title: Frequencies of circulating MDSC correlate with clinical outcome of melanoma patients treated with ipilimumab.
abstract: Metastatic melanoma has a poor prognosis with high resistance to chemotherapy and radiation. Recently, the anti-CTLA-4 antibody ipilimumab has demonstrated clinical efficacy, being the first agent to significantly prolong the overall survival of inoperable stage III/IV melanoma patients. A major aim of patient immune monitoring is the identification of biomarkers that predict clinical outcome. We studied circulating myeloid-derived suppressor cells (MDSC) in ipilimumab-treated patients to detect alterations in the myeloid cell compartment and possible correlations with clinical outcome. Lin(-) CD14(+) HLA-DR(-) monocytic MDSC were enriched in peripheral blood of melanoma patients compared to healthy donors (HD). Tumor resection did not significantly alter MDSC frequencies. During ipilimumab treatment, MDSC frequencies did not change significantly compared to baseline levels. We observed high inter-patient differences. MDSC frequencies in ipilimumab-treated patients were independent of baseline serum lactate dehydrogenase levels but tended to increase in patients with severe metastatic disease (M1c) compared to patients with metastases in skin or lymph nodes only (M1a), who had frequencies comparable to HD. Interestingly, clinical responders to ipilimumab therapy showed significantly less lin(-) CD14(+) HLA-DR(-) cells as compared to non-responders. The data suggest that the frequency of monocytic MDSC may be used as predictive marker of response, as low frequencies identify patients more likely benefitting from ipilimumab treatment. Prospective clinical trials assessing MDSC frequencies as potential biomarkers are warranted to validate these observations.
authors.affiliation: Ludwig Center for Cancer Research of the University of Lausanne, Lausanne, Switzerland.
authors.forename: Christiane
authors.initials: C
authors.lastname: Meyer
authors.forename: Laurène
authors.initials: L
authors.lastname: Cagnon
authors.forename: Carla M
authors.initials: CM
authors.lastname: Costa-Nunes
authors.forename: Petra
authors.initials: P
authors.lastname: Baumgaertner
authors.forename: Nicole
authors.initials: N
authors.lastname: Montandon
authors.forename: Loredana
authors.initials: L
authors.lastname: Leyvraz
authors.forename: Olivier
authors.initials: O
authors.lastname: Michielin
authors.forename: Emanuela
authors.initials: E
authors.lastname: Romano
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Speiser
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D054316:Biomarkers, Pharmacological; D002452:Cell Count; D005260:Female; D006801:Humans; D007108:Immune Tolerance; D000074324:Ipilimumab; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008297:Male; D008545:Melanoma / Q000097:blood / Q000188:drug therapy*; D008875:Middle Aged; D022423:Myeloid Cells / Q000187:drug effects* / Q000276:immunology; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D012878:Skin Neoplasms / Q000097:blood / Q000188:drug therapy*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D054316:Biomarkers, Pharmacological; D000074324:Ipilimumab; D018950:Lipopolysaccharide Receptors