# Presentation: 680073

## Bosentan Therapyfor PulmonaryArterial Hypertension

**Isaac Kobrin, MD**
**Head of Clinical Development**
**Actelion Pharmaceuticals**

**9001.01**

## Advisors

**PAH****	****	****	****  Lewis J Rubin, MD****	****	****	****  University of California San Diego**
**Preclin / tox****	****              R Michael McClain, PhD****                                   Consultant in Toxicology**
**Clin pharm  ****	****  Malcolm Rowland, PhD****	****	****              University of Manchester**
**Hepatology****	****              Willis C Maddrey, MD****	****	****              UT Southwestern Medical Center**
**Hematology ****	****  Jerry L Spivak, MD****	****	****	****  Johns Hopkins University**

**9002.01**

## Bosentan Therapy for PAH

**Rationale for ET receptor antagonism**
**Preclinical observations**
**Clinical pharmacology**
**Clinical program:**
**Efficacy in patients with PAH **
**Overall safety and tolerability **
**Specific safety issues**
**Drug-induced liver injury  (Dr W Maddrey)**
**Risk / benefit assessment (Dr L Rubin)**

**9003.01**

## Endothelin-1 (ET-1)

**Synthesized and secreted by endothelial cells**
**Acts via 2 receptors:**
**ET****A****, vascular smooth muscle cells (SMC)**
**ET****B****, vascular SMC, endothelial cells, fibroblasts**
**Induces vasoconstriction, fibrosis, hypertrophy****and hyperplasia**
**Increases vascular permeability**

**Endothelin-1 (ET-1)**

**9004.01**

## Rationale for ET Receptor Antagonism in PAH

**In patients with PAH:**
**Plasma ET-1 levels  are increased, and levels correlate with disease severity**
**Increased ET-1 immuno-reactivity in lung vasculature (plexiform lesions)**
**Blockade of ET-1 activity is expected to prevent its detrimental effects**
**ET receptor antagonists are effective in animal models of pulmonary hypertension **

**9005.01**

## Bosentan

**Specific, low MW, competitive ET-receptor antagonist**
**Inhibits the effects of ET-1****by inhibiting its binding****to both ET****A**** and ET****B**** receptors**

**9006.01**

## Preclinical ObservationsRelated to PAH

**Pulmonary hypertension**
**Chronic hypoxia**
**Monocrotaline**
**Pulmonary fibrosis**
**Bleomycin**
**Pulmonary inflammation**
**Sephadex**
**Oleic acid**

**Bosentan was studied in models of:**

**9007.01**

## Preclinical ObservationsRelated to PAH

**The main effects of bosentan included:**
**Decrease in pulmonary artery pressure**
**Decreases in pulmonary vascular hypertrophy****and right ventricular hypertrophy**
**Decreases in pulmonary fibrosis****and inflammation**

**9008.01**

## Preclinical ObservationsRelevant to Human Safety

**Teratogenicity **
**Decreased RBC parameters**
**Liver injury**

**9009a.01**

## Preclinical ObservationsTesticular Changes

**In a 2-year rat study, an increased incidence****of slight testicular tubular atrophy was observed**
**Not observed in a 2-year mouse study**
**The overall pattern and findings were not typical of drug-induced testicular toxicity**
**No effect  on sperm count, motility or male fertility in rats treated with oral bosentan at doses up to 50 times the recommended human dose**

**9009b.01**

## Pharmacokinetic Characteristics

**Dose proportional up to 600 mg (single dose)****and 500 mg/day (multiple doses)**
**Absorption:  t****max**** at 3.5 hours**
**No relevant food effect**
**Oral bioavailability:  approximately 50%**

**9010.01**

## Pharmacokinetic Characteristics

**Terminal elimination half-life:  5.4 hours**
**Protein binding:  98% (mainly albumin)**
**Steady state reached within 3 - 5 days**
**Age, gender, race, body weight and renal function appear not to have a relevant effect****on PK properties**

**9011.01**

## Metabolism and Excretion

**Eliminated mainly by hepatic metabolism****and subsequent biliary excretion**
**Metabolic pathways:  CYP3A4 and CYP2C9 **
**Ketoconazole, a 3A4 inhibitor, led to a 2-fold increase in bosentan exposure**
**Inhibition of 2C9 is not expected to exert a greater effect than ketoconazole **
**CsA, a nonspecific inhibitor of transporters, markedly increased bosentan exposure**

**9012.01**

## Influence on Drug Metabolism

***In vitro *****bosentan**
**Does not inhibit CYP1A2, 2C9, 2C19, 2D6****or 3A4**
**Induces CYP2C9, 2C19 and 3A4**
***In vivo *****bosentan**
**Decreases exposure to CYP2C9 and 3A4 substrates by 30-60% (HV)**
**Reduced efficacy of CYP2C9 and 3A4 substrates should be considered**

**9013a.01**

## Warfarin DDI: Clinical Relevance AC-052-352

**Clinical experience in PAH patients****(34 placebo and 59 bosentan patients) **
**No change in warfarin dose****(BL vs end of treatment)**
**No change in INR (BL vs end of treatment)**
**No difference in warfarin dose changes****during treatment vs placebo**

**9013b.01**

## Efficacy in PAH Patients

**9014.01**

## PAH Studies for Efficacy Evaluation

**Open-label, long-term**
**AC-052-354**
**(Ongoing)**
**Bos = 200**

**Overall**
**N = 245**

**Placebo-controlled**
**AC-052-351**
**Pbo = 11, Bos = 21**

**Open-label, long-term**
**AC-052-353**
**(Ongoing)**
**Bos = 29**

**Placebo-controlled**
**AC-052-352**
**Pbo = 69, Bos = 144**

**PAH Studies for Efficacy Evaluation**

**9015.01**

## Study DesignsPlacebo-controlled Studies

**Study Designs****Placebo-controlled Studies**

- 16

- BL

**Period 1 – Evaluation**

**Period 2 – Follow-up**

- 4

- Week 0

- 12

- 28

**Screen**

- Placebo

**Bosentan 125 mg bid**

**Placebo**

- 62.5 mgbid

**AC-052-351**

**AC-052-352**

- 62.5 mgbid

**Bosentan 250 mg bid**

**Screen**

- Placebo

**Bosentan 125 mg bid**

**Placebo**

- 62.5 mgbid

- 1o Endpoints

- (Variable Period 2)

- (Fixed Period 2 for pts
-  who participated)

**9016.01**

## Patient Allocation to Periods 1 and 2 AC-052-351

**Patient Allocation to Periods 1 and 2 ****AC-052-351**

**Aug 99**

**Jan 00**

**Apr 00**

**Period 1**
**(12 weeks)**

**Period 2**
**(variable)**

**P1**

**P32**

**Randomization**

**Primary Endpoint**

**Final Endpoint**

**9845.01**

## Patient Allocation to Periods 1 and 2AC-052-352

**July 00**

**Dec 00**

**Mar 01**

**Period 1**
**(16 weeks)**

**Randomization**

**Primary Endpoint**

**Period 2**
**(fixed 12 weeks)**

**Sep 00**

**Final Endpoint**

**P1**

**P48**

**P213**

**9846.01**

## Main Inclusion Criteria

**PAH due to PPH or secondary to scleroderma****or other connective tissue diseases**
**WHO functional class III - IV**
**Baseline 6-min walk test ******** 150 m and ******** 450/500 m**
**Baseline hemodynamics**
**Mean PAP **>** 25 mmHg**
**PVR **>** 240 dyn****•****sec/cm****5**
**PCWP **< **15 mmHg**

**Main Inclusion Criteria**

**9017.01**

## Main Exclusion Criteria

**PAH due to other causes (eg, congenital HD, HIV, cirrhosis, thromboembolic, COPD...)**
**SSc/PAH with mod / severe interstitial fibrosis**
**Systolic BP **<** 85 mmHg**
**ALT / AST **>** 3 x ULN**
**Hb / Hct **>** 30% below the LLN**
**PAH treatment modified within 1 month****of screening (excluding anticoagulants)**
**Received epoprostenol within 3 months****of screening**

