Melan-A/MART-1 immunity in a EWS-ATF1 translocated clear cell sarcoma patient treated with sunitinib: a case report

Abstract

Background: Clear cell sarcoma (CCS), initially named malignant melanoma of soft parts, is an aggressive soft tissue sarcoma (STS) that, due to MITF activation, shares with melanoma the expression of melanocyte differentiation antigens. CCS is poorly sensitive to chemotherapy. Multi-kinase inhibitors have been used as therapeutic agents. In the case we report here, treatment with sunitinib induced a long-lasting clinical response that was associated with an immune activation directed against Melan-A/MART-1 antigen.

Case presentation: A 28 years old female patient with an advanced molecularly confirmed CCS resistant to conventional chemotherapy was started in January 2012 on sunitinib, 37.5 mg/day, with evidence of radiologic and metabolic response at the primary and metastatic sites of disease. Pathologic response and loss of the Melan-A/MART-1 antigen were evidenced on residual tumor removed in April 2012. Immunological monitoring performed on patient's blood during pharmacological treatment revealed a systemic, Melan-A/MART-1 specific immunity and a low frequency of immunosuppressive cells. Sunitinib was restarted in May 2012, with a new response, and continued for 11 months although with repeatedly interruptions due to toxicity. Disease progression and new responses were documented at each treatment interruption and restart. Sunitinib was definitively interrupted in April 2013 for disease progression.

Conclusion: The analysis of this case proves that antigens expressed by CCS, as for melanoma, can be immunogenic in vivo and that tumor-antigen specific T cells may exert anti-tumor activity in CCS patient. Thus, manipulation of the immune response may have therapeutic potential for this STS subtype and immunotherapy approaches, can be promising therapeutic options for these patients.

Figures

Figure 1

Response to sunitinib: FDG-PET and CT scan evaluation. (A) Baseline FDG PET/CT study: sagittal fused PET/CT image showing abnormal FDG uptakes in the left foot tumor (circle; SUVmax 12.0) and in soft tissue metastatic nodules in the ankle and leg (arrows); (B) After 8 weeks of treatment with SM 37.5 mg/day, PET/CT re-evaluation shows a complete metabolic response of the foot lesion (circle; SUVmax 2.5; ΔSUV −79%) and the disappearance of the soft tissue nodules. (C) CT scan (venous phase after contrast medium) shows a complete response to a right inguinal lymph node after 3 months of treatment with sunitinib (green arrow), compared to baseline (red arrow).

Figure 2

Immunohistochemical analysis of tumor antigens expression and T cell infiltration. (A) Hematoxylin and eosin (H&E), Melan-A/MART-1 and HMB-45/gp100 stainings in pre- (November 2011) and post- (April 2012) sunitinib tumor lesions. (B) Analysis of infiltrating immune T cells (CD3 and CD8) in sunitinib-treated tumor. Higher magnification in a shows area of pathologic tumor regression associated with lymphocyte infiltration; Bottom panels show CD3 and CD8 stainings; square b reports the high magnification of area infiltrated by CD8+ T cells. All scale bars indicate 50 μm.

Figure 3

Phenotypic and functional analysis of tumor antigen-specific CD8 T cells. (A) Phenotypic analysis of pentamer+ CD8+ T cells after sensitization with the HLA2-A*0201 restricted-modified peptides (Melan-A/MART-1[27L] or gp100[210M]). (B) The tumor specificity of peptide sensitized T cells was assessed by measuring IFN-γ secretion (Enzyme-Linked ImmunoSpot (ELISpot) assay) upon stimulation with HLA-A*0201-restricted Melan A/MART-1 (modified or native)-pulsed (2 μmol/L) lymphoblastoid T2 cell line or HLA-matched HLA-A*0201+MART1+ tumor cells (#501mel and #624.38mel) pretreated or not with the anti-HLA class I (W6/32) mAb. Moreover, T cells were also incubated with HLA-mismatched allogeneic HLA-A*0201−MART1+ (#624.28mel) or HLA-A*0201+MART1− melanoma cells (#A375mel). The irrelevant peptide NEF[180–189] was used as negative control. P values were calculated by two-tailed t test.

Figure 4

Frequency of circulating mMDSCs and T cell function during sunitinib treatment. Histograms show the frequencies of CD14+HLADRneg/low (mMDSCs) in live gated CD14+CD11b+ cells of patient’s PBMCs. Average level of mMDSC frequency of healthy donors (HD) is reported. Patient’s PBMCs were assayed for IFN-γ (red line) and IL-2 (blue line) production in response to overnight activation with anti-CD3/CD28-coated beads. Dotted horizontal lines (IFN-γ (red) and IL-2 (blue)) indicate the average level of cytokine-producing T cells in HD.