Complete regression of advanced primary and metastatic mouse melanomas following combination chemoimmunotherapy.

The development of therapeutic strategies which induce effective cellular antitumor immunity represents an important goal in cancer immunology. Here, we used the unique features of the genetically engineered Hgf-Cdk4(R24C) mouse model to identify a combination chemoimmunotherapy for melanoma. These mice develop primary cutaneous melanomas which grow progressively and metastasize in the absence of immunogenic foreign proteins such as oncogenes or antigens. Primary and metastatic tumors evade innate and adaptive immune defenses, although they naturally express melanocytic antigens which can be recognized by antigen-specific T cells. We found that primary melanomas continued to grow despite infiltration with adoptively transferred, in vivo-activated, tumor-specific CD8(+) T cells. To promote tumor immune defense, we developed a treatment protocol consisting of four complementary components: (a) chemotherapeutic preconditioning prior to (b) adoptive lymphocyte transfer and (c) viral vaccination followed by (d) adjuvant peritumoral injections of immunostimulatory nucleic acids. Lymphocyte ablation and innate antiviral immune stimulation cooperatively enhanced the expansion and the effector cell differentiation of adoptively transferred lymphocytes. The efficacy of the different treatment approaches converged in the tumor microenvironment and induced a strong cytotoxic inflammatory response enabling preferential recognition and destruction of melanoma cells. This combination chemoimmunotherapy caused complete regression of advanced primary melanomas in the skin and metastases in the lung with minimal autoimmune side effects. Our results in a clinically highly relevant experimental model provide a scientific rationale to evaluate similar strategies which unleash the power of innate and adaptive immune defense in future clinical trials.

Transcriptional profiling identifies an interferon-associated host immune response in invasive squamous cell carcinoma of the skin.

Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) represent the 2 most common types of nonmelanoma skin cancer. Both derive from keratinocytes but show a distinct biological behavior. Here we present transcriptional profiling data of a large cohort of tumor patients (SCC, n = 42; BCC, n = 114). Differentially expressed genes reflect known features of SCC and BCC including the typical cytokeratin pattern as well as upregulation of characteristic cell proliferation genes. Additionally, we found increased expression of interferon (IFN)-regulated genes (including IFI27, IFI30, Mx1, IRF1 and CXCL9) in SCC, and to a lower extent in BCC. The expression of IFN-regulated genes correlated with the extent of the lesional immune-cell infiltrate. Immunohistological examinations confirmed the expression of IFN-regulated genes in association with a CXCR3+ cytotoxic inflammatory infiltrate on the protein level. Of note, a small subset of SCC samples with low expression of IFN-regulated genes included most organ transplant recipients receiving immunosuppressive medication. Collectively, our findings support the concept that IFN-associated host responses play an important role in tumor immunosurveillance in the skin.

CXCR3 <-> ligand-mediated skin inflammation in cutaneous lichenoid graft-versus-host disease.

BACKGROUND: Lichenoid graft-versus-host disease (liGVHD) histologically shares several common features with other lichenoid dermatoses, such as cutaneous lupus erythematosus and lichen planus (LP), which collectively show a junctional infiltrate of cytotoxic lymphocytes with liquefaction of the basal layer ("interface dermatitis"). Because recent studies have shown a role for type I interferon (IFN)-associated inflammation, including lymphocyte recruitment via CXCR3 <-> ligand interaction in cutaneous lupus erythematosus and LP, we hypothesized that similar mechanisms might also be involved in liGVHD. METHODS: Ten representative lesional skin biopsies taken from patients with different subsets of chronic cutaneous graft versus host disease (GvDH) were recovered from the authors' archives. Eight LP specimens and 5 punch biopsies taken from healthy skin were analyzed for control purposes. Immunohistochemistry was performed to characterize the lesional infiltrate (CD3, CD4, CD8, CD20, CD56, or CD68), to analyze type I IFN signaling (MxA), and to investigate expression of the IFN-inducible chemokines CXCL9 and CXCL10 and their ligand CXCR3. In situ hybridization was performed to visualize IFNalpha expression on the mRNA level. RESULTS: Our analyses revealed striking similarities between the inflammatory pattern seen in LP and liGVHD. Both disorders presented with a predominantly T-cellular inflammation with CD8(+) lymphocytes affecting the basal epidermal layer. The majority of lesional lymphocytes expressed the chemokine receptor CXCR3. The corresponding chemokines CXCL9 and CXCL10 were found in the epidermis and within the inflammatory infiltrate. Analyses of MxA and IFNalpha mRNA expression supported a role for type I IFNs in these conditions. LIMITATIONS: This study was limited by the number of well characterized cases in our archives. In situ hybridization was realizable only in single cases. CONCLUSION: Our results support the hypothesis that CXCR3 <-> ligand-mediated lymphocyte recruitment is involved in cutaneous liGVHD. The fact that CXCL10 was seen in precisely those areas with extensive liquefaction of the basal epidermis supports a role of this chemokine for the development of the typical histologic "interface" pattern.

The role of cytotoxic skin-homing CD8+ lymphocytes in cutaneous cytotoxic T-cell lymphoma and pityriasis lichenoides.

BACKGROUND: Pityriasis lichenoides (PL) is a rare cutaneous lymphoproliferative disorder of unknown origin. Malignant transitions of PL have been described, but are very rare. We recently observed the fatal course of a 26-year-old patient who presented with a clinical picture resembling PL but had cytotoxic CD8+ T-cell lymphoma of the skin (CxCTL). This case prompted us to reinvestigate the role of cytotoxic T lymphocytes in PL and its relationship to antiviral immunity. METHODS: Skin biopsy specimens of 11 patients with PL and two biopsy specimens of CxCTL were included. In all, 5 biopsy specimens taken from healthy skin and 5 samples of varicella-zoster virus (VZV) skin lesions were analyzed for control purposes. The inflammatory infiltrate was characterized by immunohistochemistry using monoclonal antibodies against CD3, CD4, CD8, CD20, cutaneous lymphocyte-associated antigen (CLA), CCR4, CXCR3, Granzyme B, Tia-1, and MxA. Flow cytometry was used to analyze the expression of chemokine receptors on peripheral blood mononuclear cells in CxCTL. RESULTS: The CxCTL skin lesions were dominated by a dense infiltration of CD8+ cytotoxic lymphocytes with a skin-homing CLA+ CCR4+ phenotype. PL and VZV skin lesions were also characterized by a predominantly CD8+ T cellular infiltrate with strong expression of the cytotoxic molecules Granzyme B and Tia-1 and the skin-homing molecules CLA and CCR4. Coexpression analyses confirmed that skin CLA+ CD8+ cytotoxic T cells are present in CxCTL, VZV, and PL skin lesions. Strong lesional production of the antiviral protein MxA, which is specifically induced by type I interferons, could be found in all investigated disorders. The study was based on histologic, immunohistologic, and flow cytometric analyses in a limited number of patients, because of the rareness of the investigated diseases. CONCLUSION: Our results revealed a striking similarity between the immunohistologic picture of malignant CxCTL, benign PL, and VZV skin lesions. Strong expression of the antiviral protein MxA in all disorders supports the view that a common antiviral immune response pattern leads to aberrant skin recruitment of CLA+ CCR4+ cytotoxic T lymphocytes in PL and CxCTL.