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INTRODUCTION: Despite the success of immunotherapies for melanoma in recent years, there remains a significant proportion of patients who do not yet derive benefit from available treatments. Immunotherapies currently licensed for clinical use target the adaptive immune system, focussing on Tcell interactions and functions. However, the most prevalent immune cells within the tumor microenvironment (TME) of melanoma are macrophages, a diverse immune cell subset displaying high plasticity, to which no current therapies are yet directly targeted. Macrophages have been shown not only to activate the adaptive immune response, and enhance cancer cell killing, but, when influenced by factors within the TME of melanoma, these cells also promote melanoma tumorigenesis and metastasis. AREAS COVERED: We present a review of the most up-to-date literatureavailable on PubMed, focussing on studies from within the last 10 years. We also include data from ongoing and recent clinical trials targeting macrophages in melanoma listed on clinicaltrials.gov. EXPERT OPINION: Understanding the multifaceted role of macrophages in melanoma, including their interactions with immune and cancer cells, the influence of current therapies on macrophage phenotype and functions and how macrophages could be targeted with novel treatment approaches, are all critical for improving outcomes for patients with melanoma.
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Imunoterapia , Melanoma , Microambiente Tumoral , Macrófagos Associados a Tumor , Humanos , Melanoma/imunologia , Melanoma/terapia , Melanoma/patologia , Microambiente Tumoral/imunologia , Imunoterapia/métodos , Imunoterapia/tendências , Macrófagos Associados a Tumor/imunologia , Animais , Terapia de Alvo Molecular , Ensaios Clínicos como Assunto , Macrófagos/imunologiaRESUMO
B cells are known to contribute to the anti-tumor immune response, especially in immunogenic tumors such as melanoma, yet humoral immunity has not been characterized in these cancers to detail. Here we show comprehensive phenotyping in samples of circulating and tumor-resident B cells as well as serum antibodies in melanoma patients. Memory B cells are enriched in tumors compared to blood in paired samples and feature distinct antibody repertoires, linked to specific isotypes. Tumor-associated B cells undergo clonal expansion, class switch recombination, somatic hypermutation and receptor revision. Compared with blood, tumor-associated B cells produce antibodies with proportionally higher levels of unproductive sequences and distinct complementarity determining region 3 properties. The observed features are signs of affinity maturation and polyreactivity and suggest an active and aberrant autoimmune-like reaction in the tumor microenvironment. Consistent with this, tumor-derived antibodies are polyreactive and characterized by autoantigen recognition. Serum antibodies show reactivity to antigens attributed to autoimmune diseases and cancer, and their levels are higher in patients with active disease compared to post-resection state. Our findings thus reveal B cell lineage dysregulation with distinct antibody repertoire and specificity, alongside clonally-expanded tumor-infiltrating B cells with autoimmune-like features, shaping the humoral immune response in melanoma.
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Linfócitos B , Melanoma , Humanos , Melanoma/genética , Anticorpos , Imunidade Humoral , Autoantígenos/genética , Microambiente TumoralRESUMO
Outcomes for half of patients with melanoma remain poor despite standard-of-care checkpoint inhibitor therapies. The prevalence of the melanoma-associated antigen chondroitin sulfate proteoglycan 4 (CSPG4) expression is ~70%, therefore effective immunotherapies directed at CSPG4 could benefit many patients. Since IgE exerts potent immune-activating functions in tissues, we engineer a monoclonal IgE antibody with human constant domains recognizing CSPG4 to target melanoma. CSPG4 IgE binds to human melanomas including metastases, mediates tumoricidal antibody-dependent cellular cytotoxicity and stimulates human IgE Fc-receptor-expressing monocytes towards pro-inflammatory phenotypes. IgE demonstrates anti-tumor activity in human melanoma xenograft models engrafted with human effector cells and is associated with enhanced macrophage infiltration, enriched monocyte and macrophage gene signatures and pro-inflammatory signaling pathways in the tumor microenvironment. IgE prolongs the survival of patient-derived xenograft-bearing mice reconstituted with autologous immune cells. No ex vivo activation of basophils in patient blood is measured in the presence of CSPG4 IgE. Our findings support a promising IgE-based immunotherapy for melanoma.