**9018.01**

## Demographics

**(n = 144)**

**21:79**
**49 ******** 16**
**71 ******** 20**
**77:8:15**
**55:45**

**Pbo**
**(n = 11)**

**0:100**
**47 ******** 14**
**87 ******** 18**
**82:18:0**
**82:18**

**M:F (%)**
**Age (years)**
**Weight (kg)**
**Race (% W:B:O)**
**US / Non-US (%) **

**19:81**
**52 ******** 12**
**86 ******** 23**
**76:14:10**
**81:19**

**22:78**
**47 ******** 16**
**74 ******** 18**
**86:1:13**
**56:44**

**Bos**
**(n = 21)**

**Pbo**
**(n = 69)**

- Percent or mean  SD

**AC-052-351**

**AC-052-352**

**Demographics**

**9019.01**

## Baseline Characteristics

**90:10**
**2.5 ******** 2.9**
**71****23****  6**

**100:0**
**3.0 ******** 2.8**
**91****  9**** ****—**** **

**WHO class (% III:IV)**
**Time from Diag (yrs)**
**Etiology of PAH (%)****   ****PPH ****   SSc/PAH****   Other**** **

**100:0**
**1.7 ******** 1.4**
**81****19****—**

**94:6**
**2.3 ******** 4.0**
**70****20****10**

- Percent or mean  SD

**Baseline Characteristics**

**AC-052-351**

**AC-052-352**

**Bos**
**(n = 144)**

**Pbo**
**(n = 11)**

**Bos**
**(n = 21)**

**Pbo**
**(n = 69)**

**9020.01**

## Baseline Hemodynamics

**1014 ******** 678**
**  ****2.4 ******** 0.8**
**  ****9.2 ******** 3.9**
**  ****9.8 ******** 5.9**

**56 ******** 11**
**942 ******** 430**
**2.5 ******** 1.0**
**8.3 ******** 3.3**
**9.9 ******** 4.1**

**54 ******** 13**
**896 ******** 425**
**2.4 ******** 0.7**
**9.3 ******** 2.4**
**9.7 ******** 5.6**

**53 ******** 17**
**880 ******** 540**
**2.4 ******** 0.7**
**9.2 ******** 4.1**
**8.9 ******** 5.1**

- Mean  SD

**Mean PAP (mmHg)**
**PVR (dyn****·****sec****/****cm****5****)**
**CI (L/min/m****2****)**
**PCWP (mmHg)**
**Mean RAP (mmHg) **

**Baseline Hemodynamics**

**AC-052-351**

**AC-052-352**

**Bos**
**(n = 144)**

**Pbo**
**(n = 11)**

**Bos**
**(n = 21)**

**Pbo**
**(n = 69)**

**9021.01**

## Main Concomitant Medications for PAH

**82**
**91 **
**55**
**  ****9**
**  ****9**

**Anti-thrombotics (%)**
**Diuretics**
**Calcium antagonists**
**Cardiac glycosides**
**Oxygen**

**71**
**86**
**52**
**14**
** ****29**

**73**
**51**
**52**
**19**
** ****33 **

**70**
**54**
**44**
**19**
** ****29**

**Main Concomitant Medications for PAH**

**Bos**
**(n = 144)**

**Pbo**
**(n = 11)**

**Bos**
**(n = 21)**

**Pbo**
**(n = 69)**

**AC-052-351**

**AC-052-352**

**9022.01**

## Patient DispositionAC-052-351

**Patient Disposition****AC-052-351**

**N = 32**

**n = 9**

**n = 8**

**n = 8**

**n = 21**

**n = 21**

**n = 21**

**Randomized****ITT/ Safety**

**Completed****Period 1**

**Completed****Period 2**

**To open label****(AC-052-353)**

**1 w/d**

**2 w/d**

**Bos****125 mg bid****n = 21**

**Placebo****n = 11**

**9023.01**

## Patient DispositionAC-052-352

**Patient Disposition****AC-052-352**

**Placebo****n = 69**

**N = 214**

**n = 69**

**n = 63**

**n = 62**

**Bos****250 mg bid****n = 70**

**n = 70**

**n = 67**

**n = 67**

**Randomized**

**ITT/Safety**

**6 w/d**

**1 w/d**

**To open label****(AC-052-354)**

**Bos ****125 mg bid****n = 75**

**n = 74**

**n = 71**

**n = 71**

**3 w/d**

**3 w/d**

**Completed****Period 1 **

**9024.01**

## Primary Endpoint
6-minute walk distance at end of Period 1
Secondary Endpoints
Time to clinical worsening
Death
Hospitalization due to PAH 
Discontinuation due to worsening PAH
Start of epoprostenol
Lung transplantation / septostomy

**6-minute walk distance at end of Period 1**
**Secondary Endpoints**
**Time to clinical worsening**
**Death**
**Hospitalization due to PAH **
**Discontinuation due to worsening PAH**
**Start of epoprostenol**
**Lung transplantation / septostomy**

**Efficacy Parameters**

**9026.01**

## 
Change in Borg dyspnea index 
Change in WHO functional class
Change in pulmonary hemodynamics(mean PAP, PVR, CI, mean RAP)
Increase in therapy for PAH (Period 1)

**Change in Borg dyspnea index **
**Change in WHO functional class**
**Change in pulmonary hemodynamics****(mean PAP, PVR, CI, mean RAP)**
**Increase in therapy for PAH (Period 1)**

**Efficacy Parameters**

**9850.01**

## Statistical AnalysesPrimary Endpoint

**All bosentan vs placebo:  ITT population**
**AC-052-351:  Student’s t-test**
**AC-052-352:  Mann-Whitney U-test**

**Management of patients with no valid assessment at the end of Period 1:**
**Due to worsening PAH or death:  walk test = 0 m**
**AC-052-351:  1 placebo pt**
**AC-052-352:  3 placebo, 2 bosentan 125 mg bid pts**
**Due to other reasons:  last value carried forward**

**9027.01**

## 6-minute Walk TestMean Treatment Effect

**Treatment difference (meters)**

******20**

**20**

**40**

**60**

**80**

**100**

**120**

**0**

**140**

**Bos**

**Pbo**

**125 mg bid**

**21**

**11**

**AC-052-351**

**125 mg bid**

**AC-052-352**

**74**

**69**

**250 mg bid**

**70**

**69**

**125/250 mg bid**

**144**

**69**

**Mean (95% CL)**

**75.9 (12.5, 139.2)**

**34.6   (6.2,  63.1)**

**54.3 (27.3,  81.4)**

**44.2 (21.4,  67.0)**

***P = 0.0002***

***P = 0.0205***

***(P = 0.0001)***

***(P = 0.0107)***

**9028.02**

## Robustness of ResultsPrimary Parameter

**AC-052-351**

**Mann-Whitney U-test**
**Per-protocol population**
**First 150 patients **
**Pts w/o Wk-16 endpoint**
**  ****Carry forward**
**  ****Zero substitution**
**  ****Pbo CF, bos zero **
**  ****Pbo exclude, bos zero**

**0.019**
** ****0.021***
**—**
**0.041**
**—**
**—**
**—**

**AC-052-352**

**(0.0002)**
**0.0011**
**0.0063**
**0.0002 **
**0.0008**
**0.0054**
**0.0176**

***P***** value**

- * Identical to ITT population

**9029.01**

## Change in Walk DistanceDuring Period 1

**-10**

**0**

**20**

**40**

**60**

**Change in Walk Distance****During Period 1**

**Placebo (n = 11)**

**Bosentan 125 mg bid**
**(n = 21)**

**-10**

**0**

**20**

**40**

**60**

**Change in  Walk Distance (m)**

**AC-052-352**

**AC-052-351**

- Mean  SEM

- 62.5 mg bid

- 125 or 250 mg bid

**Bosentan****125/250 mg bid**
**(n = 144)**

**Placebo**
**(n = 69)**

**9030.01**

## Change in Walk Distance by DoseDuring Period 1 in AC-052-352

**Bosentan 250 mg bid**
**         ****(n = 70)**

**Placebo (n = 69)**

- Mean  SEM

**Bosentan****125 mg bid**
**(n = 74)**

**Change in  Walk Distance (m)**

**9031.02**

## Walk Test in SubpopulationsMean Treatment Effect (AC-052-352)

**Walk Test in Subpopulations****Mean Treatment Effect (AC-052-352)**

**Bos**

**Pbo**

**All patients****        **
**Gender****     Males**
**Females**
**Age****  12 – 20 yrs**
**21 – 40 yrs**
**41 – 60 yrs**
- >** 60 yrs**
**Weight****   **<** 70 kg**
****** ****70 kg**
**Race****         White**
**Other**

