and then acquired for development by Gilead Sciences. It is currently in Phase III clinical trials.[2]

Sofosbuvir is a prodrug that is metabolized to the active antiviral agent 2′-deoxy-2′-α-fluoro-β-C-methyluridine-5′-monophosphate.[3]

Sofosbuvir is a nucleotide analogue inhibitor of the hepatitis C virus (HCV) polymerase.[4] The HCV polymerase or NS5B protein is a RNA-dependent RNA polymerase critical for the viral cycle.

Sofosbuvir is being studied in combination with pegylated interferon and ribavirin, with ribavirin alone, and with other direct-acting antiviral agents.[5] It has shown excellent clinical efficacy when used either with pegylated interferon/ribavirin or in interferon-free combinations. In particular, combinations of sofosbuvir with NS5A inhibitors, such as daclatasvir or GS-5885, have shown sustained virological response rates of up to 100% in people infected with HCV.[6]

  1. Sofia, M. J.; Bao, D.; Chang, W.; Du, J.; Nagarathnam, D.; Rachakonda, S.; Reddy, P. G.; Ross, B. S. et al. (2010). “Discovery of a β-d-2′-Deoxy-2′-α-fluoro-2′-β-C-methyluridine Nucleotide Prodrug (PSI-7977) for the Treatment of Hepatitis C Virus”. Journal of Medicinal Chemistry 53 (19): 7202–7218. doi:10.1021/jm100863x. PMID 20845908edit
  2.  “PSI-7977”. Gilead Sciences.
  3.  Murakami, E.; Tolstykh, T.; Bao, H.; Niu, C.; Steuer, H. M. M.; Bao, D.; Chang, W.; Espiritu, C. et al. (2010). “Mechanism of Activation of PSI-7851 and Its Diastereoisomer PSI-7977”. Journal of Biological Chemistry 285 (45): 34337–34347. doi:10.1074/jbc.M110.161802. PMC 2966047. PMID 20801890edit
  4.  Alejandro Soza (November 11, 2012). “Sofosbuvir”. Hepaton.
  5.  Tom Murphy (November 21, 2011). “Gilead Sciences to buy Pharmasset for $11 billion”. Bloomberg Businessweek.
  7.  AASLD: PSI-7977 plus Ribavirin Can Cure Hepatitis C in 12 Weeks without Interferon. Highleyman, L. 8 November 2011.
  8.  Nucleotide Polymerase Inhibitor Sofosbuvir plus Ribavirin for Hepatitis C. Gane, E et al. New England Journal of Medicine 368:3444. January 3, 2013.
  9.  CROI 2013: Sofosbuvir + Ledipasvir + Ribavirin Combo for HCV Produces 100% Sustained Response. Highleyman, L. 4 March 2013.


  1. medchemnintabelle says:

    Reblogged this on MedCheminAustralia.

  2. “combinations of sofosbuvir with NS5A inhibitors, such as daclatasvir or GS-5885, have shown sustained virological response rates of up to 100% in people infected with HCV”. The combination of sofosbuvir and daclatasvir cured 100% of genotypes 1, 2, and 3, without toxic ribavirin or interferon. The combination of sofosbuvir and GS-5885 (now called ledipasvir) is only somewhat effective in genotypes 1 only, and still needs the addition of ribavirin. Ribavirin is toxic and has horrendous side effects, so of which may be permanent. The SVR24 rates released at November 2012 AASLD Boston Liver Meeting confirm this 100% cure for the three genotpyes without ribavirin, when the two drugs, sofosbuvir and daclatasvir, were adminstered from day one of 24 weeks of treatment. The only side effects reported with this treatment combination were headache, fatigue, and nausea. This is the most effective and safest treatment if the history of this deadly virus and yet the hepatitis C community will be no better off than we were a year ago, if Gilead Sciences and Bristol-Myers do not come to an agreement to work together.

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DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with AFRICURE PHARMA, ROW2TECH, NIPER-G, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Govt. of India as ADVISOR, earlier assignment was with GLENMARK LIFE SCIENCES LTD, as CONSUlTANT, Retired from GLENMARK in Jan2022 Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 32 plus yrs, Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri, etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him Open superstar worlddrugtracker. His New Drug Approvals, Green Chemistry International, All about drugs, Eurekamoments, Organic spectroscopy international, etc in organic chemistry are some most read blogs He has hands on experience in initiation and developing novel routes for drug molecules and implementation them on commercial scale over a 32 PLUS year tenure till date Feb 2023, Around 35 plus products in his career. He has good knowledge of IPM, GMP, Regulatory aspects, he has several International patents published worldwide . He has good proficiency in Technology transfer, Spectroscopy, Stereochemistry, Synthesis, Polymorphism etc., He suffered a paralytic stroke/ Acute Transverse mylitis in Dec 2007 and is 90 %Paralysed, He is bound to a wheelchair, this seems to have injected feul in him to help chemists all around the world, he is more active than before and is pushing boundaries, He has 100 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 100 Lakh plus views on dozen plus blogs, 227 countries, 7 continents, He makes himself available to all, contact him on +91 9323115463, email, Twitter, @amcrasto , He lives and will die for his family, 90% paralysis cannot kill his soul., Notably he has 38 lakh plus views on New Drug Approvals Blog in 227 countries...... , He appreciates the help he gets from one and all, Friends, Family, Glenmark, Readers, Wellwishers, Doctors, Drug authorities, His Contacts, Physiotherapist, etc He has total of 32 International and Indian awards

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