Safety, Tolerability, and Pharmacokinetics of Oral Treprostinil in Pediatric PAH Patients Aged 7 to 17 Years

Study TDE-PH-206 was a multicenter, open-label study designed to investigate the safety, tolerability, and PK of oral treprostinil administered 3 times daily (TID) or 4 times daily (QID), at the discretion of the Investigator, with food in pediatric PAH subjects aged 7 to 17 years of age (1) transitioning from continuous IV/SC Remodulin, (2) transitioning from inhaled prostacyclin, or (3) as add-on to current PAH therapies in de novo prostacyclin subjects. Eligible subjects were assigned to a cohort based upon their background therapy. All subjects received oral treprostinil provided as 0.125, 0.25, 1, or 2.5 mg extended-release tablets. Subjects in Cohort 1 began the transition from IV/SC Remodulin in the hospital with a goal of complete transition to oral treprostinil within 5 days. The initial dose of oral treprostinil for Cohort 1 was calculated from the subject's dose of IV/SC Remodulin and weight. Subjects in Cohorts 2 and 3 were initiated on 0.125 mg TID or QID oral treprostinil with dose escalations possible every 24 hours in increments of 0.125 mg TID or QID at the discretion of the Investigator during the first 4 weeks, and in increments of either 0.125 mg or 0.25 mg every 24 hours thereafter. Cross titration occurred for Cohorts 1 and 2 such that doses of IV/SC Remodulin or inhaled prostacyclin were decreased as subjects were fully transitioned to oral treprostinil.

Inclusion criteria

• Legal guardian informed consent and subject assent, if appropriate, to participate in the study was voluntarily given.
• The subject was between 7 and 17 years of age, inclusive, on the date informed consent was signed.
• Cohort 3: The subject weighed a minimum of 22 kg at Screening.
• The subject had a current diagnosis of PAH (WHO Group I) associated with:

• IPAH or HPAH
• Persistent PAH for at least 1 year following surgical repair of a congenital systemic-to-pulmonary cardiac shunt, congenital heart disease, or other congenital heart lesions with no clinically significant residual defects and condition was stabilized hemodynamically
• PAH in subjects with unrepaired restricted atrial septal defect, ventricular septal defect, or patent ductus arteriosus; subject had a resting post-ductal oxygen saturation (off oxygen) of greater than 88%.
• The subject had a current diagnosis of PAH confirmed by RHC prior to the Screening Visit with the following parameters:

• PAPm of ≥25 mmHg
• Pulmonary vascular resistance index (PVRi) of >3 Wood Units*m2
• Left ventricular end-diastolic pressure (LVEDP) or pulmonary capillary wedge pressure (PCWP) of ≤15 mmHg.
• Cohort 1: The subject had received IV/SC Remodulin for at least 90 days without dose change for at least 30 days prior to Baseline. The IV/SC Remodulin dose was between 25 to 75 ng/kg/min, inclusive, for the first 5 subjects in the cohort. Following safety review, the dose range was expanded to 25 to 125 ng/kg/min, inclusive, for the remaining subjects. Subjects must have received stable doses of all other PAH medications for at least 14 days prior to the baseline assessments; exception for diuretics and anticoagulants.
• Cohort 2: The subject must have received inhaled prostacyclin for at least 90 days and had been at the current stable dose without changes for at least 30 days prior to Baseline. Subjects must have received stable doses of all other PAH medications for at least 14 days prior to the baseline assessments; exception for diuretics and anticoagulants.
• All Cohorts: All subjects were optimally treated (as determined by the Investigator) with background PAH therapies (eg, phosphodiesterase type 5 inhibitor [PDE5-I], endothelin receptor antagonist [ERA], soluble guanylate cyclase [sGC]) for at least 90 days and had been on a stable dose without changes (except documented weight based adjustments) for at least 30 days prior to the first dose of oral treprostinil. Subjects must have received stable doses of all other PAH medications for at least 14 days prior to the first dose of oral treprostinil; exception for diuretics and anticoagulants.
• The subject was willing and able to swallow intact tablets whole without chewing, breaking, or splitting.
• The subject was willing and able to comply with the dietary requirements associated with the oral treprostinil dosing regimen.
• The subject was on stable doses of other medical therapy for 14 days prior to the Baseline Visit with no dose adjustments, additions, or discontinuations. Dose changes of diuretics were allowed if within the usual dose adjustments prescribed for the subject. Anticoagulants could have been adjusted, but not discontinued or added, within 14 days of Baseline. Temporary discontinuation of anticoagulants when related to study-related procedures was allowed.
• Females of childbearing potential include any female who had experienced menarche. Females of childbearing potential must have practiced true abstinence from intercourse, had an intrauterine device, or used 2 different forms of highly effective contraception for the duration of the study and for at least 30 days after discontinuing oral treprostinil. Medically acceptable forms of effective contraception included approved hormonal contraceptives (such as birth control pills) or barrier methods (such as a condom or diaphragm) used with a spermicide. For females of childbearing potential, a negative urine pregnancy test was required at Baseline prior to oral treprostinil administration. Males participating in the study must have used a condom during intercourse for the duration of the study and for at least 48 hours after discontinuing oral treprostinil.
• Subjects with a history of metallic implants, prior neurosurgical clip placement, or other potential contraindications to cMRI were individually evaluated per site standard operating procedures for MRI performance.
• In the opinion of the Principal Investigator, the subject and/or legal guardian was able to communicate effectively with study personnel, and was considered reliable, willing, and likely to be cooperative with protocol requirements, including attending all study visits.