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Melanoma , Proteoglicanas , Humanos , Camundongos , Animais , Proteoglicanas/metabolismo , Antígenos , Proteoglicanas de Sulfatos de Condroitina , Melanoma/metabolismo , Anticorpos Monoclonais/farmacologia , Imunoglobulina E , Microambiente TumoralRESUMO
The application of monoclonal antibodies (mAbs) for the treatment of melanoma has significantly improved the clinical management of this malignancy over the last decade. Currently approved mAbs for melanoma enhance T cell effector immune responses by blocking immune checkpoint molecules PD-L1/PD-1 and CTLA-4. However, more than half of patients do not benefit from treatment. Targeting the prominent myeloid compartment within the tumor microenvironment, and in particular the ever-abundant tumor-associated macrophages (TAMs), may be a promising strategy to complement existing therapies and enhance treatment success. TAMs are a highly diverse and plastic subset of cells whose pro-tumor properties can support melanoma growth, angiogenesis and invasion. Understanding of their diversity, plasticity and multifaceted roles in cancer forms the basis for new promising TAM-centered treatment strategies. There are multiple mechanisms by which macrophages can be targeted with antibodies in a therapeutic setting, including by depletion, inhibition of specific pro-tumor properties, differential polarization to pro-inflammatory states and enhancement of antitumor immune functions. Here, we discuss TAMs in melanoma, their interactions with checkpoint inhibitor antibodies and emerging mAbs targeting different aspects of TAM biology and their potential to be translated to the clinic.
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Antineoplásicos Imunológicos , Melanoma , Anticorpos Monoclonais/uso terapêutico , Antineoplásicos Imunológicos/uso terapêutico , Antígeno B7-H1/uso terapêutico , Antígeno CTLA-4 , Humanos , Proteínas de Checkpoint Imunológico , Imunoterapia , Melanoma/tratamento farmacológico , Plásticos/uso terapêutico , Receptor de Morte Celular Programada 1/uso terapêutico , Neoplasias Cutâneas , Microambiente Tumoral , Macrófagos Associados a Tumor , Melanoma Maligno CutâneoRESUMO
B cells are emerging as key players of anti-tumor adaptive immune responses. We investigated regulatory and pro-inflammatory cytokine-expressing B cells in patients with melanoma by flow cytometric intracellular cytokine, CyTOF, transcriptomic, immunofluorescence, single-cell RNA-seq, and B:T cell co-culture analyses. We found enhanced circulating regulatory (TGF-ß+ and PD-L1+) and reduced pro-inflammatory TNF-α+ B cell populations in patients compared with healthy volunteers (HVs), including lower IFN-γ+:IL-4+ and higher TGF-ß+:TNF-α+ B cell ratios in patients. TGF-ß-expressing B cells in the melanoma tumor microenvironment assembled in clusters and interacted with T cells via lymphoid recruitment (SELL, CXCL13, CCL4, CD74) signals and with Tregs via CD47:SIRP-γ, and FOXP3-promoting Galectin-9:CD44. While reduced in tumors compared to blood, TNF-α-expressing B cells engaged in crosstalk with Tregs via TNF-α signaling and the ICOS/ICOSL axis. Patient-derived B cells promoted FOXP3+ Treg differentiation in a TGF-ß-dependent manner, while sustaining expression of IFN-γ and TNF-α by autologous T-helper cells and promoting T-helper cell proliferation ex vivo, an effect further enhanced with anti-PD-1 checkpoint blockade. Our findings reveal cytokine-expressing B cell compartments skewed toward regulatory phenotypes in patient circulation and melanoma lesions, intratumor spatial localization, and bidirectional crosstalk between B and T cell subsets with immunosuppressive attributes.
