The Discovery of Sofosbuvir: A Liver-Targeted Nucleotide Prodrug for the Treatment and Cure of HCV

  • Michael J. SofiaEmail author
  • Phillip A. Furman
Part of the Topics in Medicinal Chemistry book series (TMC, volume 31)


Over the last 15 years, an increase in knowledge of the structure, function, life cycle, and pathogenesis of hepatitis C virus (HCV) led to a focused effort on the discovery and development of interferon (IFN)-free therapies that are well tolerated and have increased cure rates. This chapter describes the discovery and development of sofosbuvir, the first live-targeting prodrug of a nucleotide analog, and contains a detailed overview of the synthesis, activity, mechanism of action, toxicity, and clinical studies of sofosbuvir (PSI-7977). The identification of the cytidine nucleoside analog PSI-6130, which was shown to be a potent and nontoxic inhibitor of HCV replication, is described. A summary of the mechanism of action of PSI-6130 is presented that describes the metabolic pathway to its corresponding 5′-triphosphate and to the uridine metabolite (PSI-6206) and the uridine mono-, di-, and triphosphate. Both PSI-6130 triphosphate and PSI-6206 triphosphate were shown to be potent alternative substrate inhibitors of the HCV NS5B polymerase. Because the triphosphate of PSI-6206 was a potent inhibitor of the NS5B polymerase and because it had a long intracellular half-life, the goal was to find an approach that could be used to deliver PSI-6206 monophosphate to the liver. The thought process and approach that led to the design and synthesize of various phosphoramidate prodrugs of the uridine monophosphate metabolite is presented. Of the compounds synthesized, PSI-7851 possessed the desired characteristics. PSI-7851 was a mixture of two diastereoisomers, PSI-7976 and PSI-7977. The two isomers were separated, and PSI-7977 (sofosbuvir) which showed tenfold greater activity was moved forward into clinical development. On December 6, 2013, sofosbuvir (Sovaldi®) was approved by the US FDA for the treatment of HCV genotype (GT) 1, 2, 3, and 4 patient populations with the combination of sofosbuvir + RBV being approved for GT 2 and 3 patient populations as the first IFN-free cure for patients infected with HCV.


2′-F-2′-C-methyl cytidine 2′-F-2′-C-methyl nucleoside 2′-F-2′-C-methyl uridine Diphosphate Epclusa® Harvoni® HCV Hepatitis C virus Liver Liver targeting Mericitabine Monophosphate NS5B polymerase Nucleoside Nucleotide Phosphoramidate Prodrug PSI-6130 PSI-6206 PSI-7851 PSI-7977 RdRp Resistance RG7128 RNA-dependent RNA polymerase S282T Sofosbuvir Sovaldi® Triphosphate Vosevi® 



The discovery and development of sofosbuvir would not have been possible if not for the dedicated staff at Pharmasset, Inc. Their commitment to finding a cure for HCV made sofosbuvir a reality. Thanks also goes to the clinical development team at Gilead Sciences, Inc. for among other things, completing the Phase III clinical studies and bringing sofosbuvir to the market so that the millions of HCV patients worldwide could realize a cure for their disease.

Compliance with Ethical Standards

Conflict of Interest Author Michael J. Sofia was an employee of Pharmasset, Inc. and Gilead Sciences Inc., and he is currently an employee and Chief Scientific Officer of Arbutus Biopharma, Inc. He is also a stockholder in Arbutus Biopharma, Inc.

Author Phillip A. Furman was an employee of Pharmasset, Inc.

Ethical Approval

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed in the studies reported in this chapter.

All procedures performed in the studies reported in this chapter involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all individual participants included in the study.


