CLINICAL PHARMACOLOGY
Mechanism Of Action
Dolutegravir is an HIV-1
antiviral agent [see Microbiology].
Pharmacodynamics
In a randomized, dose-ranging
trial, HIV-1-infected subjects treated with dolutegravir monotherapy
demonstrated rapid and dose-dependent antiviral activity with mean declines
from baseline to Day 11 in HIV-1 RNA of 1.5, 2.0, and 2.5 log10 for
dolutegravir 2 mg, 10 mg, and 50 mg once daily, respectively. This antiviral
response was maintained for 3 to 4 days after the last dose in the 50-mg group.
Effects On Electrocardiogram
In a randomized,
placebo-controlled, cross-over trial, 42 healthy subjects received single-dose
oral administrations of placebo, dolutegravir 250-mg suspension (exposures
approximately 3- fold of the 50-mg once-daily dose at steady state), and
moxifloxacin 400 mg (active control) in random sequence. After baseline and
placebo adjustment, the maximum mean QTc change based on Fridericia correction
method (QTcF) for dolutegravir was 2.4 msec (1-sided 95% upper CI: 4.9 msec).
TIVICAY did not prolong the QTc interval over 24 hours postdose.
Effects on
Renal Function
The effect of dolutegravir on
renal function was evaluated in an open-label, randomized, 3-arm, parallel,
placebo-controlled trial in healthy subjects (n = 37) who received dolutegravir
50 mg once daily (n = 12), dolutegravir 50 mg twice daily (n = 13), or placebo
once daily (n = 12) for 14 days. A decrease in creatinine clearance, as
determined by 24-hour urine collection, was observed with both doses of
dolutegravir after 14 days of treatment in subjects who received 50 mg once
daily (9% decrease) and 50 mg twice daily (13% decrease). Neither dose of
dolutegravir had a significant effect on the actual glomerular filtration rate
(determined by the clearance of probe drug, iohexol) or effective renal plasma
flow (determined by the clearance of probe drug, para-amino hippurate) compared
with the placebo.
Pharmacokinetics
The pharmacokinetic properties of dolutegravir have been
evaluated in healthy adult subjects and HIV-1-infected adult subjects. Exposure
to dolutegravir was generally similar between healthy subjects and
HIV-1-infected subjects. The non-linear exposure of dolutegravir following 50
mg twice daily compared with 50 mg once daily in HIV-1-infected subjects (Table
7) was attributed to the use of metabolic inducers in the background
antiretroviral regimens of subjects receiving dolutegravir 50 mg twice daily in
clinical trials. TIVICAY was administered without regard to food in these
trials.
Table 7: Dolutegravir Steady-State Pharmacokinetic
Parameter Estimates in HIV-1- Infected Adults
Parameter |
50 mg Once Daily Geometric Meana (%CV) |
50 mg Twice Daily Geometric Meanb (%CV) |
AUC(0-24) (mcg•h/mL) |
53.6 (27) |
75.1 (35) |
Cmax (mcg/mL) |
3.67 (20) |
4.15 (29) |
Cmin (mcg/mL) |
1.11 (46) |
2.12 (47) |
a Based on population pharmacokinetic analyses
using data from SPRING-1 and SPRING-2.
b Based on population pharmacokinetic analyses using data from
VIKING (ING112961) and VIKING-3. |
Absorption
Following oral administration
of dolutegravir, peak plasma concentrations were observed 2 to 3 hours
postdose. With once-daily dosing, pharmacokinetic steady state is achieved
within approximately 5 days with average accumulation ratios for AUC, Cmax, and
C24 h ranging from 1.2 to 1.5.
Dolutegravir plasma
concentrations increased in a less than dose-proportional manner above 50 mg.
Dolutegravir is a P-gp substrate in vitro. The absolute bioavailability of
dolutegravir has not been established.
Effects Of Food On Oral
Absorption
TIVICAY may be taken with or
without food. Food increased the extent of absorption and slowed the rate of
absorption of dolutegravir. Low-, moderate-, and high-fat meals increased
dolutegravir AUC(0-∞) by 33%, 41%, and 66%; increased Cmax by 46%, 52%,
and 67%; and prolonged Tmax to 3, 4, and 5 hours from 2 hours under fasted
conditions, respectively.
Distribution
Dolutegravir is highly bound (greater than or equal to
98.9%) to human plasma proteins based on in vivo data and binding is
independent of plasma concentration of dolutegravir. The apparent volume of
distribution (Vd/F) following 50-mg once-daily administration is estimated at
17.4 L based on a population pharmacokinetic analysis.
Cerebrospinal Fluid (CSF): In 12 treatment-naïve subjects
on dolutegravir 50 mg daily plus abacavir/lamivudine, the median dolutegravir
concentration in CSF was 13.2 ng per mL (range: 3.74 ng per mL to 18.3 ng per
mL) 2 to 6 hours postdose after 16 weeks of treatment. The clinical relevance
of this finding has not been established.
Metabolism And Elimination
Dolutegravir is primarily metabolized via UGT1A1 with
some contribution from CYP3A. After a single oral dose of [14C]
dolutegravir, 53% of the total oral dose was excreted unchanged in feces.
Thirty-one percent of the total oral dose was excreted in urine, represented by
an ether glucuronide of dolutegravir (18.9% of total dose), a metabolite formed
by oxidation at the benzylic carbon (3.0% of total dose), and its hydrolytic
N-dealkylation product (3.6% of total dose). Renal elimination of unchanged
drug was low (less than 1% of the dose).
Dolutegravir has a terminal half-life of approximately 14
hours and an apparent clearance (CL/F) of 1.0 L per hour based on population
pharmacokinetic analyses.
