Background/Purpose: To evaluate the efficacy and safety of rituximab (RTX) in the medium- to long-term for the management of progressive rheumatoid arthritis–related interstitial lung disease (RA-ILD).

Methods: We undertook an open observational study in patients with active symptomatic RA-ILD despite treatment with glucocorticoids and disease-modifying antirheumatic drugs or immunosuppressants. The main efficacy variables evaluated at the end of the follow-up period were the evolution of the respiratory functional tests, distance traveled during the 6-minute walk test (6MWT), and changes in high-resolution chest computed tomography scan (HRCT).

Results: Twenty-three patients were included. The median durations of RA and ILD were 48 months (range, 1-273 months) and 21 months (range, 1-144 months), respectively. Twenty-six percent of the cases corresponded to interstitial usual pneumonia. RA was seropositive in 91% of patients. The number of RTX cycles administered (mean ± SD) was 4 ± 1.9 (range, 2-10), and the median time of follow-up after RTX treatment was 29 months (range, 12-71 months).

At the end of follow-up, the mean DAS28-ESR score decreased to 2.6 ± 0.7 (P = 0.0001), and there were improvements in mean FVC values (Delta +0.86; P = 0.711), DLCO values (Delta + 7.93; P = 0.007), and distance covered in the 6MWT (Delta +21.63 m; P = 0.376).

Considering the total sample, an improvement or stabilization of the FVC values was achieved in 87% of the cases (improvement: 17% of the cases), in 91% of the cases in the DLCO values (improvement: 56% of cases), and in 83% of cases in the ILD radiologic features (improvement: 13% of cases). The median time between the first and the last HRCT was 26 months (range, 12-65 months).

In addition, at the end of the follow-up period, the average dose of prednisone was reduced to 4.5 mg/d, and it could be suspended in 5 patients.

A significant inverse correlation between the ACPA level and baseline DLCO was found in the entire cohort (r = –0.45, P = 0.04). This correlation was present even after adjusting for tobacco exposure (P = 0.01). In some of the patients, a decrease in the ACPA titer was documented with biologic treatment (median Delta [IQR 25th-75th]: –159 [–875, –83]), becoming negative in 4 cases, although there was no significant correlation between the decrease in the ACPA titers (Delta ACPA) and the degree of improvement of the parameters in the PFR at the end of the follow-up (FVC: r = –0.15, P = 0.949; DLCO: r = –0.20, P = 0.385).

Globally, patients with UIP had globally worse baseline values in PFTs and 6MWT. In addition, the responses obtained with RTX in this group were numerically lower than those in the group with non-UIP patterns, but the differences were only statistically significant in the case of FVC.

The frequencies of adverse effects (mainly respiratory or urinary infections and transient neutropenia) was high, occurring in 43.5% of patients, but they were severe in only 13%, causing withdrawal of treatment. Two (9%) patients died due to progression of ILD, and 2 (9%) ended up requiring a lung transplant. At the end of the follow-up period, 16 of the 23 patients (69%) were still in treatment

Conclusion: According to this preliminary experience, RTX appears to be effective in the treatment of RA-ILD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-and-safety-in-the-middle-long-period-of-rituximab-in-the-treatment-of-diffuse-interstitial-pulmonary-disease-associated-with-rheumatoid-arthritis/