**69**
**15**
**54**
**6**
**15**
**33**
**15**
**29**
**40**
**59**
**10**

**144**
**30**
**114**
**7**
**31**
**71**
**35**
**77**
**67**
**111**
**33**

******20**

**20**

**40**

**60**

**80**

**100**

**120**

**0**

**Treatment difference (meters)**

**...**

**9032.01**

## Walk Test in SubpopulationsMean Treatment Effect (AC-052-352)

**Walk Test in Subpopulations****Mean Treatment Effect (AC-052-352)**

**Bos**

**Pbo**

******20**

**20**

**40**

**60**

**80**

**100**

**120**

**0**

**All patients****      **
**WHO class****    III**
**IV**
**Etiology  ****  PPH**
**SSc/PHT**
**Time from         **
** ****< 421 days**
****** ****421 days**
**Congenital       **
**         ****Yes**
**No**

**69**
**65**
** ****4**
**48**
**14**
**40**
**29**
**2**
**66**

**144**
**130**
**14**
**102**
**33**
**66**
**77**
**11**
**133**

**diagnosis**

**heart disease**

**...**

**...**

**138.5**

**...**

**9033.01**

**Treatment difference (meters)**

## Walk Test in SubpopulationsMean Treatment Effect (AC-052-352)

**Walk Test in Subpopulations****Mean Treatment Effect (AC-052-352)**

******20**

**20**

**40**

**60**

**80**

**100**

**120**

**0**

**Location**
**BL walk test**
**Mean PAP**
**Mean RAP**
**CI**

**US**
**Non-US**
**  ****  **<** 345 m**
****** ****345 m**
- <** 52 mmHg**
****** ****52 mmHg**
- <** 8 mmHg**
****** ****8 mmHg**
- <** 2.3 L/min/m****2**
****** ****2.3 L/min/m****2**** **

**All patients**

**69**
**39**
**30**
**27**
**42**
**37**
**32**
**32**
**35**
**31**
**37**

**144**
**79**
**65**
**79**
**65**
**67**
**77**
**66**
**77**
**75**
**69**

**Bos**

**Pbo**

**9034.01**

**Treatment difference (meters)**

## Change in Borg Dyspnea IndexMean Treatment Effect

**Change in Borg Dyspnea Index****Mean Treatment Effect**

**Treatment difference (score)**

**0**

******1**

******2**

******3**

**0.5**

******0.5**

******1.5**

******2.5**

******3.5**

**Bos**

**Pbo**

**125 mg bid**

**21**

**11**

**AC-052-351**

**125 mg bid**

**AC-052-352**

**74**

**69**

**250 mg bid**

**70**

**69**

**125/250 mg bid**

**144**

**69**

**Mean (95% CL)**

******1.6 (********3.1, 0.0)**

******0.4 (********1.1, 0.3)**

******0.9 (********1.6, ********0.2)**

******0.6 (********1.2, ********0.1)**

**9035.02**

## Time to Clinical WorseningUp to Treatment End

**Percent Event-free**

**Weeks**

***p***** < 0.01**

**50**

**75**

**100**

**Bosentan****125/250 mg bid**

**Placebo**

***p***** < 0.01**

**0**

**Time to Clinical Worsening****Up to Treatment End**

**AC-052-352**

***p***** = 0.03**

**50**

**75**

**100**

**0**

**AC-052-351**

**144****69**

**142****68**

**31****10**

**141****63**

**138****62**

**103****48**

**25****7**

**13****3**

**Bosentan****125 mg bid**

**Placebo**

**21**
**11**

**21****11**

**7****1**

**21****10**

**21****8**

**12****4**

**6****1**

**2****1**

**9036.02**

## Time to Clinical Worsening by DoseUp to Treatment End (AC-052-352)

**Weeks**

**0**

**4**

**8**

**12**

**16**

**20**

**24**

**28**

**50**

**75**

**100**

**0**

***p***** = 0.01**

***p *****< 0.03**

**Time to Clinical Worsening by Dose****Up to Treatment End (AC-052-352)**

**Bosentan**

**74**
**70**
**69**

**72**
**70****68**

**18**
**13****10**

**71**
**70****63**

**70**
**68****62**

**55**
**48****48**

**14**
**11****7**

**7**
**6****3**

**Placebo**

**9037.01**

## Incidence of Clinical WorseningTo End of Period 2

**(n = 69) **

**Clinical Worsening***
**  ****Death**
**  ****Hospitalization for PAH**
**  ****D/C for worsening PAH**
**  ****Receipt of epoprostenol**

- *Patients may fall into >1 category  No cases of lung transplantation or septostomy

