Small increase in dolutegravir trough, but equivalent total dolutegravir exposure with simeprevir in HIV/HCV seronegative volunteers

Abstract

Background

Dolutegravir, an HIV integrase strand-transfer inhibitor, and simeprevir, an HCV NS3/4A PI, have the potential to interact as dolutegravir is a P-glycoprotein, uridine glucuronosyl transferase 1A1 and cytochrome P4503A substrate and simeprevir has been shown to mildly inhibit these.

Objectives

To compare dolutegravir and simeprevir pharmacokinetics (PK) when given separately versus in combination.

Methods

Healthy volunteers received: (i) 150 mg of simeprevir once daily for 7 days; (ii) 50 mg of dolutegravir once daily for 7 days; and (iii) 150 mg of simeprevir once daily plus 50 mg of dolutegravir once daily for 7 days, with randomization to treatment sequence. Twenty-four hour intensive PK sampling was performed on day 7 of each sequence following observed dosing and a standardized meal. PK parameters were determined using non-compartmental methods and compared using paired t-tests. Bioequivalence for area under the curve (AUC_tau) and maximum concentration (C_max) were also assessed. NCT02404805.

Results

Twenty-four subjects completed all three sequences. Dolutegravir trough was increased 24% (P = 0.0003) with simeprevir. Dolutegravir AUC_tau was increased 15% (P = 0.002), but was deemed bioequivalent as the 90% CI for the geometric mean ratio was 107%–123%. Dolutegravir C_max was bioequivalent. Simeprevir PK was unaffected by dolutegravir. There were no discontinuations due to adverse events and all adverse events were mild to moderate in severity.

Conclusions

Dolutegravir trough was increased slightly with simeprevir, but AUC_tau was bioequivalent. Despite the increase in trough, dolutegravir concentrations were well within the range with established safety data. Suggesting that simeprevir and dolutegravir can be safely co-administered.

Introduction

HIV accelerates the progression of HCV-related liver disease.¹ Liver-related deaths are now the leading cause of death amongst persons living with HIV.² Fortunately, with effective antiviral treatment, HCV can be cured. Rates of cure, also known as sustained virological response (SVR), with newer HCV treatments are at least 90% and similar in persons with HIV/HCV to those with HCV alone.³ An important consideration in treating HCV in persons with HIV/HCV is the potential for antiviral drug–drug interactions.

Simeprevir is an inhibitor of the NS3A/4 HCV protease enzyme. Simeprevir, in combination with the NS5B polymerase inhibitor, sofosbuvir, was the first interferon-free direct acting antiviral (DAA) combination therapy used for the treatment of HCV genotype 1. In non-cirrhotic treatment-naive and treatment-experienced individuals with HCV monoinfection, 97% achieved SVR after 12 weeks of simeprevir/sofosbuvir.⁴ Simeprevir/sofosbuvir use has declined with the availability of co-formulated DAA combinations, but an investigational triple combination DAA regimen including simeprevir, a uridine nucleotide NS5B polymerase inhibitor (AL-335) and the NS5A inhibitor odalasvir (ACH-3012) achieved 100% SVR in 60 patients after 6 or 8 weeks of therapy.⁵

Dolutegravir is an integrase strand-transfer inhibitor used in the treatment of HIV. Dolutegravir has a low potential for drug interactions, is administered once daily in antiretroviral treatment-naive patients and has a high genetic barrier to the development of resistance. Thus, it is a very attractive antiretroviral agent for persons with HIV/HCV coinfection undergoing HCV treatment. Dolutegravir is a P-glycoprotein (P-gp), uridine glucuronosyl transferase 1A1 (UGT1A1) and cytochrome P4503A (CYP3A) substrate and simeprevir has been shown mildly to inhibit these.^6–9 Thus, there is potential for these drugs to interact. The primary objective of this study was to compare dolutegravir and simeprevir pharmacokinetics (PK) when given separately versus in combination.

