GS-9350: A Pharmacoenhancer Withoutanti-HIV Activity

AA Mathias, P German, M Lee, C Callebaut, L Xu, L Tsai, B Murray, H Liu,K Yale, D Warren and BP Kearney

Gilead SciencesFoster City, CA, USA

• Potent, irreversible (mechanism-based) inhibition of CYP3A

• No anti-HIV activity

Keys to Pharmacoenhancement

GS-9350 RTV

kinact (min-1) 0.44 0.23

KI (µM) 0.94 0.26mean of 5 experiments

Antiviral Assay EC50 (M) GS-9350 RTV Fold-difference

- w/o human serum

- 40% human serum

> 30

> 90

0.015

0.060

> 2000

> 1500mean of > 5 experiments

• Greater CYP450 enzyme inhibition specificity

• Less induction of drug metabolizing enzymes and transporters

Keys to Pharmacoenhancement

1 100

20

40

60

80

100

RTV

GS-9350

hPXR Activation

Concentration (µM)

Re

sp

on

se

(%

Em

ax)

Induction of Hepatocyte CYP3A4 mRNA

mean + SD, n=3

0

20

40

60

80

100

120

1 µM 3 µM 10 µM 30 µM Rifampicin

GS-9350

% M

ax

imu

m

mean ± SD, n=3

CYP450 enzyme IC50

(µM)1A2 2B6 2C8 2C9 2C19 2D6 3A*

GS-9350 >25 2.8 30 >25 >25 9.2 0.2

RTV >25 2.9 5.5 4.4 >25 2.8 0.2

* midazolam 1’-hydroxylase (no preincubation)mean of 3 experiments conducted in duplicate

• Reduced potential for lipid abnormalities

• Improved physicochemical properties

Keys to Pharmacoenhancement

 Drug

Adipocyte Function Assays

Inhibition of Normal LipidAccumulation (EC50 µM)

% Inhibition of GlucoseUptake @ 10µM

RTV 16 55

GS-9350 > 30 9.5

ATV > 30 1.1

Aqueous Solubility (g/mL)

GS-9350 RTV Fold-difference

pH 7.4 75 ~ 2.0 35

pH 2.2 > 6500 3.1 > 2100

mean of 5 experiments /assay

mean of 2 experiments conducted in duplicate

Study GS-216-0101

• Evaluate GS-9350 safety, tolerability, PK and PD (anti-CYP3A activity)

– Double-blind, double-dummy, active and placebo controlled study in HIV(-) subjects

• 3 dose-escalation cohorts: 50, 100 and 200mg tablets (N = 12 /cohort)

• RTV 100mg & dual placebo (each N = 3 /cohort)

– Single and multiple dose PK, safety and tolerability

– Steady-state PD: change from pre-treatment PK of “metabolic probe” oral midazolam

50 mg Single

Dose PK

50 mgx 14 Days

PK/PD

100 mg Single

Dose PK

100 mgx 14 Days

PK/PD

200 mgX 14 Days

PK/PD

Pre-treatment safety and PD assessments

Study drugs administered with food

PK/PD Results

• GS-9350 exhibited non-linear increases in exposure with dose and time– Time- and dose-dependent PK consistent with mechanism-based inhibition

• GS-9350 achieved potent inhibition of CYP3A activity– Near-maximal inhibition achieved at ≥ 100mg

0 6 12 18 240.1

1

10

100

10002500

mean 95% CIn = 9 - 12

100mg200mg

50mg

RTV 100 mg GS-9350

Time (hr)

Ste

ad

y-s

tate

Dru

g C

on

cen

tra

tio

n (

ng

/mL

)

GS-9350 & RTV PK

0 6 12 18 240.1

1

10

100

10002500

mean 95% CIn = 9 - 12

100mg200mg

50mg

RTV 100 mg GS-9350

Time (hr)

Ste

ad

y-s

tate

Dru

g C

on

cen

tra

tio

n (

ng

/mL

)

GS-9350 & RTV PK

RTV

- 95%

50 mg 100 mg 200 mg

- 88%

- 92%- 95%

GS-9350

Pre-treatment0

5

10

15

20

2550

75

100

Mid

azol

am C

L/F

(L/h

r)

GS-9350 & RTV PD(midazolam apparent clearance)

RTV

- 95%

50 mg 100 mg 200 mg

- 88%

- 92%- 95%

GS-9350

RTV

- 95%

RTV

- 95%

50 mg 100 mg 200 mg

- 88%

- 92%- 95%

GS-9350

50 mg 100 mg 200 mg

- 88%

- 92%- 95%

GS-9350

Pre-treatment0

5

10

15

20

2550

75

100

Mid

azol

am C

L/F

(L/h

r)