Polymorphisms in Drug-Metabolizing Enzymes: In a
meta-analysis of healthy subject trials, subjects with UGT1A1 (n = 7) genotypes
conferring poor dolutegravir metabolism had a 32% lower clearance of
dolutegravir and 46% higher AUC compared with subjects with genotypes
associated with normal metabolism via UGT1A1 (n = 41).
Specific Populations
Hepatic Impairment: Dolutegravir is primarily
metabolized and eliminated by the liver. In a trial comparing 8 subjects with
moderate hepatic impairment (Child-Pugh Score B) with 8 matched healthy
controls, exposure of dolutegravir from a single 50-mg dose was similar between
the 2 groups. No dosage adjustment is necessary for patients with mild to
moderate hepatic impairment (Child-Pugh Score A or B). The effect of severe
hepatic impairment (Child-Pugh Score C) on the pharmacokinetics of dolutegravir
has not been studied. Therefore, TIVICAY is not recommended for use in patients
with severe hepatic impairment.
HBV/HCV Co-infection: Population analyses using
pooled pharmacokinetic data from adult trials indicated no clinically relevant
effect of HCV co-infection on the pharmacokinetics of dolutegravir. There were
limited data on HBV co-infection.
Renal Impairment: Renal clearance of unchanged
drug is a minor pathway of elimination for dolutegravir. In a trial comparing 8
subjects with severe renal impairment (CrCl less than 30 mL per min) with 8
matched healthy controls, AUC, Cmax, and C24 of dolutegravir were decreased by 40%,
23%, and 43%, respectively, compared with those in matched healthy subjects.
The cause of this decrease is unknown. Population pharmacokinetic analysis
using data from SAILING and VIKING-3 trials indicated that mild and moderate
renal impairment had no clinically relevant effect on the exposure of
dolutegravir. No dosage adjustment is necessary for treatment-naïve or
treatment-experienced and INSTI-naïve patients with mild, moderate, or severe
renal impairment or for INSTI-experienced patients (with certain
INSTI-associated resistance substitutions or clinically suspected INSTI
resistance) with mild or moderate renal impairment. Caution is warranted for
INSTI-experienced patients (with certain INSTI-associated resistance
substitutions or clinically suspected INSTI resistance [see Microbiology])
with severe renal impairment, as the decrease in dolutegravir concentrations
may result in loss of therapeutic effect and development of resistance to
TIVICAY or other coadministered antiretroviral agents. Dolutegravir has not
been studied in patients requiring dialysis.
Gender: Population analyses using pooled
pharmacokinetic data from adult trials indicated gender had no clinically
relevant effect on the exposure of dolutegravir.
Race: Population analyses using pooled
pharmacokinetic data from adult trials indicated race had no clinically
relevant effect on the pharmacokinetics of dolutegravir.
Geriatric Patients: Population analyses using
pooled pharmacokinetic data from adult trials indicated age had no clinically
relevant effect on the pharmacokinetics of dolutegravir.
Pediatric Patients: The pharmacokinetics of
dolutegravir in HIV-1-infected children (n = 17) weighing at least 30 kg were
similar to those observed in HIV-1-infected adults who received dolutegravir 50
mg once daily (Table 8) [see Clinical Studies].
Table 8: Dolutegravir Steady-State Pharmacokinetic
Parameters in Pediatric Subjects
Weight (n) |
Dose of TIVICAY |
Dolutegravir Pharmacokinetic Parameter Estimates Geometric Mean (%CV) |
Cmax (mcg/mL) |
AUC(0-24) (mcg•h/mL) |
C24 (mcg/mL) |
≥ 40 kg (n = 14) |
50 mg once daily |
3.89 (43) |
50.1 (53) |
0.99 (66) |
≥ 30 to < 40 kg (n = 3) |
35 mg once daily |
4.40 (54) |
64.6 (64) |
1.33 (93) |
Population pharmacokinetic
analyses demonstrate comparable exposures in children, at least 30 kg, dosed by
weight-bands (35 mg or 50 mg of dolutegravir) to that observed in adults.
Drug Interactions
Drug interaction trials were
performed with TIVICAY and other drugs likely to be coadministered or commonly
used as probes for pharmacokinetic interactions. As dolutegravir is not
expected to affect the pharmacokinetics of other drugs dependent on hepatic
metabolism (Table 9) [see DRUG INTERACTIONS], the primary focus of these
drug interaction trials was to evaluate the effect of coadministered drug on
dolutegravir (Table 10).
Dosing or regimen recommendations as a result of
established and other potentially significant drug-drug interactions with
TIVICAY are provided in Table 6 [see DOSAGE AND ADMINISTRATION, DRUG
INTERACTIONS].
