Effect of Biological Therapy on Biomarkers in Patients With Untreated Hepatitis C, Metastatic Melanoma, or Crohn Disease

RATIONALE: Studying samples of blood from patients with cancer, hepatitis C, or Crohn disease in the laboratory may help doctors learn more about changes that occur in DNA and identify biomarkers related to cancer and other diseases. PURPOSE: This laboratory study is looking at the effect of biological therapy on biomarkers in patients with untreated hepatitis C, metastatic melanoma, or Crohn disease.

OBJECTIVES: * To determine how a variety of immune-modulating therapies (i.e., interferon alfa \[IFN-α\] in patients with untreated acute or chronic hepatitis C, anti-tumor necrosis factor in patients with active inflammatory bowel disease (i.e., Crohn disease), and anticytotoxic T-lymphocyte antigen immunoglobulin in patients with metastatic melanoma) affect the tissue expression of indoleamine 2, 3 dioxygenase (IDO), a major immune-regulatory mechanism. * To determine whether administration of pegylated INF-α in patients with untreated acute and chronic hepatitis C causes systemic changes in the IDO pathway, as indicated by lowered serum tryptophan (TRP) and elevated serum kynurenine (KYN). * To determine whether administration of ticilimumab (i.e., anti-CTLA4 human monoclonal antibody CP-675,206) in patients with metastatic melanoma inhibits activation of the IDO pathway as indicated by normal serum TRP and normal serum KYN. * To determine whether administration of infliximab in patients with Crohn disease inhibits activation of the IDO pathway, as indicated by normal serum TRP and normal serum KYN. OUTLINE: Serum samples are collected from patients with hepatitis C and metastatic melanoma at baseline and at 3 to 4 weeks after treatment is initiated. Previously collected samples from patients with Crohn disease are also assessed at these time points. Samples are analyzed for tryptophan and kynurenine levels via high-performance liquid chromatography. PROJECTED ACCRUAL: A total of 15 patients with untreated acute or chronic Hepatitis C, 15 patients with metastatic melanoma, and 20 patients with Crohn disease will be accrued for this study.