CENTER FOR DRUG EVALUATION AND
`RESEARCH
`
`APPLICA TION NUMBER.-
`
`22-387
`
`PHARMACOLOGY REVIEW! S)
`
`

`

`PHARMACOLOGY/TOXICOLOGY REVIEW AND EVALUATION
`
`NDA NUMBER:
`
`22—387
`
`DATE RECEIVED BY CENTER:
`
`6/3 0/2008
`
`PRODUCT:
`
`INTENDED CLINICAL POPULATION:
`
`TyvasoTM (treprostinil sodium) Inhalation
`Solution (0.6 mg/ml)
`
`Pulmonary arterial hypertension (PAH)
`patients with NYHA Class III r.‘
`symptoms
`
`31(4)
`
`SPONSOR:
`
`REVIEW DIVISION:
`
`United Therapeutics Corporation,
`. Research Triangle Park, NC 27709
`
`Division of Cardiovascular and Renal
`Products
`
`PHARM/TOX REVIEWER:
`
`Xavier Joseph
`
`PHARM/TOX SUPERVISOR:
`
`Charles A. Resnick
`
`DIVISION DIRECTOR:
`
`Norman Stockbridge
`
`PROJECT MANAGER:
`
`Dan Brum
`
`

`

`NDA 22—387
`
`2
`
`REVIEW AND EVALUATION OF PHARMACOLOGY
`AND TOXICOLOGY DATA
`
`Xavier Joseph, D.V.M.
`March 23, 2009
`
`ORIGINAL NDA DATED: June 26, 2008
`CENTER RECEIPT DATE: June 30, 2008
`REVIEWER RECEIPT DATE: July 7, 2008
`
`SPONSOR: United Therapeutics Corporation
`One Park Drive
`
`Research Triangle Park, NC 27709
`
`DRUG PRODUCT:
`
`Trade name - TyvasoTM Inhalation Solution
`
`DRUG SUBSTANCE: Generic name — treprostinil sodium
`Code names — UT-15, LRX-IS and 15AU81
`
`Chemical Structure
`
`.0“.
`
`
`
`
`Cl'iHHOS
`Moi. Wt: 390.52
`
`1:: mo};
`
`FORMULATION: TyvasoTM Inhalation Solution contains 0.6 mg treprostinil/ml,
`sodium chloride, sodium citrate (dihydrate), 1N hydrochloric acid, sodium hydroxide and
`water for injection. (1N sodium hydroxide is used for adjusting the pH of the product.)
`The sodium salt of treprostinil, the active ingredient, is formed during the drug product
`
`manufacturing procedure. Treprostinil inhalation solution (2.9 ml) is
`7
`‘
`'
`’1 packaged into
`f...
`ampoules.
`[Remodulin® (treprostinil sodium)
`Injection, the marketed product, has the same formulation as Tyvaso except for the
`
`
`hm)
`
`MODE OF ADMINISTRATION: Tyvaso is administered by oral inhalation using an
`Optineb-ir ultrasonic, pulsed delivery nebulizer; each pulse of Tyvaso contains 6 pg of
`treprostinil.
`
`

`

`NDA 22-387
`
`3
`
`PHARMACOLOGICAL CLASS: Prostacyclin (PGIz) analogue (vasodilator)
`
`PROPOSED INDICATIONS: For the treatment of pulmonary arterial hypertension
`(PAH)1n patients with NYHA Class III * symptoms
`
`33(4)
`
`PROPOSED DOSAGE REGIMEN: Treatment should be started with 3 breaths (18 pg
`of treprostinil) per treatment session given 4 times daily. If 3 breaths are not tolerated, the
`dose may be reduced to 1 or 2 breaths and later increased to 3 breaths as tolerated. The
`dosage should be increased to 6 breaths and subsequently to the target maintenance dose
`of 9 breaths (54 ug of treprostinil) per inhalation session given 4 times daily, as tolerated.
`The maximum dose studied in clinical trials was 12 breaths (72 pg of treprostinil) per
`inhalation session.
`
`IND UNDER WHICH CLINICAL TRIALS WERE CONDUCTED: IND 70,362 (for
`inhalation therapy of PAH patients)
`
`RELATED NDAs: United Therapeutics’ NDA 21-272 — Remodulin for the 30 treatment
`of PAH patients, and United Therapeutics’ NDA 21-272 SE3 — Remodulin for the iv
`treatment of PAH patients.
`
`