Methods

This was a prospective, single-centre, open-label, three-treatment, three-period, crossover study to evaluate the drug interaction potential between dolutegravir and simeprevir in healthy volunteers aged 18–60 years. Subjects received three treatment sequences and were randomized to sequence order using block randomization for balance. The three sequences included: (i) 150 mg of simeprevir once daily for 7 days; (ii) 50 mg of dolutegravir once daily for 7 days; and (iii) 150 mg of simeprevir once daily plus 50 mg of dolutegravir once daily for 7 days, with at least a 14 day ‘washout’ between sequences. Intensive 24 h PK sampling was performed on day 7 of each sequence following observed dosing and a standardized moderate fat breakfast (600–700 kcal; 45% carbohydrates, 15% protein, 40% fat). For the intensive 24 h PK visits, samples were obtained at pre-dose and 1, 2, 3, 4, 5, 6, 8, 10, 12 and 24 h post-dose for quantification of simeprevir and/or dolutegravir.

Eligibility laboratories (HIV and HCV antibody, urine pregnancy, comprehensive metabolic panel and complete blood count) were obtained at screening and safety laboratories (urine pregnancy, comprehensive metabolic panel and complete blood count) were obtained at the three intensive PK visits. Clinical and laboratory adverse events were graded using the 2014 Division of AIDS Table for Grading the Severity of Adult and Pediatric Adverse Experiences.¹⁰ Adherence was assessed by participant self-report and pill count during the three intensive PK study visits.

This study was powered to detect a change in dolutegravir or simeprevir area under the curve over the dosing interval (AUC_tau) of >40%. Seven and 16 subjects provided 90% power to detect a 40% change in dolutegravir and simeprevir AUC (two-sided, alpha = 0.05), respectively. Power calculations were performed in SAS version 9.3. Secondary endpoints included maximum concentration (C_max), minimum concentration (C_min), trough, time to C_max (T_max), apparent oral clearance (CL/F), apparent volume of distribution (V/F) and half-life (t_½). The bioequivalence of dolutegravir and simeprevir AUC_tau and C_max with the combination versus individual agents was also determined. To account for potential dropouts, 25 participants were enrolled.

Simeprevir and dolutegravir were simultaneously quantified using an LC/MS/MS assay validated per the FDA guidance.¹¹ This assay was developed and validated for use with K₂ EDTA anticoagulant plasma matrix. The method utilized stable-labelled internal standards that included three deuterium (²H) atoms on the structure of both dolutegravir and simeprevir. A protein precipitation extraction procedure with acetonitrile (MeCN) was used to extract the samples. Mobile phases consisted of 0.1% formic acid in 25:75 acetonitrile/ultrapure water (MP1) and 0.1% formic acid in 90:10 acetonitrile/ultrapure water (MP2). Chromatographic separation was achieved with a Kinetix XB-C18; 2.6 μm 50 × 2.1 mm reversed-phase analytical column. The analytes were separated with a gradient elution of 85% MP1:15% MP2 to 35% MP1:65% MP2 over a 2 min run time at 0.5 mL/min flow rate. The gradient was held for 4 min and re-equilibrated to 85% MP1:15% MP2 for 1 min. Total gradient run time was 7 min. The detection and quantification of dolutegravir, dolutegravir internal standard, simeprevir and simeprevir internal standard was achieved by protonated electrospray ionization (ESI⁺) MS/MS detection. The assay utilized a linear (1/x weighted) fit in the range of 5.00–5000 ng/mL for dolutegravir and 2.00–2000 ng/mL for simeprevir. The minimum quantifiable limit for the method was 5.00 ng/mL for dolutegravir and 2.00 ng/mL for simeprevir when 0.100 mL of human plasma was analysed.

