This was a multicenter, randomized (1:1 inhaled treprostinil: placebo), double-blinded, placebo-controlled trial to evaluate the safety and efficacy of inhaled treprostinil in subjects with pre-capillary pulmonary hypertension (PH) associated with interstitial lung disease (ILD) including combined pulmonary fibrosis and emphysema (CPFE). The study included 326 patients at approximately 120 clinical trial centers. The treatment phase of the study lasted approximately 16 weeks. Patients who completed all required assessments were eligible to enter an open-label, extension study (RIN-PH-202).

Study RIN-PH-201 was a multicenter, randomized, double-blind, placebo controlled, 16 week, parallel group study designed to investigate the safety and efficacy of inhaled treprostinil in subjects with PH-ILD. Subjects initiated inhaled treprostinil or placebo at a dose of 3 breaths (18 mcg) 4 times daily (QID) (during waking hours). Study drug doses were maximized throughout the study. Dose escalations (additional 1 breath QID) could occur up to every 3 days with a target dosing regimen of 9 breaths (54 mcg) QID and a maximum dose of 12 breaths (72 mcg) QID, as clinically tolerated. Subjects were assessed during Screening and Baseline to determine eligibility for the study. Once eligible, 5 Treatment Phase visits to the clinic were required at Week 4, Week 8, Week 12, Week 15, and Week 16 (final study visit). An Early Termination (ET) Visit was conducted for subjects who discontinued prior to Week 16; all assessments planned for the final Week 16 Visit were conducted during the ET Visit, if applicable. Subjects were contacted at least weekly by telephone or email to assess tolerance to study drug, AEs, and changes to concomitant medications. Efficacy assessments consisted of 6-minute walk distance (6MWD), plasma N-terminal prohormone brain natriuretic peptide (NT-proBNP) concentration, and incidence of clinical worsening. Exploratory endpoints included change in St. George's Respiratory Questionnaire (SGRQ), change in distance saturation product (DSP), time to exacerbation of underlying lung disease, and pulmonary function tests (PFT). Safety assessments consisted of the development of AEs, vital signs, clinical laboratory parameters, ECG parameters, hospitalizations due to cardiopulmonary indications, exacerbations of underlying lung disease, and oxygenation. Subjects who remained on study drug, completed all assessments during the 16-week Treatment Phase, and met all eligibility criteria were eligible for the open-label extension study (RIN-PH-202). Additionally, subjects who withdrew from study drug prior to Week 16 due to clinical worsening and returned to the clinic for scheduled visits (excluding the Week 15 Visit) were eligible for RIN PH-202.

Inclusion Criteria:

1. Subject voluntarily gave informed consent to participate in the study.

2. Males and females aged 18 years or older at the time of informed consent.

   a. Females of reproductive potential were non-pregnant (as confirmed by a urine pregnancy test at screening) and non-lactating, and: i. Abstained from intercourse (when in line with their preferred and usual lifestyle), or ii. Used 2 medically acceptable, highly effective forms of contraception for the duration of study, and at least 30 days after discontinuing study drug.

   b. Males with a partner of childbearing potential used condoms for the duration of treatment and for at least 48 hours after discontinuing study drug.

3. The subject had a confirmed diagnosis of WHO Group 3 PH based on computed tomography (CT) imaging which was performed within 6 months prior to randomization and demonstrated evidence of diffuse parenchymal lung disease. Subjects had any form of ILD or CPFE.

4. Subjects were required to have a right heart catheterization (RHC) within 1 year prior to randomization with the following documented parameters:

   1. Pulmonary vascular resistance (PVR) >3 Wood Units (WU) and
   2. A pulmonary capillary wedge pressure (PCWP) of <15 mmHg and
   3. A mean pulmonary arterial pressure (mPAP) of >25 mmHg

5. Baseline 6MWD ≥100 m.

6. Subjects on a chronic medication for underlying lung disease (ie, pirfenidone, nintedanib, etc) were on a stable and optimized dose for ≥30 days prior to randomization.

7. In the opinion of the Investigator, the subject 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.

8. Subjects with connective tissue disease (CTD) had a Baseline forced vital capacity (FVC) of <70%.

Exclusion criteria:

1. The subject had a diagnosis of PAH or PH for reasons other than WHO Group 3 PH ILD as outlined in Inclusion Criterion 3.

2. The subject showed intolerance or significant lack of efficacy to a prostacyclin or prostacyclin analogue that resulted in discontinuation or inability to effectively titrate that therapy.

3. The subject received any PAH-approved therapy including: prostacyclin therapy (ie, epoprostenol, treprostinil, iloprost, or beraprost; except for acute vasoreactivity testing), prostacyclin (IP) receptor agonist (selexipag), endothelin receptor antagonist (ERA), phosphodiesterase type 5 inhibitor (PDE5-I), or soluble guanylate cyclase (sGC) stimulator within 60 days of randomization.

4. The subject had evidence of clinically significant left-sided heart disease as defined by:

   1. PCWP >15 mmHg
   2. Left ventricular ejection fraction <40%. Note: Subjects with abnormal left ventricular function attributable entirely to impaired left ventricular filling due to the effects of right ventricular overload (ie, right ventricular hypertrophy and/or dilatation) were not excluded.

5. The subject was receiving >10 L/min of oxygen supplementation by any mode of delivery at rest at Baseline.

6. Current use of any inhaled tobacco/marijuana products or significant history of drug abuse at the time of informed consent.

7. Exacerbation of underlying lung disease or active pulmonary or upper respiratory infection within 30 days of randomization.

8. Initiation of pulmonary rehabilitation within 12 weeks prior to randomization.

9. In the opinion of the Investigator, the subject had any condition that would interfere with the interpretation of study assessments or has any disease or condition (ie, peripheral vascular disease, musculoskeletal disorder, morbid obesity) that would likely be the primary limit to ambulation (as opposed to PH).

10. Use of any investigational drug/device, or participation in any investigational study with therapeutic intent within 30 days prior to randomization.

11. Severe concomitant illness limiting life expectancy (<6 months).

12. Acute pulmonary embolism within 90 days of randomization.