Table 9: Summary of Effect of Dolutegravir on the
Pharmacokinetics of Coadministered Drugs
Coadministered Drug(s) and Dose(s) |
Dose of TIVICAY |
n |
Geometric Mean Ratio (90% CI) of Pharmacokinetic Parameters of Coadministered Drug with/without Dolutegravir No Effect = 1.00 |
Cmax |
AUC |
Cτ or C24 |
Daclatasvir 60 mg once daily |
50 mg once daily |
12 |
1.03 (0.84 to 1.25) |
0.98 (0.83 to 1.15) |
1.06 (0.88 to 1.29) |
Ethinyl estradiol 0.035 mg |
50 mg twice daily |
15 |
0.99 (0.91 to 1.08) |
1.03 (0.96 to 1.11) |
1.02 (0.93 to 1.11) |
Metformin 500 mg twice daily |
50 mg once daily |
15a |
1.66 (1.53 to 1.81) |
1.79 (1.65 to 1.93) |
- |
Metformin 500 mg twice daily |
50 mg twice daily |
15a |
2.11 (1.91 to 2.33) |
2.45 (2.25 to 2.66) |
- |
Methadone 16 to 150 mg |
50 mg twice daily |
11 |
1.00 (0. 94 to 1.06) |
0.98 (0.91 to 1.06) |
0.99 (0.91 to 1.07) |
Midazolam 3 mg |
25 mg once daily |
10 |
- |
0.95 (0.79 to 1.15) |
- |
Norelgestromin 0.25 mg |
50 mg twice daily |
15 |
0.89 (0.82 to 0.97) |
0.98 (0.91 to 1.04) |
0.93 (0.85 to 1.03) |
Rilpivirine 25 mg once daily |
50 mg once daily |
16 |
1.10 (0.99 to 1.22) |
1.06 (0.98 to 1.16) |
1.21 (1.07 to 1.38) |
Tenofovir disoproxil fumarate 300 mg once daily |
50 mg once daily |
15 |
1.09 (0.97 to 1.23) |
1.12 (1.01 to 1.24) |
1.19 (1.04 to 1.35) |
a The number of subjects represents the
maximum number of subjects that were evaluated. |
Table 10: Summary of Effect of Coadministered Drugs on
the Pharmacokinetics of Dolutegravir
Coadministered Drug(s) and Dose(s) |
Dose of TIVICAY |
n |
Geometric Mean Ratio (90% CI) of Dolutegravir Pharmacokinetic Parameters with/without Coadministered Drugs No Effect = 1.00 |
Cmax |
AUC |
Cτ or C24 |
Atazanavir 400 mg once daily |
30 mg once daily |
12 |
1.50 (1.40 to 1.59) |
1.91 (1.80 to 2.03) |
2.80 (2.52 to 3.11) |
Atazanavir/ritonavir 300/100 mg once daily |
30 mg once daily |
12 |
1.34 (1.25 to 1.42) |
1.62 (1.50 to 1.74) |
2.21 (1.97 to 2.47) |
Darunavir/ritonavir 600/100 mg twice daily |
30 mg once daily |
15 |
0.89 (0.83 to 0.97) |
0.78 (0.72 to 0.85) |
0.62 (0.56 to 0.69) |
Efavirenz 600 mg once daily |
50 mg once daily |
12 |
0.61 (0.51 to 0.73) |
0.43 (0.35 to 0.54) |
0.25 (0.18 to 0.34) |
Etravirine 200 mg twice daily |
50 mg once daily |
16 |
0.48 (0.43 to 0.54) |
0.29 (0.26 to 0.34) |
0.12 (0.09 to 0.16) |
Etravirine + darunavir/ritonavir 200 mg + 600/100 mg twice daily |
50 mg once daily |
9 |
0.88 (0.78 to 1.00) |
0.75 (0.69 to 0.81) |
0.63 (0.52 to 0.76) |
Etravirine + lopinavir/ritonavir 200 mg + 400/100 mg twice daily |
50 mg once daily |
8 |
1.07 (1.02 to 1.13) |
1.11 (1.02 to 1.20) |
1.28 (1.13 to 1.45) |
Fosamprenavir/ritonavir 700 mg/100 mg twice daily |
50 mg once daily |
12 |
0.76 (0.63 to 0.92) |
0.65 (0.54 to 0.78) |
0.51 (0.41 to 0.63) |
Lopinavir/ritonavir 400/100 mg twice daily |
30 mg once daily |
15 |
1.00 (0.94 to 1.07) |
0.97 (0.91 to 1.04) |
0.94 (0.85 to 1.05) |
Rilpivirine 25 mg once daily |
50 mg once daily |
16 |
1.13 (1.06 to 1.21) |
1.12 (1.05 to 1.19) |
1.22 (1.15 to 1.30) |
Tenofovir 300 mg once daily |
50 mg once daily |
15 |
0.97 (0.87 to 1.08) |
1.01 (0.91 to 1.11) |
0.92 (0.82 to 1.04) |
Tipranavir/ritonavir 500/200 mg twice daily |
50 mg once daily |
14 |
0.54 (0.50 to 0.57) |
0.41 (0.38 to 0.44) |
0.24 (0.21 to 0.27) |
Antacid (Maalox®) simultaneous administration |
50 mg single dose |
16 |
0.28 (0.23 to 0.33) |
0.26 (0.22 to 0.32) |
0.26 (0.21 to 0.31) |
Antacid (Maalox®) 2 h after dolutegravir |
50 mg single dose |
16 |
0.82 (0.69 to 0.98) |
0.74 (0.62 to 0.90) |
0.70 (0.58 to 0.85) |
Boceprevir 800 mg every 8 hours |
50 mg once daily |
13 |
1.05 (0.96 to 1.15) |
1.07 (0.95 to 1.20) |
1.08 (0.91 to 1.28) |
Calcium carbonate 1,200 mg simultaneous administration (fasted) |
50 mg single dose |
12 |
0.63 (0.50 to 0.81) |
0.61 (0.47 to 0.80) |
0.61 (0.47 to 0.80) |
Calcium carbonate 1,200 mg simultaneous administration (fed) |
50 mg single dose |
11 |
1.07 (0.83 to 1.38) |
1.09 (0.84 to 1.43) |
1.08 (0.81 to 1.42) |
Calcium carbonate 1,200 mg 2 h after dolutegravir |
50 mg single dose |
11 |
1.00 (0.78 to 1.29) |
0.94 (0.72 to 1.23) |
0.90 (0.68 to 1.19) |
Carbamazepine 300 mg twice daily |
50 mg once daily |
16c |
0.67 (0.61 to 0.73) |
0.51 (0.48 to 0.55) |
0.27 (0.24 to 0.31) |
Daclatasvir 60 mg once daily |
50 mg once daily |
12 |
1.29 (1.07 to 1.57) |
1.33 (1.11 to 1.59) |
1.45 (1.25 to 1.68) |
Ferrous fumarate 324 mg simultaneous administration (fasted) |
50 mg single dose |
11 |
0.43 (0.35 to 0.52) |
0.46 (0.38 to 0.56) |
0.44 (0.36 to 0.54) |
Ferrous fumarate 324 mg simultaneous administration (fed) |
50 mg single dose |
11 |
1.03 (0.84 to 1.26) |
0.98 (0.81 to 1.20) |
1.00 (0.81 to 1.23) |
Ferrous fumarate 324 mg 2 h after dolutegravir |