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Linfócitos B Reguladores , Melanoma , Neoplasias Cutâneas , Linfócitos T Reguladores , Linfócitos B Reguladores/imunologia , Fatores de Transcrição Forkhead/metabolismo , Humanos , Melanoma/imunologia , Neoplasias Cutâneas/imunologia , Linfócitos T Reguladores/imunologia , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismo , Microambiente Tumoral , Fator de Necrose Tumoral alfa/metabolismoRESUMO
INTRODUCTION: The treatment of cutaneous melanoma has been revolutionized by the development of small-molecule inhibitors targeting the MAPK pathway, including inhibitors of BRAF (BRAFi) and MEK (MEKi), and immune checkpoint blockade antibodies, occurring in tandem. Despite these advances, the 5-year survival rate for patients with advanced melanoma remains only around 50%. Although not designed to alter immune responses within the tumor microenvironment (TME), MAPK pathway inhibitors (MAPKi) exert a range of effects on the host immune compartment that may offer opportunities for therapeutic interventions. AREAS COVERED: We review the effects of MAPKi, especially BRAFi, on the TME, focusing on alterations in inflammatory cytokine secretion, recruitment of immune cells and their functions, both during response to BRAFi treatment and as resistance develops. We outline potential combinations of MAPKi with established and experimental treatments. EXPERT OPINION: MAPKi in combination or in sequence with established treatments such as checkpoint inhibitors, anti-angiogenic agents, or new therapies such as adoptive cell therapies, may augment their immunological effects, reverse tumor-associated immune suppression, and offer the prospect of longer-lived clinical responses. Refining therapeutic tools at our disposal and embracing 'old friends' in the melanoma treatment arsenal, alongside new target identification, may improve the chances of therapeutic success.
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Melanoma , Neoplasias Cutâneas , Humanos , Melanoma/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas B-raf , Neoplasias Cutâneas/tratamento farmacológico , Microambiente TumoralRESUMO
Cytotoxic T-lymphocyte associated protein-4 (CTLA-4) and the Programmed Death Receptor 1 (PD-1) are immune checkpoint molecules that are well-established targets of antibody immunotherapies for the management of malignant melanoma. The monoclonal antibodies, Ipilimumab, Pembrolizumab, and Nivolumab, designed to interfere with T cell inhibitory signals to activate immune responses against tumors, were originally approved as monotherapy. Treatment with a combination of immune checkpoint inhibitors may improve outcomes compared to monotherapy in certain patient groups and these clinical benefits may be derived from unique immune mechanisms of action. However, treatment with checkpoint inhibitor combinations also present significant clinical challenges and increased rates of immune-related adverse events. In this review, we discuss the potential mechanisms attributed to single and combined checkpoint inhibitor immunotherapies and clinical experience with their use.
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Anticorpos Monoclonais/imunologia , Antígeno CTLA-4/imunologia , Inibidores de Checkpoint Imunológico/imunologia , Melanoma/imunologia , Melanoma/terapia , Receptor de Morte Celular Programada 1/imunologia , Neoplasias Cutâneas/imunologia , Neoplasias Cutâneas/terapia , Animais , Humanos , Imunoterapia/métodos , Melanoma/metabolismo , Neoplasias Cutâneas/metabolismo , Melanoma Maligno CutâneoAssuntos
Técnicas Cosméticas , Acessibilidade aos Serviços de Saúde/tendências , Necessidades e Demandas de Serviços de Saúde/tendências , Hialuronoglucosaminidase/provisão & distribuição , Hialuronoglucosaminidase/uso terapêutico , Procedimentos de Cirurgia Plástica , Adjuvantes Farmacêuticos/uso terapêutico , Anestesia Local/métodos , Técnicas Cosméticas/efeitos adversos , Técnicas Cosméticas/tendências , Preenchedores Dérmicos/efeitos adversos , Extravasamento de Materiais Terapêuticos e Diagnósticos/tratamento farmacológico , Humanos , Ácido Hialurônico/efeitos adversos , Procedimentos de Cirurgia Plástica/efeitos adversos , Procedimentos de Cirurgia Plástica/métodos , Procedimentos de Cirurgia Plástica/tendências , Reino UnidoRESUMO
We report a case of rapidly enlarging metastatic melanoma in 45-year-old White male following primary resection of thin melanoma five years ago. Location and large size of the lesion possessed significant risk of complications from surgery, therefore provided a challenge in treatment options. Neoadjuvant targeted chemotherapy was commenced and resulted in a significant reduction in size of the lesion, which allowed subsequent safe surgical resection with no residual disease on histopathology results. This case provides a good example of successful utilization of neoadjuvant systemic therapy in advanced metastatic melanoma.
