Hewlett, J C

Abstract Rationale Lymphangioleiomyomatosis (LAM) is a rare, progressive, cystic lung disease affecting women. Sirolimus has been shown to stabilize lung function in women with LAM, but real-world data on long-term safety and efficacy are limited. Methods The NIH Multicenter Safety and Durability of Sirolimus for LAM (MIDAS, NCT02432560) observational registry was launched in 2015. All adult (≥18 years) women with LAM (treated or untreated) were eligible to enroll at any of the 20 U.S. sites and followed longitudinally with serial assessments of lung function, health-related quality of life, and treatment related adverse event (TRAEs). Baseline cohort characteristics and TRAEs are summarized using descriptive analyses. Marginal structural models (MSMs) with inverse probability of treatment weighting estimated the causal effect of sirolimus on annualized forced expiratory volume in one-second (FEV1) decline, adjusting for age at LAM diagnosis, prior treatment with sirolimus, menopausal status, race, presence of angiomyolipomas, supplemental oxygen use; time-varying covariates included diffusing capacity for carbon monoxide (DLCO) and serum vascular endothelial growth factor-D (VEGF-D) levels. Results Longitudinal data was available in 350 LAM patients, most of whom (246, 70.3%) had sporadic LAM. The median age at the baseline pulmonary function test (PFT) measurement was 46 years (range: 19 - 74) and the median (IQR) number of serial PFTs obtained per patient was 3 (1 - 5). The average follow-up duration per patient was 2.8 years. Over half of the patients (196, 56%) were treated with sirolimus during the MIDAS observation period for a median (IQR) treatment duration of 4.9 (2.4 - 7.5) years. MSM analysis demonstrated that sirolimus treatment was durably effective and reduced FEV₁ decline by 74.36 mL/year (95% CI: 15.87 - 132.85) compared with no treatment (-85.31 mL/year for the untreated group vs. -10.95 mL/year for the treated group, p = 0.01). Sirolimus was generally well tolerated; treatment interruption ≥3 months was observed in 38 (19.4%) of the 196 sirolimus treated patients. Logistic regression analysis showed that higher levels of FEV1 (odds ratio: OR = 3.12 [1.45 - 7.11], p = 0.005), VEGF-D (OR = 1.0007 [1.0004 - 1.001], p < 0.001), and DLCO (OR = 1.023 [1.0053 - 1.0413, p = 0.01]), were associated with treatment interruption. Conclusions In the MIDAS cohort, sirolimus treatment resulted in durable stabilization of lung function with a favorable safety profile over a 5-year period. These real-world data support sirolimus as a chronic suppressive therapy for LAM, demonstrating durable efficacy in slowing lung disease progression and tolerability with long-term use. This abstract is funded by: National Institutes of Health

Abstract Rationale Patients with interstitial lung disease related to systemic autoimmune rheumatic diseases (SARD-ILD) may develop progressive pulmonary fibrosis (PPF), characterized by irreversible loss of lung function and high mortality risk. The risk of PPF by SARD subtype is not well characterized in large, representative real-world data sources. We characterized patients with SARD-ILD and compared the risk of PPF by SARD subtype in a multicenter cohort derived from the national Patient-Centered Clinical Research Network (PCORnet). Methods Harmonized electronic health record (EHR) data was collected from seven PCORnet centers. Included patients had at least two ICD-9/ICD-10 codes for ILD between 2015-2021, an ILD diagnosis that persisted following chest CT and/or lung biopsy, at least one year of potential follow-up, and sufficient lung function data to assess PPF. The presence of SARD, subtypes of which were classified by ICD codes, was also required. PPF was defined by ≥ 5% absolute decline in FVC, lung transplantation or death. The incidence of PPF was compared across SARD subtypes using Kaplan Meier estimates and Cox proportional hazards models adjusted for age, sex, enrolling center and baseline FVC. Results The cohort included 6,288 patients with SARD-ILD, of whom 68.4% were female, with a mean (SD) age of 61.2 (13.9) years. The most common underlying SARD was rheumatoid arthritis (RA, 42.8%), followed by systemic sclerosis (SSc, 22.3%), mixed connective tissue disease (MCTD, 21.5%), Sjögren’s syndrome (16.9%), systemic lupus erythematosus (SLE, 14.5%) and polymyositis/dermatomyositis (PM/DM, 12.0%). Mean FVC and DLCO at baseline were 78.7 (22.9) % and 51.9 (21.3) % of predicted, respectively. Patients with PM/DM had the lowest mean FVC (70.4 [SD 21.3]) % of predicted) and DLCO (45.1 [SD 18.5] % of predicted). During the follow-up period, antifibrotic, corticosteroid, and non-steroidal immunosuppressive drugs were used by 7.6%, 89.3% and 77.5% of the overall cohort, respectively. The cumulative incidence of PPF, transplant or death at one year ranged from 20.6% to 29.0%, depending on SARD-ILD subtype, with higher risk among those with RA, SSc or MCTD as compared with PM/DM (figure). Conclusions In a large, harmonized EHR dataset, the risk of PPF at one year among patients with SARD-ILD was high. Variability of PPF risk by SARD-ILD subtype was similar to that observed in traditional cohort studies, with lower risk among patients with myositis despite poorer lung function at baseline. These findings establish the feasibility of PCORnet as a tool to understand PPF among patients with SARD-ILD. This abstract is funded by: Genentech