50 mg single dose |
10 |
0.99 (0.81 to 1.21) |
0.95 (0.77 to 1.15) |
0.92 (0.74 to 1.13) |
Multivitamin (One-A-Day®) simultaneous administration |
50 mg single dose |
16 |
0.65 (0.54 to 0.77) |
0.67 (0.55 to 0.81) |
0.68 (0.56 to 0.82) |
Omeprazole 40 mg once daily |
50 mg single dose |
12 |
0.92 (0.75 to 1.11) |
0.97 (0.78 to 1.20) |
0.95 (0.75 to 1.21) |
Prednisone 60 mg once daily with taper |
50 mg once daily |
12 |
1.06 (0.99 to 1.14) |
1.11 (1.03 to 1.20) |
1.17 (1.06 to 1.28) |
Rifampina 600 mg once daily |
50 mg twice daily |
11 |
0.57 (0.49 to 0.65) |
0.46 (0.38 to 0.55) |
0.28 (0.23 to 0.34) |
Rifampinb 600 mg once daily |
50 mg twice daily |
11 |
1.18 (1.03 to 1.37) |
1.33 (1.15 to 1.53) |
1.22 (1.01 to 1.48) |
Rifabutin 300 mg once daily |
50 mg once daily |
9 |
1.16 (0.98 to 1.37) |
0.95 (0.82 to 1.10) |
0.70 (0.57 to 0.87) |
a Comparison is rifampin taken with
dolutegravir 50 mg twice daily compared with dolutegravir 50 mg twice daily.
b Comparison is rifampin taken with dolutegravir 50 mg twice daily
compared with dolutegravir 50 mg once daily.
c The number of subjects represents the maximum number of subjects
that were evaluated. |
Microbiology
Mechanism Of Action
Dolutegravir inhibits HIV
integrase by binding to the integrase active site and blocking the strand
transfer step of retroviral deoxyribonucleic acid (DNA) integration which is
essential for the HIV replication cycle. Strand transfer biochemical assays
using purified HIV-1 integrase and pre-processed substrate DNA resulted in IC50
values of 2.7 nM and 12.6 nM.
Antiviral Activity In Cell
Culture
Dolutegravir exhibited antiviral activity against
laboratory strains of wild-type HIV-1 with mean EC50 values of 0.5 nM (0.21 ng
per mL) to 2.1 nM (0.85 ng per mL) in peripheral blood mononuclear cells
(PBMCs) and MT-4 cells. Dolutegravir exhibited antiviral activity against 13
clinically diverse clade B isolates with a mean EC50 value of 0.52 nM in a
viral integrase susceptibility assay using the integrase coding region from
clinical isolates. Dolutegravir demonstrated antiviral activity in cell culture
against a panel of HIV-1 clinical isolates (3 in each group of M clades A, B,
C, D, E, F, and G, and 3 in group O) with EC50 values ranging from 0.02 nM to
2.14 nM for HIV-1. Dolutegravir EC50 values against 3 HIV-2 clinical isolates
in PBMC assays ranged from 0.09 nM to 0.61 nM.
Antiviral Activity In Combination With Other Antiviral
Agents
The antiviral activity of dolutegravir was not
antagonistic when combined with the INSTI, raltegravir; non-nucleoside reverse
transcriptase inhibitors (NNRTIs), efavirenz or nevirapine; the nucleoside
reverse transcriptase inhibitors (NRTIs), abacavir or stavudine; the protease
inhibitors (PIs), amprenavir or lopinavir; the CCR5 co-receptor antagonist, maraviroc;
or the fusion inhibitor, enfuvirtide. Dolutegravir antiviral activity was not
antagonistic when combined with the HBV reverse transcriptase inhibitor,
adefovir, or inhibited by the antiviral, ribavirin.
Resistance
Cell Culture: Dolutegravir-resistant viruses were
selected in cell culture starting from different wild-type HIV-1 strains and
clades. Amino acid substitutions E92Q, G118R, S153F or Y, G193E or R263K
emerged in different passages and conferred decreased susceptibility to
dolutegravir of up to 4-fold. Passage of mutant viruses containing the Q148R or
Q148H substitutions selected for additional substitutions in integrase that
conferred decreased susceptibility to dolutegravir (fold-change increase of 13
to 46). The additional integrase substitutions included T97A, E138K, G140S, and
M154I. Passage of mutant viruses containing both G140S and Q148H selected for
L74M, E92Q, and N155H.
Treatment-Naïve Subjects: No subjects in the
dolutegravir 50-mg once-daily treatment arms of treatment-naïve trials SPRING-2
(96 weeks) and SINGLE (144 weeks) had a detectable decrease in susceptibility
to dolutegravir or background NRTIs in the resistance analysis subset (n = 12
with HIV-1 RNA greater than 400 copies per mL at failure or last visit and
having resistance data). Two virologic failure subjects in SINGLE had
treatment-emergent G/D/E193D and G193G/E integrase substitutions at Week 84 and
Week 108, respectively, and 1 subject with 275 copies per mL HIV-1 RNA had a
treatment-emergent Q157Q/P integrase substitution detected at Week 24. None of
these subjects had a corresponding decrease in dolutegravir susceptibility. No
treatment-emergent genotypic resistance to the background regimen was observed
in the dolutegravir arm in either the SPRING-2 or SINGLE trials. No
treatment-emergent primary resistance substitutions were observed in either
treatment group in the FLAMINGO trial through Week 96.