  1. 1.
    Poch O, Sauvaget I, Delarue M, Tordo N (1989) Identification of four conserved motifs among the RNA-dependent polymerase encoding elements. EMBO J 8(12):3867–3874CrossRefGoogle Scholar
  2. 2.
    Sofia MJ, Chang W, Furman PA, Mosley RT, Ross BS (2012) Nucleoside, nucleotide and non-nucleoside inhibitors of hepatitis C virus NS5B RNA-dependent RNA polymerase. J Med Chem 55:2481–2531CrossRefGoogle Scholar
  3. 3.
    Clark JL, Hollecker L, Mason JC, Stuyver LJ, Tharnish PM, Lostia S, McBrayer TR, Schinazi RF, Watanabe KA, Otto MJ, Furman PA, Stec WJ, Patterson SE, Pankiewicz KW (2005) Design, synthesis, and antiviral activity of 2′-Deoxy-2′-fluoro-2'-C-methyl-cytidine, a potent inhibitor of hepatitis C virus replication. J Med Chem 48(17):5504–5508CrossRefGoogle Scholar
  4. 4.
    Stuyver LJ, McBrayer TR, Tharnish PM, Clark J, Hollecker L, Lostia S, Nachman T, Grier J, Bennett MA, Xie M-Y, Schinazi RF, Morrey JD, Julander JL, Furman PA, Otto MJ (2006) Inhibition of hepatitis C replicon RNA synthesis by beta-D-2′-deoxy-2′-fluoro-2'-C-methylcytidine: a specific inhibitor of hepatitis C virus replication. Antivir Chem Chemother 17(2):79–87CrossRefGoogle Scholar
  5. 5.
    Sofia MJ, Furman PA, Symonds WT (2010) 2'-F-2'-C-methyl nucleosides and nucleotides for the treatment of hepatitis C virus: from discovery to the clinic. In: Barrish JC, Carter PH, Cheng PTW, Zahler R (eds) RSC drug discovery ser. Accounts in drug discovery, vol 4. Royal Society of Chemistry, London, pp 238–266CrossRefGoogle Scholar
  6. 6.
    Sofia MJ (2013) Nucleotide prodrugs for the treatment of HCV infection. Adv Pharmacol 67:39–73. CrossRefPubMedGoogle Scholar
  7. 7.
    Wang P, Ching B-K, Rachakonda S, Du J, Khan N, Shi W, Stec D, Cleary D, Sofia MJ (2009) An efficient and diastereoselective synthesis of PSI-6130: a clinically efficacious inhibitor of HCV NS5B polymerase. J Org Chem 74:6819–6824CrossRefGoogle Scholar
  8. 8.
    Murakami E, Bao H, Ramesh M, McBrayer TR, Whitaker T, Micolochick SHM, Schinazi RF, Stuyver LJ, Obikhod A, Otto MJ, Furman PA (2007) Mechanism of activation of b-D-2′-deoxy-2′-fluoro-2'-C-methylcytidine and inhibition of hepatitis C virus NS5B RNA polymerase. Antimicrob Agents Chemother 51(2):503–509CrossRefGoogle Scholar
  9. 9.
    Ma H, Jiang WR, Robledo N, Leveque V, Ali S, Lara-Jaime T, Masjedizadeh M, Smith DB, Cammack N, Klumpp K, Symons J (2007) Characterization of the metabolic activation of hepatitis C virus nucleoside inhibitor beta-D-2′-Deoxy-2′-fluoro-2'-C-methylcytidine (PSI-6130) and identification of a novel active 5′-triphosphate species. J Biol Chem 282(41):29812–29820CrossRefGoogle Scholar
  10. 10.
    Murakami E, Niu C, Bao H, Micolochick SHM, Whitaker T, Nachman T, Sofia MA, Wang P, Otto MJ, Furman PA (2008) The mechanism of action of beta-D-2′-deoxy-2′-fluoro-2'-C-methylcytidine involves a second metabolic pathway leading to beta-D-2′-deoxy-2′-fluoro-2'-C-methyluridine 5′-triphosphate, a potent inhibitor of the hepatitis C virus RNA-dependent RNA polymerase. Antimicrob Agents Chemother 52(2):458–464CrossRefGoogle Scholar
  11. 11.