`

`NDA 22-387
`
`4
`
`EXECUTIVE SUMMARY
`
`TyvasoTM (treprostinil sodium for inhalation), a chemically stable tricyclic benzindene
`analogue of prostacyclin (PGIZ), with potent systemic and pulmonary vasodilatory as well
`as platelet antiaggregatory effects,
`is being developed for inhalation treatment of
`pulmonary arterial hypertension (PAH) patients. An injectable formulation of treprostinil
`sodium has been approved for marketing (Remodulin®) for the treatment of PAH patients
`either by continuous subcutaneous (so) or intravenous (iv) routes. Infusion site pain and
`reactions, and catheter—related infection or sepsis were reported to be the most common
`adverse events among patients treated 50 or iv with treprostinil. With inhalation therapy,
`by directly applying the drug at the primary site of manifestation of the condition, the
`adverse effects associated with sc or iv infusion can be avoided.
`
`1. Recommendations
`
`A. Recommendation on Approvability
`
`TyvasoTM is approvable from a nonclinical perspective.
`
`B. Recommendations for Additional Nonclinical Studies
`
`None
`
`C. Recommendations for Labeling
`
`l. Sponsor’s proposed text under section 8. USE IN SPECIFIC POPULATION, 8.1‘
`Pregnancy presently read as follows:
`
`Wax/r-
`
`33(4)
`
`We recommend that the above text be revised to read as follows:
`
`hi4}
`
`

`

`NDA 22-387
`
`5
`
`M4}
`
`M
`
`section 13. NONCLINICAL TOXICOLOGY, 13.1 Carcinogenesis,
`2. Under
`Mutagenesis, Impairment of Fertility, sponsor’s proposed text presently reads as
`follows:
`
`~24-.‘a.uum¢.ravob.wzw.Mm
`
`bid}
`
`“ ""' ""“"“c r -.._ '” ' “""'" " "‘ “"‘"" "' "" " " 'V"" r"‘" " "”"““D “'”" D"""""‘“ “”J "
`
`We recommend that the above text be revised to read as follows and to add a new
`
`section 13.3 on Developmental Toxicology.
`
`Long-term studies have not been performed to evaluate the carcinogenic potential of
`treprostinil. In vitro and in vivo genetic toxicology studies did not demonstrate any
`mutagenic or clastogenic effects of treprostinil. Treprostinil sodium did not ajfectfertility
`or mating performance of male or female rats given continuous subcutaneous (sc)
`infusions at rates of up to 450 ng treprostinil/kg/min [about 59 times the recommended
`starting human sc infusion rate (1.25 ng/kg/min) and 8 times the average rate (9.3
`ng/kg/min) achieved in clinical trials, on a ng/mZ basis.] In this study, males were dosed
`fiom 8 weeks prior to mating and through the 2-week mating period. Females were dosed
`from 2 weeks prior to mating until gestational day 6.
`
`13.3 Developmental Toxicity
`
`In pregnant rats, continuous sc infusions of treprostinil sodium during organogenesis
`and late gestational development, at rates as high as 900 ng treprostinil/kg/min (about
`117 times the recommended starting human sc infusion rate and about 16 times the
`average rate achieved in clinical trials, on a ng/m2 basis), resulted in no evidence of
`harm to the fetus. In pregnant rabbits, efi’ects of continuous sc infusions of treprostinil
`during organogenesis were limited to an increased incidence offetal skeletal variations
`(bilateralfull rib or right rudimentary rib on lumbar 1) associated with maternal toxicity
`(reduction in body weight and food consumption) at an infusion rate of 150 ng
`treprostinil/kg/min (about 41 times the starting human dose rate for sc infusion and 5
`times the average rate used in clinical trials, on a ng/mz basis).
`
`

