Could a lung scarring drug ease rare windpipe narrowing?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adults 18-65 years of age * Confirmed diagnosis of idiopathic subglottic stenosis (iSGS) * History of at least 2 endoscopic dilations within the past 12 months or -Receiving regular intralesional steroid injections as part of iSGS management (every 3 months) * Clinically stable at enrollment (no acute infection or active inflammation) * Adequate liver and renal function on screening laboratory tests * Willing and able to comply with study procedures, visits, and follow-up * Ability to provide written informed consent * For participants of childbearing potential: negative pregnancy test and agreement to use effective contraception during treatment and for the protocol-specified period after the last dose Exclusion Criteria: * Subglottic stenosis due to another identifiable cause (e.g., intubation, granulomatosis with polyangiitis, malignancy) * Known hypersensitivity or allergic reaction to pirfenidone or any component of its formulation * Severe hepatic impairment or active liver disease (AST or ALT above the upper limit of normal) * Severe renal impairment or requirement for dialysis * Concurrent use of fluvoxamine * Use of high-dose ciprofloxacin or other strong CYP1A2 inhibitors where dose adjustment is not feasible * Current smoking or unwillingness to abstain from smoking during treatment * Pregnant or breastfeeding individuals * Clinically significant comorbid illness that could increase risk or confound results (e.g., advanced cardiac, pulmonary, or autoimmune disease) * History of photosensitivity disorders or inability to adhere to sun protection precautions * Participation in another investigational clinical trial within the previous 30 days * Any condition that, in the investigator's judgment, would interfere with safety monitoring, adherence, or study assessments