Pregnancy Category C.

Animal reproductive studies with treprostinil diolamine have shown an adverse effect on the fetus. There are no adequate and well-controlled studies in humans.

In rats, treatment with treprostinil diolamine had no effect on reproductive performance or sperm motility at doses up to 10 mg/kg/day. The exposures at this dose level are about 10- (male) to 18- (female) fold the usual human exposure at the mean dose of 3.4 mg BID.

In pregnant rats, reversible, dose-dependent decreases in body weight gain and food consumption were observed during the first four days of dosing in animals administered 10, 20 and 30 mg/kg/day treprostinil diolamine. In a dose range-finding study, there was a 17% decrease in the pregnancy rate in the animals administered 20 and 30 mg/kg/day. One dam in each of the 20 and 30 mg/kg/day had litters with no viable fetuses. In the definitive study (0, 5, 10 and 20 mg/kg/day), there were four treatment-related deaths, and a 32% decrease in the pregnancy rate for rats administered 20 mg/kg/day. There was an 8% decrease in the pregnancy rate in the animals administered 10 mg/kg/day. Across both studies, an increase in post-implantation loss was observed in animals administered 10 to 30 mg/kg/day, and a significant decrease in the mean number of live births was seen at dose levels ≥10 mg/kg/day. The no observed adverse effect level was 5 mg/kg/day (maternal, fetal viability and growth), and 20 mg/kg/day (teratogenicity), the highest dose tested in the definitive study. The exposures at 5 and 20 mg/kg/day doses represent 13 and 55 times, respectively, the human exposure.

For F 1 progeny, a decreased copulation index was observed at the 5 and 10 mg/kg/day treprostinil diolamine dose levels in rats. The no observed effect levels for physical development, reflex development, exploratory behavior, learning and memory, and sexual maturation was 10 mg/kg/day. The no observed effect level for F 1 progeny general development (based on body weight) was 10 mg/kg/day for females and ≤ 2.5 mg/kg/day for males; the no observed effect level for F 1 reproductive performance was 2.5 mg/kg/day or 6 times the human exposure.

In pregnant rabbits, the primary maternal adverse effects were gastrointestinal disturbance; dose-dependent decreases in mean body weight, body weight gain, and food consumption were observed. During the post-dose phase, the effect was reversed. In a dose range-finding study, there was a 17% decrease in the pregnancy rate for animals administered 4 mg/kg/day. A dose-dependent increase in post-implantation loss was observed. Two dams administered 4 mg/kg/day had litters with no viable fetuses; the mean fetal weight was slightly decreased in animals administered 4 mg/kg/day. In the definitive study, mean fetal weights were significantly decreased in animals administered 0.5 to 3 mg/kg/day of treprostinil diolamine. At doses of 1.5 and 3 mg/kg/day, external fetal and soft tissue malformations were observed in a few fetuses, and the total fetal skeletal malformations were significantly increased. The no observed adverse effect level was less than 0.5 mg/kg/day (maternal), 1.5 mg/kg/day (fetal viability and growth), and 0.5 mg/kg/day (teratogenicity). The 0.5 mg/kg/day dose represents about 5 times the human exposure.

Absorption

The absolute oral bioavailability of Orenitram is approximately 17%. Maximum treprostinil concentrations occur between approximately 4 and 6 hours following Orenitram administration. Time to reach steady-state concentrations for both BID and TID regimens is approximately 1 to 2 days.

The absorption of Orenitram is affected by food. The AUC inf of treprostinil was increased by 49% and the C max was increased by an average of 13% when Orenitram was administered following a high-fat, high-calorie meal compared to fasting conditions in healthy volunteers. The relative bioavailability of treprostinil following oral administration of Orenitram 1 mg is not significantly altered by meal types ranging from 250 to 500 calories in healthy volunteers.

When Orenitram 1 mg was administered with alcohol at 0.5 mg/kg or the equivalent of 3 servings (at the same time, or ± 1 hour relative to alcohol consumption), there was no significant change (10% to 20% increase) in the exposure to treprostinil compared to Orenitram administered alone.

Distribution

The treprostinil component of Orenitram is highly bound to human plasma proteins, approximately 96% over a treprostinil concentration range of 0.01-10 μg/mL.

Metabolism and Excretion

In a study conducted in healthy volunteers using [ 14C] treprostinil, treprostinil was extensively metabolized on the side chain of the molecule via oxidation, oxidative cleavage, dehydration, and glucuronic acid conjugation. Treprostinil is primarily metabolized by CYP2C8 and to a lesser extent by CYP2C9. No new metabolites are found upon oral administration compared to parenteral administration of treprostinil. Only 1.13% and 0.19% is excreted as unchanged parent drug in the feces and urine, respectively. Based on in vitro studies treprostinil does not inhibit or induce major CYP enzymes [see Drug Interactions (7.3)] .

Specific Populations

Drug Interactions

Results of drug interaction studies are shown in Figure 1. Only for the strong CYP2C8 inhibitor does the interaction affect dosing [see Dosage and Administration (2.4)] .