`

`NDA 22-387
`
`’
`
`6
`
`II. Summary of Nonclinical Findings
`
`Nonclinical studies conducted with treprostinil were reviewed under NDA 21 —272 for
`Remodulin® Injection. The sponsor is referencing the above NDA for the support of the
`present NDA for Tyvaso Additional nonclinical studies conducted with treprostinil,
`including safety pharmacology studies (hERG assay, cardiac action potential assay in
`rabbit Purkinje fibers and in viva cardiovascular and respiratory studies) and repeat-dose
`inhalation toxicity studies in rats and dogs are included in this Tyvaso NDA and are
`reviewed below.
`
`treprostinil was tested (at different concentrations) to
`In the in vitro hERG assay,
`determine its potential for the inhibition of hERG-mediated In current (the most common
`cause of increased cardiac action potential duration that could lead to QT interval
`prolongation and fatal ventricular arrhythmias in animals and humans) in cultured human
`embryonic kidney cells. Treprostinil did not
`inhibit hERG-mediated current at
`concentrations up to 100 11M (39,052 ng/ml), while terfenadine, the positive control, at
`60 nM, inhibited hERG current by 85%.
`
`The in vitro effects of treprostinil on cardiac action potential duration were determined in
`isolated rabbit Purkinje fibers. Treprostinil did not prolong action potential duration at
`concentrations up to 300 1.1M (117,156 ng/ml), whi1e the positive control dl-sotalol, at 50
`11M, significantly prolonged the action potential duration. (The Cmax value in patients
`receiving Tyvaso at the maximum recommended dose is 1.8 ng/ml.)
`
`Female beagle dogs were given single iv bolus injections of treprostinil sodium solution
`at dose levels of 0, 2, 20 or 200 ug/kg and cardiovascular parameters were evaluated.
`Treprostinil caused an initial drop in arterial blood pressure and a compensatory increase
`of heart rates at all dose levels during the first hour after dosing. The initial drop in
`arterial blood pressure was followed by a period (up to 6 hours) of elevated systolic,
`diastolic and mean blood pressure at the 200 ug/kg dose level. Increased incidences of
`atrioventricular block were observed in 1 of 4 dogs at 2 pig/kg and in l of 4 dogs at 200
`pg/kg; however, PR interval was not affected. Treprostinil did not affect QT interval at
`any dose level.
`
`.
`
`In a study to evaluate potential effects on respiratory function, nebulized treprostinil
`sodium was administered to groups of male rats, via nose-only inhalation, at an aerosol
`concentration of about-50 ug/L for 2, 3 or 4 hours. Treprostinil, at achieved inhaled dose
`levels of 300, 416 and 569 pig/kg, produced significant decreases in respiratory rates and
`derived minute volumes compared to predose and control values. All values returned to
`predose and control levels 24 hours following treatment.
`
`In a 13-week inhalation toxicity study, groups of rats were exposed, by nose only
`administration, to aerosol concentrations of 7.1 ug/L for 20 minutes/day, 44.0 ug/L for
`30 minutes/day, and 40.3 ug/L for 225 minutes/day, resulting in estimated achieved dose
`levels of 7, 67 and 464 ug/kg/day, respectively. Control animals were exposed to
`conditioned room air for the same duration as the high dose animals. At the termination
`
`

`

`NDA 22-387
`
`7
`
`of the study, there were reductions in body weight gain at all dose levels [17 - 65%
`(dose-dependent) in males and 22 - 23% in females]. Other treatment-related findings
`included decreased food consumption (mid and high dose groups), decreased platelet,
`white cell and lymphocyte counts (high dose males), increased reticulocyte counts (high
`dose males and females), increased adrenal and lung weights and decreased testis and
`thymus weights (mid and high dose groups).
`
`Microscopically, lesions observed in the respiratory tract included squamous metaplasia
`in
`the
`larynx,
`hemorrhage
`and macrophage
`accumulation
`in
`the
`lung
`and
`hyperplasia/hypertrophy of goblet cells
`in the nasal
`cavity (all dose groups);
`degeneration/regeneration of the respiratory epithelium in the nasal cavity. (mid and high
`dose groups); and respiratory epithelium ulceration and olfactory epithelium degeneration
`in the nasal cavity (high dose). Other histopathological findings included myocardial
`degeneration/fibrosis in the heart and degeneration of seminiferous epithelium in the
`testis (all treated groups); oligo/aspermia in the epididymis and cortical hypertrophy in
`the adrenals (mid and high dose groups); and vacuolation of the zona glomerulosa in the
`adrenals (high dose). Treatment-related microscopic findings were still present in the
`adrenals, heart, testis, larynx, lung and nasal cavity of high dose recovery group animals.
`Epididymal lesions showed reversibility. A NOAEL was not achieved in this study.
`
`Dose-related increases in 24 hr AUC values were noted in the study. At each dose level,
`the AUC values were generally'similar after the 15‘, 30th and 80th doses except for high
`dose males in which the levels were twice as high at week 13 (80th dose) than at day 30.
`The mean AUC values in males at mid and high dose levels were higher than the
`respective values in females. The terminal phase half—life values for treprostinil ranged
`from 20 to 50 minutes.
`
`In another 13-week inhalation toxicity study, groups of dogs were exposed, by oronasal
`inhalation, to treprostinil aerosol concentrations of 0.025 mg/L for 15 minutes and 0.224
`mg/L for 6 and 30 minutes daily for 13 weeks, resulting in achieved dose levels of 107,
`322 and 1558 ug/kg/day, respectively. The controls were exposed to the vehicle for the
`same duration as the high dose group. One high dose female died on day 22; the death
`was attributed to choking on food. Decreased activity, salivation, tremors, vomiting and
`labored breathing were noted at the high dose. There were no effects on EKG. Although a
`dose~related sinus tachycardia was seen at mid and high dose levels during the early part
`of the study, by day 80, tachycardia had decreased and was limited to the high dose
`group. There were no treatment-related findings in hematology, clinical chemistry,
`respiratory minute volume, urinalysis, organ weight or gross pathology parameters.
`
`Microscopically, treatment-related lesions were observed only in the respiratory tract,
`especially in the nasal cavity and larynx of mid and high dose group animals. Focal or
`multifocal
`respiratory epithelial degeneration/regeneration in the nasal cavity was
`observed in these groups, the incidence and/or severity being higher at the highest dose.
`Other nasal cavity findings, observed only at the highest dose level, included goblet cell
`hyperplasia/hypertrophy, ulceration in the squamous or respiratory epithelium, and
`degeneration/necrosis in the squamous epithelium. Degeneration of the ciliated
`
`

