|
Pharmacotherapeutic group: Direct-acting antiviral, ATC code: J05AX14
Mechanism of action
Daclatasvir is an inhibitor of nonstructural protein 5A (NS5A), a multifunctional protein that is an essential component of the HCV replication complex. Daclatasvir inhibits both viral RNA replication and virion assembly.
Antiviral activity in cell culture
Daclatasvir is an inhibitor of HCV genotypes 1a and 1b replication in cell-based replicon assays with effective concentration (50% reduction, EC50) values of 0.003-0.050 and 0.001-0.009 nM, respectively, depending on the assay method. The daclatasvir EC50 values in the replicon system were 0.003-1.25 nM for genotypes 3a, 4a, 5a and 6a, and 0.034-19 nM for genotype 2a as well as 0.020 nM for infectious genotype 2a (JFH-1) virus.
Daclatasvir showed additive to synergistic interactions with interferon alfa, HCV nonstructural protein 3 (NS3) PIs, HCV nonstructural protein 5B (NS5B) non-nucleoside inhibitors, and HCV NS5B nucleoside analogues in combination studies using the cell-based HCV replicon system. No antagonism of antiviral activity was observed.
No clinically relevant antiviral activity was observed against a variety of RNA and DNA viruses, including HIV, confirming that daclatasvir, which inhibits a HCV-specific target, is highly selective for HCV.
Resistance in cell culture
Substitutions conferring daclatasvir resistance in genotypes 1-4 were observed in the N-terminal 100 amino acid region of NS5A in a cell-based replicon system. L31V and Y93H were frequently observed resistance substitutions in genotype 1b, while M28T, L31V/M, Q30E/H/R, and Y93C/H/N were frequently observed resistance substitutions in genotype 1a. These substitutions conferred low level resistance (EC50 <1 nM) for genotype 1b, and higher levels of resistance for genotype 1a (EC50 up to 350 nM). The most resistant variants with single amino acid substitution in genotype 2a and genotype 3a were F28S (EC50 >300 nM) and Y93H (EC50 >1,000 nM), respectively. In genotype 4, amino acid substitutions at 30 and 93 (EC50 < 16 nM) were frequently selected.
Cross-resistance
HCV replicons expressing daclatasvir-associated resistance substitutions remained fully sensitive to interferon alfa and other anti-HCV agents with different mechanisms of action, such as NS3 protease and NS5B polymerase (nucleoside and non-nucleoside) inhibitors.
Clinical efficacy and safety
In clinical studies of daclatasvir in combination with sofosbuvir or with peginterferon alfa and ribavirin, plasma HCV RNA values were measured using the COBAS TaqMan HCV test (version 2.0), for use with the High Pure System, with a lower limit of quantification (LLOQ) of 25 IU/ ml. SVR was the primary endpoint to determine the HCV cure rate, which was defined as HCV RNA less than LLOQ at 12 weeks after the end of treatment (SVR12) for studies AI444040, ALLY-1 (AI444215), ALLY-2 (AI444216), ALLY-3 (AI444218), AI444042 and AI444043 and as HCV RNA undetectable at 24 weeks after the end of treatment (SVR24) for study AI444010.
Daclatasvir in combination with sofosbuvir
The efficacy and safety of daclatasvir 60 mg once daily in combination with sofosbuvir 400 mg once daily in the treatment of patients with chronic HCV infection were evaluated in four open-label studies (AI444040, ALLY-1, ALLY-2 and ALLY-3).
