Send Orders for Reprints to [email protected] Current Drug Discovery Technologies, 2017, 14, 000-000 1

REVIEW ARTICLE A New Potent NS5A Inhibitor in the Management of Virus: Ravidasvir

Enas Hafez1, Tamer Elbaz2, Mohamed El Kassas3,* and Gamal Esmat2

1Clinical Pharmacy Unit, New Cairo Viral Hepatitis Treatment Unit, Cairo, Egypt; 2Endemic Hepa- togastroenterology Department, Faculty of Medicine, Cairo University, Cairo, Egypt and 3Endemic Medicine Department, Faculty of Medicine, Helwan University, Cairo, Egypt

Abstract: Background: Chronic hepatitis C virus (HCV) is a worldwide health problem that can lead to liver cirrhosis, liver cell failure and numerous subsequent complications such as hepatocellular carcinoma. Till the near past, pegylated was the standard of care therapy. However, it was associated with suboptimal success rates and many side effects. Thereafter, direct antiviral agents (DAA) appeared and played the key role in

A R T I C L E H I S T O R Y management of HCV. One of those recent DAAs is ravidasvir.

Received: April 21, 2017 Revised: July 06, 2017 Summary: It is a potent NS5A inhibitor that was formerly known as PPI-668. It is pro- Accepted: July 06, 2017 duced by the cooperation of Presidio pharmaceuticals and Pharco International pharma-

DOI: ceutical company. Since its first production, it has been enrolled in different successive 10.2174/1570163814666170713104435 clinical trials. Phase 1 and 2 trials confirmed its safety and tolerability and its great effica- cy in suppressing viral loads in short periods. It has a pangenotypic activity with favorable pharmacokinetic properties. Ravidasvir inhibits the replication of HCV variants that de- velop resistance mutations for different DAA classes. Even more, HCV variants that had reduced susceptibility to ravidasvir are completely susceptible to other DAA. Finally, a large multicenteric registrational phase 3 clinical trial that included large percentages of difficult to treat patients (such as cirrhotic and interferon experienced patients) has been fully accomplished and proved great SVR12 rates. Conclusion: Ravidasvir is a potent new NS5A inhibitor with excellent safety and toler- ability in management of genotype 4 HCV patients.

Keywords: Ravidasvir, PPI-668, , hepatitis C, NS5A, direct acting antiviral (DAA).

1. INTRODUCTION the presence of imidazole – spacer – imidazole moie- Ravidasvir (PPI-668) is an NS5A HCV RNA ty. Efforts to identify series of novel NS5A inhibitors inhibitor and is chemically classified as a benzim- led to the development of ravidasvir with a well- idazole -naphthylene –imidazole core containing known structure activity relationship (SAR), good compound. It was developed after the introduction pharmacokinetics and activity profile. [1]. of (BMS-790052), the first member of NS5A class which is chemically characterized by 2. PRECLINICAL DEVELOPMENT Several in-vitro and in-vivo preclinical studies *Address correspondence to this author at the Endemic Medicine were performed to evaluate ravidasvir activity. To Department, Faculty of Medicine, Helwan University, Cairo, Egypt; investigate the new compound antiviral activity, a Tel: + (20) 2-3389959; Fax: + (20) 2-3682774; E-mail: [email protected] primary cell-based assay was performed using HCV

1570-1638/17 $58.00+.00 © 2017 Bentham Science Publishers 2 Current Drug Discovery Technologies, 2017, Vol. 14, No. 3 Hafez et al.

