title: Gene expression profiling of whole blood in ipilimumab-treated patients for identification of potential biomarkers of immune-related gastrointestinal adverse events.
abstract: BACKGROUND
  Treatment with ipilimumab, a fully human anti-CTLA-4 antibody approved for the treatment of advanced melanoma, is associated with some immune-related adverse events (irAEs) such as colitis (gastrointestinal irAE, or GI irAE) and skin rash, which are managed by treatment guidelines. Nevertheless, predictive biomarkers that can help identify patients more likely to develop these irAEs could enhance the management of these toxicities.
  
  
  METHODS
  To identify candidate predictive biomarkers associated with GI irAEs, gene expression profiling was performed on whole blood samples from 162 advanced melanoma patients at baseline, 3 and 11 weeks after the start of ipilimumab treatment in two phase II clinical trials (CA184004 and CA184007). Overall, 49 patients developed Grade 2 or higher (grade 2+) GI irAEs during the course of treatment. A repeated measures analysis of variance (ANOVA) was used to evaluate the differences in mean expression levels between the GI irAE and No-GI irAE groups of patients at the three time points.
  
  
  RESULTS
  In baseline samples, 27 probe sets showed differential mean expression (≥ 1.5 fold, P ≤ 0.05) between the GI irAE and No-GI irAE groups. Most of these probe sets belonged to three functional categories: immune system, cell cycle, and intracellular trafficking. Changes in gene expression over time were also characterized. In the GI irAE group, 58 and 247 probe sets had a ≥ 1.5 fold change in expression from baseline to 3 and 11 weeks after first ipilimumab dose, respectively. In particular, on-treatment expression increases of CD177 and CEACAM1, two neutrophil-activation markers, were closely associated with GI irAEs, suggesting a possible role of neutrophils in ipilimumab-associated GI irAEs. In addition, the expression of several immunoglobulin genes increased over time, with greater increases in patients with grade 2+ GI irAEs.
  
  
  CONCLUSIONS
  Gene expression profiling of peripheral blood, sampled before or early in the course of treatment with ipilimumab, resulted in the identification of a set of potential biomarkers that were associated with occurrence of GI irAEs. However, because of the low sensitivity of these biomarkers, they cannot be used alone to predict which patients will develop GI irAEs. Further investigation of these biomarkers in a larger patient cohort is warranted.
authors.forename: Vafa
authors.initials: V
authors.lastname: Shahabi
authors.forename: David
authors.initials: D
authors.lastname: Berman
authors.forename: Scott D
authors.initials: SD
authors.lastname: Chasalow
authors.forename: Lisu
authors.initials: L
authors.lastname: Wang
authors.forename: Zenta
authors.initials: Z
authors.lastname: Tsuchihashi
authors.forename: Beihong
authors.initials: B
authors.lastname: Hu
authors.forename: Lisa
authors.initials: L
authors.lastname: Panting
authors.forename: Maria
authors.initials: M
authors.lastname: Jure-Kunkel
authors.forename: Rui-Ru
authors.initials: RR
authors.lastname: Ji
mesh_terms: D000911:Antibodies, Monoclonal / Q000009:adverse effects* / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000097:blood*; D058851:GPI-Linked Proteins / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000473:pathology*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007107:Immune System / Q000187:drug effects / Q000378:metabolism*; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism; D000074324:Ipilimumab; D007519:Isoantigens / Q000378:metabolism; D007958:Leukocyte Count; D008545:Melanoma / Q000097:blood / Q000188:drug therapy / Q000235:genetics*; D009504:Neutrophils / Q000378:metabolism; D012372:ROC Curve; D011956:Receptors, Cell Surface / Q000378:metabolism; D015203:Reproducibility of Results; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; C407242:CD177 protein, human; D058851:GPI-Linked Proteins; D007136:Immunoglobulins; D000074324:Ipilimumab; D007519:Isoantigens; D011956:Receptors, Cell Surface