PK parameters were determined using non-compartmental methods (WinNonlin 6.4, Phoenix 64), log-transformed and compared using paired t-tests (GraphPad Prism version 6.07). There were no adjustments for multiple comparisons. Bioequivalence for dolutegravir and simeprevir AUC_tau and C_max was declared when the 90% CI for the geometric mean ratio (GMR) of the combination versus single drug fell within 80%–125%.¹²

Ethics

The study (NCT02404805) was approved by the Colorado Multiple Institutional Review Board. All participants provided written informed consent and all study procedures were in accordance with the Helsinki Declaration of 1975, as revised in 2000.

Results

Twenty-seven subjects consented to participate, 25 subjects enrolled, and 24 subjects completed all three sequences (15 female, 21 Caucasian, 3 Hispanic). The mean age was 35 years and the mean weight was 69.4 kg. Participant baseline demographics are shown in Table 1. Of the two subjects who were not enrolled in the study, one failed screening due to laboratory abnormalities and the other was taking concomitant medications that could not be stopped. One participant withdrew from the study for personal reasons. All but one participant reported 100% adherence. One participant missed both dolutegravir and simeprevir on day 5 of the 7 day combination sequence.

Table 1.

Baseline participant demographics; number of enrolled participants = 25

Age (years), mean ± SD	34.33 ±10.35
Female, n (%)	16 (64)
Caucasian, n (%)	22 (88)
Hispanic, n (%)	3 (12)
Height (inches), mean ± SD	66.69 ±3.66
Weight (kg), mean ± SD	69.4 ±13.17

The PK of dolutegravir and simeprevir alone and in combination are shown in Table 2. The geometric mean dolutegravir trough and AUC_tau were increased 24% (P = 0.0003) and 15% (P = 0.002), respectively, with simeprevir, but the AUC was deemed bioequivalent as the 90% CI for the GMR was 107%–123%. Dolutegravir C_max was bioequivalent (GMR 106%; 90% CI 100%–114%). Dolutegravir T_max increased by 0.5 h while dolutegravir CL/F decreased by ∼100 mL/h. Simeprevir AUC_tau (GMR 99%; 90% CI 82%–119%) and C_max (GMR 105%; 90% CI 88%–125%) were bioequivalent with dolutegravir. There were no significant differences in other simeprevir PK parameters with dolutegravir (Table 2).

Table 2.

PK parameters of dolutegravir and simeprevir alone and in combination

	Dolutegravir PK			Simeprevir PK
	dolutegravir alone, geometric mean (%CV)	dolutegravir + simeprevir, geometric mean (%CV)	P	simeprevir alone, geometric mean (%CV)	simeprevir + dolutegravir, geometric mean (%CV)	P
AUCtau (ng·h/mL)	68186 (30)	78433 (24)	0.002	30946 (80)	30333 (82)	0.93
Cmax (ng/mL)	5203 (23)	5547 (19)	0.11	2409 (73)	2533 (67)	0.56
Ctrough (ng/mL)	1384 (38)	1723 (36)	0.0003	632 (102)	592 (114)	0.59
Cmin (ng/mL)	1218 (54)	1652 (43)	0.002	456 (113)	497 (115)	0.63
Tmax (h)	2.5 (41)	3.0 (42)	0.06	6.3 (37)	7.0 (53)	0.39
CL/F (mL/h)	730 (24)	634 (23)	0.002	4720 (74)	4818 (87)	0.74
V/F (mL)	13488 (22)	12415 (23)	0.12	63054 (117)	54933 (67)	0.43
t½ (h)	12.8 (17)	13.6 (22)	0.92	10.5 (132)	8.9 (36)	0.28

AUC, area under the concentration–time curve; C_max, maximum concentration; C_trough, concentration at the end of the dosing interval (24 h); C_min, minimum concentration over the dosing interval; %CV, percentage coefficient of variation; T_max, time to maximum concentration; CL/F, apparent oral clearance; V/F, apparent volume of distribution; t_½, half-life.