    Ali S, Leveque V, Le Pogam S, Ma H, Philipp F, Inocencio N, Smith M, Alker A, Kang H, Najera I, Klumpp K, Symons J, Cammack N, Jiang WR (2008) Selected replicon variants with low-level in vitro resistance to the hepatitis C virus NS5B polymerase inhibitor PSI-6130 lack cross-resistance with R1479. Antimicrob Agents Chemother 52(12):4356–4369CrossRefGoogle Scholar
  12. 12.
    Brown NA (2009) Progress towards improving antiviral therapy for hepatitis C with hepatitis C virus polymerase inhibitors. Part I: nucleoside analogues. Expert Opin Investig Drugs 18(6):709–725. CrossRefPubMedGoogle Scholar
  13. 13.
    Burton JR (2009) HCV NS5B polymerase inhibitors. Clin Liver Dis 13:12CrossRefGoogle Scholar
  14. 14.
    Gane EJ, Roberts SK, Stedman CA, Angus PW, Ritchie B, Elston R, Ipe D, Morcos PN, Baher L, Najera I, Chu T, Lopatin U, Berrey MM, Bradford W, Laughlin M, Shulman NS, Smith PF (2010) Oral combination therapy with a nucleoside polymerase inhibitor (RG7128) and danoprevir for chronic hepatitis C genotype 1 infection (INFORM-1): a randomised, double-blind, placebo-controlled, dose-escalation trial. Lancet 376(9751):1467–1475CrossRefGoogle Scholar
  15. 15.
    Hecker SJ, Erion MD (2008) Prodrugs of phosphates and phosphonates. J Med Chem 51(8):2328–2345CrossRefGoogle Scholar
  16. 16.
    Sofia MJ, Bao D, Chang W, Du J, Nagarathnam D, Rachakonda S, Reddy PG, Ross BS, Wang P, Zhang H-R, Bansal S, Espiritu C, Keilman M, Lam AM, Steuer HMM, Niu C, Otto MJ, Furman PA (2010) Discovery of a beta-D-2′-Deoxy-2′-alpha-fluoro-2′-b-C-methyluridine nucleotide prodrug (PSI-7977) for the treatment of hepatitis C virus. J Med Chem 53(19):7202–7218CrossRefGoogle Scholar
  17. 17.
    McGuigan C, Wedgwood OM, De Clercq E, Balzarini J (1996) Phosphoramidate derivatives of 2′,3′-didehydro-2′,3′-dideoxyadenosine (d4A) have markedly improved anti-HIV potency and selectivity. Bioorg Med Chem Lett 6:2359–2362CrossRefGoogle Scholar
  18. 18.
    McGuigan C, Cahard D, Sheeka HM, De CE, Balzarini J (1996) Phosphoramidate derivatives of d4T with improved anti-HIV efficacy retain full activity in thymidine kinase-deficient cells. Bioorg Med Chem Lett 6(10):1183–1186CrossRefGoogle Scholar
  19. 19.
    Lam AM, Murakami E, Espiritu C, Steuer HM, Niu C, Keilman M, Bao H, Zennou V, Bourne N, Julander JG, Morrey JD, Smee DF, Frick DN, Heck JA, Wang P, Nagarathnam D, Ross BS, Sofia MJ, Otto MJ, Furman PA (2010) PSI-7851, a pronucleotide of beta-D-2′-deoxy-2′-fluoro-2'-C-methyluridine monophosphate, is a potent and pan-genotype inhibitor of hepatitis C virus replication. Antimicrob Agents Chemother 54(8):3187–3196CrossRefGoogle Scholar
  20. 20.
    Arnold JJ, Sharma SD, Feng JY, Ray AS, Smidansky ED, Kireeva ML, Cho A, Perry J, Vela JE, Park Y, Xu Y, Tian Y, Babusis D, Barauskus O, Peterson BR, Gnatt A, Kashlev M, Zhong W, Cameron CE (2012) Sensitivity of mitochondrial transcription and resistance of RNA polymerase II dependent nuclear transcription to antiviral ribonucleosides. PLoS Pathog 8(11):e1003030. CrossRefPubMedPubMedCentralGoogle Scholar
  21. 21.
    Murakami E, Tolstykh T, Bao H, Niu C, Steuer HMM, Bao D, Chang W, Espiritu C, Bansal S, Lam AM, Otto MJ, Sofia MJ, Furman PA (2010) Mechanism of activation of PSI-7851 and its diastereoisomer PSI-7977. J Biol Chem 285(45):34337–34347CrossRefGoogle Scholar