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The contributions of the humoral immune response to melanoma are now widely recognized, with reports of positive prognostic value ascribed to tumor-infiltrating B cells (TIL-B) and increasing evidence of B cells as key predictors of patient response to treatment. There are disparate views as to the pro- and anti-tumor roles of B cells. B cells appear to play an integral role in forming tumor-associated tertiary lymphoid structures (TLSs) which can further modulate T cell activation. Expressed antibodies may distinctly influence tumor regulation in the tumor microenvironment, with some isotypes associated with strong anti-tumor immune response and others with progressive disease. Recently, B cells have been evaluated in the context of cancer immunotherapy. Checkpoint inhibitors (CPIs), targeting T cell effector functions, have revolutionized the management of melanoma for many patients; however, there remains a need to accurately predict treatment responders. Increasing evidence suggests that B cells may not be simple bystanders to CPI immunotherapy. Mature and differentiated B cell phenotypes are key positive correlates of CPI response. Recent evidence also points to an enrichment in activatory B cell phenotypes, and the contribution of B cells to TLS formation may facilitate induction of T cell phenotypes required for response to CPI. Contrastingly, specific B cell subsets often correlate with immune-related adverse events (irAEs) in CPI. With increased appreciation of the multifaceted role of B cell immunity, novel therapeutic strategies and biomarkers can be explored and translated into the clinic to optimize CPI immunotherapy in melanoma.
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Anticorpos Antineoplásicos/uso terapêutico , Linfócitos B , Inibidores de Checkpoint Imunológico/uso terapêutico , Melanoma , Linfócitos B/imunologia , Linfócitos B/patologia , Humanos , Melanoma/imunologia , Melanoma/patologia , Melanoma/terapiaRESUMO
The immune system employs several checkpoint pathways to regulate responses, maintain homeostasis and prevent self-reactivity and autoimmunity. Tumor cells can hijack these protective mechanisms to enable immune escape, cancer survival and proliferation. Blocking antibodies, designed to interfere with checkpoint molecules CTLA-4 and PD-1/PD-L1 and counteract these immune suppressive mechanisms, have shown significant success in promoting immune responses against cancer and can result in tumor regression in many patients. While inhibitors to CTLA-4 and the PD-1/PD-L1 axis are well-established for the clinical management of melanoma, many patients do not respond or develop resistance to these interventions. Concerted efforts have focused on combinations of approved therapies aiming to further augment positive outcomes and survival. While CTLA-4 and PD-1 are the most-extensively researched targets, results from pre-clinical studies and clinical trials indicate that novel agents, specific for checkpoints such as A2AR, LAG-3, IDO and others, may further contribute to the improvement of patient outcomes, most likely in combinations with anti-CTLA-4 or anti-PD-1 blockade. This review discusses the rationale for, and results to date of, the development of inhibitory immune checkpoint blockade combination therapies in melanoma. The clinical potential of new pipeline therapeutics, and possible future therapy design and directions that hold promise to significantly improve clinical prognosis compared with monotherapy, are discussed.
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Anticorpos Monoclonais/imunologia , Sistema Imunitário/efeitos dos fármacos , Sistema Imunitário/imunologia , Melanoma/imunologia , Melanoma/terapia , Animais , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais/uso terapêutico , Antígeno B7-H1/imunologia , Antígeno CTLA-4/imunologia , Humanos , Imunoterapia/métodosRESUMO
Cancer cells are thought to use actin rich invadopodia to facilitate matrix degradation. Formation and maturation of invadopodia requires the co-ordained activity of Rho-GTPases, however the molecular mechanisms that underlie the invadopodia lifecycle are not fully elucidated. Previous work has suggested a formation and disassembly role for Rho family effector p-21 activated kinase 1 (PAK1) however, related family member PAK4 has not been explored. Systematic analysis of isoform specific depletion using in vitro and in vivo invasion assays revealed there are differential invadopodia-associated functions. We consolidated a role for PAK1 in the invadopodia formation phase and identified PAK4 as a novel invadopodia protein that is required for successful maturation. Furthermore, we find that PAK4 (but not PAK1) mediates invadopodia maturation likely via inhibition of PDZ-RhoGEF. Our work points to an essential role for both PAKs during melanoma invasion but provides a significant advance in our understanding of differential PAK function.