`

`NDA 22387
`
`8
`
`epithelium in the larynx was noted in mid and high dose males and females. Lesions in
`the larynx were still present in 1 of 2 male dogs (not in females) after the recovery period.
`Although lung hemorrhage (minimal in severity) was observed in 1 of 6 low dose dogs,
`since the incidence rate for this lesion is same or lower than the concurrent or historical
`control incidence rates, andvalso because the low dose did not produce any nasal or larynx
`lesions, the low dose (107 ug/kg/day) could be considered as a NOAEL for the dog
`study.
`
`The Cmax and AUC values increased between day 1 and week 6, but generally no
`additional increases were observed between weeks 6 and 13. The terminal phase half-life
`values ranged from 18 to 26 minutes.
`
`Animal reproduction and developmental toxicity studies have not been conducted with
`treprostinil administered by the inhalation route. Animal reproduction and developmental
`toxicity studies were conducted previously with treprostinil administered by continuous
`sc infusion. In those studies, treprostinil did not affect fertility or mating performance of
`male or female rats at infusion rates of up to 450 ng/kg/min (about 59 times the
`recommended starting human 30 infusion rate and 8 times the average rate achieved in
`clinical trials). In pregnant rats, continuous sc infusions of treprostinil sodium during
`organogenesis and late gestational development, at rates as high as 900 ng treprostinil/
`kg/min (about 117 times the recommended starting human 30 infusion rate and about 16
`times the average rate achieved in clinical trials), resulted in no evidence of harm to the
`fetus.
`In pregnant rabbits, effects of continuous 50 infusions of treprostinil during
`organogenesis were limited to an increased incidence of fetal
`skeletal variations
`associated with maternal toxicity at an infusion rate of 150 ng treprostinil/kg/min (about
`41 times the starting human dose rate for so infusion and 5 times the average rate used in
`clinical trials).
`‘
`
`The sponsor is planning to conduct a 2-year bioassay in rats by the inhalation route. The
`range-finding study for the selection of the doses for the carcinogenicity study is being
`repeated as per the recommendations of the Executive CAC. In vitro and in viva genetic
`toxicology studies did not demonstrate any mutagenic or clastogenic effects of
`treprostinil.
`.
`
`Nonclinical Safety Issues Relevant to Clinical Use
`
`13-week inhalation toxicity studies with treprostinil revealed respiratory tract lesions,
`attributed to local irritation, in both rats and dogs. (In previous studies with treprostinil,
`local
`irritation was noted at
`the site of infusion when the drug was administered
`subcutaneously.)
`In
`the
`rat, no-observable-adverse-effect-levels
`(NOAELs)
`for
`respiratory or other treatment-related findings (myocardial, adrenal or testicular lesions)
`were not demonstrated. Myocardial
`lesions were considered to be due to reflex
`tachycardia induced by the exaggerated pharmacological action of treprostinil because of
`higher cardiac exposure to the drug when given by inhalation. Adrenal
`lesions were
`considered to be related to the stress of dosing and/or to the prolonged period of exposure
`
`

