Serological biomarkers predict immune-related adverse events and clinical benefit in patients with advanced gastrointestinal cancers

Abstract

Background: Immune checkpoint inhibitors (ICIs) have dramatically improved survival in advanced gastrointestinal (GI) cancer patients, but also resulted in immune-related adverse events (irAEs). This study aimed to evaluate serological biomarkers of irAEs and treatment response in GI cancer patients.

Patients and methods: Metastatic GI cancer patients were enrolled between August 1, 2015, and July 31, 2017. Serum samples were collected at baseline, and a panel of 59 serum biomarkers was tested. The occurrence of irAEs was analyzed, and serological biomarker expression was correlated with irAE incidence and prognosis.

Results: Fifty-one patients were enrolled, of whom 47.1% (24/51) were diagnosed with irAEs, including 4 patients (7.8%) with grade 3-5 irAEs. The most common irAE was thyroiditis (9/51, 17.6%), followed by colitis (7/51, 13.7%). The expression of CD28 (P = 0.042), IL-4 (P = 0.033), IL-15 (P = 0.024) and PD-L1 (P = 0.018) was significantly elevated in patients with grade 3-5 irAEs. For organ-specific irAEs, IL-6 levels were higher in patients with thyroiditis and colitis, while IL-22 and SCF levels were higher in patients with colitis. Increased IL-1α, IL-21, LIF, and PIGF-1 levels were significantly associated with myositis incidence, while the serum levels of six cytokines (BTLA, GM-CSF, IL-4, PD-1, PD-L1 and TIM-3) were higher in patients with rash. Prognostic analysis showed that patients with irAEs had better tumor response (P = 0.029), improved PFS (median survival: undefined vs. 2.1 months, P = 0.002), and extended OS (median survival: undefined vs. 4.3 months, P = 0.003). The prognostic value of irAEs was only significant in patients who received anti-PD-1 inhibitors, but not in those who received anti-PD-L1 inhibitors. Besides, elevated BTLA (median OS: not reached vs. 7 months; P = 0.0168) and PD-1 (median OS: not reached vs. 7 months; P = 0.0223) concentrations were associated with longer OS.

Conclusions: Serological proteins are promising markers for predicting immune-related toxicity and prognosis in GI cancer patients. Organ-specific irAEs have various cytokine profiles. Although further validation is needed before clinical application, this study provided a direction for identifying patients at risk for irAEs, and guiding patient selection for ICI therapy.

Keywords: biomarker; cytokines; gastrointestinal cancers; immune checkpoint inhibitors; immune-related adverse events.

Figure 1

Baseline serum cytokine levels are significantly associated with irAE development and severity. Box plots (left) showing the distribution of serum cytokines (A) CD28, (B) IL-4, (C) IL-15, and (D) PD-L1 in grade 0-2 and 3-5 patients. ROC curve (right) analysis of sensitivity and specificity of serum cytokines (A) CD28, (B) IL-4, (C) IL-15, and (D) PD-L1 from baseline, to distinguish between grade 0-2 and 3-5 irAEs. The median of each group and P-value were calculated using the Mann-Whitney U test (P < 0.05). irAEs: immune-related adverse events, ROC: receiver operating characteristics.

Figure 2

Association between serum cytokine levels and organ-specific irAEs. (A) Box plots representing serum IL-6 levels (pg/mL) in thyroiditis (n = 9) and non-thyroiditis (n = 42) patients. (B) Box plots representing serum IL-6, IL-22, and SCF levels (pg/mL) in colitis (n = 7) and non-colitis (n = 44) patients. (C) Box plots representing serum IL-1α, IL-21, LIF, and PIGF-1 levels (pg/mL) in myositis (n = 5) and non-myositis (n = 46) patients. (D) Box plots representing serum BTLA, GM-CSF, IL-4, TIM-3, PD-L1, and PD-1 levels (pg/mL) in patients with (n = 3) and without rash (n = 48). The median of each group and P-value were calculated using the Mann-Whitney U test (P < 0.05).

Figure 3

Baseline serum cytokine levels related to clinical outcomes. (A) Bar Chart showing the response rate in patients with (n = 24) and without irAEs (n = 27). (B) Kaplan-Meier survival curve of PFS and OS in the irAE (n = 24) and non-irAE (n = 27) groups. (C) Kaplan-Meier survival curve of progression-free survival (PFS) and overall survival (OS) following anti-PD-L1 (n = 18) and anti-PD-1 (n = 33) treatment in irAE and non-irAE groups. (D) OS of gastrointestinal cancer patients based on BTLA and PD-1 levels. CR: complete response, PR: partial response, SD: stable disease, PD: progressive disease, PFS: progression-free survival, OS: overall survival. Kaplan-Meier survival curves were plotted for patients using the median cutoff. Statistical significance was determined using the log‐rank (Mantel-Cox) regression analysis, with the level of significance at P ≤ 0.05.