GT-1a and GT-1b replicons while a GT-3a replicon bility and pharmacokinetic properties of ravidasvir was used for secondary assay to detect multiple geno- in healthy volunteers (first part of the study) using typic activities. Results of cell replicon studies re- sequential dosing of 80, 160 and 320 mg. Each vealed that the EC50 values were 0.12 nM, 0.010 nM single dose was investigated in healthy subjects (n and 1.14 nM for GT-1a, GT-2a and GT-3a respec- =8) who were randomized to 6:2; active ravidasvir tively. Pangenotypic activity of ravidasvir was con- versus placebo respectively. An additional (fourth) firmed by comparison with the daclatasvir cell repli- cohort was performed to test multiple dosing (320 con results demonstrating higher activity for GT-3a mg once daily for 5 days) completing part 1 of the (EC50=0.67 for daclatasvir) despite the lower antivi- study. Second part of the study included four co- ral activity for GT-1a and GT-1b (EC50=0.073 and hort groups of HCV GT-1 treatment naïve patients 0.14 nM respectively). The promising in-vitro results (n=10 in each group) who received 40, 80, 160 and encouraged the conduction of pharmacokinetic stud- 240 mg once daily for three days and were ran- ies on animals using Sprague-Dawley rats. PK pa- domized to 8:2 active versus placebo in order to rameters including plasma peak concentration, expo- assess pangenotypic activity. A group of HCV sure, steady state, bioavailability and liver-uptake GT-2a and 3a patients was added to the study and studies suggested further testing in Beagle-dogs and received 160 mg of ravidasvir (once daily for 3 Cynomolgus monkeys in which PK parameters days). Evaluation parameters were safety data showed marked enhancement even with dose escalat- (both laboratory and clinical), antiviral activity and ing PK studies. In addition, ravidasvir proved to be viral resistance testing. well tolerated in the three animals under tests. Com- pleted preclinical studies were obtained after investi- 3.1.2. Assessments gating the safety data including cellular toxicity, cy- Several follow up techniques were applied on tochrome enzymes inhibition, screening of other re- the predetermined time intervals to detect the PK ceptor for secondary pharmacology, viral resistance and drug activity. PK was investigated via testing and the combination with other DAAs. The final in- the collected blood samples on specific predeter- tegrated pre-clinical work strongly recommended mined schedule for each cohort, antiviral activity proceedings to the next phase of drug testing; clinical was tested by serial plasma sample collection with evaluation in healthy volunteers [1]. the aim of detecting HCV RNA using TaqMan™ PCR v2.0. Population sequencing was performed 3. CLINICAL DEVELOPMENT at baseline, day 1, day 2 and day 3. Susceptibility was assessed in transient transfection assays to en- 3.1. Phase 1 Clinical Trial code specific substitution or population insert from 3.1.1. Study Design clinical samples by using HCV replicons while resistance substitutions were identified, either to A phase 1 randomized placebo controlled clini- be genetically linked or not, by clonal sequencing cal trial was conducted to assess the safety, tolera-

Table 1. Follow up parameter schedule [2].

Part 1:

PK Collect blood sample on day 1,2,3,4,6

Multi-dose cohort:collect sample on day 1,2,3,4,6 and 8

Part 2: Collect blood sample on day 1,2,3,4,8,11 &17

HCVRNA

Part 2: plasma samples analyzed using TaqMan™ PCR v2.0 on day 1,2,3,4,8, 11 &17

Resistance screening Population sequencing: at day0, 1,2 and 3

Susceptibility: by transient transfection assay

Clonal sequencing: to detect genetically linked resistance substitution

A New Potent NS5A Inhibitor in the Management of Hepatitis C Virus Current Drug Discovery Technologies, 2017, Vol. 14, No. 3 3

