Abstract 1233: Immunological biomarkers predicting survival in late-stage melanoma patients.
Authors: Martens Alexander , Zelba Henning , Weide Benjamin , Garbe Claus , Pawelec Graham P. 
Published: August 2014

Malignant melanoma patients with unresectable distant metastasis have a very poor prognosis, with median survival of 9 months. Although immunotherapeutic approaches do sometimes lead to impressive results, this can only be seen in a few patients. The level of Lactate dehydrogenase (LDH), the only established biomarker so far, cannot predict the clinical outcome of single patients. We have previously reported that the presence of peripheral T cells able to recognize the tumor antigens NY-ESO-1 and/or Melan-A not only predicts clinical outcome in late-stage melanoma but is even superior to the AJCC M category. Furthermore, we were also able to show that of the many peripheral blood immune cells, including activated, resting T-regulatory cells and dendritic cells (DCs), only the frequency of one subset of myeloid-derived suppressor cells (MDSCs) also predicted survival. The current study investigates whether these immunological parameters have independent impacts on individual patient survival.

We measured T cells reactive against NY-ESO-1 and Melan-A in stage IV melanoma patients with unresectable distant metastases. In order to include patients of any HLA type, overlapping peptides spanning the whole protein were used to expand reactive T cells within the peripheral blood in vitro. Polychromatic flow cytometry with intracellular cytokine staining of six different cytokines (IFN-γ, TNF-α, IL-2, IL-4, IL-10 and IL-17) allowed us to analyze the phenotype (CD4-versus-CD8) and effector function (pro- versus anti-inflammatory responses) of the antigen-reactive T cells on a single-cell basis. Different immune cell populations (MDSCs, regulatory T cells, DCs) were identified using polychromatic flow cytometry measurements.

Based on our previous data, we defined three independent “risk groups” for late-stage melanoma patients: (i) Patients without T cells capable of recognizing the cancer/testis antigen NY-ESO-1, (ii) patients without T cells capable of recognizing the differentiation antigen Melan-A and (iii) patients with high amounts of a certain subset of MDSCs (CD14+HLA-DR-/low cells at &gt;11.8% of PBMCs using a previously-defined cut-off). Each of these parameters separately predicted poorer survival of the patient compared to the reciprocal group. Here, we show that patients falling into all 3 risk groups have by far the shortest survival time (≤6 months) of all tested patients. Thus, patients with no T cells reactive to NY-ESO-1 or Melan-A, and with higher levels of MSDCs, were at a significant survival disadvantage. In contrast, longest survivors (&gt;30 months) reacted against both NY-ESO-1 and Melan-A and also had low CD14+HLA-DR-/low MDSCs. Our results confirm the importance of NY-ESO-1 and Melan-A as major target antigens in melanoma and indicate that inhibition of CD14+HLA-DR-/low MDSCs might be a promising therapeutic approach, as their lower percentages correlate with better prognosis and clinical outcome.

Citation Format: Alexander Martens, Henning Zelba, Benjamin Weide, Claus Garbe, Graham P. Pawelec. Immunological biomarkers predicting survival in late-stage melanoma patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1233. doi:10.1158/1538-7445.AM2013-1233