`

`NDA 22-387
`
`9
`
`of rats in the inhalation apparatus (225 minutes/day at the high dose level vs 6 to 8
`minutes/day in humans; lesions were mainly limited to the high dose).
`
`The histopathological findings in the adrenal, heart, respiratory or reproductive organs
`observed in the 13-week inhalation study were not seen in a previous 26-week
`continuous sc infusion study (50, 150, 450 ng treprostinil/kg/min) in rats. This may be
`related to'the higher plasma drug concentration obtained in the inhalation study; the mean
`maximum plasma treprostinil concentration obtained at the high dose in the rat inhalation
`study (307 ng/ml) was about 15—fold higher than the mean steady state concentration
`achieved at the high dose (20 ng/ml) in the 26-week sc continuous infusion study. (The
`Cmax value in patients receiving Tyvaso at the maximum recommended dose appears to
`be about 2 ng/ml.)
`
`The NOAEL in the dog (107 ug/kg/day) for the respiratory findings is about 12 times
`higher than the maximum dose used1n clinical studies [72 uglinhalation session (4. Sug/
`kg/day)], on a mg/m2 basis. The other treatment-related findings (myocardial, adrenal or
`testicular lesions) observed1n the rat were not seen in the dog even at doses as high as
`178 times the maximum clinical trial dose, on a body surface area basis. Since the above
`lesions were not seen in dogs even at relatively high dose multiples, and also because the
`plasma drug levels in patients at the recommended therapeutic dose level are far less than
`that seen in rats in the inhalation toxicity study, we do not consider the rat toxicity
`findings to constitute an approvability issue. Also, the long term clinical experience with
`treprostinil supports the safety of the drug.
`
`In conclusion, there are no approvability issues for Tyvaso based on the non—clinical
`toxicity-testing program.
`
`TABLE OF CONTENTS -— PIL4RMA COLOGY/TOXICOLOGY RE VIEW
`
`SAFETY PHARMACOLOGY STUDIES ......................................
`
`INHALATION TOXICITY STUDIES
`
`......................................
`
`page
`
`10
`
`12
`
`

`

`NDA 22-387
`
`‘
`
`10
`
`NONCLINICAL SUPPORT FOR THE PROPOSED NDA FOR TYVASO
`
`Nonclinical studies®conducted with treprostinil sodium were reviewed under NDA 21-
`272 for Remodulin® Injection for sc and1v administration. The sponsor is referencing the
`above NDA for the support of the present NDA for Tyvaso. Additional nonclinical
`studies conducted with treprostinil sodium included safety pharmacology studies (an in
`vitro hERG assay, an ex vivo action potential assay in rabbit Purkinje fibers, a cardio-
`vascular iv safety pharmacology study in dogs and a respiratory safety pharmacology
`study in rats) and repeat-dose inhalation toxicity studies in rats and dogs. These studies
`are summarized below.
`
`SAFETY PHARMACOLOGY STUDIES
`
`The hERG (human ether-a—go——go——related gene) assay and the action potential assay in
`A
`rabbit Purkinje fibers were conducted
`_ N
`
`11(4)
`
`In the hERG assay, the effects of treprostinil on cloned hERG potassium channels
`expressed in cultures of human embryonic kidney cells were determined using electro-
`physiological procedures. The cardiac potassium channel, hERG,
`is responsible for a
`rapid delayed rectifier current (kg) in ventricles. The inhibition of IKr current is the most
`common cause of cardiac action potential prolongation by non-cardiac drugs. Increased
`action potential duration causes prolongation of the QT interval which has been shown to
`be associated with a lethal ventricular arrhythmia, torsade de pointes. In this study,
`treprostinil was tested at concentrations of 0, 5, 10, 50 and 100 11M to determine its
`potential
`for
`the inhibition of hERG-mediated current. Treprostinil, at different
`concentrations, inhibited hERG current at the following rates: 0.5% inhibition for the
`vehicle control, 0.7% at 5 11M, 0.5% at 10 11M, 1.9% at 50 pM and 1.4% at 100 “M.
`Terfenadine,
`the positive control, at 60 nM,
`inhibited hERG current by 85.0%.
`In
`summary, treprostinil did not inhibit hERG—mediated current at concentrations up to 100
`11M [39,052 ng/ml;
`the Cmax value in patients receiving Tyvaso at the maximum
`recommended dose is 1.8 ng/ml.]
`
`The in vitro effects of treprostinil on cardiac action potentials were determined in isolated
`rabbit Purkinje fibers. Increased action potential duration (APD) is associated with
`prolongation of QT interval. Rabbit Purkinje fibers-have been shown to be more sensitive
`to drug-induced APD prolongation than Purkinje fibers from other species. In rabbit
`Purkinje fibers, the action potential wave form and the underlying ionic currents are
`similar to those of humans. In this study, the test drug treprostinil, at concentrations of 3,
`30 and 300 11M, was added to isolated rabbit Purkinje fiber preparations (r1 = 4) at two
`stimulus intervals [basic cycle lengths (BCL) of l and 0.5 s] and the effects of treprostinil
`on action potential parameters were compared to the time-matched vehicle controls.
`Treprostinil at 3 pM did not induce any significant changes in APD60 and APDgo (action
`
`