Treatment-Experienced, Integrase Strand Transfer
Inhibitor-Naïve Subjects: In the dolutegravir arm of the SAILING trial for
treatment-experienced and INSTI-naïve subjects (n = 354), treatment-emergent
integrase substitutions were observed in 6 of 28 (21%) subjects who had
virologic failure and resistance data. In 5 of the 6 subjects' isolates
emergent INSTI substitutions included L74L/M/I, Q95Q/L, V151V/I (n = 1 each),
and R263K (n = 2). The change in dolutegravir phenotypic susceptibility for
these 5 subject isolates was less than 2-fold. One subject isolate had
pre-existing raltegravir resistance substitutions E138A, G140S, and Q148H at
baseline and had additional emergent INSTI-resistance substitutions T97A and
E138A/T with a corresponding 148-fold reduction in dolutegravir susceptibility
at failure. In the comparator raltegravir arm, 21 of 49 (43%) subjects with
post-baseline resistance data had evidence of emergent INSTI-resistance
substitutions (L74M, E92Q, T97A, E138Q, G140S/A, Y143R/C, Q148H/R, V151I,
N155H, E157Q, and G163K/R) and raltegravir phenotypic resistance.
Treatment-Experienced, Integrase Strand Transfer
Inhibitor-Experienced Subjects: VIKING-3 examined the efficacy of
dolutegravir 50 mg twice daily plus optimized background therapy in subjects
with prior or current virologic failure on an INSTI-(elvitegravir or raltegravir)
containing regimen.
In VIKING-4 (ING116529), 30 subjects with current
virological failure on an INSTI-containing regimen and genotypic evidence of
INSTI-resistance substitutions at screening were randomized to receive either
dolutegravir 50 mg twice daily or placebo with the current failing regimen for
7 days and then all subjects received open-label dolutegravir plus optimized
background regimen from Day 8. Virologic responses at Week 48 by baseline
genotypic and phenotypic INSTI-resistance categories and the INSTI
resistance-associated substitutions that emerged on dolutegravir treatment in
VIKING-4 were consistent with those seen in VIKING-3.
Response By Baseline Genotype
Of the 183 subjects with baseline data, 30% harbored
virus with a substitution at Q148, and 33% had no primary INSTI-resistance
substitutions (T66A/I/K, E92Q/V, Y143R/C/H, Q148H/R/K, and N155H) at baseline,
but had historical genotypic evidence of INSTI-resistance substitutions,
phenotypic evidence of elvitegravir or raltegravir resistance, or genotypic
evidence of INSTI-resistance substitutions at screening.
Response rates by baseline genotype were analyzed in an
“as-treated” analysis at Week 48 (n = 175) (Table 11). The response rate at
Week 48 to dolutegravir-containing regimens was 47% (24 of 51) when Q148
substitutions were present at baseline; Q148 was always present with additional
INSTI-resistance substitutions (see Table 11). In addition, a diminished
virologic response of 40% (6 of 15) was observed when the substitution E157Q or
K was present at baseline with other INSTI-resistance substitutions but without
a Q148H or R substitution.
Table 11: Response by Baseline Integrase Genotype in
Subjects with Prior Experience to an Integrase Strand Transfer Inhibitor in
VIKING-3
Baseline Genotype |
Week 48 ( < 50 copies/mL)
n = 175 |
Overall Response |
66% (116/175) |
No Q148 substitutiona |
74% (92/124) |
Q148H/R + G140S/A/C without additional INSTI-resistance substitutionb |
61% (17/28) |
Q148H/R + ≥ 2 INSTI-resistance substitutionsb,c |
29% (6/21) |
a Includes INSTI-resistance substitutions
Y143R/C/H and N155H.
b INSTI-resistance substitutions included T66A, L74I/M, E138A/K/T,
G140S/A/C, Y143R/C/H, E157Q, G163S/E/K/Q, or G193E/R. Two additional subjects
had baseline genotypes of Q148Q/R plus L74L/I/M (virologic failure) and Q148R
plus E138K (responder).
c The most common pathway with Q148H/R + greater than or equal to 2
INSTI-resistance substitutions had Q148+G140+E138
substitutions (n = 16). |
Response By Baseline Phenotype
Response rates by baseline
phenotype were analyzed in an as-treated analysis using all subjects with
available baseline phenotypes through Week 48 (n = 163) (see Table 12). These
baseline phenotypic groups are based on subjects enrolled in VIKING-3 and are not
meant to represent definitive clinical susceptibility cut points for
dolutegravir. The data are provided to guide clinicians on the likelihood of
virologic success based on pretreatment susceptibility to dolutegravir in
INSTI-resistant patients.
Table 12: Response by
Baseline Dolutegravir Phenotype (Fold-Change from Reference) in Subjects with
Prior Experience to an Integrase Strand Transfer Inhibitor in VIKING-3
Baseline Dolutegravir Phenotype (Fold-Change from Reference) |
Response at Week 48 ( < 50 copies/mL) Subset
n = 163 |
Overall Response |
64% (104/163) |
< 3-fold change |
72% (83/116) |
3- < 10-fold change |
53% (18/34) |
> 10-fold change |
23% (3/13) |
Integrase Strand Transfer
Inhibitor Treatment-Emergent Resistance
There were 50 subjects with
virologic failure on the dolutegravir twice-daily regimen in VIKING-3 with
HIV-1 RNA greater than 400 copies per mL at the failure timepoint, Week 48 or
beyond, or the last timepoint on trial. Thirty-nine subjects with virologic
failure had resistance data that were used in the Week 48 analysis. In the Week
48 resistance analysis 85% (33 of 39) of the subjects with virologic failure
had treatment-emergent INSTI-resistance substitutions in their isolates. The
most common treatment-emergent INSTI-resistance substitution was T97A. Other
frequently emergent INSTI-resistance substitutions included L74M, I or V, E138K
or A, G140S, Q148H, R or K, M154I, or N155H. Substitutions E92Q, Y143R or C/H,
S147G, V151A, and E157E/Q each emerged in 1 to 3 subjects' isolates. At
failure, the median dolutegravir fold-change from reference was 61-fold (range:
0.75 to 209) for isolates with emergent INSTI-resistance substitutions (n =
33).