  22. 22.
    Lawitz E, Rodriguez-Torres M, Denning J, Albanis E, Compropst M, Berrey MM, Symonds WT (2013) Pharmacokinetics, pharmacodynamics, and tolerability of GS-7851 a nucleotide analog polymerase inhibitor, following multiple ascending doses in patients with chronic hepatitis C infection. Antimicrob Agents Chemother 57(3):1209–1217CrossRefGoogle Scholar
  23. 23.
    Ross BS, Reddy GP, Zhang H-R, Rachakonda S, Sofia MJ (2011) Synthesis of diastereomerically pure nucleotide phosphoramidates. J Org Chem 76(20):8311–8319CrossRefGoogle Scholar
  24. 24.
    Lam AM, Espiritu C, Bansal S, Micolochick Steuer HM, Niu C, Zennou V, Keilman M, Zhu Y, Lan S, Otto MJ, Furman PA (2012) Genotype and subtype profiling of PSI-7977 as a nucleotide inhibitor of hepatitis C virus. Antimicrob Agents Chemother 56(6):3359–3368. CrossRefPubMedPubMedCentralGoogle Scholar
  25. 25.
    Zennou V, Lam AM, Keilman M, Espiritu C, Micolochick Steuer H, Sofia MJ, Reddy PG, Chang W, Rachakonda S, Otto MJ, Furman PA (2010) Combination of two complementary nucleotide analogues, PSI-7977 and PSI-938, effectively clears wild type and NS5b:S282T HCV replicons-comparison with combinations of other antiviral compounds. In: Paper presented at the 61st annual meeting of the European Association for the Study of the Liver, Vienna, 14–18 AprGoogle Scholar
  26. 26.
    Gilead Sciences (2013) Sovaldi(™) [package insert]Google Scholar
  27. 27.
    Mosley RT, Edwards TE, Murakami E, Lam AM, Grice RL, Du J, Sofia MJ, Furman PA, Otto MJ (2012) Structure of hepatitis C virus polymerase in complex with primer-template RNA. J Virol 86(12):6503–6511CrossRefGoogle Scholar
  28. 28.
    Appleby TC, Perry JK, Murakami E, Barauskas O, Feng J, Cho A, Fox IIID, Wetmore DR, McGrath ME, Ray A, Sofia MJ, Swaminathan S, Edwards TE (2015) Structural basis of RNA replication by the hepatitis C virus polymerase. Science 347(6223):771–775CrossRefGoogle Scholar
  29. 29.
    Rodriguez-Torres M, Lawitz E, Kowdley KV, Nelson DR, Dejesus E, McHutchison JG, Cornpropst MT, Mader M, Albanis E, Jiang D, Hebner CM, Symonds WT, Berrey MM, Lalezari J (2013) Sofosbuvir (GS-7977) plus peginterferon/ribavirin in treatment-naive patients with HCV genotype 1: a randomized, 28-day, dose-ranging trial. J Hepatol 58(4):663–668. CrossRefPubMedGoogle Scholar
  30. 30.
    Lawitz E, Rodriguez-Torres M, Denning JM, Cornpropst MT, Clemons D, McNair L, Berrey MM, Symonds WT (2011) Once daily dual-nucleotide combination of PSI-938 and PSI-7977 provides 94% HCV RNA < LOD at day 14: first purine/pyrimidine clinical combination data (the nuclear study). In: Paper presented at the 46th annual meeting of the European Association for the Study of the Liver, Berlin, 30 Mar–3 AprGoogle Scholar
  31. 31.
    Reddy PG, Bao D, Chang W, Chun B-K, Du J, Nagarathnam D, Rachakonda S, Ross BS, Zhang H-R, Bansal S, Espiritu CL, Keilman M, Lam AM, Niu C, Steuer HM, Furman PA, Otto MJ, Sofia MJ (2010) 2′-Deoxy-2′-alpha-fluoro-2′-beta-C-methyl 3′,5′-cyclic phosphate nucleotide prodrug analogs as inhibitors of HCV NS5B polymerase: discovery of PSI-352938. Bioorg Med Chem Lett 20(24):7376–7380CrossRefGoogle Scholar