There were no serious adverse events or discontinuations due to adverse events in this study. There were 41 total adverse events, which were mild to moderate in severity. The most common clinical adverse events were gastrointestinal upset and headache reported by 7 of 24 (29.2%) of participants during all three sequences. The most common laboratory abnormality was a decline in creatinine clearance (CL_CR) by an average of 18.2 mL/min, which occurred in 6 of 24 (25%) of participants while taking dolutegravir, consistent with dolutegravir’s inhibition of renal creatinine transporters.¹³ The mean baseline CL_CR of study participants was 113.8 mL/min.

Discussion

The primary objective of this study was to compare dolutegravir and simeprevir PK when given alone versus in combination. Simeprevir had a small effect on dolutegravir; increasing the dolutegravir C_trough by 24% and AUC_tau by 15%. However, based on the 90% CI of the GMR, which fell between 80% and 125%, the dolutegravir AUC_tau and C_max were equivalent. Simeprevir PK was unchanged with dolutegravir.

This study was performed in HIV/HCV seronegative volunteers as it allowed comparisons of simeprevir and dolutegravir PK alone and in combination. Theoretically, the magnitude of the interaction could differ in HIV/HCV-coinfected individuals given simeprevir exposures are higher in individuals with HCV relative to individuals without HCV infection.¹⁴ However, a prior study of dolutegravir troughs with and without simeprevir/sofosbuvir in 12 HIV/HCV-coinfected individuals with cirrhosis found remarkably similar levels to those observed in our study.¹⁵ Dolutegravir troughs were 1157 ng/mL alone versus 1564 and 1414 ng/mL after 2 and 4 weeks of simeprevir/sofosbuvir treatment, respectively, in this prior study in patients with cirrhosis¹⁵ compared with 1384 ng/mL alone and 1723 ng/mL in combination with simeprevir in our healthy volunteers.

The mechanism by which simeprevir causes a slight increase in the dolutegravir concentrations is unknown. Dolutegravir is a P-gp substrate and is metabolized by UGT1A1 and CYP3A.¹⁶ The delayed dolutegravir T_max suggests simeprevir may inhibit P-gp in the gut. Simeprevir increases the AUC and C_max of the P-gp probe digoxin by 31% and 39%, respectively.⁹ Simeprevir mildly inhibits intestinal CYP3A and UGT1A1.⁹ When simeprevir was given with oral midazolam (a CYP3A substrate), midazolam C_max and AUC were increased 31% and 45%, respectively.¹⁴ Exposures of raltegravir, a UGT1A1 substrate, were unchanged with simeprevir.⁹ Other DAAs also increase dolutegravir exposure. Daclatasvir, which inhibits P-gp, increases dolutegravir AUC_tau, C_max and C_trough by 29%–45%, respectively.¹⁷ Ritonavir-boosted paritaprevir/ombitasvir plus dasabuvir, which inhibits CYP3A4, increases dolutegravir AUC_tau, C_max and C_trough by 22%–38%.¹⁸ Collectively, these data suggest inhibition of P-gp and/or CYP3A by simeprevir results in the slight increase in dolutegravir trough.

The small increase in dolutegravir exposures with simeprevir observed in this study is unlikely to have any clinical implications. The exposures of dolutegravir when given with simeprevir in this study are within those observed in the dose ranging trials with established safety data.¹⁹ Though dolutegravir has been associated recently with concentration-dependent CNS toxicities,^20,21 we did not observe an increased incidence of these toxicities when participants received the combination of simeprevir and dolutegravir in this study. Furthermore, dolutegravir is FDA-approved for use in antiretroviral treatment-experienced patients at twice the dose evaluated in this study (50 mg twice daily versus 50 mg once daily).

In conclusion, dolutegravir trough was increased slightly with simeprevir, but AUC_tau was bioequivalent. Despite the increase in trough values, dolutegravir concentrations were well within the range with established safety data, suggesting that simeprevir and dolutegravir can be safely co-administered.