Resistance to one or more
background drugs in the dolutegravir twice-daily regimen also emerged in 49%
(19 of 39) subjects in the Week 48 resistance analysis.
Cross-Resistance
Site-Directed Integrase
Strand Transfer Inhibitor-Resistant Mutant HIV-1 and HIV-2 Strains: The susceptibility of dolutegravir was tested against 60
INSTI-resistant site-directed mutant HIV-1 viruses (28 with single
substitutions and 32 with 2 or more substitutions) and 6 INSTI-resistant
site-directed mutant HIV-2 viruses. The single INSTI-resistance substitutions
T66K, I151L, and S153Y conferred a greater than 2-fold decrease in dolutegravir
susceptibility (range: 2.3-fold to 3.6-fold from reference). Combinations of
multiple substitutions T66K/L74M, E92Q/N155H, G140C/Q148R, G140S/Q148H, R or K,
Q148R/N155H, T97A/G140S/Q148, and substitutions at E138/G140/Q148 showed a
greater than 2-fold decrease in dolutegravir susceptibility (range: 2.5-fold to
21-fold from reference). In HIV-2 mutants, combinations of substitutions
A153G/N155H/S163G and E92Q/T97A/N155H/S163D conferred 4-fold decreases in
dolutegravir susceptibility, and E92Q/N155H and G140S/Q148R showed 8.5-fold and
17-fold decreases in dolutegravir susceptibility, respectively.
Reverse Transcriptase
Inhibitor-and Protease Inhibitor-Resistant Strains: Dolutegravir demonstrated
equivalent antiviral activity against 2 NNRTI-resistant, 3 NRTI-resistant, and
2 PI-resistant HIV-1 mutant clones compared with the wild-type strain.
Clinical Studies
The efficacy of TIVICAY is based on analyses of data from
3 trials, SPRING-2 (ING113086), SINGLE (ING114467), and FLAMINGO (ING114915),
in treatment-naïve, HIV-1-infected subjects (n = 2,125); one trial, SAILING
(ING111762), in treatment-experienced, INSTI-naïve HIV-1-infected subjects (n =
715); and from VIKING-3 (ING112574) trial in INSTI-experienced HIV-1-infected
subjects (n = 183). The use of TIVICAY in pediatric patients aged 6 years and
older is based on evaluation of safety, pharmacokinetics, and efficacy in a
multicenter, open-label trial in subjects without INSTI resistance.
Adult Subjects
Treatment-Naïve Subjects
In SPRING-2, 822 subjects were randomized and received at
least 1 dose of either TIVICAY 50 mg once daily or raltegravir 400 mg twice
daily, both in combination with fixed-dose dual NRTI treatment (either abacavir
sulfate and lamivudine [EPZICOM] or emtricitabine/tenofovir [TRUVADA]). There
were 808 subjects included in the efficacy and safety analyses. At baseline,
the median age of subjects was 36 years, 13% female, 15% non-white, 11% had
hepatitis B and/or C virus co-infection, 2% were CDC Class C (AIDS), 28% had
HIV-1 RNA greater than 100,000 copies per mL, 48% had CD4+ cell count less than
350 cells per mm³, and 39% received EPZICOM; these characteristics were similar
between treatment groups.
In SINGLE, 833 subjects were randomized and received at
least 1 dose of either TIVICAY 50 mg once daily with fixed-dose abacavir
sulfate and lamivudine (EPZICOM) or fixed-dose
efavirenz/emtricitabine/tenofovir (ATRIPLA). At baseline, the median age of
subjects was 35 years, 16% female, 32% non-white, 7% had hepatitis C
co-infection (hepatitis B virus coinfection was excluded), 4% were CDC Class C
(AIDS), 32% had HIV-1 RNA greater than 100,000 copies per mL, and 53% had CD4+
cell count less than 350 cells per mm³; these characteristics were similar
between treatment groups.
Outcomes for SPRING-2 (Week 96 analysis) and SINGLE (Week
144 open-label phase analysis which followed the Week 96 double-blind phase)
are provided in Table 13. Side-by-side tabulation is to simplify presentation;
direct comparisons across trials should not be made due to differing trial
designs.
Table 13: Virologic Outcomes of Randomized Treatment
in SPRING-2 at Week 96 and SINGLE at Week 144 (Snapshot Algorithm)
|
SPRING-2 Week 96 |
SINGLE Week 144 |
TIVICAY 50 mg Once Daily + 2NRTIs
(n = 403) |
Raltegravir 400 mg Twice Daily + 2NRTIs
(n = 405) |
TIVICAY 50 mg +EPZICOM Once Daily
(n = 414) |
ATRIPLA Once Daily
(n = 419) |
HIV-1 RNA < 50 copies/mL |
82% |
78% |
71% |
63% |
Treatment differencea |
4.9% (95% CI:-0.6%, 10.3%)d |
8.3% (95% CI: 2.0%, 14.6%)e |
Virologic nonresponse |
5% |
10% |
10% |
7% |
Data in window not < 50 copies/mL |
1% |
3% |
4% |
< 1% |
Discontinued for lack of efficacy |
2% |
3% |
3% |
3% |
Discontinued for other reasons while not suppressed |
< 1% |
3% |
3% |
4% |
Change in ART regimen |
< 1% |
< 1% |
0 |
0 |
No virologic data |
12% |
12% |
18% |
30% |
Reasons |
|
|
|
|
Discontinued study/study drug due to adverse event or deathb |
2% |
2% |
4% |
14% |
Discontinued study/study drug for other reasonsc |
8% |
9% |
12% |
13% |
Missing data during window but on study |
2% |
< 1% |
2% |
3% |
Proportion (%) of Subjects with HIV-1 RNA < 50 copies/mL by Baseline Category |
Plasma viral load (copies/mL) |
≤ 100,000 |
84% |
83% |
73% |
64% |
> 100,000 |
79% |
63% |
69% |
61% |
Gender |
Male |
84% |
79% |
72% |
66% |
Female |
70% |
68% |
69% |
48% |
Race |
White |
83% |
78% |
72% |
71% |
African-American/African Heritage/Other |
77% |
75% |
71% |
47% |
a Adjusted for pre-specified stratification
factors.