  32. 32.
    Gane EJ, Stedman CA, Hyland R, Ding X, Svarovskaia E, Symonds WT, Hindes R, Berrey MM (2013) Nucleotide polymerase inhibitor sofosbuvir plus ribavirin for hepatitis C. N Engl J Med 368:34–44CrossRefGoogle Scholar
  33. 33.
    Babusis D, Curry MP, Denning J, Park Y, Murakami E, Afdhal N, Symonds W, McHutchinson JG, Ray A (2013) Nucleotide analog levels in liver explants form HCV infected subjects undergoing liver transplantation after up to 24 weeks sofosbuvir (GS-7977) with ribavirin treatment. Hepatology 58(Suppl):737AGoogle Scholar
  34. 34.
    Martel-Laferriere V, Dieterich DT (2012) GS-7977: a promising nucleotide analog NS5B polymerase inhibitor of HCV. Futur Virol 7(6):537–546CrossRefGoogle Scholar
  35. 35.
    Karageorgopoulos DE, El-Sherif O, Bhagani S, Khoo SH (2014) Drug interactions between antivirals and new or emerging direct-acting antivirals in HIV/hepatitis C virus coinfection. Curr Opin Infect Dis 27(1):36–45CrossRefGoogle Scholar
  36. 36.
    Koff RS (2014) Review article: the efficacy and safety of sofosbuvir, a novel, oral nucleotide NS5B polymerase inhibitor, in the treatment of chronic hepatitis C virus infection. Aliment Pharmacol Ther 39(5):478–487. CrossRefPubMedGoogle Scholar
  37. 37.
    Mathias A, Cornpropst MT, Clemons D, Denning J, Symonds W (2012) No clinically significant pharmacokinetic drug-drug interactions between sofosbuvir (GS-7977) and the immunosuppressants cyclosporine A or tacrolimus in healthy volunteers. In: Paper presented at the 63rd annual meeting of the American Association for the Study of Liver Diseases, Boston, 9–13 NovGoogle Scholar
  38. 38.
    Jacobson IM, Gordon SC, Kowdley KV, Yoshida EM, Rodriguez-Torres M, Sulkowski MS, Shiffman ML, Lawitz E, Everson G, Bennett M, Schiff E, Al-Assi MT, Subramanian GM, An D, Lin M, McNally J, Brainard D, Symonds WT, McHutchison JG, Patel K, Feld J, Pianko S, Nelson DR (2013) Sofosbuvir for hepatitis C genotype 2 or 3 in patients without treatment options. N Engl J Med 368(20):1867–1877. CrossRefPubMedGoogle Scholar
  39. 39.
    Lawitz E, Mangia A, Wyles D, Rodriguez-Torres M, Hassanein T, Gordon SC, Schultz M, Davis MN, Kayali Z, Reddy KR, Jacobson IM, Kowdley KV, Nyberg L, Subramanian GM, Hyland RH, Arterburn S, Jiang D, McNally J, Brainard D, Symonds WT, McHutchison JG, Sheikh AM, Younossi Z, Gane EJ (2013) Sofosbuvir for previously untreated chronic hepatitis C infection. N Engl J Med 368(20):1878–1887. CrossRefPubMedGoogle Scholar
  40. 40.
    Osinusi A, Meissner EG, Lee YJ, Bon D, Heytens L, Nelson A, Sneller M, Kohli A, Barrett L, Proschan M, Herrmann E, Shivakumar B, Gu W, Kwan R, Teferi G, Talwani R, Silk R, Kotb C, Wroblewski S, Fishbein D, Dewar R, Highbarger H, Zhang X, Kleiner D, Wood BJ, Chavez J, Symonds WT, Subramanian M, McHutchison J, Polis MA, Fauci AS, Masur H, Kottilil S (2013) Sofosbuvir and ribavirin for hepatitis C genotype 1 in patients with unfavorable treatment characteristics: a randomized clinical trial. JAMA 310(8):804–811. CrossRefPubMedPubMedCentralGoogle Scholar
  41. 41.