`

`NDA 22-387
`
`11
`
`potential duration measured at 60 and 90% repolarization) when compared to vehicle
`controls. Treprostinil at 30 11M produced shortening in APDso and APDgo at 1 s BCL, but
`not at 0.5 s BCL. Treprostinil at 300 uM induced significant shortening in APD60 and
`APDgo at both 1 and 0.5 s BCL. Treprostinil at all
`three concentrations did not
`significantly change the resting membrane potentials of the Purkinje fibers, the action
`potential amplitude and the maximum rate of depolarization (dV/dt max). The positive
`control dl-sotalol (50 uM) significantly prolonged the APD60 and the APDgo at both
`stimulus intervals without significant changes in resting membrane potential, action
`potential amplitude and the maximum rate of depolarization. In conclusion, treprostinil
`did not prolong action potential duration at concentrations up to 300 uM (117,156 ng/ml).
`
`A cardiovascular safety pharmacology study in dogs was conducted A
`.
`_
`,.//——
`'
`Treprostinil sodium solution was administered as a
`single iv bolus injection to 4 female beagle dogs (radiotelemetry-implanted) at dose
`levels of 0, 2, 20 or 200 ug/kg, according to a Latin-square design, such that each dog
`received each treatment once, with at least a 3-day washout period between doses. Heart
`rate, arterial blood pressure and EKG parameters were evaluated every 10 minutes for
`about 24 hours post-dose. As expected, treprostinil caused an initial drop in arterial blood
`pressure (systolic, diastolic and mean) and a compensatory increase in heart rate at all
`dose levels during the first hour after dosing. Elevated heart rates (up to 39%) were seen
`at the 200 ug/kg dose level 3 hr post-dose. The initial drop in arterial blood pressure was
`followed by a period (up to 6 hours) of elevated systolic (up to 15%), diastolic (27%)
`and mean (23%) blood pressures at 200 ug/kg dose level. The increase in blood pressure
`is considered to be due to a compensatory sympathetic reflex mechanism after the initial
`drop in pressure. Increased incidences of atrioventricular block were observed in one dog
`at 2 pig/kg and another dog at 200 ug/kg. However,.PR interval was not affected.
`Prolongation of QRS complex was observed at 200 rig/kg. Treprostinil did not affect QT
`interval at any dose level.
`
`31(4)
`
`[In a separate study, the hemodynamic activity of treprostinil and four of its metabolites
`(M334, M388, M392 and M566) on mean arterial pressure (MAP) and heart rate (HR)
`were investigated in anesthetized rats given iv bolus doses of treprostinil at 0.13, 1.3,
`12.7 and 127 pg/kg or each metabolite at 10, 100, 1000 or 10000 ug/kg. At the lowest
`dose levels, neither treprostinil (0.13 pig/kg) nor its metabolites (10 ug/kg) affected MAP
`or HR. At the highest dose levels, treprostinil (127 rig/kg) and its 3 metabolites (M388,
`M392 and M566; 10000 rig/kg) caused a fall in MAP within 1 minute and a subsequent
`rise in HR, indicating that the metabolites were much less active than treprostinil itself.
`The metabolite M344 did not affect MAP or HR at any dose level]
`
`'
`
`.
`«
`A respiratory safety pharmacology study was conducted in rats
`
`,
`. To evaluate the potential effects on respiratory
`function, nebulized treprostinil sodium was administered to groups of male rats via nose-
`only inhalation at an aerosol concentration of about 50 ug/L for 2, 3 or 4 hours. An
`additional group of male rats was given citrate buffer vehicle for 4 hours. Respiratory rate
`and tidal volume were measured, and the minute volume was calculated. Treprostinil, at
`achieved inhaled dose levels of 300, 416 and 569 pig/kg, produced significant decreases
`
`
`
`[3(4)
`
`