In study AI444040, 211 adults with HCV genotype 1, 2, or 3 infection and without cirrhosis received daclatasvir and sofosbuvir, with or without ribavirin. Among the 167 patients with HCV genotype 1 infection, 126 were treatment-naïve and 41 had failed prior therapy with a PI regimen (boceprevir or telaprevir). All 44 patients with HCV genotype 2 (n=26) or 3 (n=18) infection were treatment-naïve. Treatment duration was 12 weeks for 82 treatment-naïve HCV genotype 1 patients, and 24 weeks for all other patients in the study. The 211 patients had a median age of 54 years (range: 20 to 70); 83% were white; 12% were black/African-American; 2% were Asian; 20% were Hispanic or Latino. The mean score on the FibroTest (a validated non-invasive diagnostic assay) was 0.460 (range: 0.03 to 0.89). Conversion of the FibroTest score to the corresponding METAVIR score suggests that 35% of all patients (49% of patients with prior PI failure, 30% of patients with genotype 2 or 3) had ≥F3 liver fibrosis. Most patients (71%, including 98% of prior PI failures) had IL-28B rs12979860 non-CC genotypes.
SVR12 was achieved by 99% patients with HCV genotype 1, 96% of those with genotype 2 and 89% of those with genotype 3 (see Tables 6 and 7). Response was rapid (viral load at Week 4 showed that more than 97% of patients responded to therapy), and was not influenced by HCV subtype (1a/1b), IL28B genotype, or use of ribavirin. Among treatment-naïve patients with HCV RNA results at both follow-up Weeks 12 and 24, concordance between SVR12 and SVR24 was 99.5% independent of treatment duration.
Treatment-naïve patients with HCV genotype 1 who received 12 weeks of treatment had a similar response as those treated for 24 weeks (Table 6).
|
Table 6: Treatment outcomes, daclatasvir in combination with sofosbuvir, HCV genotype 1 in Study AI444040
| |
|
Treatment-naïve
|
Prior telaprevir or boceprevir failures
| |
|
daclatasvir + sofosbuvir
N=70
|
daclatasvir + sofosbuvir + ribavirin
N=56
|
All
N=126
|
daclatasvir + sofosbuvir
N=21
|
daclatasvir + sofosbuvir + ribavirin
N=20
|
All
N=41
| |
End of treatment
HCV RNA undetectable
|
70 (100%)
|
56 (100%)
|
126 (100%)
|
19 (91%)
|
19 (95%)
|
38 (93%)
| |
SVR12 (overall)*
|
70 (100%)
|
55 (98%)*
|
125 (99%)*
|
21 (100%)
|
20 (100%)
|
41 (100%)
| |
12 weeks treatment duration
|
41/41 (100%)
|
40/41 (98%)
|
81/82 (99%)
|
--
|
--
|
--
| |
24 weeks treatment duration
|
29/29 (100%)
|
15/15 (100%)
|
44/44 (100%)
|
21 (100%)
|
20 (100%)
|
41 (100%)
| |
≥ F3 liver fibrosis
|
--
|
--
|
41/41 (100%)
|
--
|
--
|
20/20 (100%)
|
* Patients who had missing data at follow-up Week 12 were considered responders if their next available HCV RNA value was <LLOQ. One treatment-naïve patient was missing both post-treatment Weeks 12 and 24 data.
|
Table 7: Treatment outcomes, daclatasvir in combination with sofosbuvir for 24 weeks, treatment-naïve patients with HCV genotype 2 or 3 in Study AI444040
| |
|
Genotype 2
|
Genotype 3
| |
|
daclatasvir + sofosbuvir
N=17
|
daclatasvir + sofosbuvir + ribavirin
N=9
|
All Genotype 2
N=26
|
daclatasvir + sofosbuvir
N=13
|
daclatasvir + sofosbuvir + ribavirin
N=5
|
All Genotype 3
N=18
| |
End of treatment
HCV RNA undetectable
|
17 (100%)
|
9 (100%)
|
26 (100%)
|
11 (85%)
|
5 (100%)
|
16 (89%)
| |
SVR12*
|
17 (100%)
|
8 (89%)*
|
25 (96%)*
|
11 (85%)
|
5 (100%)
|
16 (89%)
| |
≥ F3 liver fibrosis
|
|
|
8/8 (100%)
|
|
|
5/5 (100%)
| |
Virologic failure
| |
Virologic breakthrough**
|
0
|
0
|
0
|
1 (8%)
|
0
|
1 (6%)
| |
Relapse**
|
0
|
0
|
0
|
1/11 (9%)
|
0
|
1/16 (6%)
|
* Patients who had missing data at follow-up Week 12 were considered responders if their next available HCV RNA value was <LLOQ. One patient with HCV genotype 2 infection was missing both post-treatment Week 12 and 24 data.