Fig. (1). AEs noticed in part2 patients regardless of attributability to ravidasvir. detection. Schedule of sample collection is illus- 3.1.5 Antiviral Efficacy and Resistance trated in Table 1 [2]. Initial antiviral efficacy of ravidasvir (studied over 3.1.3. Safety 72 hours) for doses of 40, 80, 160 and 240 mg reveals HCV RNA reduction that was maximal at doses Concerning adverse events (AEs), ravidasvir higher than 80 mg with mean value of 3.54-3.75 appeared to be well tolerated with no reported log10 IU/mL in HCV GT-1 (1a -1b) patients. Similar treatment discontinuation in both healthy volunteer efficacy was clearly evident in GT-3a patients [2]. and patient groups. Also, no ECG changes were detected. Several AEs were detected, regardless of Concerning resistance, among enrolled patient being linked to ravidasvir or not. They included population, only one GT-2a patient with 3 viral headache, diarrhea, fatigue, nausea, dyspepsia, hy- genetically linked substitutions at base line linked pertension and oropharyngeal pain (Fig. 1). (F28L+A30K+L31M) showed no response to rav- idasvir. Three GT-3a patients with substitutions 3.1.4. Pharmacokinetics (either Y93H or A30K) showed minimal response Ravidasvir shows rapid absorption and steady- (0.25 to 0.48 log10 IU/mL), while subjects with state achieved with the first dose with T 2 hours single ones (six GT-1 patients) showed viral HCV max RNA decline (2.82-3.95 log10 IU/mL) due to the and mean Cmax 1.5-5.0µg/ml. It follows dose - proportional increase in plasma concentration pat- suppressive effect of high plasma levels of ravi- tern in part 1 group. Plasma levels that exceed dasvir that was quickly achieved as well as main- EC90 across genotypes GT1-GT7 are maintained tained. These resistant variants necessarily require for 24 hours following administration (no need for combined treatment strategies and the promising loading dose) with doses higher than 80 mg and results of phase 1 studies supported proceeding to with minor reduction in C max with food. Im- phase 2 studies using ravidasvir combined with portantly, a preserved inter-dose plasma concen- other members of DAAs [2]. tration (> 100-400 nM) has been noticed that ex- ceeds EC50 for most pre-existing resistant strains 3.2. Phase 2 Clinical Trial (HCV GT-1) and once daily administration is Three DAAs were evaluated in this trial: the highly suggested based on the PK study [2]. study drugs were ravidasvir (NS5A inhibitor), fal- 4 Current Drug Discovery Technologies, 2017, Vol. 14, No. 3 Hafez et al. daprevir (FDV; protease inhibitor) and decompensation. Fibro Test score was less than (DBV; non-nucleoside NS5B inhibitor). DBV was 0.75 and APRI score less than 2 at screening. All tested at two doses (600 and 400 mg BID) with or patients had their PCR levels for HCV RNA without RBV (weight based dose 1000 or 1200 mg higher that 500.000 IU/mL. NS3, NS5A and NS5B for <75 kg & ≥75 mg respectively). The primary sequencing was performed at baseline, outcome was to detect the efficacy of 12 week breakthrough or relapses and IL28B genotype treatment regimen of the 3 DAAs in GT-1 HCV screening was done to stratify treatment groups to infected patients (SVR 12). HCV RNA was quan- CC, CT and TT genotypes (36, 58 and 6 % titatively detected by Roche TaqManTM HCV 2.0 respectively). (Fig. 2) [3, 4] with high-pure system, with lower limit of quanti- fication (LLOQ) =25 IU/mL and lower limit of 3.2.2. HCV RNA Response detection (LLOD) = 10IU/mL. The secondary out- Across the three cohorts; rapid virologic re- comes were to evaluate the efficacy of the two sponse (LLOQ < 25 IU/mL) was achieved in 97% dose levels of DBV (600 and 400 mg BID), PK of patients at week 4, while 83% of patients and safety as well [3]. achieved complete rapid virologic response cRVR (LLOQ < 10 IU/mL). By week 12, 17 patients 3.2.1. Study Design have completed treatment with HCV RNA main- HCV infected patients were equally enrolled in tained below LLOD and 13 of them reached week- 3 different cohort groups to receive the treatment 16 visit with persistent negative viremia (SVR4). regimen for 12 weeks (n=12 per cohort). They Only one patient discontinued treatment at week 5 received FDV loading dose of 240 mg at day 1 due to viral breakthrough attributed to viral re- then cohort 1 received 600 mg of DBV twice sistance (next section for details). At week 24, 22 daily, 200 mg of ravidasvir once daily, 120 mg of out of 24 patients of cohort 1 and cohort 2 (92 %) FDV once daily and weight based dose of RBV for achieved SVR 12 regardless of DBV dose (400 or 12 weeks. Cohort 2 received the same treatment 600 mg BID) with one treatment failure in each regimen but with lower doses of DBV (400 mg cohort due to the presence of a resistant variant twice daily). Cohort 3 was initiated only when [3]. more than 70% of the first 12 patients achieved RNA ≤ LLOQ by week 2 with accepted safety 3.2.3. Resistance & Polymorphism assessments. This cohort received the same Screening of the enrolled patients at baseline treatment regimen but with 600 mg of DBV twice revealed the presence of resistant variants which daily and without RBV. Criteria for included may affect the antiviral response, substitution of patients were patients who were aged 18-65 years NS5A amino acid residue 28, 30, 31, 58 and 93 with clinically documented chronic HCV GT-1 contributed to resistance to NS5A inhibitors while , absence of other etiologies of liver Q80K and A421V substitutions acquired viral disease and absence of evidence of hepatic

