Faculty Bibliography

Brain metastasis (B-Met) from melanoma remains mostly incurable and the main cause of death from the disease. Early stage clinical trials and case studies show some promise for targeted therapies in the treatment of melanoma B-Met. However, the progression-free survival for currently available therapies, although significantly improved, is still very short. The development of new potent agents to eradicate melanoma B-Met relies on the elucidation of the molecular mechanisms that allow melanoma cells to reach and colonize the brain. The discovery of such mechanisms depends heavily on pre-clinical models that enable the testing of candidate factors and therapeutic agents in vivo. In this review we summarize the effects of available targeted therapies on melanoma B-Met in the clinic. We provide an overview of existing pre-clinical models to study the disease and discuss specific molecules and mechanisms reported to modulate different aspects of melanoma B-Met and finally, by integrating both clinical and basic data, we summarize both opportunities and challenges currently presented to researchers in the field.

Objectives: Age is an understudied factor when considering treatment options for melanoma. Here, we examine the impact of age on primary melanoma treatment in a prospective cohort of patients. Methods: We used logistic regression models to examine the associations between age and initial treatment, using recurrence and melanoma-specific survival as endpoints. Results: 444 primary melanoma patients were categorized into three groups by age at diagnosis: 19-45 years (24.3%), 46-70 (50.2%), and 71-95 (25.5%). In multivariate models, older patients experienced a higher risk of recurrence (hazard ratio 3.34, 95% confidence interval, CI, 1.53-7.25; p < 0.01). No significant differences were observed in positive biopsy margin rates or extent of surgical margins across age groups. Patients in the middle age group were more likely to receive adjuvant therapy than those in the older group (odds ratio 2.78, 95% CI 1.19-6.45; p = 0.02) and showed a trend to longer disease-free survival when receiving adjuvant therapy (p = 0.09). Conclusion: Our data support age as an independent negative prognostic factor in melanoma. Our data suggest that age does not affect primary surgical treatment but may affect decisions of whether or not patients receive postoperative treatment(s). Further work is needed to better understand the biological variables affecting treatment decisions and efficacy in older patients.

T-cells have evolved the unique ability to discriminate "self" from "non-self" with high sensitivity and selectivity. However, tissue-specific autoimmunity, tolerance or eradication of cancer does not fit into the self/non-self paradigm because the T-cell responses in these situations are most often directed to non-mutated self-proteins. To determine the TCR affinity threshold defining the optimal balance between effective antitumor activity and autoimmunity in vivo, we used a novel self-antigen system comprised of seven human melanoma gp100209-217-specific TCRs spanning physiological affinities (1 to 100 muM). We found that in vitro and in vivo T cell responses are determined by TCR affinity. Strikingly, we found that T cell antitumor activity and autoimmunity are closely coupled but plateau at a defined TCR affinity of 10 muM, likely due to diminished contribution of TCR affinity to avidity above the threshold. Our results suggest a relatively low affinity threshold is necessary for the immune system to avoid selfdamage given the close relationship between antitumor activity and autoimmunity. This, in turn, indicates that treatment strategies focusing on TCRs in the intermediate affinity range (KD ~10 muM) or targeting or targeting shared tumor antigens would dampen the potential for autoimmunity during adoptive T cell therapy for the treatment of cancer