** The patient with virologic breakthrough met the original protocol definition of confirmed HCV RNA <LLOQ, detectable at treatment Week 8. Relapse was defined as HCV RNA ≥LLOQ during follow-up after HCV RNA <LLOQ at end of treatment. Relapse includes observations through follow-up Week 24.
Advanced cirrhosis and post-liver transplant (ALLY-1)
In study ALLY-1, the regimen of daclatasvir, sofosbuvir, and ribavirin administered for 12 weeks was evaluated in 113 adults with chronic hepatitis C and Child-Pugh A, B or C cirrhosis (n=60) or HCV recurrence after liver transplantation (n=53). Patients with HCV genotype 1, 2, 3, 4, 5 or 6 infection were eligible to enroll. Patients received daclatasvir 60 mg once daily, sofosbuvir 400 mg once daily, and ribavirin (600 mg starting dose) for 12 weeks and were monitored for 24 weeks post treatment. Patients demographics and main disease characteristics are summarised in Table 8.
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Table 8: Demographics and main disease characteristics in Study ALLY-1
| |
|
Cirrhotic cohort
N = 60
|
Post-Liver Transplant
N = 53
| |
Age (years): median (range)
|
58 (19-75)
|
59 (22-82)
| |
Race: White
|
57 (95%)
|
51 (96%)
| |
Black/African American
|
3 (5%)
|
1 (2%)
| |
Other
|
0
|
1 (2%)
| |
HCV genotype:
1a
|
34 (57%)
|
31 (58%)
| |
1b
|
11 (18%)
|
10 (19%)
| |
2
|
5 (8%)
|
0
| |
3
|
6 (10%)
|
11 (21%)
| |
4
|
4 (7%)
|
0
| |
6
|
0
|
1 (2%)
| |
Fibrosis stage
|
|
| |
F0
|
0
|
6 (11%)
| |
F1
|
1 (2%)
|
10 (19%)
| |
F2
|
3 (5%)
|
7 (13%)
| |
F3
|
8 (13%)
|
13 (25%)
| |
F4
|
48 (80%)
|
16 (30%)
| |
Not reported
|
0
|
1 (2%)
| |
CP classes
|
|
ND
| |
CP A
|
12 (20%)
|
| |
CP B
|
32 (53%)
|
| |
CP C
|
16 (27%)
|
| |
MELD score
|
|
ND
| |
mean
|
13.3
|
| |
median
|
13.0
|
| |
Q1, Q3
|
10, 16
|
| |
Min, Max
|
8, 27
|
|
ND: Not determined
SVR12 was achieved by 83% (50/60) of patients in the cirrhosis cohort, with a marked difference between patients with Child-Pugh A or B (92-94%) as compared to those with Child-Pugh C and 94% of patients in the post-liver transplant cohort (Table 9). SVR rates were comparable regardless of age, race, gender, IL28B allele status, or baseline HCV RNA level. In the cirrhosis cohort, 4 patients with hepatocellular carcinoma underwent liver transplantation after 1–71 days of treatment; 3 of the 4 patients received 12 weeks of post-liver transplant treatment extension and 1 patient, treated for 23 days before transplantation, did not receive treatment extension. All 4 patients achieved SVR12.