`

`NDA 22-387
`
`12
`
`in respiratory rates and derived minute volumes compared to predose and control values.
`These decreases occurred within 15 minutes of aerosol administration and rates and
`
`volumes remained decreased for the duration of exposure. However, all values returned
`to predose and control levels 24 hours following treatment.
`
`INHALATION TOXICITY STUDIES
`
`13-week inhalation toxicity studies were conducted in rats and dogs (with a 4-week
`recovery period)
`"I“ 7‘ _
`' 3.4.“, ‘
`'
`.These studies
`were reviewed earlier under IND 70,362, and are summarized below.
`
`Thirteen-Week Study in Rats With 4—Week Recovery Period
`
`Groups of Sprague—Dawley rats [15/sex/group for the main study; 9/sex/treatment for the
`toxicokinetic (TK) evaluations and 5/sex in the control and high dose groups for
`reversibility studies] were exposed, by nose only administration, to treprostinil aerosol
`concentrations of 7 pig/L for 20 minutes/day, 44 ug/L for 30 minutes/day and 40 ug/L for
`225 minutes/day for 13 weeks, resulting in estimated achieved dose levels of 7, 67 and ~
`464 pg/kg/day. Control animals were exposed to conditioned room air for the same
`duration as the high dose animals. All animals were observed twice daily for mortality
`and clinical
`signs. Body weight and food consumption were recorded weekly.
`Respiratory minute volume was recorded on 5 rats/sex/group for 15 minutes prior to
`closing and then for
`the first 15 minutes post-dose during weeks
`1, 6 and 13.
`Ophthalmoscopic examination was performed on all rats before the initiation of treatment
`and during weeks 13 and 17 (recovery group). Hematology, serum chemistry and
`urinalysis parameters were evaluated during weeks 4 and 13 and at the end of the
`recovery period. Plasma samples were collected from TK rats just before dosing and at 5,
`15, 30, 75 and 105 minutes post-dose on days 1, 30 and 80 for TK evaluations.
`
`Complete necropsy was performed on all animals found dead during the study and those
`sacrificed at the termination of the study, select organs weighed, and the following tissues
`were collected and preserved: adrenals, aorta, bone and marrow (sternum), brain, bronchi,
`cecum, colon, duodenum, epididymides, esophagus, eyes, Harderian glands, heart, ileum,
`jejunum, kidneys, larynx, lacrimal glands, liver, lungs, lymph nodes, mammary gland,
`nasal cavities, optic nerves, ovaries, pancreas, pharynx, pituitary, prostate, salivary gland,
`sciatic nerve, seminal vesicles, skeletal muscle, skin, spinal cord, spleen, stomach, testes,
`thymus, thyroid, tongue, trachea, urinary bladder, uterus, vagina and all gross lesions. All
`tissues from control and high dose group rats, and also respiratory tract tissues, adrenals,
`epididymides, heart, sternum, testis, thymus and all gross lesions from low and mid dose
`group rats, were examined microscopically.
`
`Five rats (1 low dose male, 2 HD males and 2HD females) died during the study. Two
`deaths (low dose male and 1 HD female) were attributed to bleeding procedures; the
`cause of the other deaths was not determined. Labored breathing and decreased activity
`and muscle tone were observed in high dose rats; At the termination of the study, body
`
`

`

`NDA 22-387
`
`'
`
`13
`
`weight gains at 7, 67 and 464 ug/kg/day were 17, 36 and 65% lower than control for
`males and 22, 23 and 23% lower than control for females, respectively. Treatment-related
`decreases in food consumption were observed in mid and high dose males and females.
`Respiratory minute volume was reduced at mid and high dose levels during weeks 6 and
`13. Decreased platelet, white cell and lymphocyte counts in high dose males, and
`increased reticulocyte counts in high dose males and females were observed. Organ
`weight findings included significantly higher than control adrenal (mid and high dose
`male and female groups) and lung weights (high dose — both sexes) and lower than
`control testis (high dose) and thymus weights (mid and high dose groups —- both sexes).
`Apart from the above organ weight findings, there were no gross pathology findings at
`necropsy.
`
`included squamous
`the lesions observed in the respiratory tract
`Microscopically,
`metaplasia in the larynx, hemorrhage and macrophage accumulation in the lung and
`hyperplasia/hypertrophy of goblet cells
`in the nasal cavity (all dose groups);
`degeneration/regeneration of the respiratory epithelium in the nasal cavity (mid and high
`dose groups); and respiratory epithelium ulceration and olfactory epithelium degeneration
`in the nasal cavity (high dose; Table 1). Other histopathological findings included
`myocardial degeneration/fibrosis
`in the heart and degeneration .of seminiferous
`epithelium in the testis (all treated groups); oligo/aspermia in the epididymis and cortical
`hypertrophy in the adrenals (mid and high dose groups); and vacuolation of the zona
`glomerulosa in the adrenals (high dose; Table 2).
`
`food consumption, platelet count and epididymal
`Treatment—related body weight,
`findings appeared to be reversible. However, treatment-related microscopic findings in
`the adrenals, heart, testis, larynx, lung and nasal cavity of high dose animals were also
`present in recovery animals.
`
`A NOAEL was not achieved in this study.
`
`