GS-9350 & RTV PD(midazolam apparent clearance)

Pre-treatment0

5

10

15

20

2550

75

100

Mid

azol

am C

L/F

(L/h

r)

GS-9350 & RTV PD(midazolam apparent clearance)

Study GS-236-0101

• Evaluate the relative bioavailability, PK and safety ofEVG/FTC/TDF/GS-9350 FDC tablet vs. EVG/r and FTC + TDF

– Open-label, partially-randomized, adaptive study design in HIV(-) subjects(N = 44)

• 100 mg starting GS-9350 dose → 75 or 150 mg GS-9350 containing FDC

EVG/FTC/TDF/GS-9350150/200/300/100mg

EVG + RTV 150mg + 100mg

FTC + TDF200mg + 300mg

EVG/FTC/TDF/GS-9350150/200/300/100mg

EVG + RTV150mg + 100mg

EVG/FTC/TDF/GS-9350150/200/300/150mg

Real-time GS-9350 & EVG PK analysis

Study drugs administered with food

Mean (CV%)EVG PK (n = 42)

GS-9350 100mg FDC GS-9350 150mg FDC EVG + RTV 100mg

AUCtau (ng.hr/mL) 21100 (25.4) 27000 (29.4) 22500 (23.4)

Cmax (ng/mL) 2250 (26.3) 2660 (27.6) 2500 (32.1)

Ctau (ng/mL) 282 (60.4) 490 (52.9) 409 (40.5)

Elvitegravir PK

• GS-9350 effectively boosts EVG within FDC tablet

• High EVG trough concentrations maintained w/ GS-9350 150mg

– 11-fold above the protein binding-adjusted IC95 (44.5 ng/mL)

– Low within-subject variability (15% CV)

IC95

100 mg 150 mg RTV0

200

400

600

800

1000

1200

IC95

GS-9350Bars represent geometric mean ( 95% CI)

Elv

iteg

ravi

r C

tau (

ng

/mL

)

• FTC and TFV exposures clinically equivalent

– FTC exposures increased 20% as FDC vs. FTC capsule

– TFV AUC bioequivalent as FDC or TDF tablet

EVG/FTC/TDF/GS-9350 150 mg FTC + TDF

Mean (CV%) PK(n = 42)

FTC TFV FTC TFV

AUCtau

(ng.hr/mL)11500 (19.3) 3010 (20.4) 9330 (22.1) 2550 (22.6)

Cmax (ng/mL) 1850 (22.5) 332 (28.9) 1600 (26.1) 252 (24.9)

Ctau (ng/mL) 101 (26.8) 65.0 (26.0) 80.1 (25.9) 52.0 (25.4)

FTC/TDF PK

Safety Summary

• GS-9350 first-in-man, dose-ranging study– Single and multiple doses up to 200 mg well tolerated

– No drug-related Grade 3/4 laboratory abnormalities

– Single Grade 3 adverse event of discoordination (GS-9350 100mg)

– No changes or differences observed in serum lipids across treatments over 14 days

• Integrase FDC “Quad” tablet study– All treatments well tolerated

– Two Grade 3 adverse events• Single subject with drug-related ALT elevation (GS-9350 100mg FDC)• One subject with acute appendicitis

– No other drug-related Grade 3/4 laboratory abnormalities

Conclusions

• GS-9350 is a potent, selective, mechanism-based CYP3A inhibitor that lacks anti-HIV activity and has limited effects on adipocyte function in vitro

• GS-9350 boosts CYP3A substrates comparable to RTV in humans

• EVG/FTC/TDF/GS-9350 FDC tablet achieves desired exposures of EVG, FTC and TFV

GS-9350 & Ritonavir PK

Mean (CV%) PK(n = 42)

GS-9350 100mg FDC GS-9350 150mg FDC RTV 100mg

AUCtau (ng.hr/mL) 5150 (31.7) 10400 (35.2) 5750 (38.4)

Cmax (ng/mL) 855 (27.6) 1570 (29.7) 1030 (47.8)

Ctau (ng/mL) 7.6 (124) 22.7 (107) 37.6 (52.2)

0 6 12 18 241

10

100

1000

2500

EVG/FTC/TDF/GS-9350 100 mg

mean 95% CI

EVG/FTC/TDF/GS-9350 150 mg

EVG + RTV 100 mg

Time (hr)

Dru

g C

on

ce

ntr

ati

on

(n

g/m

L)