|
Table 9: Treatment outcomes, daclatasvir in combination with sofosbuvir and ribavirin for 12 weeks, patients with cirrhosis or HCV recurrence after liver transplantation, Study ALLY-1
| |
|
Cirrhotic cohort
N=60
|
Post-LiverTransplant
N=53
| |
End of treatment
HCV RNA undetectable
|
58/60 (97%)
|
53/53 (100%)
| |
|
SVR12
|
Relapse
|
SVR12
|
Relapse
| |
All patients
|
50/60 (83%)
|
9/58* (16%)
|
50/53 (94%)
|
3/53 (6%)
| |
Cirrhosis
|
|
|
ND
|
ND
| |
CP A
|
11/12 (92%)
|
1/12 (8%)
|
|
| |
CP B
|
30/32 (94%)
|
2/32 (6%)
|
|
| |
CP C
|
9/16 (56%)
|
6/14 (43%)
|
|
| |
Genotype 1
|
37/45 (82%)
|
7/45 (16%)
|
39/41 (95%)
|
2/41 (5%)
| |
1a
|
26/34 (77%)
|
7/33 (21%)
|
30/31 (97%)
|
1/31 (3%)
| |
1b
|
11/11 (100%)
|
0%
|
9/10 (90%)
|
1/10 (10%)
| |
Genotype 2
|
4/5 (80%)
|
1/5 (20%)
|
--
|
--
| |
Genotype 3
|
5/6 (83%)
|
1/6 (17%)
|
10/11 (91%)
|
1/11 (9%)
| |
Genotype 4
|
4/4 (100%)
|
0%
|
--
|
--
| |
Genotype 6
|
--
|
--
|
1/1 (100%)
|
0%
|
ND: Not determined
* 2 patients had detectable HCV RNA at end of treatment; 1 of these patients achieved SVR.
HCV/HIV co-infection (ALLY-2)
In study ALLY-2, the combination of daclatasvir and sofosbuvir administered for 12 weeks was evaluated in 153 adults with chronic hepatitis C and HIV co-infection; 101 patients were HCV treatment-naïve and 52 patients had failed prior HCV therapy. Patients with HCV genotype 1, 2, 3, 4, 5, or 6 infection were eligible to enroll, including patients with compenstated cirrhosis (Child-Pugh A). The dose of daclatasvir was adjusted for concomitant antiretroviral use. Patient demographics and baseline disease characteristics are summarised in Table 10.
|
Table 10: Demographics and baseline characteristics in Study ALLY-2
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Patient disposition
|
daclatasvir + sofosbuvir
12 weeks
N = 153
| |
Age (years): median (range)
|
53 (24-71)
| |
Race:
White
|
97 (63%)
| |
Black/African American
|
50 (33%)
| |
Other
|
6 (4%)
| |
HCV genotype:
1a
|
104 (68%)
| |
1b
|
23 (15%)
| |
2
|
13 (8%)
| |
3
|
10 (7%)
| |
4
|
3 (2%)
| |
Compensated cirrhosis
|
24 (16%)
| |
Concomitant HIV therapy:
PI-based
|
70 (46%)
| |
NNRTI-based
|
40 (26%)
| |
Other
|
41 (27%)
| |
None
|
2 (1%)
|
Overall, SVR12 was achieved by 97% (149/153) of patients administered daclatasvir and sofosbuvir for 12 weeks in ALLY-2. SVR rates were >94% across combination antiretroviral therapy (cART) regimens, including boosted-PI-, NNRTI-, and integrase inhibitor (INSTI)-based therapies.
SVR rates were comparable regardless of HIV regimen, age, race, gender, IL28B allele status, or baseline HCV RNA level. Outcomes by prior treatment experience are presented in Table 11.