Fig. (2). Study design with follow- up time interval (3, 4)l. A New Potent NS5A Inhibitor in the Management of Hepatitis C Virus Current Drug Discovery Technologies, 2017, Vol. 14, No. 3 5

Table 2. Resistant variants, polymorphism and relapses.

Cohort 1 After week 5:One patient discontinued treatment due to breakthrough attributed to the Presence of Q30L+Y3H linked NS5A substitution & A421V NS5B substitution at baseline 1

After week 9: one patient self- discontinued tretment due to GIT side effects 2[3, 4]

Cohort 2

4 weeks post tretment: one patient relapsed due to Q80K subsitution at base line [3]

Day 10 vist:1 patient was incarcerated with HCV RNA< LLOQ

Week 8: viral rebound in one patient due to non-compliance, One patient self-discontinued tratment

Cohort 3 Week 12:one patient relapsed due to low plasma concentration of the 3 tested DAAs caused by Q30E, R155K and A421V substitutions

4 Weeks post treatment: 2 patient relapsed; one relapse is attriuted to M28T + Q30H/R and R155K substitutions and the other relapse was associated with low concentration of virus which disable idintification of the relapsing virus

Between Baseline and Screening one patient decompensated with variceal bleeding mostly irrelevant to study drugs but remained on treatment with the result of HCV

Fig. (3). Study design and follow up time intervals of Pyramid 1 study.

GT-4 HCV cirrhotic and non-cirrhotic Egyptian ravidasvir 200 mg for 12 weeks with or without infected patients (ClinicalTri- RBV (weight based dose 1000 or 1200 mg for <75 als.govIdentifier:NCT02371408) [7] or ≥ 75 kg respectively) as they were randomized 1:1. Eighty non-cirrhotic IFN- experienced pa- 3.3.1. Pyramid 1 Trial Study tients are enrolled in group 2 to receive the same 3.3.1.1 Methods regimen for 12 weeks while 70 cirrhotic IFN – ex- perienced patients in group 3 were 1:1 randomized Pyramid 1 study is a multicenter investigation- for same regimen treatment for 12 or 16 weeks. al, interventional randomized open label study that (Fig. 3) [8]. aimed to assess the antiviral efficacy of ravidasvir and sofosbuvir with and without RBV in patients Patients with mixed genotypes or non-typical with GT-4 HCV chronic infection. Three hundred HCV infection, HIV and HBV co- are adult patients within the age range of 18 to 65 excluded as were uncontrolled diabetic patients or years and body mass index of 18 to 37 kg/m2 were those with previous history of solid organ or bone enrolled and screened for cirrhosis by Fi- marrow transplantation. The primary end point of broscan™. Non-cirrhotic patients are those with the study is focused on proportion of patients who FIB-4 score < 3.25 & liver stiffness measurement succeeded to achieve SVR12 in each group (de- ≤ 12.5 kPa while FIB-4 score for cirrhotic patients fined as HCV RNA <12 IU/mL by Abbott™ Real- is ≥ 3.25 & liver stiffness measurement ≥12.5 kPa Time). Secondary end point is the achievement of or by liver biopsy. Based on these criteria, 170 SVR 4 & SVR24. Safety is assessed via frequency non-cirrhotic and 130 cirrhotic patients (Child of clinical adverse effects and laboratory abnor- Pugh A) were enrolled; all of them were GT-4 malities [8, 10]. HCV infected with serum HCV RNA ≥ 10000 3.3.1.3. Results IU/mL. They were either interferon-experienced or treatment naïve patients with no history of hepatic Among the 300 enrolled patients, 294 patients decompensation and they further enrolled to group have completed treatment at the time of the last 1 (treatment naïve) or group 2&3 (treatment expe- available data. All patients had undetectable HCV rienced) [8,9]. RNA by week 8 demonstrating rapid virologic re- sponse. 3.3.1.2. Study Design Hundred and fifty treatment naïve patients are SVR 12 was successfully achieved by 98% of patients (287/294). After exclusion of three early enrolled as group 1 to receive sofosbuvir 400 mg, A New Potent NS5A Inhibitor in the Management of Hepatitis C Virus Current Drug Discovery Technologies, 2017, Vol. 14, No. 3 7