    Charlton M, Gane E, Manns MP, Brown RS, Curry MP, Kwo P, Fontana RJ, Gilroy R, Teperman L, Muir A, McHutchinson JG, Symonds W, Denning J, McNair L, Arterburn S, Terrault N, Samuel D, Forns X (2013) Sofosbuvir and ribavirin for the treatment of established recurrent hepatitis C infection after liver transplantation: preliminary results of a prospective, multicenter study. In: Paper presented at the 64th annual meeting of the American Association for the Study of Liver Diseases, Washington, 1–5 NovGoogle Scholar
  42. 42.
    Tong X, Le Pogam S, Li L, Haines K, Piso K, Baronas V, Yan JM, So SS, Klumpp K, Najera I (2014) In vivo emergence of a novel mutant L159F/L320F in the NS5B polymerase confers low-level resistance to the HCV polymerase inhibitors mericitabine and sofosbuvir. J Infect Dis 209(5):668–675. CrossRefPubMedGoogle Scholar
  43. 43.
    Gentile I, Maracolo AE, Buonomo AR, Zappulo E, Borgia F (2015) The discovery of sofosbuvir: a revolution for therapy of chronic hepatitis C. Expert Opin Drug Discovery 10(12):1363–1377CrossRefGoogle Scholar
  44. 44.
    Afdhal N, Zeuzem S, Kwo P, Chojkier M, Gitlin N, Puoti M, Romero-Gomez M, Zarski JP, Agarwai K, Buggisch P, Foster G, Brau N, Buti M, Jacobson I, Subramanian GM, Ding X, Hong M, Yang JC, Pang PS, Symonds WT, McHutchinson JG, Muir A, Mangia A, Marcellin P (2014) Ledipasvir and sofosbuvir for untreated HCV genotype 1 infection. N Engl J Med 370:1889–1898CrossRefGoogle Scholar
  45. 45.
    Kowdley KV, Lawitz E, Poordad F, Cohen DE, Nelson DR, Zeuzem S, Everson GT, Kwo P, Foster GR, Sulkowski MS, Xie W, Pilot-Matias T, Liossis G, Larsen L, Khatri A, Podsadecki T, Bernstein B (2014) Phase 2b trial of interferon-free therapy for hepatitis C virus genotype 1. N Engl J Med 370(3):222–232. CrossRefPubMedPubMedCentralGoogle Scholar
  46. 46.
    Afdhal N, Reddy KR, Nelson DR, Lawitz E, Gordon SC, Schiff E, Nahass R, Ghalib R, Gitlin N, Herring R, Lalezari J, Younes ZH, Pockros PJ, Di Bisceglie AM, Arora S, Subramanian GM, Zhu Y, Dvory-Sobol H, Yang JC, Pang PS, Symonds WT, McHutchison JG, Muir AJ, Sulkowski M, Kwo P, Investigators ION (2014) Ledipasvir and sofosbuvir for previously treated HCV genotype 1 infection. N Engl J Med 370(16):1483–1493. CrossRefPubMedGoogle Scholar
  47. 47.
    Everson G, Towner WJ, Davis MN, Wyles D, Nahass R, Thuluvath PJ, Etzkorn K, Hinestrosa F, Tong M, Rabinovitz M, McNally J, Brainard DM, Han L, Doehle B, McHutchinson JG, Morgan T, Chung RT, Tran TT (2015) Sofosbuvir with velpatasvir in treatment-naive noncirrhotic patients with genotype 1 to 6 hepatitis C virus infection: a randomized trial. Ann Intern Med 163(11):818–826CrossRefGoogle Scholar
  48. 48.
    Bourleire M, Gordon SC, Flamm SL, Cooper CL, Ramji A, Tong M, Ravendhran N, Vierling JM, Tran TT, Pianko S, Bansal MB, de Ledinghen V, Hyland R, Stamm LM, Dvory-Sobol H, Svarovskaia E, Zhang J, Huang KC, Subramanian GM, Brainard DM, McHutchinson JG, Verna EC, Buggisch P, Landis CS, Younes ZH, Curry MP, Strasser SI, Reddy KR, Manns M, Kowdley KV, Zeuzem S, Investigators P-aP (2017) Sofosbuvir, velpatasvir, and voxilaprevir for previously treated HCV infection. N Engl J Med 376(22):2134–2146CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Arbutus Biopharma, Inc.WarminsterUSA
  2. 2.Saint Augustine USA

Personalised recommendations