A third treatment group in study ALLY-2 included 50 HCV treatment-naïve HIV co-infected patients who received daclatasvir and sofosbuvir for 8 weeks. Demographic and baseline characteristics of these 50 patients were generally comparable to those for patients who received 12 weeks of study treatment. The SVR rate for patients treated for 8 weeks was lower with this treatment duration as summarized in Table 11.
|
Table 11: Treatment outcomes, daclatasvir in combination with sofosbuvir in patients with HCV/HIV co-infection in Study ALLY-2
| |
|
8 weeks therapy
|
12 weeks therapy
| |
|
HCV Treatment-naïve
N=50
|
HCV Treatment-naïve
N=101
|
HCV Treatment-experienced*
N=52
| |
End of treatment
HCV RNA undetectable
|
50/50 (100%)
|
100/101 (99%)
|
52/52 (100%)
| |
SVR12
|
38/50 (76%)
|
98/101 (97%)
|
51/52 (98%)
| |
No cirrhosis**
|
34/44 (77%)
|
88/90 (98%)
|
34/34 (100%)
| |
With cirrhosis**
|
3/5 (60%)
|
8/9 (89%)
|
14/15 (93%)
| |
Genotype 1
|
31/41 (76%)
|
80/83 (96%)
|
43/44 (98%)
| |
1a
1b
|
28/35 (80%)
3/6 (50%)
|
68/71 (96%)
12/12 (100%)
|
32/33 (97%)
11/11 (100%)
| |
Genotype 2
|
5/6 (83%)
|
11/11 (100%)
|
2/2 (100%)
| |
Genotype 3
|
2/3 (67%)
|
6/6 (100%)
|
4/4 (100%)
| |
Genotype 4
|
0
|
1/1 (100%)
|
2/2 (100%)
| |
Virologic failure
|
|
|
| |
Detectable HCV RNA at end of treatment
|
0
|
1/101 (1%)
|
0
| |
Relapse
|
10/50 (20%)
|
1/100 (1%)
|
1/52 (2%)
| |
Missing post-treatment data
|
2/50 (4%)
|
1/101 (1%)
|
0
|
* Mainly interferon-based therapy +/-NS3/4 PI.
** Cirrhosis was determined by liver biopsy, FibroScan >14.6 kPa, or FibroTest score ≥0.75 and aspartate aminotransferase (AST): platelet ratio index (APRI) >2. For 5 patients, cirrhosis status was indeterminate.
HCV Genotype 3 (ALLY-3)
In study ALLY-3, the combination of daclatasvir and sofosbuvir administered for 12 weeks was evaluated in 152 adults infected with HCV genotype 3; 101 patients were treatment-naïve and 51 patients had failed prior antiviral therapy. Median age was 55 years (range: 24 to 73); 90% of patients were white; 4% were black/African-American; 5% were Asian; 16% were Hispanic or Latino. The median viral load was 6.42 log10 IU/ml, and 21% of patients had compensated cirrhosis. Most patients (61%) had IL-28B rs12979860 non-CC genotypes.
SVR12 was achieved in 90% of treatment-naïve patients and 86% of treatment-experienced patients. Response was rapid (viral load at Week 4 showed that more than 95% of patients responded to therapy) and was not influenced by IL28B genotype. SVR12 rates were lower among patients with cirrhosis (see Table 12).
|
Table 12: Treatment outcomes, daclatasvir in combination with sofosbuvir for 12 weeks, patients with HCV genotype 3 in Study ALLY-3
| |
|
Treatment-naïve
N=101
|
Treatment-experienced*
N=51
|
Total
N=152
| |
End of treatment
HCV RNA undetectable
|
100 (99%)
|
51 (100%)
|
151 (99%)
| |
SVR12
|
91 (90%)
|
44 (86%)
|
135 (89%)
| |
No cirrhosis**
|
73/75 (97%)
|
32/34 (94%)
|
105/109 (96%)
| |
With cirrhosis**
|
11/19 (58%)
|
9/13 (69%)
|
20/32 (63%)
| |
Virologic failure
|
|
|
| |
Virologic breakthrough
|
0
|
0
|
0
| |
Detectable HCV RNA at end of treatment
|
1 (1%)
|
0
|
1 (0.7%)
| |
Relapse
|
9/100 (9%)
|
7/51 (14%)
|
16/151 (11%)
|
* Mainly interferon-based therapy, but 7 patients received sofosbuvir + ribavirin and 2 patients received a cyclophilin inhibitor.