**  ****14 (20.3) **
**    ****2   (2.9) **
**    ****9 (13.0) **
**    ****6   (8.7) **
**    ****3   (4.3)**

**9 (6.3)**
**1 (0.7)**
**6 (4.2)**
**5 (3.5)**
**4 (2.8)**

**Bos**
**(n = 144) **

**Pbo **
**(n = 11) **

**Bos**
**(n = 21) **

**0**
**0**
**0**
**0**
**0**

**3 (27.3)**
**0**
**3 (27.3)**
**3 (27.3)**
**3 (27.3)**

**AC-052-351 **

**AC-052-352 **

**Incidence of Clinical Worsening****To End of Period 2**

**9038.01**

## Improvement in WHO ClassEnd of Period 1

**(n = 69) **

**Improved**
**Treatment effect**
**  ****95% CL**

**Bos**
**(n = 144) **

**Pbo **
**(n = 11) **

**Bos**
**(n = 21) **

**43%**

**9%**

**AC-052-351 **

**AC-052-352 **

**Improvement in WHO Class****End of Period 1**

**42%**

**30%**

**Treatment effect of both studies combined**** 14.9% (1.3%, 27.0%)**

** ****33.8%**
******5.6%, 58.0%**

**11.9%**
******2.9%, 25.2%**

**9039.01**

## Change in WHO ClassAC-052-351 and AC-052-352

**Worsened 1 class (%)**
**No change**
**Improved 1 class**
**Improved 2 classes**
**Mann-Whitney U-test**

** ****0**
** ****57**
** ****43**
** ****0**

**6**
** ****64**
**30**
**  ****0**

**  ****2**
**56**
**38**
**4**

**Pbo****(n = 11)**

**Change from BL****to end of Period 1**

**Bos****(n = 21)**

** ****18**
** ****73**
**9**
**  ****0**

**Pbo****(n = 69)**

**Bos****(n = 144)**

***P***** = 0.019**

***P***** = 0.042**

**AC-052-351 **

**AC-052-352 **

**9040.01**

## Changes in HemodynamicsChange to Week 12 (AC-052-351)

******12**

******8**

******6**

******4**

******2**

**0**

**2**

******10**

**Mean PAP (mmHg)**

**PVR (dyn****•****sec/cm****5****)**

**Cardiac Index**
**  ****(L/min/m****2****)**

**PCWP (mmHg)**

**Mean RAP (mmHg)**

**Mean (95% CL)**

******6.7 (********11.9, ********1.5)**

******415 (********608, ********221)**

**1.02 (0.65, 1.39)**

******3.8   (********7.3, ********0.3)**

******6.2   (********9.6, ********2.7)**

******600**

******400**

******300**

******200**

******100**

**0**

**100**

******500**

- Placebo = 10
- Bos 125 mg bid = 20

******0.25**

**0.5**

**1**

**1.5**

**0**

**Changes in Hemodynamics****Change to Week 12 (AC-052-351)**

**Placebo-corrected treatment difference**

**9041.01**

## Increase in Therapy for PAHAC-052-352 (Period 1)

**Treatment effect****   95% CL**
**% Pts with ******** 2 increases**
**Treatment effect****   95% CL**

**Bosentan**
**(n = 144)**

**Placebo**
**(n = 69)**

**22.2**
** **
**11.1**

**29.0**
**18.8**
** **

- Period 1 was 16 weeks

**Increase in Therapy for PAH****AC-052-352 (Period 1)**

******6.8**** ********19.5, 7.1**
******7.7**** ********18.1, 4.7**

**9042.01**

## Patient Allocation to Periods 1 and 2 AC-052-351

**Patient Allocation to Periods 1 and 2 ****AC-052-351**

**Aug 99**

**Jan 00**

**Apr 00**

**Period 1**
**(12 weeks)**

**Period 2**
**(variable)**

**P1**

**P32**

**Randomization**

**Primary Endpoint**

**Final Endpoint**

**9845.01**

## Patient DispositionAC-052-351

**Patient Disposition****AC-052-351**

**N = 32**

**n = 9**

**n = 8**

**n = 8**

**n = 21**

**n = 21**

**n = 21**

**Randomized****ITT/ Safety**

**Completed****Period 1**

**Completed****Period 2**

**To open label****(AC-052-353)**

**1 w/d**

**2 w/d**

**Bos****125 mg bid****n = 21**

**Placebo****n = 11**

**9023.01**

## Patient Allocation to Periods 1 and 2AC-052-352

**July 00**

**Dec 00**

**Mar 01**

**Period 1**
**(16 weeks)**

**Randomization**

**Primary Endpoint**

**Period 2**
**(fixed 12 weeks)**

**Sep 00**

**Final Endpoint**

**P1**

**P48**

**P213**

**9846.01**

## Disposition of Pts Scheduled for Period 2 AC-052-352

**Disposition of Pts Scheduled for Period 2**** ****AC-052-352**

**Placebo****n = 13**

**N = 48**

**n = 11**

**n = 8**

**Bos****250 mg bid****n = 16**

**n = 15**

**n = 12**

**Randomized**

**Completed****Period 2 **

**Entered****Period 2**

**3 w/d**

**1 w/d**

**Bos ****125 mg bid****n = 19**

**n = 18**

**n = 13**

**5 w/d**

**3 w/d**

**1 w/d**

**2 w/d**

**9025.01**

## Maintenance of Efficacy Walk Test Up to 28 Weeks

**50**

**75**

**100**

**0**

**AC-052-351**

**Bosentan****125 mg bid**

**n = 21**

**n = 20**

**n = 6**

**25**

**Weeks**

**AC-052-352**

**50**

**75**

**100**

**0**

**25**

**0**

**4**

**8**

**12**

**16**

**20**

**24**

**28**

**Bosentan****125/250 mg bid****(n = 35)**

**Placebo****(n = 13)**

**Change from Baseline (meters)**

**9493.01**

- Mean  SEM

## Open-label ExtensionAC-052-353

- 62.5 mg bid

**Bosentan 125 mg bid**

- 1 - 4 weeks

- Bosentan 250 mg bid

- Bosentan 62.5 mg bid

**Assessments**
**Walk test at Week 4**
**WHO class each 6 months**

**Patients **
**  ****8 / 11 ex-placebo**
**21 / 21 ex-bosentan**

**3/31/01 cut off**

**Open-label Extension****AC-052-353**

**9043.01**

## 6-minute Walk DistanceOpen-label Extension Study AC-052-353

**Baseline (end of 351)**
**Change to Week 4***

**393.8 ******** 37.9 **
**  ****22.5 ******** 14.3**

- Mean  SEM in meters

**Ex-placebo****(n = 8)**

**Ex-bosentan****(n = 21)**

** ****438.9 ******** 14.2 **
**   ****3.0 ******** 9.2**

- * **Treatment in AC-052-351 still blinded for 26 of 29 patients**

**6-minute Walk Distance****Open-label Extension Study AC-052-353**

**9044.01**

## WHO Functional ClassOpen-label Extension Study AC-052-353

**Class I (n)**
**Class II**
**Class III**
**Class IV**

**0**
**0**
**29**
**0**

**  ****1**
**12**
**15**
**  ****1**

**  ****1**
**11**
**16**
**  ****1**

**Start of ****AC-052-351**

**6 months**

**1 year**

**Open-label bosentan **

**WHO class **

**WHO Functional Class****Open-label Extension Study AC-052-353**

- 29 patients entered the open-label study

**9045.01**

## Efficacy Conclusions

**Increased exercise capacity**
**Consistent in all subpopulations**
**Improved dyspnea on exercise**
**Improved WHO functional class**

**Efficacy Conclusions**

**9046.01**

## Efficacy Conclusions

**Improved pulmonary hemodynamics: ****cardiac index, mean PAP, PVR and mean RAP****(125 mg bid)**
**Decreased risk of clinical worsening**
**With extended treatment:**
**Clinical benefits maintained; no evidence****for tolerance**

**9047.01**

**9048.01**

## Safety and Tolerability

**9049.01**

## Bosentan Therapeutic StudiesSafety Database

**9050.01**

**Therapeutic Studies****N = 972**

**PAH****N = 252**

**BD14884****2000 mg/d****PC, DB (n = 7)**

**AC-052-351****250 mg/d****PC, DB (n = 32)**

**AC-052-353****250 mg/d****OL (n = 29)**

**AC-052-352****250/500 mg/d****PC, DB (n = 213)**

**AC-052-354****250 mg/d****OL (n = 200)**

## Bosentan Therapeutic StudiesSafety Database

**9051.01**

**CHF****N = 447**

**Therapeutic Studies****N = 972**

**PAH****N = 252**

**BC15064/part I****1000 mg/d****OL (n = 7)**

**NC15462****1000 mg/d****PC, DB (n = 370) **

**BC15064/part II****2000 mg/d****PC, DB (n = 36)**

**NC15018****2000 mg/d****PC, DB (n = 34)**

**NC15464B****250 mg/d**
**OL (n = 86)**

**BD14884****2000 mg/d****PC, DB (n = 7)**

**AC-052-351****250 mg/d****PC, DB (n = 32)**

**ENABLE****250 mg/d****PC, DB (n = 1613)**

**AC-052-353****250 mg/d****OL (n = 29)**

**AC-052-352****250/500 mg/d****PC, DB (n = 213)**

**AC-052-354****250 mg/d****OL (n = 200)**

## Bosentan Therapeutic StudiesSafety Database

**9052.01**

**CHF****N = 447**

**HTN****N = 243**

**Therapeutic Studies****N = 972**

**PAH****N = 252**

**BC15064/part I****1000 mg/d****OL (n = 7)**

**NC15462****1000 mg/d****PC, DB (n = 370) **

**BC15064/part II****2000 mg/d****PC, DB (n = 36)**

**NC15018****2000 mg/d****PC, DB (n = 34)**

**NC15464B****250 mg/d**
**OL (n = 86)**

**NC15020****100-2000 mg/d****PC, DB (n = 243)**

**BD14884****2000 mg/d****PC, DB (n = 7)**

**AC-052-351****250 mg/d****PC, DB (n = 32)**

**ENABLE****250 mg/d****PC, DB (n = 1613)**

**AC-052-353****250 mg/d****OL (n = 29)**

**AC-052-352****250/500 mg/d****PC, DB (n = 213)**

**AC-052-354****250 mg/d****OL (n = 200)**

## Bosentan Therapeutic StudiesSafety Database

**CHF****N = 447**

**HTN****N = 243**

**SAH****N = 30**

**Therapeutic Studies****N = 972**

**PAH****N = 252**

**BC15064/part I****1000 mg/d****OL (n = 7)**

**NC15462****1000 mg/d****PC, DB (n = 370) **

**BC15064/part II****2000 mg/d****PC, DB (n = 36)**

**NC15018****2000 mg/d****PC, DB (n = 34)**

**NC15464B****250 mg/d**
**OL (n = 86)**

**NC15020****100-2000 mg/d****PC, DB (n = 243)**

**NN15031****1500 mg/d****PC, SB (n = 30)**

**BD14884****2000 mg/d****PC, DB (n = 7)**

**AC-052-351****250 mg/d****PC, DB (n = 32)**

**ENABLE****250 mg/d****PC, DB (n = 1613)**

**AC-052-353****250 mg/d****OL (n = 29)**

**AC-052-352****250/500 mg/d****PC, DB (n = 213)**

**Bosentan Therapeutic Studies****Safety Database**

**AC-052-354****250 mg/d****OL (n = 200)**

**9053.01**

## Subjects in the Database

**Pharmacology (23 studies)**
**Therapeutic trials**
**8 Placebo-controlled**
**3 Open-label (2 extensions)**
**ENABLE (blinded)**