b Includes subjects who discontinued due to an adverse event or
death at any time point if this resulted in no virologic data on treatment
during the analysis window.
c Other includes reasons such as withdrew consent, loss to
follow-up, moved, and protocol deviation.
d The primary endpoint was assessed at Week 48 and the virologic
success rate was 88% in the group receiving TIVICAY and 86% in the raltegravir
group, with a treatment difference of 2.6% and 95% CI of (-1.9%, 7.2%).
e The primary endpoint was assessed at Week 48 and the virologic
success rate was 88% in the group receiving TIVICAY and 81% in the ATRIPLA
group, with a treatment difference of 7.4% and 95% CI of (2.5%, 12.3%). SPRING-2:
Virologic outcomes were also comparable across baseline characteristics
including CD4+ cell count, age, and use of EPZICOM or TRUVADA as NRTI
background regimen. The median change in CD4+ cell counts from baseline were
276 cells per mm³ in the group receiving TIVICAY and 264 cells per mm³ for the
raltegravir group at 96 weeks. |
There was no treatment-emergent resistance to
dolutegravir or to the NRTI background.
SINGLE: Treatment differences were maintained
across baseline characteristics including baseline viral load, CD4+ cell count,
age, gender, and race.
The adjusted mean changes in CD4+ cell counts from
baseline were 378 cells per mm³ in the group receiving TIVICAY + EPZICOM and
332 cells per mm³ for the ATRIPLA group at 144 weeks. The adjusted difference
between treatment arms and 95% CI was 46.9 cells per mm³ (15.6 cells per mm³,
78.2 cells per mm³) (adjusted for pre-specified stratification factors:
baseline HIV-1 RNA, and baseline CD4+ cell count).
There was no treatment-emergent resistance to
dolutegravir, abacavir, or lamivudine.
FLAMINGO: In FLAMINGO, 485 subjects were randomized and
received at least 1 dose of either TIVICAY 50 mg once daily (n = 243) or
darunavir + ritonavir 800 mg/100 mg once daily (n = 242), both in combination
with investigator-selected NRTI background regimen (either fixed-dose abacavir
and lamivudine [EPZICOM] or fixed-dose emtricitabine/tenofovir disoproxil
fumarate [TRUVADA]). There were 484 subjects included in the efficacy and
safety analyses. At baseline, the median age of subjects was 34 years, 15%
female, 28% non-white, 10% had hepatitis B and/or C virus co-infection, 3% were
CDC Class C (AIDS), 25% had HIV-1 RNA greater than 100,000 copies per mL, and
35% had CD4+ cell count less than 350 cells per mm³; these characteristics were
similar between treatment groups. Overall response rates by Snapshot algorithm
through Week 96 were 80% for TIVICAY and 68% for darunavir/ritonavir. The
proportion of subjects who were non-responders (HIV-1 RNA greater than or equal
to 50 copies per mL) at Week 96 was 8% and 12% in the arms receiving TIVICAY
and darunavir + ritonavir, respectively; no virologic data were available for
12% and 21% for subjects treated with TIVICAY and darunavir + ritonavir,
respectively. The adjusted overall response rate difference in proportion and
95% CI was 12.4% (4.7%, 20.2%). No treatment-emergent primary resistance
substitutions were observed in either treatment group.
Treatment-Experienced, Integrase Strand Transfer
Inhibitor-Naïve Subjects
In the international, multicenter, double-blind trial
(SAILING), 719 HIV-1-infected, antiretroviral treatment-experienced adults were
randomized and received either TIVICAY 50 mg once daily or raltegravir 400 mg
twice daily with investigator-selected background regimen consisting of up to 2
agents, including at least 1 fully active agent. There were 715 subjects
included in the efficacy and safety analyses. At baseline, the median age was
43 years, 32% were female, 50% non-white, 16% had hepatitis B and/or C virus
co-infection, 46% were CDC Class C (AIDS), 20% had HIV-1 RNA greater than
100,000 copies per mL, and 72% had CD4+ cell count less than 350 cells per mm³;
these characteristics were similar between treatment groups. All subjects had
at least 2-class antiretroviral treatment resistance, and 49% of subjects had
at least 3-class antiretroviral treatment resistance at baseline. Week 48
outcomes for SAILING are shown in Table 14.
