Anti-integrin αvβ6 autoantibodies are a potential biomarker for ulcerative colitis-like immune checkpoint inhibitor-induced colitis

Abstract

Background: No specific biomarker for immune checkpoint inhibitor (ICI)-induced colitis has been established. Previously, we identified anti-integrin αvβ6 autoantibodies in >90% of patients with ulcerative colitis (UC). Given that a subset of ICI-induced colitis is similar to UC, we aimed to clarify the relationship between such autoantibodies and ICI-induced colitis.

Methods: Serum anti-integrin αvβ6 autoantibody levels were compared between 26 patients with ICI-induced colitis and 157 controls. Endoscopic images of ICI-induced colitis were centrally reviewed. Characteristics of anti-integrin αvβ6 autoantibodies in the ICI-induced colitis patients were compared with those of UC patients.

Results: Anti-integrin αvβ6 autoantibodies were found in 8/26 (30.8%) patients with ICI-induced colitis and 3/157 (1.9%) controls (P < 0.001). Patients with anti-integrin αvβ6 autoantibodies had significantly more typical UC endoscopic features than those without the autoantibodies (P < 0.001). Anti-integrin αvβ6 autoantibodies in ICI-induced colitis patients were associated with grade ≥3 colitis (P = 0.001) and steroid resistance (P = 0.005). Anti-integrin αvβ6 autoantibody titers correlated with ICI-induced colitis disease activity. Anti-integrin αvβ6 autoantibodies of ICI-induced colitis exhibited similar characteristics to those of UC.

Conclusions: Anti-integrin αvβ6 autoantibodies may serve as potential biomarkers for the diagnosis, classification, risk management, and monitoring the disease activity, of ICI-induced colitis.

Fig. 1. Detection of anti-integrin αvβ6 autoantibodies in serum samples of patients with ICI-induced colitis.

Serum IgG antibodies against integrin αvβ6 were quantified using ELISA. The sera of 26 patients with ICI-induced colitis, 39 ICI-treated patients with other types of irAEs (18 with hepatitis, 11 with endocrine dysfunction, 6 with pneumonitis, 4 with other irAEs), 77 patients with cancer without irAEs (16 with colon cancer, 15 with non-small cell lung cancer, 15 with gastric cancer, 15 with bile duct cancer, 12 with pancreatic cancer, 4 with melanoma), and 41 healthy volunteers were examined (Supplementary Table S1, Supplementary Table S3). IgG antibodies against integrin αvβ6 were identified in 8/26 (30.8%) patients with ICI-induced colitis and 3/157 (1.9%) controls. The cutoff OD value, defined as the mean plus three SDs of sera from the healthy volunteers, is indicated using a dashed line. The experiment was repeated independently twice with similar results. ELISA enzyme-linked immunosorbent assay, ICI immune checkpoint inhibitor, IgG immunoglobulin G, irAEs immune-related adverse events, OD optical density, SD standard deviation.

Fig. 2. Differences in endoscopic findings between patients with ICI-induced colitis with and without anti-integrin αvβ6 autoantibodies.

a Endoscopic images of patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies revealed findings similar to those of UC, including erythema, granularity, decreased vascular pattern, bleeding, and ulcer formation (Supplementary Table S5). In contrast, negative cases showed findings atypical of UC, such as punched ulcers. All patients underwent colonoscopy at the onset of the disease. b The average total number of typical UC findings assessed by two endoscopists was significantly higher in patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies compared to that in those without autoantibodies (median scores, 4.5 vs. 1.5; P < 0.001). The horizontal lines represent the median. ICI immune checkpoint inhibitor, UC ulcerative colitis.

Fig. 3. Correlation between anti-Integrin αvβ6 autoantibody titers and disease activity in patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies.

Serial blood samples from four patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies (Case 1, 10, 14, and 20) were used. Changes in autoantibody titers against integrin αvβ6 in ICI-induced colitis patients with anti-integrin αvβ6 autoantibodies correlated with the changes in the full or partial Mayo score. The left y-axis and the red points represent the OD values of anti-integrin αvβ6 serum IgG levels, while the right y-axis and the blue points represent the full or partial Mayo score. ICI immune checkpoint inhibitor, IgG immunoglobulin G, OD optical density.

Fig. 4. Blocking of integrin αvβ6-fibronectin binding by IgG from patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies.

a Inhibition of integrin αvβ6-fibronectin binding by IgG of patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies in the solid-phase binding assay. The cutoff OD value, defined as the mean plus three SDs of IgG from healthy volunteers, is indicated using a dashed line. IgG from six of eight (75%) patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies blocked integrin αvβ6-fibronectin binding. However, no control IgG showed blocking activity. b, c Peptide RGDS, but not RGES, dose-dependently impaired the binding of IgG of patients with ICI-induced colitis with anti-integrin αvβ6 autoantibodies against integrin αvβ6. The RGDS and RGES peptides represented the RGD and RGE motifs, respectively. The experiments were repeated independently twice with similar results. ICI immune checkpoint inhibitor, IgG immunoglobulin G, OD optical density, RGD Arg-Gly-Asp, RGDS Arg-Gly-Asp-Ser, RGE Arg-Gly-Glu, RGES Arg-Gly-Glu-Ser, SD standard deviation.

Fig. 5. Expression of integrin αvβ6 in tumor tissues of the patients with ICI-induced colitis with and without anti‐integrin αvβ6 autoantibodies.

a Representative H&E staining and immunohistochemical staining of integrin β6 in tumors of ICI-induced colitis patients with or without integrin αvβ6 autoantibodies. Scale bars, 100 µm. b H-score for integrin β6 immunostaining in tumors of patients with ICI-induced colitis with or without integrin αvβ6 autoantibodies. Horizontal lines indicate median values. The experiments were repeated independently twice with similar results. H&E hematoxylin-eosin, ICI immune checkpoint inhibitor.