**155**
**288**
**31**

**Placebo**

**Bosentan**

**434**
**677**
**91**

**1 : 1**

**All**

**571**
**965**
**122**
**1613**

**About 1522 bosentan-treated patients **
**Additional 62 PAH patients (ex-placebo) given****bosentan in AC-052-354**

**9054.01**

## Subjects in the Database8 Placebo-controlled Studies

**Indication [n (%)]****  ****PAH****  CHF****  HTN****  SAH****Treatment****  Placebo****  Bos 100 mg/d**
**  ****Bos 250-500 mg/d**
**  ****Bos 1000-1500 mg/d**
**  ****Bos 2000 mg/d**

**  ****(28.8)****(51.0)**** (17.0)**** (3.1)**
**(100)**

**  ****(25.0) **
**(43.3)****  (28.7)**** (3.1)**
**(7.4)**
**(31.6)**
**(45.8)**
**(15.2)**

**Placebo**** (N = 288)**

**Bosentan**** (N = 677)**

**  ****83  **
**147  ****  49**
**9**
**288**
**—**
**—**
**—**
**—**

**169  **
**293  ****194  ****  21**
**—**
**50**
**214**
**310**
**103**

**9055.01**

## Exposure to BosentanOverall and Placebo-controlled Studies

**11 Therapeutic Studies**

**1200**

**1000**

**800**

**600**

**400**

**200**

**0**

**Days**

**0**

**25**

**50**

**75**

**100**

**Percent of Patients**

**All bosentan doses (N = 715)**

**Mean (SD): 168 ******** 271 d**

**8 Placebo-controlled Studies**

**Days**

**Percent of Patients**

**4 weeks    526 (73.6%)****3 months   352 (49.2%)****6 months   141 (19.7%)****1 year          88 (12.3%)**
**3 years        28   (3.9%)**

**200**

**100**

**0**

**0**

**25**

**50**

**75**

**100**

**All bosentan doses (N = 677)**

**Placebo (N = 288)**

**Mean (SD):****    101 ******** 61 d**

**Mean (SD): 85 ******** 64 d**

**50**

**150**

**9056.01**

## Patient Demographics8 Placebo-controlled studies

**Age (years)**
**Weight (kg)**
**Race (% W:B:O)**
**US / Non-US (%)**

**Placebo**
**(N = 288)**

**57:43**
**57 ******** 14**
**77 ******** 15**
**90:4:7**
**32:68**

**61:39**
**57 ******** 13**
**78 ******** 17**
**89:6:6**
**28:72**

**Bosentan**
**(N = 677)**

- Percent or mean  SD

**Patient Demographics****8 Placebo-controlled studies**

**9057.01**

## Treatment-emergent AEs8 Placebo-controlled Studies

**Leg edema / edema**
**Abnormal hepatic func**
**Headache **
**Anemia**
**% with ******** 1 AE**

**Placebo**
**(N = 288)**

**1.7 **
**2.7**
**2.1 **
**12.8**
**1.0**
**76.4**

- With a placebo-subtracted difference of  2%

**6.6 **
**7.4**
**5.9**
**15.8**
**3.4**
**78.1**

**Bosentan**
**(N = 677)**

**4.9**
**4.6 **
**3.8**
**3.0**
**2.4**
**1.7**

**Placebo-subtracted**

**Treatment-emergent AEs****8**** ****Placebo-controlled Studies**

**9058.01**

## AEs of Specific Interest8 Placebo-controlled Studies

**Dyspnea**
**Aggravated PAH**
**Angina pectoris/****      chest pain**

**Syncope**
**Hypotension**
**Postural hypotension**
**Dizziness**

**All were more frequent among placebo-treated than bosentan-treated patients**

**Abdominal pain / nausea / vomiting**

**AEs of Specific Interest****8 Placebo-controlled Studies**

**9059.01**

## Worsening Heart Failure

**Starting dose (125 and 250 mg bid)**
**Speed of up-titration (weekly to 500 mg bid)**
**Overall incidence of hospitalization for HF was significantly lower with bosentan vs placebo **

**Placebo**

**Bosentan**

**Worsening Heart Failure**

**Overall incidence**

**64 (22.2%)   120 (17.7%)**
**60 (40.8%)   114 (38.9%) **

**PC studies (288/677)**
**CHF studies (147/293)**

**9060.01**

**REACH-1 (NC15462)**

## Most Frequent ( 5%) Treatment-emergent AEsAC-052-351 and AC-052-352

**Leg edema / edema **
**Flushing**
**Nasopharyngitis**
**Hypotension**
**% with ******** 1 AE**

**Placebo**
**(N = 80)**

**2.5**
**8.8**
**5.0**
**7.5**
**3.8**
**93.8**

-  With a placebo-subtracted difference of  2%

**8.5**
**13.9**
**9.1**
**10.9**
**6.7**
**94.5**

**Bosentan**
**(N = 165)**

**6.0**
**5.2**
**4.1**
**3.4**
**2.9**
**0.7**

**Placebo-subtracted**

**Most Frequent (******** 5%) Treatment-emergent AEs****AC-052-351 and AC-052-352**

**9061.01**

## Most Frequent ( 5%) Treatment-emergent AEsAC-052-351 and AC-052-352

**Cardiac failure**
**Dyspnea**
**Cough**
**Dizziness**

****** ****2% more frequent on placebo**

**Abdominal pain**
**Nausea/vomiting **
**Gastritis**
**Influenza**
**Limb pain**

**Most Frequent (******** 5%) Treatment-emergent AEs****AC-052-351 and AC-052-352**

**9062.01**

## AEs ( 1.0%) Leading to Withdrawal8 Placebo-controlled Studies

**Headache**
**Pts with ******** 1 AE**

**Placebo**
**(N = 288)**

**2 (0.7)**
**2 (0.7)**
**27 (9.4)**

**28 (4.1)**
**  ****8 (1.2)**
**75 (11.1)**

**Bosentan**
**(N = 677)**

**AEs (******** 1.0%) Leading to Withdrawal****8 Placebo-controlled Studies**

**9063.01**

## AEs Leading to WithdrawalAC-052-351 and AC-052-352

**(N = 80)**

**Bosentan**
**(N = 165)**

**Abnormal hepatic func [n (%)]**
**Aggravated PAH**
**Cardiac failure **
**Syncope**
**Pts with ******** 1 AE**

- Occurring in > 1 patient per treatment group

**3 (1.8)**
**2 (1.2)**
**2 (1.2)**
**0**
**9 (5.5)**

**0**
**6 (7.5)**
**1 (1.3)**
**2 (2.5)**
**  ****8 (10.0)**

**AEs Leading to Withdrawal****AC-052-351 and AC-052-352**

**9064.01**

## Reasons for Death ( 3 patients)8 Placebo-controlled Studies

**Sudden death**
**Cardiac arrest**
**Myocardial infarction**
**Total deaths**

**Placebo**
**(N = 288)**

**  ****1 (0.3)**
**  ****5 (1.7)**
**0**
**0**
**15 (5.2)**

**  ****6 (0.9)**
**  ****3 (0.4)**
**  ****3 (0.4)**
**  ****3 (0.4)**
**31 (4.6)**

**Bosentan**
**(N = 677)**

**Reasons for Death (******** 3 patients)****8 Placebo-controlled Studies**

**9065.01**

## Reasons for DeathAC-052-351 and AC-052-352

**Aggravated PHT**
**Pneumonia**
**Pulmonary hemorrhage**
**Sepsis**
**Total deaths**

**Placebo**
**(N = 80)**

**0**
**2 (2.5)**
**0**
**0**
**0**
**2 (2.5)**

**2 (1.2)**
**0**
**1 (0.6)**
**1 (0.6)**
**1 (0.6)**
**4 (2.4)**

**Bosentan**
**(N = 165)**

- All deaths occurring during the study or within 28 days of treatment end

**Reasons for Death****AC-052-351 and AC-052-352**

**9066.01**

## Vital Signs

**   ****Pulse rate (bpm)**
**   ****SBP (mmHg)**
**   ****DBP (mmHg)****Incidence**
**  ****SBP < 80 mmHg**
**  ****AE hypotension**