Exclusion criteria

• The subject had a diagnosis of large unrestrictive ventricular septal defect or patent ductus arteriosus, Eisenmenger syndrome, congenital diaphragmatic hernia, or a chronic lung disease, such as bronchopulmonary dysplasia or interstitial lung disease.
• The subject had a current disease severity of Panama FC IIIb or IV.
• The subject had previously been exposed to oral treprostinil.
• Cohort 1: The subject had previous intolerance to treprostinil or epoprostenol due to systemic adverse effects that resulted in discontinuation of therapy. This did not include site pain reactions or central venous catheter-related blood stream infections.
• Cohort 1 and 2: The subject was receiving IV/SC Remodulin or Tyvaso® (as the inhaled prostacyclin) for any other disease or condition other than the treatment of PAH in accordance with the IV/SC Remodulin or Tyvaso package inserts (ie, eligible subjects must have had a WHO Group I PAH classification as defined in inclusion criterion #4).
• Cohort 3: The subject had been previously exposed to a prostacyclin within 30 days of Screening, with the exception of vasoreactivity testing.
• The subject was pregnant or lactating.
• The subject had a current diagnosis of uncontrolled sleep apnea as defined by their physician.
• The subject had severe renal insufficiency as defined by an estimated creatinine clearance <30 mL/min (Schwartz Formula) or the requirement for dialysis at Screening.
• The subject had moderate to severe hepatic dysfunction as defined by elevated liver function tests (aspartate aminotransferase or alanine aminotransferase) ≥3 times the upper limit of normal at Screening, or Child Pugh class B or C hepatic disease.
• The subject had clinically significant anemia as defined by a hemoglobin and/or hematocrit level <75% of the lower limit of normal ranges according to age and gender.
• The subject had Down Syndrome.
• The subject had uncontrolled systemic hypertension as evidenced by a systolic or diastolic blood pressure greater than the 95th percentile for age, height, and gender at Screening or Baseline.
• The subject and/or legal guardian had an unstable psychiatric condition or was mentally incapable of understanding the objectives, nature, or consequences of the study, or had any condition in which the Investigator's opinion would constitute an unacceptable risk to the subject's safety.
• The subject had an active infection or any other cardiovascular, liver, renal, hematologic, gastrointestinal, immunologic, endocrine, metabolic, or central nervous system disease or condition that, in the opinion of the Investigator, might have adversely affected the safety of the subject or interfered with the interpretation of study assessments.
• Subject was actively listed for transplantation.
• The subject was receiving an investigational drug, had an investigational device in place, or had participated in an investigational drug or device study within 30 days prior to Baseline. Participation in an observational study did not disqualify a potential subject from study participation.