Faculty Bibliography

Background: PP6C binds to regulatory units toaffect a number of important pathways including cell proliferation and DNA repair. Recently two independent groups reported for the first time the presence of somatic mutations in the PPP6C gene in ~10% of short term cultures and limited number of human melanoma tissues. However, the clinical or biological relevance of PPP6C mutations in melanoma patients is unknown. Our objectives were to examine the clinical relevance of PPP6C mutations in a well characterized cohort of melanoma specimens linked to extensive, prospectively-collected clinical information and to explore the functional consequence of different categories of mutations. Methods: Sanger dideoxy sequencing was performed on PCR-amplified DNA from macro-dissected FFPE tumors. Associations between PPP6C mutations and baseline characteristics, recurrence, survival, and BRAF/ NRAS mutational status were examined. The impact of mutations on binding PP6C regulatory units was assessed as well as the effect on additional downstream pathways. Results: 308 primary melanoma patients (118 Stage I, 92 Stage II, and 98 Stage III) were examined (median follow up: 5.3 years). 50 PPP6C mutations in 33 patients (10.7%) were identified with 11 tumors harboring more than one mutation. One mutation (R301C) was identified in 6 patients. PPP6C mutations occurred with similar frequencies across stages and showed no association with BRAF or NRAS mutations.Mutations were categorized into 3 groups: Mutations resulting in premature stop codon (n=9), those occurring in the active site (n=16) and others (n=8). 8/9 (89%) patients with stop mutations recurred and developed visceral metastases. Functional studies revealed that PPP6C mutants also behaved differently; some PPP6C mutations led to decreased binding to regulatory subunits, others, including the R301C mutation did not. Conclusions: Our data suggest that PPP6C mutation is an early event in melanoma progression and independent of BRAF or NRAS mutations. Data also!

Background: Although patient age at diagnosis is not currently included in guidelines for treatment of primary melanoma, several lines of evidence suggest that patient age is an important, yet understudied, factor when considering treatment options. Here, we attempt to address the limited knowledge of the impact of age on primary melanoma treatment. Methods: In a prospectively enrolled and followed-up cohort of melanoma patients at NYU, we used logistic regression models to evaluate the association between patient age at diagnosis, tumor baseline characteristics, including BRAF and NRAS mutation status, and likelihood of receiving and responding to adjuvant therapy. We examined adjuvant therapy effectiveness using recurrence and melanoma-specific survival as endpoints. Results: 444 primary melanoma patients were included in the study (median follow-up: 6.3 years; age range: 19-95 years). Age was categorized into three groups spanning the range of age at presentation: younger (19-45 years; 24%), middle (46-70 years; 50%), and older (71-95 years; 26%). Older patients were significantly more likely to have advanced stage, nodular subtype (P < 0.01, both variables), and BRAF wildtype tumors (P = 0.04). Controlling for these factors as well as gender, older patients experienced a higher risk of recurrence (HR older vs. younger 3.34, 95% CI 1.53-7.25; P < 0.01). Of the 128/444 (29%) patients who were eligible for adjuvant treatment (clinical stage IIB), only 67/128 (52%) received treatment. Using a propensity score that accounts for stage at presentation, patients in the middle age group were more likely to receive adjuvant therapy than those in the older group (OR 2.61, 95% CI 1.12-6.08; P = 0.03). In addition, a trend suggesting benefit from adjuvant therapy (defined as longer melanoma-specific survival) was observed only in the middle age group (P = 0.07). Conclusions: Our data suggest that older melanoma patients, despite having a significantly worse prognosis, are less likely to receive and bene!