Figure 1: Impact of Co-Administered Drugs on the Systemic Exposure of Treprostinil 1 mg Compared to Orenitram Administered Alone

Study 1 (effect seen with no background vasodilator)

Study 1 was a 12-week, randomized (2:1 Orenitram to placebo), double-blind, placebo-controlled, international efficacy and safety study of Orenitram in patients with WHO Group 1 PAH not currently receiving PAH therapy. The primary efficacy endpoint was placebo-corrected change in six-minute walk distance (6MWD) from Baseline to Week 12. Study drug dose was titrated to a maximum of 12 mg BID based on clinical response and study drug tolerability. Study 1 enrolled 349 patients (overall analysis population) who were not receiving any PAH medication. At the beginning of the study, subjects were dosed with only the 1 mg tablets with 0.5 and 0.25 mg tablets introduced at sequentially later dates during the study. The primary analysis population consisted of the 228 patients who had access to the 0.25 mg tablet at the time of randomization. Patients were administered Orenitram or placebo twice daily, with the doses titrated to effect over the course of the 12-week trial. Patients were in WHO functional class II (~33%) and class III (~66%) with either idiopathic or heritable PAH (~75%), collagen vascular disease associated PAH (~19%), or PAH associated with HIV (1%) or congenital heart defect (5%) or other conditions (~6%). The patients' mean baseline 6MWD was approximately 330 meters. In the primary analysis population, 17% of patients discontinued Orenitram compared to 14% of patients on placebo.

The primary efficacy endpoint of the trial was the change in 6MWD at 12 weeks for the primary analysis population. Analysis of Study 1 results demonstrated that those patients receiving Orenitram compared to patients receiving placebo improved their median 6MWD by approximately +23 meters (Hodges-Lehmann estimate; p=0.013, non-parametric analysis of covariance in accordance with the pre-specified statistical analysis plan) as compared to patients receiving placebo as demonstrated in (Figure 2). The within group median change from baseline was +25 meters for Orenitram and -5 meters for placebo at week 12 (N=228). Mean dose (±SD) in the Orenitram group was 2.3 ± 1.3, 3.2 ± 1.9, and 3.4 ± 1.9 mg BID at Weeks 4, 8, and 12, respectively, with a maximum dose of 12 mg BID. The distribution of the 6MWD change from baseline at Week 12 was also plotted across the range of observed values (Figure 3).

Figure 2: Hodges-Lehmann Estimate of Treatment Effect by Visit for the Primary Analysis Population (Study 1)

Figure 3: Plot of the Distribution of Peak 6MWD Changes at Week 12 for the Primary Analysis Population (Study 1)

The placebo-corrected median treatment effect on 6MWD was estimated (using the Hodges Lehmann estimator) within various subpopulations defined by age, gender, disease etiology, and baseline 6MWD (Figure 4).

Figure 4: Placebo Corrected Median Treatment Effect (Hodges-Lehmann estimate with 95% CI) on 6MWD Change from Baseline at Week 12 for Various Subgroups in the Primary Analysis Population (Study 1)

Studies 2 and 3 (no effect on a background of ERA, PDE-5 inhibitor, or both)

Studies 2 (N=350) and 3 (N=310) were 16-week, randomized, double-blind, placebo-controlled, international efficacy and safety studies of Orenitram in patients with WHO Group 1 PAH. The primary efficacy endpoint was placebo-corrected change in 6MWD from Baseline to Week 16. Patients were in WHO functional class II (~23%) and class III (~77%) with either idiopathic or heritable PAH (~66%), collagen vascular disease associated PAH (~29%), or PAH associated with HIV (1%) or congenital heart defect (4%). The patients' mean baseline 6MWD was approximately 340 meters. Approximately 40% were receiving both an ERA and a PDE-5 inhibitor. The results did not demonstrate a benefit in exercise testing with median 6MWD at Week 16 (11 meters [Hodges-Lehmann estimate; p=0.072] and 10 meters [Hodges-Lehmann estimate; p=0.089], respectively).

Long-Term Treatment of Pulmonary Hypertension

Patients (N=824) from the placebo-controlled studies entered a long-term, uncontrolled, open-label extension study. The average exposure to Orenitram was approximately 2 years with a maximum exposure of approximately 6 years. The dose of Orenitram continued to increase over time with doses (mean ± SD) of 3.6 ± 2.7, 4.2 ± 3.1, and 5 ± 3.7 mg BID at 6 (n=649), 12 (n=433), and 24 months (n=238), respectively, with a maximum dose of 21 mg BID. Reasons for discontinuation from the study included adverse event (16%), progression of disease (15%), death (13%), and withdrawn consent (7%). In the 522 subjects that completed the 12-month efficacy assessment, their mean 6MWD improved by 24 meters compared to baseline (30 meters in monotherapy patients and 20 meters when Orenitram was used in combination with an ERA and/or a PDE-5 inhibitor). Of the patients that remained in the study, overall survival was 92%, 87%, and 82% at the end of 1, 2, and 3-years, respectively, with progression-free survival (progression defined as death, discontinuation or addition of a PAH therapy) of 74%, 61%, and 47%. Without a control group, these data must be interpreted cautiously.

Remodulin to Orenitram Transition Study

A 24-week, multicenter, open-label study enrolled 33 WHO Group 1 patients on stable doses of Remodulin. All patients received background therapy with a PDE-5 inhibitor and/or ERA. Patients were WHO Functional Class I or II and hemodynamically stable at baseline with a cardiac index >2.2 L/m 2, RAP<11 mmHg, and PVR<10 Woods units. The primary endpoint of the study was the safety and tolerability of the transition. Successful transition was defined as transition from Remodulin to Orenitram at Week 4 (no longer receiving Remodulin) and clinically maintained on Orenitram through Week 24 (as measured by 6MWD and hemodynamics).

All patients transitioned from Remodulin to Orenitram (median time to transition of 3 days) with thirty-one patients (94%) completing transition in 5 days (range 2 to 29 days). Two subjects discontinued Orenitram. The mean Orenitram total daily dose at the end of transition was 27 mg ± 12 mg compared to a mean Remodulin dose prior to transition of 59 ng/kg/min (25 to 111 ng/kg/min). The mean Orenitram total daily dose at Week 24 was 36 mg ± 16 mg. After 24 weeks of treatment with Orenitram, 6MWD and hemodynamics remained stable. Without a control group, these data must be interpreted cautiously.