Chromatin dynamics exert a critical function in a number of cancers, and only recently has the role of histone variants in cancer initiation and/or progression begun to be unraveled.Wepreviously probed the H2A variant profile in malignant melanoma (MM) and revealed that macroH2A levels are significantly decreased during melanoma progression, exerting a tumor-suppressive function mediated by direct transcriptional regulation of CDK8. Here, we demonstrate that global protein levels of another variant, H2A.Z, follow an opposite pattern compared to macroH2A - H2A.Z levels increase as cells become increasingly malignant. We differentiate the two isoforms of H2A.Z, namely H2A.Z.1 and H2A.Z.2 (encoded by H2AFZ and H2AFV, respectively), and we show that expression of both is higher in metastatic melanoma specimens from patients as compared to benign nevi. In addition, higher H2A.Z.1 and 2 levels significantly correlate with shorter time to recurrence and lower overall survival in patients followed up for 3 years after excision of the metastatic lesion. Our combined FISH (Fluorescent In Situ Hybridization) and CGH (Comparative Genomic Hybridization) analyses implicate gene amplification as a likely mechanism underlining H2AFZ and H2AFV overexpression. Moreover, loss of function studies revealed that H2A.Z.2-depleted cells were profoundly delayed in the progression through the cell cycle, in particular during DNA replication. Gene expression profiling showed that many cell cycle-regulating genes were significantly down-regulated upon H2A.Z.2 depletion. Collectively, our data strongly suggest that H2A.Z.2 drives MM progression through the regulation of cell-cycle-regulating genes and we anticipate that our studies will provide imperative knowledge for rationally guided epigenetic therapies as well as for the identification of novel diagnostic and prognostic markers for MM

Melanoma incidence and associated mortality continue to increase worldwide. The lack of treatments with durable responses for stage IV melanoma may be due, at least in part, to an incomplete understanding of the molecular mechanisms that regulate tumor initiation and/or progression to metastasis. Recent evidence supports miRNA dysregulation in melanoma impacting several well-known pathways such as the PI3K/AKT or RAS/MAPK pathways, but also underexplored cellular processes like protein glycosylation and immune modulation. There is also increasing evidence that miRNA can improve patient prognostic classification over the classical staging system and provide new therapeutic opportunities. The integration of this recently acquired knowledge with known molecular alterations in protein coding genes characteristic of these tumors (i.e., BRAF and NRAS mutations, CDKN2A inactivation) is critical for a complete understanding of melanoma pathogenesis. Here, we compile the evidence of the functional roles of miRNAs in melanomagenesis and progression, and of their clinical utility as biomarkers, prognostic tools and potential therapeutic targets. Characterization of miRNA alterations in melanoma may provide new angles for therapeutic intervention, help to decipher mechanisms of drug resistance, and improve patient classification for disease surveillance and clinical benefit.

BACKGROUND: In patients with multiple primary melanomas (MPM), mean tumor thickness tends to decrease from the first melanoma to the second melanoma, and prognosis may be improved compared with the prognosis for patients who have a single primary melanoma (SPM). In this study, the authors compared the clinicopathologic features of patients with MPM and SPM to better characterize the differences between these 2 groups and to determine whether or not there is an inherent difference in tumor aggression. METHODS: In total, 788 patients with melanoma who were enrolled prospectively in the Interdisciplinary Melanoma Cooperative Group database from 2002 to 2008 were studied. Patients with SPM and with MPM were compared with regard to clinical and primary melanoma characteristics. RESULTS: Of 788 patients with melanoma, 61 patients (7.7%) had 2 or more primary melanomas. The incidence of developing a second primary melanoma 1 year and 5 years after initial melanoma diagnosis was 4.1% and 8.7%, respectively, and most of the risk accumulated within the first year. The incidence of MPM was greater in patients aged >/=60 years than in those aged </=60 years. The absence or presence of mitosis and other tumor characteristics did not differ significantly between patients with SPM and patients with MPM (P = .61). CONCLUSIONS: No difference was observed in the presence or absence of mitoses, a marker of tumor proliferation, in SPM and MPM. Because it has been demonstrated that the presence of mitosis is a powerful prognostic marker, the current findings suggested that the tumors behave similarly in patients with SPM and patients with MPM. The authors concluded that differences in tumor thickness and prognosis between SPM and MPM more likely are caused by factors other than tumor biology, such as increased surveillance. Cancer 2012;. (c) 2012 American Cancer Society