** Cirrhosis was determined by liver biopsy (METAVIR F4) for 14 patients, FibroScan >14.6 kPa for 11 patients or FibroTest score ≥0.75 and aspartate aminotransferase (AST): platelet ratio index (APRI) >2 for 7 patients. For 11 patients, cirrhosis status was missing or inconclusive (FibroTest score >0.48 to <0.75 or APRI >1 to ≤2).
Compassionate Use
Patients with HCV infection (across genotypes) at high risk of decompensation or death within 12 months if left untreated were treated under compassionate use programmes. Patients with genotype 3 infection were treated with daclatasvir + sofosbuvir +/- ribavirin for 12 or 24 weeks, where the longer treatment duration was associated with a lower risk for relapse (around 5%) in a preliminary analysis. The relevance of including ribavirin as part of the 24-week regimen is unclear. In one cohort the majority of patients were treated with daclatasvir + sofosbuvir + ribavirin for 12 weeks. The relapse rate was around 15%, and similar for patients with Child-Pugh A, B and C. The programmes do not allow for a direct comparison of efficacy between the 12- and 24-week regimens.
Daclatasvir in combination with peginterferon alfa and ribavirin
AI444042 and AI444010 were randomised, double-blind studies that evaluated the efficacy and safety of daclatasvir in combination with peginterferon alfa and ribavirin (pegIFN/RBV) in the treatment of chronic HCV infection in treatment-naïve adults with compensated liver disease (including cirrhosis). AI444042 enrolled patients with HCV genotype 4 infection and AI444010 enrolled patients with either genotype 1 or 4. AI444043 was an open-label, single-arm study of daclatasvir with pegIFN/RBV in treatment-naïve adults with chronic HCV genotype 1 infection who were co-infected with HIV.
AI444042: Patients received daclatasvir 60 mg once daily (n=82) or placebo (n=42) plus pegIFN/RBV for 24 weeks. Patients in the daclatasvir treatment group who did not have HCV RNA undetectable at both Weeks 4 and 12 and all placebo-treated patients continued pegIFN/RBV for another 24 weeks. Treated patients had a median age of 49 years (range: 20 to 71); 77% of patients were white; 19% were black/African-American; 4% were Hispanic or Latino. Ten percent of patients had compensated cirrhosis, and 75% of patients had IL-28B rs12979860 non-CC genotypes. Treatment outcomes in study AI444042 are presented in Table 13. Response was rapid (at Week 4 91% of daclatasvir-treated patients had HCV RNA <LLOQ). SVR12 rates were higher for patients with the IL-28B CC genotype than for those with non-CC genotypes and for patients with baseline HCV RNA less than 800,000 IU/ml but consistently higher in the daclatasvir-treated patients than for placebo-treated patients in all subgroups.
AI444010: Patients received daclatasvir 60 mg once daily (n=158) or placebo (n=78) plus pegIFN/RBV through Week 12. Patients assigned to daclatasvir 60 mg once-daily treatment group who had HCV RNA <LLOQ at Week 4 and undetectable at Week 10 were then randomised to receive another 12 weeks of daclatasvir 60 mg + pegIFN/RBV or placebo + pegIFN/RBV for a total treatment duration of 24 weeks. Patients originally assigned to placebo and those in the daclatasvir group who did not achieve HCV RNA <LLOQ at Week 4 and undetectable at Week 10 continued pegIFN/RBV to complete 48 weeks of treatment. Treated patients had a median age of 50 years (range: 18 to 67); 79% of patients were white; 13% were black/African-American; 1% were Asian; 9% were Hispanic or Latino. Seven percent of patients had compensated cirrhosis; 92% had HCV genotype 1 (72% 1a and 20% 1b) and 8% had HCV genotype 4; 65% of patients had IL-28B rs12979860 non-CC genotypes.