`

`NDA 22-387
`
`14
`
`Table 1.
`
`'
`
`Incidence and Severity of Treprostinll-related Histopathological
`Changes In Respiratory Tract Organs
`
`
`Tissue/findings
`Group ID
`Dose level ggflgday}
`Larynx
`Squamous metaplasia -
`
`Lung
`Hemorrhage
`
`Macrophage accumulation
`
`'
`
`sex
`
`Male
`3
`2
`1
`70
`10
`0
`15
`15
`15
`No examined
`1 1
`3
`Total No. affected —-
`3
`Minimal - 3
`Slight — — 8
`No examined
`15
`15
`15
`Total No. affected — 3
`7
`Minimal
`—-—
`3
`6
`Slight — —
`1
`Total No. afl‘ected
`——
`5
`7
`Minimal — 5
`7
`Sli
`t — -—
`—-
`
`4
`526
`16
`l3
`4
`9
`16
`7
`3
`4
`12
`10
`2
`
`Female
`4
`3
`2
`1
`526
`70
`10
`0
`15
`15
`15
`15
`13
`5
`— 1
`6
`3
`——-
`1
`7
`2
`—-
`—-
`15
`15
`15
`15
`5
`l
`— 2
`3
`— 2 —
`2
`— —
`1
`9
`——
`1
`1
`9
`— l
`1
`— —— — ——
`
`15
`
`15
`
`1’5
`
`16
`
`No examined
`v Nasal cavity
`Degeneration/regeneration: respiratory epithelium
`15
`— — —
`16
`2
`Total No. affected — —-
`3
`—— — —
`5
`2
`Minimal
`——
`~—
`Slight — —— —
`9
`—-—
`—- —
`11
`
`Moderate
`—— — —
`2
`— — —
`1
`Infiltration: neutrophilic cells Total No. afl'ected — ——
`-—
`6
`-—- — —~
`1
`Minimal
`—~ — —
`6
`— — ——
`-—-—
`Sli
`t — —— — ——
`—~ — —
`1
`
`15
`
`15
`
`15
`
`15
`
`Ulcerafion: respiratory epithelium
`Total No. afl‘ected — ‘— —
`Minimal — -——
`—-—
`Sli
`t — —— —
`
`Degeneration/regeneration: olfactory epithelium
`—-—
`——
`—~—
`Total No. affected
`-—
`Minimal — —-
`Slight —- — —
`
`2
`——
`2
`
`3
`——
`3
`
`~ — —-
`— — —
`——
`——
`——
`
`~— — ——
`3
`-— — ~
`— — —— -
`
`Hyperplasia/hypertrophy: goblet cells
`7
`4
`5
`——
`10
`1
`Total No. affected — 6
`7
`4
`— 5
`5
`1 .
`Minimal
`——
`6
`Slight—~——.5 —————
`
`.
`
`

`

`NDA 22-387
`
`.
`
`15
`
`Table 2.
`
`Incidence and Severity of Treprostinil-related Histopathological
`Changes in Non-Respiratory Tract Organs
`
`Tissue/findmgg
`Groung
`Dose levelgggljgdaxl
`Adrenal
`Hypertrophy: cortical
`
`Vacuolation: Iona granulosa
`
`.
`
`Heart
`Degeneration/fibrosis
`
`sex
`
`Male
`
`1
`0
`15
`
`Female
`3
`2
`70
`10
`15
`15
`3
`4
`3
`4
`—~
`— -— —
`—— — —
`— — —
`— — -—-
`—— — —
`15
`15
`15
`— 5
`4
`~ — 5
`4
`——
`~— —
`
`.
`
`4
`526
`15
`12
`ll
`l
`4
`3
`1
`—
`15
`3
`2
`1
`
`4
`3
`, 2
`1
`526
`70
`10
`0
`16
`15
`15
`15
`No examined
`12
`-— — l
`Total No. affected
`11
`—— — 1
`Minimal
`1
`—-— — —~
`Slight
`——-
`-— — 4
`Total N01 affected
`Minimal — —-
`——
`3
`Slight
`—— — —— —
`Moderate — — —
`1
`No examined
`15
`15
`15
`16
`Total No. affected —
`2
`2
`8
`Minimal —
`2
`2
`5
`Slight — — —
`3
`m
`No examined
`15
`15
`15
`1
`Testis
`Degeneration: seminiferous epithelium
`2
`2
`——
`Total No. affected
`~—
`2
`——
`Minimal
`— l
`——
`Slight
`——
`——
`Moderate
`l
`Marked — —
`
`Epidldymis
`Oligo/aspermia
`
`15
`15
`15
`No examined
`7
`Total No. afi'ected — — 2
`3
`Minimal
`—— — -—
`Slight — . —- — 3
`Moderate — ——
`-—
`-—
`l
`
`Marked — —- 2W
`
`

`

`NDA 22-387
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`16
`
`The Cmax and AUC values obtained at different intervals (after 18‘, 30th and 80th doses) in
`the 13 week study are prese