**Bosentan****(N = 677)**

******1.0 ******** 1.1**
******4.2 ******** 1.4**
** ********3.3 ******** 1.0**

**Bosentan****(N = 165)**

- Mean change  SEM or percent

**Placebo****(N = 80)**

** **
**0.2 ******** 0.5**
**3.1 ******** 0.7**
**3.0 ******** 0.4**** **

**Placebo****(N = 288)**

** **
**0.3 ******** 0.7**
******2.4 ******** 1.0**
** ********0.4 ******** 0.7**

**PC Studies**

**AC-052-351 + 352**

** **
**3.3 ******** 1.5**
******3.8 ******** 1.8**
** ****0.7 ******** 1.2**

**Vital Signs**

** **
**2.8%**
**7.6%**

** **
**0.8%**
**6.8%**

** **
**0**
**3.8%**

** **
**0.6%**
**6.7%**

**9067.01**

## Evidence for Rebound?

**Experience limited to 22 PAH patients **
**5 pts had treatment discontinued after dose reduction**
**7 pts had treatment interrupted for 2-14 days**
**10 pts had open-label treatment discontinued **
**PAH-related adverse experiences**
**1 pt with aggravated PAH (29 days after d/c)**
**No evidence in hypertensive or CHF patients**

**9068.01**

## Outcomes in PAH Patients Started on Epoprostenol

**Outcomes in PAH Patients Started on Epoprostenol**

**Ex-placebo****n = 8**

**5 pts improved**
**1 death**
**2 pts worse**

**Concomitant bosentan****n = 6**

**Ex-bosentan****n = 8**

**5 pts improved**
**2 deaths**
**1 pt worse**

**5 pts improved**
**1 death**

**9071.01**

## Long-term ExperienceOpen-label Extension Study AC-052-353

**29 patients:  21 of 21 ex-bosentan****                        8 of 11 ex-placebo**
**485 ******** 97 days (range 105 – 595 days)**
**28 patients with ******** 1 year ****  7 patients with ******** 1.5 years**
**Outcomes:**
**No deaths**
**1 d/c for worsening PAH (epoprostenol)**
**4 patients up-titrated to 250 mg bid****(after 348 – 548 days of treatment)**

**Long-term Experience****Open-label Extension Study AC-052-353**

**9069.01**

## Long-term ExperienceOpen-label Extension Study AC-052-354

**Overall exposure to bosentan**
**200 patients: 138 of 144 ex-bosentan ****                         62 of 69 ex-placebo **
**171 ******** 73 days (range 25 – 321 days)**
**100 patients with ******** 6 months****  13 patients with ******** 9 months**
**Outcomes:**
**2 deaths (pulmonary hemorrhage)**
**2 d/c for worsening PAH (epoprostenol)**
**6 d/c for elevated ALT/AST**
**4 d/c for AE/administrative reasons**

**9070.01**

## Overall ExposurePAH Patients

**0**

**Overall Exposure****PAH Patients**

**90**

**180**

**270**

**40**

**0**

- May 31, 2001 cut off

**360**

**540**

**630**

**100**

**60**

**Days**

**80**

**Percent of Patients**

**20**

**450**

**Bosentan**

**>  3 months    191 (81.3%)****>  6 months    128 (54.5%)****>  9 months      41 (17.4%)****>12 months      28 (11.9%)**
**>18 months      12   (5.1%)**

**137.2 patient-years**

**N = 235**

**9072.01**

## SurvivalAC-052-351, AC-052-352 and OL Extensions

**0**

**Survival****AC-052-351, AC-052-352 and OL Extensions**

**0.25**

**0.5**

**0.75**

**85**

**0**

**1.0**

**1.25**

**1.5**

**100**

**90**

**Years**

**95**

**Percent Survivors**

**235**

**190**

**125**

**40**

**29**

**21**

**10**

**At risk:**

**9074.01**

## Additional Safety Observations

**No relevant changes in ECG parameters****or treatment-emergent ECG findings **
**No relevant changes in laboratory tests except:**
**Decreases in RBC parameters **
**Increases in liver enzymes**

**Additional Safety Observations**

**9075.01**

## Decreases in Hemoglobin Concentration

**9076.01**

## Preclinical ObservationsDecreases in Hemoglobin

**Mild (7–13%) decreases in Hb concentration****in rats and dogs**
**No evidence for:**
**Hemolysis or immuno-allergic reaction**
**Bone marrow toxicity**
**Bleeding**
**Evidence for increased plasma volume****with hemodilution in rats**

**9077.01**

## Incidence of Decreased Hb Conc8 Placebo-controlled Studies

**  ****Chg to end of treatment**
**  ****Chg to lowest value**** **
**% of Patients with**
**  ****Decrease of ******** 1.0 g/dl**
**  ****Value < LLN**
**  ****Marked decrease (LL)**
**  ****LL and < 10.0 g/dl**

******0.78**
******0.77 **
**27.8**
**  ****7.5**
**  ****3.1**
**  ****0**

******0.14**
******0.55**
**29.0**
**24.4**
**  ****2.6**
**  ****2.2**

**Placebo**
**(N = 269)**

******0.92**
******1.32**
**  ****56.8**
**  ****32.0**
**    ****5.6**
**    ****2.2**

**Bosentan**
**(N = 618)**

**Incidence of Decreased Hb Conc****8 Placebo-controlled Studies**

**Placebo-subtracted**

-  LL = < 11.0 g/dl and >15% decrease from baseline

**9078.01**

## Incidence of Decreased Hb ConcAC-052-351 and AC-052-352

**  ****Chg to end of treatment**
**  ****Chg to lowest value**** **
**% of Patients with**
**  ****Decrease of ******** 1.0 g/dl**
**  ****Value < LLN**
**  ****Marked decrease (LL)**
**  ****LL and < 10.0 g/dl**

******0.96**
******1.09 **
**34.8**
**13.8**
**  ****1.8**
**  ****1.2**

**  ****0.01**
******0.48**
**30.4**
**  ****8.9**
**  ****1.3**
**  ****1.3**

**Placebo**
**(N = 79)**

**Placebo-subtracted**

******0.96**
******1.57**
**  ****65.2**
**  ****22.7**
**    ****3.0**
**    ****2.4**

**Bosentan**
**(N = 161)**

**Incidence of Decreased Hb Conc****AC-052-351 and AC-052-352**

-  LL = < 11.0 g/dl and >15% decrease from baseline

**9079.01**

## Incidence of Decreased Hb ConcPlacebo-corrected Incidence

**  ****Chg to end of treatment**
**  ****Chg to lowest value**** **
**% of Patients with**
**  ****Decrease of ******** 1.0 g/dl**
**  ****Value < LLN**
**  ****Marked decrease (LL)**
**  ****LL and < 10.0 g/dl**

******1.02**
******1.12 **
**35.5**
**14.6**
**  ****2.3**
**  ****1.1**

******0.41**
******0.44**
**14.0**
**  ****3.2**
**  ****0**
**  ****0**

**HTN**
**(N = 231)**

**PAH****(N = 248)**

******0.91**
******0.87**
**  ****36.5**
**  ****13.5**
**    ****5.0**
**  ********0.3**

**CHF**
**(N = 405)**

**Incidence of Decreased Hb Conc****Placebo-corrected Incidence**

-  LL = < 11.0 g/dl and >15% decrease from baseline

**9080.01**

## Among PAH Patients with Anemia

**No evidence for increase in bilirubin**
**No associated decrease in WBCs or platelets**
**No increase in eosinophils above the ULN**
**No premature withdrawal due to anemia**
**Blood transfusions in 4 patients (2.4%)**
**1 epistaxis, 2 GI bleeding, and 1 anemia**
**All 8 PC studies:**

**1.8% on bosentan**
**1.0% on placebo**

**9081.01**

## Time to OccurrenceDecreases in Hemoglobin

**8**

**0**

**16**

**24**

**32**

**Weeks**

**Percent of Patients at Risk**

**Marked decrease**
**(   ********15% and **<** 11 g/dl)**

**Marked decrease**
**(   ********15% and **<** 10 g/dl)**

**Decrease of ******** 1 g/dl**

- Bosentan (N = 636)
- Placebo   (N = 271)