ABSTRACT: BACKGROUND: Identification of melanoma patients at high risk for recurrence and monitoring for recurrence are critical for informed management decisions. We hypothesized that serum microRNAs (miRNAs) could provide prognostic information at the time of diagnosis unaccounted for by the current staging system and could be useful in detecting recurrence after resection. METHODS: We screened 355 miRNAs in sera from 80 melanoma patients at primary diagnosis (discovery cohort) using a unique quantitative reverse transcription-PCR (qRT-PCR) panel. Cox proportional hazard models and Kaplan-Meier recurrence-free survival (RFS) curves were used to identify a miRNA signature with prognostic potential adjusting for stage. We then tested the miRNA signature in an independent cohort of 50 primary melanoma patients (validation cohort). Logistic regression analysis was performed to determine if the miRNA signature can determine risk of recurrence in both cohorts. Selected miRNAs were measured longitudinally in subsets of patients pre-/post-operatively and pre-/post-recurrence. RESULTS: A signature of 5 miRNAs successfully classified melanoma patients into high and low recurrence risk groups with significant separation of RFS in both discovery and validation cohorts (p = 0.0036, p = 0.0093, respectively). Significant separation of RFS was maintained when a logistic model containing the same signature set was used to predict recurrence risk in both discovery and validation cohorts (p < 0.0001, p = 0.033, respectively). Longitudinal expression of 4 miRNAs in a subset of patients was dynamic, suggesting miRNAs can be associated with tumor burden. CONCLUSION: Our data demonstrate that serum miRNAs can improve accuracy in identifying primary melanoma patients with high recurrence risk and in monitoring melanoma tumor burden over time.

We examined the microRNA signature that distinguishes the most common melanoma histological subtypes, superficial spreading melanoma (SSM) and nodular melanoma (NM). We also investigated the mechanisms underlying the differential expression of histology-specific microRNAs. MicroRNA array performed on a training cohort of 82 primary melanoma tumors (26 SSM, 56 NM), and nine congenital nevi (CN) revealed 134 microRNAs differentially expressed between SSM and NM (P<0.05). Out of 134 microRNAs, 126 remained significant after controlling for thickness and 31 were expressed at a lower level in SSM compared with both NM and CN. For seven microRNAs (let-7g, miR-15a, miR-16, miR-138, miR-181a, miR-191, and miR-933), the downregulation was associated with selective genomic loss in SSM cell lines and primary tumors, but not in NM cell lines and primary tumors. The lower expression level of six out of seven microRNAs in SSM compared with NM was confirmed by real-time PCR on a subset of cases in the training cohort and validated in an independent cohort of 97 melanoma cases (38 SSM, 59 NM). Our data support a molecular classification in which SSM and NM are two molecularly distinct phenotypes. Therapeutic strategies that take into account subtype-specific alterations might improve the outcome of melanoma patients.

Melanoma brain metastasis that develops as the isolated first visceral site challenges the current paradigm of tumor progression in which brain metastasis is regarded as the final stage. Here we test the hypothesis that melanoma patients who develop brain metastasis as the isolated first visceral site have distinct clinicopathological features at the time of primary melanoma diagnosis. Cutaneous melanoma patients enrolled in 2 prospectively collected databases were studied (Cohort 1: 1972-1982, Cohort 2: 2002-2009). Patients who developed brain metastasis as isolated first visceral site were compared with (1) all other patients, (2) patients who developed visceral metastasis: extracranial only or extracranial and brain, and (3) patients who progressed to other isolated visceral sites first. Two hundred seven of 2280 (9.1%) patients developed brain metastasis (median follow-up, 5.2 y). Seventy-four of 207 (35.7%) brain metastasis patients progressed to brain metastasis as the isolated first visceral site. These patients presented with primaries that were thinner and had no mitosis compared with all other visceral metastasis patients (Fisher's combined P = .02, .05, respectively), and there was a significant difference in American Joint Committee on Cancer stage distribution at initial melanoma diagnosis (combined P = .02). Post-visceral metastasis survival, however, was shorter in patients with brain metastasis as isolated first visceral site than in patients with visceral metastasis: extracranial and brain (combined P = .03). Brain metastasis as isolated first visceral site is a distinct clinicopathological entity. Studies are needed to better understand the biological factors driving this phenotype at the time of primary melanoma diagnosis and to determine its clinical implications.