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Melanoma/patologia , Podossomos/patologia , Fatores de Troca de Nucleotídeo Guanina Rho/metabolismo , Neoplasias Cutâneas/patologia , Quinases Ativadas por p21/metabolismo , Actinas , Animais , Linhagem Celular Tumoral , Imunofluorescência , Células HEK293 , Humanos , Invasividade Neoplásica/patologia , Isoformas de Proteínas/metabolismo , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Peixe-Zebra , Quinases Ativadas por p21/genéticaRESUMO
B cells participate in immune surveillance in human circulation and tissues, including tumors such as melanoma. By contrast, the role of humoral responses in cutaneous immunity is underappreciated. We report circulating skin-homing CD22+CLA+B cells in healthy volunteers and melanoma patients (n = 73) and CD22+ cells in melanoma and normal skin samples (n = 189). Normal and malignant skin featured mature IgG and CD22 mRNA, alongside mRNA for the transiently-expressed enzyme Activation-induced cytidine Deaminase (AID). Gene expression analyses of publically-available data (n = 234 GEO, n = 384 TCGA) confirmed heightened humoral responses (CD20, CD22, AID) in melanoma. Analyses of 51 melanoma-associated and 29 normal skin-derived IgG sequence repertoires revealed lower IgG1/IgGtotal representation compared with antibodies from circulating B cells. Consistent with AID, comparable somatic hypermutation frequencies and class-switching indicated affinity-matured antibodies in normal and malignant skin. A melanoma-associated antibody subset featured shorter complementarity-determining (CDR3) regions relative to those from circulating B cells. Clonal amplification in melanoma-associated antibodies and homology modeling indicated differential potential antigen recognition profiles between normal skin and melanoma sequences, suggesting distinct antibody repertoires. Evidence for IgG-expressing B cells, class switching and antibody maturation in normal and malignant skin and clonally-expanded antibodies in melanoma, support the involvement of mature B cells in cutaneous immunity.
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Linfócitos B/imunologia , Switching de Imunoglobulina/imunologia , Imunoglobulina G/imunologia , Melanoma/imunologia , Neoplasias Cutâneas/imunologia , Linfócitos B/metabolismo , Perfilação da Expressão Gênica/métodos , Regulação Neoplásica da Expressão Gênica/imunologia , Humanos , Melanoma/genética , Melanoma/metabolismo , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/genética , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/imunologia , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/metabolismo , Pele/imunologia , Pele/metabolismo , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/metabolismoRESUMO
BACKGROUND: Pain at split skin graft donor sites is common. Fibrin sealant has been demonstrated to reduce time to hemostasis at wound sites, and patients receiving this treatment were incidentally noted to report less pain. This study aimed to evaluate pain and incapacity in split skin graft donor sites treated with and without fibrin sealant. METHODS: Fifty patients requiring thigh donor-site split skin grafts were prospectively randomized to receive either a self-adhesive fabric dressing alone or fibrin sealant plus the self-adhesive fabric dressing as primary donor-site dressings. External secondary dressings were the same. Patients were blinded with regard to treatment group. Using visual analogue scales (scored 0 to 5), patients rated their donor-site pain and incapacity for 14 days postoperatively. Secondary endpoints were length of hospital stay and duration of requirement for dressings. RESULTS: Forty patients were included in the study analysis and completed self-reported pain and incapacity scores. Twenty received the fibrin sealant plus self-adhesive fabric dressing and 20 received the fabric dressing only (controls). Patients using the fibrin sealant plus the dressing reported significantly less pain (mean score, 0.42 versus 1.60, p < 0.001) and significantly less incapacity (mean score, 0.48 versus 1.71, p < 0.001). Patients allocated to the fibrin sealant group recorded shorter lengths of stay and faster time to discontinuation of dressing, though statistical significance was not achieved. CONCLUSION: Patients whose split skin graft donor sites were dressed with fibrin sealant plus self-adhesive fabric dressing experienced significantly less pain and incapacity than patients with self-adhesive fabric dressings alone, allowing a more rapid return to normal activity. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.