**20**

**10**

**0**

**20**

**10**

**0**

**0**

**100**

**50**

**8 Placebo-controlled Studies**

**9082.01**

## Change in Hb ConcentrationNC15462 and NC15464B

**Change in Hb Concentration****NC15462 and NC15464B**

**Change from Baseline****Hb (g/dl)**

**Bosentan (n = 29)****    500 mg bid**
**Placebo (n = 7)**

**BL**

**3**

**4**

**12**

**26**

**BL**

**12**

**Weeks**

**Weeks**

- Median and 25th and 75th percentiles

**Bosentan (n = 29)**
**Bosentan (n = 7)****   125 mg bid**

**NC15462 (REACH-1)**

**NC15464B (open label)**

**9083.01**

## Change in Hb ConcentrationAC-052-352

**Change in Hb Concentration****AC-052-352**

**BL**

**4**

**16**

- Median and 25th and 75th percentiles

**8**

**12**

**Weeks**

**Bosentan (n = 120)****  125 mg bid**
**Placebo (n = 53)**

**Change from Baseline****Hb (g/dl)**

**9084.01**

## Unlikely ReasonsDecrease in Hemoglobin

**Hemolysis:**
**No increase in bilirubin**
**No increase in reticulocytes or MCV**
**Bone marrow toxicity:**
**No concomitant marked decreases in WBC or platelet counts**
**Normal bone marrow evaluations (2 cases)**
**Bleeding tendency:**
**No evidence for bleeding in most cases**

**9085.01**

## Possible MechanismsDecrease in Hemoglobin

**Hemodilution / fluid shift**
**Preclinical evidence for increased plasma volume**
**Compatible with clinical picture**
**Compatible with mechanism of action**
**Vasodilation**
**Decreased capillary permeability**
**Decrease in elevated erythropoetin levels**

**9086.01**

## Risk ManagementDecrease in Hemoglobin

**Hb concentration should be evaluated****after 1 and 3 months of treatment and quarterly thereafter**
**Cases of marked decrease in Hb concentration should be further evaluated and/or treated,****based on clinical judgment**

**Risk Management****Decrease in Hemoglobin**

**9087.01**

## Increases inLiver Aminotransferases

**9088.01**

## Preclinical Observations

**Evidence for cholestasis**
**Increase in plasma bile salts and alk phos**
**No evidence for:**
**Reactive or toxic metabolites **
**Immuno-allergic reaction **
**Centrolobular necrosis**
**Mitochondrial toxicity**
**Competitive inhibition of bile salt excretion****(Bsep), which can lead to accumulation****of bile salts and hepatocellular lysis**

**9089.01**

## Elevated ALT/AST > 3 x ULN by DoseSafety Database

**PAH (%) **
**CHF **
**HTN **
**All **

** —**
**  ****4.2**
**10.0**
**  ****6.9**

**—**
**15.8**
**11.4**
**14.5**

**12.7**
** ****13.8**
**6.9**
**11.2**

**All**

**250/500**

**1000/1500**

**12.7**
** —**
**  ****4.3**
**10.9**

**100 **

**—**
**—**
**2.1**
**2.1**

**Bosentan Dose (mg/d)**

- Incidence on placebo was approximately 2%

**Elevated ALT/AST > 3 x ULN by Dose****Safety Database**

**Database **

**9090.01**

## Severity of Elevated ALT/ASTSafety Database

**PAH (N = 165) **
**Others (N = 493)**
**All (N = 658)**
**ENABLE (N ******** 807)***

**4.2**
**3.9**
**4.0**
**2.8**

**1.8**
** ****3.2**
**2.9**
**2.0**

**12.7**
** ****10.8**
**11.2**
**8.6**

- >**3 - **<** 5**

- **5 - **<** 8**

**6.7**
** ****3.7**
**4.4**
**3.8**

- * Percentages assume all events occur on bosentan, as data are still blinded

**ALT / AST (x ULN)**

**Severity of Elevated ALT/AST****Safety Database**

**All**

**Database (%) **

**9091.01**

## Elevated AminotransferasesAC-052-351 and AC-052-352

**125****(N = 95)**

**AE abn hepatic func [n (%)]**
**ALT/AST > 3 x ULN**
**ALT/AST > 8 x ULN**
**Transient cases****   ****At target dose****   With dose reduction**
**Discontinued**
**   **

**10 (14.3)**
**10 (14.3)**
**  ****5   (7.1)**
**4****2****2**
**3**

** ****4   (4.2)**
**11 (11.6)**
**  ****2   (2.1)**
**8****7****1**
**0**

**250****(N = 70)**

**Elevated Aminotransferases****AC-052-351 and AC-052-352**

**9092.01**

## Time CourseElevated Aminotransferases

**Gradual over several weeks**
**Normalized or reduced to < 2 x ULN during continued treatment (transient)**
**70% (8/11) with bosentan 125 mg bid (PAH)**
**40% (4/10) with bosentan 250 mg bid (PAH)**
**16% (6/38) with bosentan 500 mg bid (CHF)**
**Complete resolution after treatment cessation**

**9093.01**

## Time to ResolutionALT/AST Returned to Baseline or < 2 x ULN

**AC-052-354**
**ENABLE **

**  ****3 – 64**
**18 – 56**
**10 – 44**

**Range****(days)**

**33**
**  ****6**
**23**

**Number****of cases**

**26 ******** 13**
**32 ******** 13**
**23 ******** 10**

**Mean ******** SD****(days)**

- Time following treatment end depended on time of evaluation

**97% of elevations were resolved within 8 weeks**

**Time to Resolution****ALT/AST Returned to Baseline or < 2 x ULN**

**9094.01**

## Predisposing FactorsIncidence of Elevated ALT/AST > 3 x ULN

**ALT/AST > 3 x ULN**

**No effect of age or gender**

**With ****Factor**

**W/o**** Factor**

**Predisposing factor**

**ALT/AST > ULN at BL****   (n = 133, 521)**
**Alk phos > ULN at BL****   (n = 83, 572)**
**Concomitant glibenclamide****   (n = 31, 213)**

**   ****10.0%**
**  ****11.4%**
**   ****13.3%**

**   ****16.5%**
**  ****10.8%**
**   ****27.5%**

**9095.01**

## Time to First OccurrenceElevated Liver Aminotransferases

**Time to First Occurrence****Elevated Liver Aminotransferases**

**Percent of Patients at Risk**

**Bosentan**
**Placebo**

**40**

**20**

**0**

**0**

**40**

**20**

** ****8 Placebo-controlled****Studies**

**AC-052-352**

**Bosentan**
**Placebo**

**8**

**0**

**16**

**24**

**32**

**Weeks**

**(N = 144) **
**(N = 68)**

**(N = 658) **
**(N = 280)**

**9096.01**

## Time to First OccurrenceElevated Liver Aminotransferases

**0**

**Time to First Occurrence****Elevated Liver Aminotransferases**

**12**

**24**

**36**

**48**

**20**

**10**

**0**

**Bosentan**

**(N ******** 807) **

**69 cases (8.6%)****assuming all on bosentan**

**60**

**72**

**84**

**96**

**40**

**30**

**Week**

**ENABLE**

**Percent of Patients at Risk**

**9097.01**

## Associated SymptomsElevated Liver Aminotransferases

**Pts with symptoms**
**   ****Nausea/vomiting (n)**
**   ****Abdominal pain**
**   ****Fever**
**   ****Jaundice/bili > 3xULN**

-  *Assuming all cases on bosentan

**  ****9 / 74**
**  ****3**
**  ****2**
**  ****4**
**  ****1**

**PC Studies**
**(N = 677)**

**2 / 5**
**2**
**1**
**0**
**1 **

**OL Studies**
**(N = 122)**

**11 / 69**
**4**
**6**
**2**
**1 **

**ENABLE**
**(N = 807*)**

**9098.01**

## Type of Liver InjuryCouncil for Intl Org of Medical Science

**Cholestatic       ****(****ratio ******** 2****)**
**Hepatocellular  ****(****ratio ******** 5)**
**Mixed              ****(****ratio **>**2, **<** 5)**

**Type of Injury**

**Ratio =**

- * The ULN, respectively

**ALT / 30 U/L***

**Alk Phos / 95 U/L***

**9099.01**

## Type of Liver InjuryCouncil for Intl Org of Medical Science

**Total number (%) of cases**
**Cholestatic       ****(****ratio ******** 2****)**
**Hepatocellular  ****(****ratio ******** 5)**
**Mixed              ****(****ratio **>**2, **<** 5)**