Table 3. Cases of drug discontinuations of the study (10).

Non IFN-experienced Discontinued at week1, not attributed to safety or efficacy of treatment

patients

-

C

irrhotic IFN-experienced Discontinued at week 1due accidental femur fracture unrelated to study

IFN-naïve treated with SOF/RDV + RBV for 2 Cerebrovascular event likely unrelated to the study weeks

Cirrhotic

patients IFN- experienced treated with SOF/RDV + RBV Discontinued by week 2 not attributed to safety or efficacy of treatment

IFN- naïve, received SOF/RDV+RBV for 12 week Patient achieved SVR 8

treatment discontinuations that were unrelated to CONCLUSION drugs and that have been observed in the non- cirrhotic group, SVR12 in non-cirrhotic patients is Ravidasvir is a new drug that emerged in the considered 100% (167/167) while SVR12 in the pipeline of successful direct acting antivirals. It is cirrhotic group is 120/127 (94%). Cirrhotic pa- related to the family of NS5A inhibitors and must tients of group 3 who were treated for 16 weeks be used in combination, certainly with sofosbuvir have shown 97% (34/35) SVR 12 achievement. with or without . It proved to be very ef- Drug discontinuation is illustrated in Table 3. Post fective, even in difficult to treat cirrhotic patients, treatment relapses were documented in seven cir- with an excellent margin of safety and tolerability. rhotic patients. Three INF – naïve cases had re- Also, it inhibits the replication of HCV variants lapsed by week 8 post treatment: 2 of them had that developed resistance mutations for different undetectable RNA at week 4 and received DAA classes so possibly can be used in relapsers SOF/RDV regimen while the third case had RNA of other NS5A including regimens. undetectable at week 2 and received SOF/RDV+RBV. Rest of relapsed cases were CONFLICT OF INTEREST IFN-experienced: three patients relapsed 4 weeks The author (editor) declares no conflict of inter- post treatment with a single case caused by early est, financial or otherwise. drug discontinuation due to serious AE (bradycar- dia that subsequently resolved without sequelae) and the fourth one relapsed at week 8 post treat- ACKNOWLEDGEMENTS ment [10] Declared none. 3.3.1.4. Safety REFERENCES Study treatment is generally well tolerated with [1] Zhong M, Peng E, Huang N, et al. Discovery of ravidasvir (PPI- no marked difference between different groups 668) as a potent pan-genotypic HCV NS5A inhibitor. Bioorg Med (cirrhotic vs non-cirrhotic, treatment naïve vs ex- Chem Lett 2016; 26(18): 4508-12. [2] Lalezari J, Shah P, Lawitz E, et al. PPI-668, A Potent New Pan- perienced). Till that time, AE are only available in Genotypic HCV NS5A Inhibitor: Phase 1 Efficacy and Safety. percentages without detailed data regarding the 2012, 63rd Annual Meeting of the American Association for the Study of Liver Diseases ASSLD: Nov 9-13 2012 Boston. patient numbers. Most common AEs are headache [3] Lalezari J, Glutzer E, Vig P, et al. High Rate Of Sustained Viroloic (13%), abdominal discomfort (6%), fatigue (5%), Response In Patients With HCV Genotype-1A Infection: A Phase 2 Trial Of Fladaprevir, Deleobuvir And PPI-668, With And Without pruritus (4%), diarrhea (2%) and pruritus (1%). Ribvirin. Headache and fatigue were more common in the [4] Lalezari J, Glutzer E, Vig P, et al. Rapid and Consistent Virologic Responses in a Phase 2 Trial of a New All-Oral Combination of RBV dosing groups. A single serious adverse ef- , Deleobuvir and PPI-668, with and without Ribavirin, fect is documented to be possibly related to study in Patients with HCV Genotype-1a Infection. 2013, 64th Annual drugs. A cirrhotic patient experienced transient Meeting of the American Association for the Study of Liver Dis- eases, November 1-5, 2013, Washington DC, USA. bradycardia and thereafter resolved without seque- [5] Zeuzem S, Soriano V, Asselah T, et al. Faldaprevir and Deleobuvir lae. Data regarding detailed clinical patient condi- for HCV Genotype 1 Infection. N Engl J Med 2013; 369(7): 630-9. [6] A Phase II b/ III a, Randomized Study to Evaluate the Efficacy and tion is not available yet and may be revealed later Safety of PPI-668 (NS5A inhibitor) plus Sofosbuvir, with or with- by the clinical investigators. Data regarding re- out Ribavirin, in Patients with Chronic Hepatitis C Genotype-417, Version 4.0 [protocol]. 17 Mar 2015, Pharco Pharmaceuticals. sistance in patients who failed to achieve SVR12 [7] ClinicalTrials.gov, Sofosbuvir Plus Ravidasvir for the Treatment of is still not available as well [10]. HCV Chronic Infection [Online]. Available from: 8 Current Drug Discovery Technologies, 2017, Vol. 14, No. 3 Hafez et al.

https://clinicaltrials.gov/ct2/show/NCT02961426. (Accessed 6 Patients With Chronic Hepatitis C Genotype-4, [Online]. Available March 2017). in: https://clinicaltrials.gov/ct2/show/NCT02371408 (Accessed 6 [8] Abdel-Maguid A; Colonno R; Brown N; Ruby E; Vig P; Waked I, March 2017). E.G.E.R.M.G.A.E.T.A.M.S.A.G.E.H.K.M.A.-H.M.N.O.H.S., High [10] Esmat G, Gomaa A, Elbaz T, et al. Waked, Final Results of the Response Rate in HCV-Genotype 4 Patients Treated With Ravi- Pyramid 1 Study, a Phase 3 Registrational Trial of Ravidasvir (PPI- dasvir and Sofosbuvir, in CROI Confeerence. February 22-25: Bos- 668) and Sofosbuvir in HCV Genotype-4 Patients: High Rates of ton, Massachusetts. Sustained Viral Clearance in Cirrhotic and Non-Cirrhotic Patients. [9] ClincalTrials.gov, A Study of the Efficacy and Safety of PPI-668 April 13-17, 2016, EASL 2015 Meeting: Barcelona, Spain. (NS5A Inhibitor) Plus Sofosbuvir, With or Without Ribavirin, in

DISCLAIMER: The above article has been published in Epub (ahead of print) on the basis of the materials provided by the author. The Editorial Department reserves the right to make minor modifications for further improvement of the manuscript. PMID: 28707600