Recent advances in genetics and epigenetics have provided critical insights into the pathogenesis of both idiopathic and non-idiopathic interstitial lung diseases (ILDs). Mutations in telomere-related genes and surfactant proteins have been linked to familial pulmonary fibrosis, while variants in MUC5B and TOLLIP increase the risk of ILD, including idiopathic pulmonary fibrosis and rheumatoid arthritis-associated ILD. Epigenetic mechanisms, such as DNA methylation, histone modifications, and non-coding RNAs such as miR-21 and miR-29, regulate fibrotic pathways, influencing disease onset and progression. Although no standardized genetic panel for ILD exists, understanding the interplay of genetic mutations and epigenetic alterations could aid in the development of personalized therapeutic approaches. This review highlights the genetic and epigenetic factors driving ILD, emphasizing their potential for refining diagnosis and treatment.

Background: Generic formulations of pirfenidone are increasingly adopted in idiopathic pulmonary fibrosis (IPF), yet real-world evidence supporting their clinical equivalence to the originator remains limited. We aimed to evaluate whether switching from branded pirfenidone (Esbriet ^® ) to a generic formulation affects treatment efficacy or tolerability. Methods: We conducted a retrospective, within-patient observational study including consecutive patients with IPF treated with Esbriet ^® for ≥ 6 months before switching to generic pirfenidone. Pulmonary function was assessed at three time points: 6 months before the switch (T − 6), at switch (T0), and 6 months after (T + 6). The primary endpoint was the within-patient percentage change in FVC over two consecutive 6-month periods (T − 6 → T0 vs T0 → T + 6), analysed within a pre-specified equivalence framework (± 5 percentage points). Secondary endpoints included DLCO changes and treatment-related adverse events (AEs), analysed at the patient level using paired comparisons. Results: Sixty-five patients (median age 77.0 years [72.3–80.0] years, 78% male) had complete functional follow-up. The mean percentage decline in FVC was − 1.9% before the switch and − 1.7% after the switch. The estimated between-period difference in FVC change was 0.2 percentage points (95% CI − 1.1 to 1.5), fully contained within the pre-specified equivalence margins. Similar findings were observed for DLCO, with no significant difference between periods. Overall, 43% of patients experienced at least one AE during treatment. Gastrointestinal AEs were the most frequent, but paired analyses showed no significant difference in patient-level AE occurrence between branded and generic periods. No severe AEs or treatment discontinuations were observed. Conclusions: In this real-world cohort of patients with IPF, switching from branded to generic pirfenidone was not associated with clinically meaningful differences in lung function decline or treatment tolerability.