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Adesivo Tecidual de Fibrina/uso terapêutico , Dor Pós-Operatória/prevenção & controle , Transplante de Pele/métodos , Doadores de Tecidos , Adulto , Idoso , Idoso de 80 Anos ou mais , Bandagens , Método Duplo-Cego , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Dor Pós-Operatória/diagnóstico , Estudos Prospectivos , Coxa da Perna , Adesivos Teciduais/uso terapêutico , Resultado do Tratamento , Adulto JovemRESUMO
Host-induced antibodies and their contributions to cancer inflammation are largely unexplored. IgG4 subclass antibodies are present in IL-10-driven Th2 immune responses in some inflammatory conditions. Since Th2-biased inflammation is a hallmark of tumor microenvironments, we investigated the presence and functional implications of IgG4 in malignant melanoma. Consistent with Th2 inflammation, CD22+ B cells and IgG4(+)-infiltrating cells accumulated in tumors, and IL-10, IL-4, and tumor-reactive IgG4 were expressed in situ. When compared with B cells from patient lymph nodes and blood, tumor-associated B cells were polarized to produce IgG4. Secreted B cells increased VEGF and IgG4, and tumor cells enhanced IL-10 secretion in cocultures. Unlike IgG1, an engineered tumor antigen-specific IgG4 was ineffective in triggering effector cell-mediated tumor killing in vitro. Antigen-specific and nonspecific IgG4 inhibited IgG1-mediated tumoricidal functions. IgG4 blockade was mediated through reduction of FcγRI activation. Additionally, IgG4 significantly impaired the potency of tumoricidal IgG1 in a human melanoma xenograft mouse model. Furthermore, serum IgG4 was inversely correlated with patient survival. These findings suggest that IgG4 promoted by tumor-induced Th2-biased inflammation may restrict effector cell functions against tumors, providing a previously unexplored aspect of tumor-induced immune escape and a basis for biomarker development and patient-specific therapeutic approaches.
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Antineoplásicos/farmacologia , Imunoglobulina G/fisiologia , Melanoma/imunologia , Neoplasias Cutâneas/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Citotoxicidade Celular Dependente de Anticorpos , Linfócitos B/imunologia , Linfócitos B/metabolismo , Polaridade Celular , Técnicas de Cocultura , Feminino , Fatores de Transcrição Forkhead/metabolismo , Humanos , Imunoglobulina G/biossíntese , Imunoglobulina G/sangue , Interleucina-10/metabolismo , Interleucina-10/fisiologia , Interleucina-4/metabolismo , Estimativa de Kaplan-Meier , Metástase Linfática , Masculino , Melanoma/sangue , Melanoma/mortalidade , Melanoma/secundário , Camundongos , Pessoa de Meia-Idade , Receptores de IgG/metabolismo , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/metabolismo , Neoplasias Cutâneas/sangue , Neoplasias Cutâneas/mortalidade , Neoplasias Cutâneas/patologia , Células Th2/imunologia , Células Tumorais Cultivadas , Evasão Tumoral , Fator A de Crescimento do Endotélio Vascular/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Melanoma, a potentially lethal skin cancer, is widely thought to be immunogenic in nature. While there has been much focus on T cell-mediated immune responses, limited knowledge exists on the role of mature B cells. We describe an approach, including a cell-based ELISA, to evaluate mature IgG antibody responses to melanoma from human peripheral blood B cells. We observed a significant increase in antibody responses from melanoma patients (nâ=â10) to primary and metastatic melanoma cells compared to healthy volunteers (nâ=â10) (P<0.0001). Interestingly, we detected a significant reduction in antibody responses to melanoma with advancing disease stage in our patient cohort (nâ=â21) (P<0.0001). Overall, 28% of melanoma patient-derived B cell cultures (nâ=â1,800) compared to 2% of cultures from healthy controls (nâ=â600) produced antibodies that recognized melanoma cells. Lastly, a patient-derived melanoma-specific monoclonal antibody was selected for further study. This antibody effectively killed melanoma cells in vitro via antibody-mediated cellular cytotoxicity. These data demonstrate the presence of a mature systemic B cell response in melanoma patients, which is reduced with disease progression, adding to previous reports of tumor-reactive antibodies in patient sera, and suggesting the merit of future work to elucidate the clinical relevance of activating humoral immune responses to cancer.