Treatment outcomes in study AI444010 for patients with HCV genotype 4 are presented in Table 13. For HCV genotype 1, SVR12 rates were 64% (54% for 1a; 84% for 1b) for patients treated with daclatasvir + pegIFN/RBV and 36% for patients treated with placebo + pegIFN/RBV. For daclatasvir-treated patients with HCV RNA results at both follow-up Weeks 12 and 24, concordance of SVR12 and SVR24 was 97% for HCV genotype 1 and 100% for HCV genotype 4.
|
Table 13: Treatment outcomes, daclatasvir in combination with peginterferon alfa and ribavirin (pegIFN/RBV), treatment-naïve patients with HCV genotype 4
| |
|
Study AI444042
|
Study AI444010
| |
daclatasvir + pegIFN/RBV
N=82
|
pegIFN/RBV
N=42
|
daclatasvir + pegIFN/RBV
N=12
|
pegIFN/RBV
N=6
| |
End of treatment
HCV RNA undetectable
|
74 (90%)
|
27 (64%)
|
12 (100%)
|
4 (67%)
| |
SVR12*
|
67 (82%)
|
18 (43%)
|
12 (100%)
|
3 (50%)
| |
No cirrhosis
With cirrhosis
|
56/69 (81%)**
7/9 (78%)**
|
17/38 (45%)
1/4 (25%)
|
12/12 (100%)
0
|
3/6 (50%)
0
| |
Virologic failure
| |
On-treatment virologic failure
|
8 (10%)
|
15 (36%)
|
0
|
0
| |
Relapse
|
2/74 (3%)
|
8/27 (30%)
|
0
|
1/4 (25%)
|
* Patients who had missing data at follow-up Week 12 were considered responders if their next available HCV RNA value was <LLOQ.
** Cirrhosis status was not reported for four patients in the daclatasvir + pegIFN/RBV group.
AI444043: 301 treatment-naïve patients with HCV genotype 1 infection and HIV co-infection (10% with compensated cirrhosis) were treated with daclatasvir in combination with pegIFN/RBV. The dose of daclatasvir was 60 mg once daily, with dose adjustments for concomitant antiretroviral use (see section 4.5). Patients achieving virologic response [HCV RNA undetectable at weeks 4 and 12] completed therapy after 24 weeks while those who did not achieve virologic response received an additional 24 weeks of treatment with pegIFN/RBV, to complete a total of 48 weeks of study therapy. SVR12 was achieved by 74% of patients in this study (genotype 1a: 70%, genotype 1b: 79%).
Long term efficacy data
Limited data are available from an ongoing follow-up study to assess durability of response up to 3 years after treatment with daclatasvir. Among patients who achieved SVR12 with daclatasvir and sofosbuvir (± ribavirin) with a median duration of post-SVR12 follow-up of 15 months, no relapses have occurred. Among patients who achieved SVR12 with daclatasvir + pegIFN/RBV with a median duration of post-SVR12 follow-up of 22 months, 1% of patients relapsed.
Resistance in clinical studies
Frequency of baseline NS5A resistance-associated variants (RAVs)
Baseline NS5A RAVs were frequently observed in clinical studies of daclatasvir. In 9 phase 2/3 studies with daclatasvir in combination with peginterferon alfa + ribavirin or in combination with sofosbuvir +/- ribavirin, the following frequencies of such RAVs were seen at baseline: 7% in genotype 1a infection (M28T, Q30, L31, and/or Y93); 11% in genotype 1b infection (L31 and/or Y93H), 51% in genotype 2 infection (L31M), 8% in genotype 3 infection (Y93H) and 64% in genotype 4 infection (L28 and/or L30).