Background: Patients with metastatic melanoma are eligible for BRAF inhibitor therapy if the BRAF V600E mutation can be identified in their tumor specimen. Patients lacking an available specimen for genotyping are unable to receive inhibitor therapy. We developed two mutation-specific genotyping platforms and tested their ability to detect BRAF and NRAS mutations in archived plasma and tumor samples to determine the potential utility of blood-based tumor genotyping in melanoma. Methods: We analyzed a group of 96 patients with stage III or IV melanoma, prospectively enrolled and followed in the NYU Melanoma Biorepository program. Each patient had a plasma sample and one or more tumor samples available for analysis. We used a combination of allele-specific PCR (Taqman) and SNaPshot assays to identify BRAF V600 and NRAS Q61 mutations in the tumor and plasma samples. Results: Among the 96 patients, 51 had stage III disease at the time of analysis; 45 had stage IV disease. Seventy-two patients had 2 or more tumor samples available for analysis, for a total of 204 tumors analyzed. In total, 52/96 (54%) patients had one or more BRAF or NRAS mutant tumors, including one patient with separate BRAF and NRAS mutant tumors (BRAF, n=35 (36%); NRAS, n=18 (19%)). We successfully amplified plasma DNA from 39/52 (75%) patients with tumor-associated mutations. Among those patients with amplifiable plasma DNA we detected mutations in 7 (18%) patients including 3 BRAF V600E, one V600K, 2 NRAS Q61K and one Q61L. Plasma-based mutations matched tumor-associated mutations in all 7 patients. All 7 patients had active disease at the time of blood draw. There were 32 patients with tumor-associated mutations in which a mutation could not be detected in the plasma. Only 15 of those 32 (47%) had active disease at the time of blood draw. There were no mutations detected in the plasma of the 44 patients whose tumors lacked BRAF or NRAS mutations. Conclusions: These data suggest that plasma-based detection of BRAF and NRAS mut!

Background: Small reported studies have provided some evidence implicating immune related genes in melanoma susceptibility and prognosis; however candidate selection of these prior efforts has been limited. In this study, we performed an analysis of germline variants in immuno-modulatory genes for their association with melanoma survival in a well characterized cohort of prospectively accrued melanoma patients. Methods: Germline DNA isolated from blood samples of 817 melanoma patients was genotyped for 94 SNPs tagging 55 immuno-modulatory genes using Sequenom iPLEX. Cox models were used to test associations between each SNP and recurrence-free and overall survival (RFS and OS), with adjustments for age, gender, subtype, thickness, ulceration, and anatomic site. ROC curves were constructed from different SNP/clinical covariate combinations and the area under the curve (AUC) was used to assess their utility in the classification of 3-year recurrence. Results: The SNP rs2796817 in TGFB2 had strong associations with both RFS (HR=3.8, CI 95%: 1.3-11, p=0.02) and OS (HR=5.5, CI 95%: 1.6-19, p=0.029). Other interesting associations with OS came from IRF8 (rs4843861, HR=0.62, CI 95%: 0.39-0.99, p=0.017), CCL5 (rs4796120, HR=7.6, CI 95%: 2.3-25, p=0.035), and CD8A (rs3810831, HR=2.4, CI 95%: 0.91-6.2, p=0.048). A multivariate model including stage, subtype, and one of the SNPs (rs3810831 from CD8A), was shown to improve the AUC when compared to a model including only stage and subtype (0.77 vs. 0.79). Conclusions: We identified several immune-related loci associated with melanoma RFS and OS. The strongest association, rs2796817, maps in TGFB2, which among other functions suppresses IL-2 dependent T-cell growth. In addition to other associations found in the study these findings provide evidence for the involvement of immuno-modulatory genes in melanoma prognosis and suggest further investigations of immune related genes in disease progression. This is currently underway in the second stage validation an!

T cells expressing antigen-specific T-cell receptors (TCRs) can mediate effective tumor regression, but they often also are accompanied by autoimmune responses. To determine the TCR affinity threshold defining the optimal balance between effective antitumor activity and autoimmunity in vivo, we used a unique self-antigen system comprising seven human melanoma gp100(209-217)-specific TCRs spanning physiological affinities (1-100 muM). We found that in vitro and in vivo T-cell responses are determined by TCR affinity, except in one case that was compensated by substantial CD8 involvement. Strikingly, we found that T-cell antitumor activity and autoimmunity are closely coupled but plateau at a defined TCR affinity of 10 microM, likely due to diminished contribution of TCR affinity to avidity above the threshold. Together, these results suggest that a relatively low-affinity threshold is necessary for the immune system to avoid self-damage, given the close relationship between antitumor activity and autoimmunity. The low threshold, in turn, indicates that adoptive T-cell therapy treatment strategies using in vitro-generated high-affinity TCRs do not necessarily improve efficacy.

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.