Elevation of KL-6 serum levels in clinical trials of tumor necrosis factor inhibitors in patients with rheumatoid arthritis: a report from the Japan College of Rheumatology Ad Hoc Committee for Safety of Biological DMARDs

Biomarkers for interstitial lung disease and acute-onset diffuse interstitial lung disease in rheumatoid arthritis

Interstitial lung disease (ILD) is frequently a complication of rheumatoid arthritis (RA) as an extra-articular manifestation which has a poor prognosis. Acute-onset diffuse ILD (AoDILD) occasionally occurs in RA and includes acute exacerbation of ILD, drug-induced ILD, and Pneumocystis pneumonia. AoDILD also confers a poor prognosis in RA. Previously-established biomarkers for ILD include Krebs von den lungen-6 and surfactant protein-D originally defined in patients with idiopathic pulmonary fibrosis; the sensitivity of these markers for RA-associated ILD (RA-ILD) is low. Although many studies on ILD markers have been performed in idiopathic pulmonary fibrosis, only a few validation studies in RA-ILD or AoDILD have been reported. Biomarkers for RA-ILD and AoDILD are thus still required. Recently, genomic, cytokine, antibody, and metabolomic profiles of RA-ILD or AoDILD have been investigated with the aim of improving biomarkers. In this review, we summarize current preliminary data on these potential biomarkers for RA-ILD or AoDILD. The development of biomarkers on RA-ILD has only just begun. When validated, such candidate biomarkers will provide valuable information on pathogenesis, prognosis, and drug responses in RA-ILD in future.

Serum KL-6 elevation in a uveitis patient with Behçet's disease treated with adalimumab

Purpose

To report a case of uveitis with Behçet's disease in which serum levels of Krebs von den Lungen (KL)-6, a marker of interstitial lung disease, were elevated during treatment with adalimumab and returned to baseline after discontinuation of the agent.

Observations

A 67-year-old man complaining of vision disturbance was referred to our hospital. The patient had a history of recurrent episodes of bilateral uveitis and oral ulcers, and had been diagnosed with Behçet's disease. While uveitis activity was not well controlled under administration of oral prednisolone and cyclosporin, cataract of the right eye developed and required surgery. Biweekly administration of adalimumab 40 mg was therefore initiated with prednisolone at 15 mg/day. Uveitis became well controlled and cataract surgery was successfully carried out for the right eye. However, serum KL-6 gradually elevated to 1002 U/ml by 6 months after adalimumab initiation and 1277 U/ml at 9 months. Because serum KL-6 >1000 U/ml has been reported to predict interstitial lung disease, we discontinued adalimumab and started cyclosporine at 100 mg/day. Serum KL-6 gradually decreased and returned to baseline levels, no interstitial lung disease developed and exacerbation of uveitis was avoided.

Conclusions and importance

This case implies the clinical importance of monitoring serum KL-6 in patents with non-infectious uveitis being treated with adalimumab.

A Patient with KL-6 Elevation with Anti-TNFα Who Could Receive Long-Term Use without Interstitial Pneumonia after Class Switch of Anti-TNFα

A 40-year-old man with refractory ulcerative colitis (UC) was treated with tumor necrosis factor α inhibitor (anti-TNFα), infliximab. One month later, the chest computed tomography and laboratory test showed noninfectious interstitial lung disease (ILD) and elevation of serum Krebs von den Lungen-6 (KL-6). Fortunately, ILD disappeared after the discontinuation with anti-TNFα. Two and a half years after his first UC treatment, he was treated again with another anti-TNFα, adalimumab, for relapse and he had a second ILD. This course suggested anti-TNFα induced ILD. The characteristics of anti-TNFα-induced ILD in inflammatory bowel disease (IBD) are not well understood. We summarized and investigated the characteristics of such patients based on a literature review including 15 cases. It suggested that anti-TNFα-induced ILD in IBD might be rare and tends to have a better outcome compared with ILD in rheumatoid arthritis.

Phase III study of the efficacy and safety of subcutaneous versus intravenous tocilizumab monotherapy in patients with rheumatoid arthritis

Objective

To evaluate the efficacious noninferiority of subcutaneous tocilizumab injection (TCZ-SC) monotherapy to intravenous TCZ infusion (TCZ-IV) monotherapy in Japanese patients with rheumatoid arthritis (RA) with an inadequate response to synthetic and/or biologic disease-modifying antirheumatic drugs (DMARDs).

Methods

This study had a double-blind, parallel-group, double-dummy, comparative phase III design. Patients were randomized to receive TCZ-SC 162 mg every 2 weeks or TCZ-IV 8 mg/kg every 4 weeks; no DMARDs were allowed during the study. The primary end point was to evaluate the noninferiority of TCZ-SC to TCZ-IV regarding the American College of Rheumatology criteria for 20% improvement in disease activity (ACR20) response rates at week 24 using an 18% noninferiority margin. Additional efficacy, safety, pharmacokinetic, and immunogenicity parameters were assessed.

Results

At week 24, ACR20 response was achieved in 79.2% (95% confidence interval [95% CI] 72.9, 85.5) of the TCZ-SC group and in 88.5% (95% CI 83.4, 93.5) of the TCZ-IV group; the weighted difference was −9.4% (95% CI −17.6, −1.2), confirming the noninferiority of TCZ-SC to TCZ-IV. Remission rates of the Disease Activity Score in 28 joints using the erythrocyte sedimentation rate and the Clinical Disease Activity Index at week 24 were 49.7% and 16.4% in the TCZ-SC group and 62.2% and 23.1% in the TCZ-IV group, respectively. Serum trough TCZ concentrations were similar between the groups over time. Incidences of all adverse events and serious adverse events were 89.0% and 7.5% in the TCZ-SC group and 90.8% and 5.8% in the TCZ-IV group, respectively. Anti-TCZ antibodies were detected in 3.5% of the TCZ-SC group; no serious hypersensitivity was reported in these patients.

Conclusion

TCZ-SC monotherapy demonstrated comparable efficacy and safety to TCZ-IV monotherapy. TCZ-SC could provide additional treatment options for patients with RA.

A retrospective study of serum KL-6 levels during treatment with biological disease-modifying antirheumatic drugs in rheumatoid arthritis patients: a report from the Ad Hoc Committee for Safety of Biological DMARDs of the Japan College of Rheumatology

OBJECTIVE

We investigated associations between treatment with methotrexate (MTX) or biological disease-modifying antirheumatic drugs (DMARDs) and elevation of serum Krebs von den Lungen-6 (KL-6) levels in Japanese patients with rheumatoid arthritis (RA).

METHODS

Using a standardized form, data were collected retrospectively from medical records and analyzed descriptively.

RESULTS

Of a total of 198 RA patients with KL-6 serum levels measured at initiation of treatment (month 0) and two or more times by month 12, 27 (17.9 %) of 151 RA patients treated with biological DMARDs, including infliximab, etanercept, adalimumab, and tocilizumab (the biological DMARDs group), and 5 (10.6 %) of 47 patients treated without biological DMARDs but with MTX (MTX group), met criterion B (max. KL-6 ≥500 U/ml and >1.5-fold from baseline) by 12 months. The majority of patients (n = 28) meeting criterion B had no apparent interstitial lung disease or malignancy. Of these 28 patients, 21 had serum KL-6 levels available after reaching their maximum level, and 13 (61.9 %) of the 21 then met criterion R [decrease to less than 500 U/ml or to less than (baseline + 0.5 × (maximum - baseline))] by month 12.

CONCLUSION

Serum KL-6 levels may increase during treatment with MTX or these biological DMARDs without significant clinical events.