The primary objective of this study is to evaluate the safety and tolerability of the long-term use of TPIP in participants with PH-ILD from Study INS1009-311 (NCT07179380).

Inclusion Criteria

• Participants who have completed the lead-in PH-ILD TPIP Study INS1009-311 (NCT07179380).
• Capable of giving signed informed consent that includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.
• Agree not to participate in any other interventional trials or use investigational drugs or devices while participating in the INS1009-312 study.

Exclusion Criteria

• Participants who experienced any adverse events (AEs) evaluated as causally related to TPIP by the Investigator in a lead-in study, which in the opinion of the Investigator, could pose an unreasonable risk of continued treatments for the participant.
• Current use or expected need for pulmonary arterial hypertension (PAH)-approved therapy, including prostacyclin, prostacyclin analogues or other prostacyclin receptor agonists, endothelin receptor antagonists, and/or soluble guanylate cyclase stimulator, or any PH-ILD approved treprostinil therapy. Use of phosphodiesterase 5 inhibitors in line with applicable guidelines is allowed.
• Diagnosis of Pulmonary Hypertension World Health Organisation (WHO) Groups 1, 2, 4, or 5, or subtypes of PH WHO Group 3 other than interstitial lung disease (including combined pulmonary fibrosis and emphysema).
• Evidence of left ventricular failure, heart failure with preserved ejection fraction (HFpEF) or postcapillary PH.
• Known hypersensitivity or contraindication to treprostinil or TPIP or TPIP formulation excipients (eg, mannitol, leucine).

Note: Other protocol-defined inclusion/exclusion criteria may apply.