Increased frequency of ICOS+ CD4 T cells as a pharmacodynamic biomarker for anti-CTLA-4 therapy

• Published in: Cancer immunology research Vol. 1; no. 4; p. 229
• Main Authors: Ng Tang, Derek, Shen, Yu, Sun, Jingjing, Wen, Sijin, Wolchok, Jedd D, Yuan, Jianda, Allison, James P, Sharma, Padmanee
• Format: Journal Article
• Language: English
• Published: United States 01.10.2013
• Subjects: Antibodies, Monoclonal - therapeutic use; Biomarkers; CD4-Positive T-Lymphocytes - immunology; CTLA-4 Antigen - immunology; Cytokines - immunology; Flow Cytometry; Healthy Volunteers; Humans; Inducible T-Cell Co-Stimulator Protein - immunology; Ipilimumab; Lymphocyte Activation - immunology; Melanoma - drug therapy; Melanoma - immunology; Randomized Controlled Trials as Topic; Sensitivity and Specificity; Vaccines, DNA - therapeutic use
• ISSN: 2326-6074
• DOI: 10.1158/2326-6066.CIR-13-0020

Pharmacodynamic biomarkers can play an important role in understanding whether a therapeutic agent has "hit its target" to impact biologic function. A pharmacodynamic biomarker for anti-CTLA-4 therapy remains to be elucidated. We previously reported that anti-CTLA-4 therapy increases the frequency of CD4 T cells expressing the inducible costimulator (ICOS) molecule. To determine whether the frequency of ICOS(+) CD4 T cells could be used as a pharmacodynamic biomarker for anti-CTLA-4 therapy, we carried out flow cytometric studies and statistical analyses on data from 56 individuals, which included 10 healthy donors, 36 patients who received anti-CTLA-4 monoclonal antibody (mAb), and 10 patients who received treatment with a different immunomodulatory agent (gp100 DNA vaccine). After treatment with anti-CTLA-4 mAb (ipilimumab; Bristol-Myers Squibb), we detected a statistically significant increase in the frequency of ICOS(+) CD4 T-cells. After two doses of anti-CTLA-4 therapy, the assay was found to have an estimated specificity of 96% [95% confidence interval (CI), 88-100] and sensitivity of 71% (95% CI, 54-85), with positive expression defined as a frequency that is more than the upper bound of 95% CI among baseline samples from all subjects. Our data suggest that an increased frequency of ICOS(+) CD4 T cells measured by flow cytometry can be used as a reproducible pharmacodynamic biomarker to indicate biologic activity in the setting of anti-CTLA-4 therapy, which should enable appropriate immune monitoring to determine whether patients receiving anti-CTLA-4 monotherapy or combination treatment strategies are having an adequate biologic response.