Table 14: Virologic Outcomes of Randomized Treatment
in SAILING at 48 Weeks (Snapshot Algorithm)
|
TIVICAY 50 mg Once Daily + BRa
(n = 354) |
Raltegravir 400 mg Twice Daily + BRa
(n = 361) |
HIV-1 RNA < 50 copies/mL |
71% |
64% |
Adjustedb treatment difference |
7.4% (95% CI: 0.7%, 14.2%) |
Virologic nonresponse |
20% |
28% |
No virologic data |
9% |
9% |
Reasons |
Discontinued study/study drug due to adverse event or death |
3% |
4% |
Discontinued study/study drug for other reasonsc |
5% |
4% |
Missing data during window but on study |
2% |
1% |
Proportion (%) with HIV-1 RNA < 50 copies/mL by Baseline Category |
Plasma viral load (copies/mL) |
≤ 50,000 copies/mL |
75% |
71% |
> 50,000 copies/mL |
62% |
47% |
Background regimen |
No darunavir use |
67% |
60% |
Darunavir use with primary PI substitutions |
85% |
67% |
Darunavir use without primary PI substitutions |
69% |
70% |
Gender |
Male |
70% |
66% |
Female |
74% |
60% |
Race |
White |
75% |
71% |
Afri can-Ameri can/African Heritage/Other |
67% |
57% |
a BR = Background regimen. Background regimen
was restricted to less than or equal to 2 antiretroviral treatments with at
least 1 fully active agent.
b Adjusted for pre-specified stratification factors.
c Other includes reasons such as withdrew consent, loss to
follow-up, moved, and protocol deviation. |
Treatment differences were maintained across the baseline
characteristics including CD4+ cell count and age.
The mean changes in CD4+ cell counts from baseline were
162 cells per mm³ in the group receiving TIVICAY and 153 cells per mm³ in the
raltegravir group.
Treatment-Experienced, Integrase Strand Transfer
Inhibitor-Experienced Subjects
VIKING-3 examined the effect of TIVICAY 50 mg twice daily
over 7 days of functional monotherapy, followed by optimized background therapy
(OBT) with continued treatment of TIVICAY 50 mg twice daily.
In the multicenter, open-label, single-arm VIKING-3
trial, 183 HIV-1-infected, antiretroviral treatment-experienced adults with
virological failure and current or historical evidence of raltegravir and/or
elvitegravir resistance received TIVICAY 50 mg twice daily with the current
failing background regimen for 7 days, then received TIVICAY with OBT from Day
8. A total of 183 subjects enrolled: 133 subjects with INSTI resistance at
screening and 50 subjects with only historical evidence of resistance (and not
at screening). At baseline, median age of subjects was 48 years; 23% were
female, 29% non-white, and 20% had hepatitis B and/or C virus coinfection.
Median baseline CD4+ cell count was 140 cells per mm³, median duration of prior
antiretroviral treatment was 13 years, and 56% were CDC Class C. Subjects
showed multiple-class antiretroviral treatment resistance at baseline: 79% had
greater than or equal to 2 NRTI, 75% greater than or equal to 1 NNRTI, and 71%
greater than or equal to 2 PI major substitutions; 62% had non-R5 virus.
Mean reduction from baseline in HIV-1 RNA at Day 8
(primary endpoint) was 1.4 log10 (95% CI: 1.3 log10, 1.5 log10). Response at
Week 48 was affected by baseline INSTI substitutions [see Microbiology].
After the functional monotherapy phase, subjects had the
opportunity to re-optimize their background regimen when possible. Week 48
virologic outcomes for VIKING-3 are shown in Table 15.
Table 15: Virologic Outcomes of Treatment of VIKING-3
at 48 Weeks (Snapshot Algorithm)
|
TIVICAY 50 mg Twice Daily + OBT
(n = 183) |
HIV-1 RNA < 50 copies/mL |
63% |
Virologic nonresponse |
32% |
No virologic data |
|
Reasons |
Discontinued study/study drug due to adverse event or death |
3% |
Proportion (%) with HIV-1 RNA < 50 copies/mL by Baseline Category |
Gender |
Male |
63% |
Female |
64% |
Race |
White |
63% |
African-American/African Heritage/Other |
64% |
Subjects harboring virus with
Q148 and with additional Q148-associated secondary substitutions also had a
reduced response at Week 48 in a stepwise fashion [see Microbiology].
The median change in CD4+ cell count from baseline was 80
cells per mm³ at Week 48.
Pediatric Subjects
IMPAACT P1093 is a Phase ½,
48-week, multicenter, open-label trial to evaluate the pharmacokinetic
parameters, safety, tolerability, and efficacy of TIVICAY in combination
treatment regimens in HIV-1-infected infants, children, and adolescents.
Subjects were stratified by age, enrolling adolescents first (Cohort 1: aged 12
to less than 18 years) and then younger children (Cohort 2A: aged 6 to less
than 12 years). All subjects received a weight-based dose of TIVICAY [see
DOSAGE AND ADMINISTRATION].
These 46 subjects had a mean age of 12 years (range: 6 to
17), were 54% female and 52% black. At baseline, mean plasma HIV-1 RNA was 4.6
log10 copies per mL, median CD4+ cell count was 639 cells per mm³ (range: 9 to
1,700), and median CD4+% was 23% (range: 1% to 44%). Overall, 39% had baseline
plasma HIV-1 RNA greater than 50,000 copies per mL and 33% had a CDC HIV
clinical classification of category C. Most subjects had previously used at
least 1 NNRTI (50%) or 1 PI (70%).
At Week 24, the proportion of
subjects with HIV-1 RNA less than 50 copies per mL in Cohort 1 and Cohort 2A
was 70% (16/23) and 61% (14/23), respectively. At Week 48, the proportion of
subjects from Cohort 1 with HIV-1 RNA less than 50 copies per mL was 61%
(14/23). Virologic outcomes were also evaluated based on body weight. Across
both cohorts, virologic suppression (HIV-1 RNA less than 50 copies per mL) at
Week 24 was achieved in 75% (18/24) of subjects weighing at least 40 kg and 55%
(6/11) of subjects in the 30 to less than 40 kg weight-band. At
Week 48, 63% (12/19) of the subjects in Cohort 1 weighing
at least 40 kg were virologically suppressed.
The median CD4+ cell count increase from baseline to Week
48 was 84 cells per mm³ in Cohort 1. For Cohort 2A, the median CD4+ cell count
increase from baseline to Week 24 was 209 cells per mm³.