Daclatasvir in combination with sofosbuvir
Impact of baseline NS5A RAVs on cure rates
The baseline NS5A RAVs described above had no major impact on cure rates in patients treated with sofosbuvir + daclatasvir +/- ribavirin, with the exception of the Y93H RAV in genotype 3 infection (seen in 16/192 [8%] of patients). The SVR12 rate in genotype-3 infected patients with this RAV is reduced (in practice as relapse after end of treatment response), especially in patients with cirrhosis. The overall cure rate for genotype-3 infected patients who were treated for 12 weeks with sofosbuvir + daclatasvir (without ribavirin) in the presence and absence of the Y93H RAV was 7/13 (54%) and 134/145 (92%), respectively. There was no Y93H RAV present at baseline for genotype-3 infected patients treated for 12-weeks with sofosbuvir + daclatasvir + ribavirin, and thus SVR outcomes cannot be assessed.
Emerging resistance
In a pooled analysis of 629 patients who received daclatasvir and sofosbuvir with or without ribavirin in Phase 2 and 3 studies for 12 or 24 weeks,34 patients qualified for resistance analysis due to virologic failure or early study discontinuation and having HCV RNA greater than 1,000 IU/ml. Observed emergent NS5A resistance-associated variants are reported in Table 14.
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Table 14: Summary of noted newly emergent HCV NS5A substitutions on treatment or during follow-up in treated non-SVR12 subjects infected with HCV genotypes 1 through 3
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Category/ Substitution, n (%)
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Genotype 1a
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Genotype 1b
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Genotype 2
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Genotype 3
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N=301
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N=79
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N=44
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N=197
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Non-responders (non-SVR12)
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14*
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1
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2*
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21**
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with baseline and post-baseline sequence
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12
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1
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1
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20
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with emergent NS5A RAVs***
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10 (83%)
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1 (100%)
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0
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16 (80%)
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M28: T
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2 (17%)
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--
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--
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0
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Q30: H, K, R
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9 (75%)
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--
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--
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--
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L31: I, M, V
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2 (17%)
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0
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0
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1 (5%)
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P32-deletion
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0
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1 (100%)
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0
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0
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H58: D, P
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2 (17%)
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--
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--
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--
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S62: L
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--
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--
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--
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2 (10%)
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Y93: C, H, N
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2 (17%)
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0
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0
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11 (55%)
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* Patient(s) lost to follow-up
** One patient considered a protocol failure (non-SVR) achieved SVR
*** NS5A RAVs monitored at amino acid positions are 28, 29, 30, 31, 32, 58, 62, 92, and 93
The sofosbuvir resistance-associated substitution S282T emerged in only 1 non-SVR12 patient infected with genotype 3.
No data are available on the persistence of daclatasvir resistance-associated substitutions beyond 6 months post-treatment in patients treated with daclatasvir and sofosbuvir with/without ribavirin. Emergent daclatasvir resistance-associated substitutions have been shown to persist for 2 years post-treatment and beyond for patients treated with other daclatasvir-based regimens.
Daclatasvir in combination with peginterferon alfa and ribavirin
Baseline NS5A RAVs (at M28T, Q30, L31, and Y93 for genotype 1a; at L31 and Y93 for genotype 1b) increase the risk for non-response in treatment-naive patients infected with genotype 1a and genotype 1b infection. The impact of baseline NS5A RAVs on cure rates of genotype 4 infection is not apparent..
In case of non-response to therapy with daclatasvir + peginterferon alfa + ribavirin, NS5A RAVs generally emerged at failure (139/153 genotype 1a and 49/57 genotype 1b). The most frequently detected NS5A RAVs included Q30E or Q30R in combination with L31M. The majority of genotype 1a failures had emergent NS5A variants detected at Q30 (127/139 [91%]), and the majority of genotype 1b failures had emergent NS5A variants detected at L31 (37/49 [76%]) and/or Y93H (34/49 [69%]). In limited numbers of genotype 4-infected patients with non-response, substitutions L28M and L30H/S were detected at failure.
Paediatric population
The European Medicines Agency has deferred the obligation to submit the results of studies with daclatasvir in one or more subsets of the paediatric population in the treatment of chronic hepatitis C (see section 4.2 for information on paediatric use).
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