**   ****67 (100)**
**     ****3   (4.5)**
**   ****25 (37.3)**
**   ****39 (58.2)**

**ENABLE****(N = 807****†****)**

**  ****74 (100)**
**     ****7   (9.5)**
**   ****34 (45.9)**
**   ****33 (44.6)**

**PC Studies****(N = 658)**

**Type of Injury**

- * The ULN, respectively
**† **Assuming all cases are on bosentan

**ALT / 30 U/L***

**Alk Phos / 95 U/L***

**Ratio =**

**9100.01**

## MechanismElevated Aminotransferases

**Not yet fully elucidated**
**Competitive inhibition of bile salt excretion may be a contributory factor**
**No evidence for immuno-allergic reaction **
**During treatment**
**At reintroduction**

**9101.01**

## Risk AssessmentHyman Zimmerman’s Suggestions

**Increased risk of acute liver failure in patients****with predominantly hepatocellular disease:**
**ALT/AST > 3 x ULN**
**Clinical jaundice (bilirubin > 3 x ULN)**
**May be associated with small changes****in alkaline phosphatase**
**Estimated that 10% of patients who have drug-****induced liver injury will develop acute liver failure**

**9102.01**

## Long-term Exposureto Bosentan

**Pts (%) treated**
**  ****>  3 months**
**  ****>  6 months**
**  ****>  9 months**
**  ****>12 months**
**  ****>18 months**
**  ****>24 months**

**PAH Studies**
**(N = 235)**

**0.58 ******** 0.37**** **** **
**(0.07 – 1.71)**

**0.87 ******** 1.16**
**(0 – 4.11)**
**183 (68.5)**
**  ****95 (35.6)**
**  ****71 (26.6)**
**  ****61 (22.8)**
**  ****49 (18.4)**
**  ****39 (14.6)**

**NC15462****NC15464B**
**(N = 267)**

**1.13 ******** 0.48**
**(0 – 1.93)**
**1483 (91.9)**
**1386 (85.9)**
**1316 (81.6)**
**1079 (66.9)**
**  ****412 (25.5)**
**—**

**ENABLE*****(N = 1613)**

**Long-term Exposure****to Bosentan**

**191 (81.3)**
**128 (54.5)**
**  ****41 (17.4)**
**  ****28 (11.9)**
**12   (5.1)**

**  **
**  **
**—**

- * Treatment still blinded; about half on bosentan

**9512.01**

## Risk Assessment with Bosentan

**Among the 1522 bosentan-treated patients:**
**No cases of acute liver failure **
**3 pts have had ALT/AST and bilirubin > 3 x ULN****and also had alk phosphatase 2-3 x ULN**
**1 in AC-052-352 (250 mg bid)**
**1 in NC15464B (open-label 125 mg bid)**
**1 in ENABLE (blinded treatment)**
**All 3 had complete resolution within 24-64 days****of treatment cessation (based on evaluation date)**

**9103.01**

## Clinical PictureElevated Aminotransferases

**Overall incidence of 11.2%**
**Incidence and severity are dose related**
**Onset mainly during the first 16 weeks****of treatment**
**Gradual increase over several weeks**
**Transient in 50% of cases**

**9104.01**

## Clinical PictureElevated Aminotransferases

**Typically asymptomatic**
**Associated with elevated alkaline phosphatase****in about 50% of cases**
**Infrequently associated with elevated bilirubin****(> 3 x ULN)**
**Rapid and complete resolution with treatment cessation**
**No evidence for continued liver injury**

**9105.01**

## Is the Risk of Increased Liver Aminotransferases Manageable?

**PAH patients are very compliant and have****a close relationship with their physicians **
**Recommendations:**
**Monthly monitoring for first 6 months and quarterly thereafter**
**Monitoring can be incorporated into the routine management of these patients (INR/chemistries)**

**9106.01**

## Is the Risk of Increased Liver Aminotransferases Manageable?

**Guidelines for treatment modification**
**Reduce or interrupt treatment:****ALT/AST > 3 and < 5 x ULN**
**Stop treatment: ALT/AST > 5 x ULN, or increase in ALT/AST associated with symptoms of liver injury, or bilirubin****> 3 x ULN**
**Education of physicians, nurses, pharmacists**
**Information to patients, directly via drug distribution and through patient organizations **

**Is the Risk of Increased Liver Aminotransferases Manageable?**

**9107.01**

## Recommended Dosages

**Target dose:**

**No dose adjustment needed for most subgroups**
**Not recommended for:**
**Pts with moderate to severe liver impairment**
**Pts with ALT/AST > 3 x ULN at baseline**
**Pts on glibenclamide or cyclosporin A**
**Pregnant women**

**Recommended Dosages**

**9108.01**

**bosentan 125 mg bid**

## Overall Summary

**Improvement in all clinical and hemodynamic efficacy measures**
**Reduction in risk of clinical worsening**
**Good tolerability**
**Potential risks related to:**
**Modest decrease in Hb concentration**
**Increase incidence of elevated liver enzymes**
**   ****Both can be managed by appropriate monitoring ****   and education**

**Overall Summary**

**9109.01**

## Risk Related to Elevated Liver Aminotransferases

**Willis C Maddrey, MD**
**Executive VP for Clinical Affairs **
**UT Southwestern Medical Center****   and Aston Ambulatory Care Ctr **

**9110.01**

## Signals of Drug-induced Hepatotoxicity

**Major:              Development of acute liver failure****                         Onset of clinically apparent jaundice****                         Appearance of ascites, encephalopathy, ****                         coagulopathy **
**Intermediate:  ALT > 8 x ULN****                         ALT > 5 x ULN****                         ALT > 3 x ULN**
**Minor:              Any elevation in ALT (< 3 x ULN)****                         in an asymptomatic patient**

**9111.01**

## Relevance of Elevated Liver Aminotranferases

**Inexact correlations with injury **
**Important role of associated signs and symptoms**
**> 3 x ULN    equal to inflammation on liver biopsy**
**> 5 x ULN    triggers considerably heightened ****                     awareness and follow-up (treatment ****                     withdrawal should be considered)**
**Drugs associated with liver injury tend to have****a signature pattern**

**9112.01**

## Drug-induced Hepatocellular JaundiceZimmerman Observations / Rule

**In patients with drug-induced hepatoxicity who****have elevated aminotransferase levels (> 3 x ULN),****clinical jaundice (bilirubin > 3 mg/dl), and a****relatively little change in alkaline phosphatase,****there is an approximately 10% mortality rate.**
**Drugs studied:**

**Isoniazid****	****	****~10%**
**Methyldopa****	****~10%**
**Tienilic acid****	****~10%**

**9114.01**

## Bosentan-induced Hepatotoxicity

**Injury – hepatocellular or mixed**
**Incidence of elevated ALT/AST**
**11.2% with > 3 x ULN**
**  ****0.6% with > 20 x ULN**
**Onset usually (> 90%) within 16 weeks**
**All elevations resolved upon drug withdrawal****(97% within 8 weeks) **
**No cases of acute liver failure**

**9115.01**

## Risk ReductionBosentan Monitoring Guidelines

**Determination of biochemical tests of liver:**
**Pretreatment**
**Monthly for 6 months**
**Quarterly thereafter**
**Discontinue treatment if:**
**ALT/AST > 5 x ULN**
**Increased ALT/AST is associated****with symptoms of liver injury**

**9116.01**

**9117.01**

## Risks vs. Benefits

**Lewis J Rubin, MD****Professor of Medicine****Director of Pulmonary****   and Critical Care Medicine**
**Univ of California, San Diego**

**9118.01**

## Benefits of Bosentan Treatment 

**Treatment with oral bosentan is associated with:**
**Improvement in 6-min walk test**
**Improvement in dyspnea score during exercise**
**Improvement in WHO functional class**
**Delay in time to clinical worsening**
**Improvement in hemodynamic parameters**
**Maintenance of treatment effect, with no evidence for tolerance**

**9123.01**

## Risks with Bosentan Treatment

**Treatment with bosentan is associated with:**
**Decreases in hemoglobin concentration**
**Increased incidence of elevated liver aminotransferases**

**9125.01**

## Elevated Liver Aminotransferases

**Have been characterized**
**Have been quantified**
**Incidence**
**Degree of severity**
**Can be monitored****within PAH treatment paradigm**

**9126.01**

## Risks / Benefits Conclusion

**Treatment with bosentan produces clinically meaningful benefits that substantially outweigh its characterized risks. **
**Oral bosentan fulfills an unmet medical need in patients with PAH.  **

**9128.01**