Faculty Bibliography

CD8+ T cells develop increased sensitivity following Ag experience, and differences in sensitivity exist between T cell memory subsets. How differential TCR signaling between memory subsets contributes to sensitivity differences is unclear. We show in mouse effector memory T cells (TEM) that >50% of lymphocyte-specific protein tyrosine kinase (Lck) exists in a constitutively active conformation, compared with <20% in central memory T cells (TCM). Immediately proximal to Lck signaling, we observed enhanced Zap-70 phosphorylation in TEM following TCR ligation compared with TCM Furthermore, we observed superior cytotoxic effector function in TEM compared with TCM, and we provide evidence that this results from a lower probability of TCM reaching threshold signaling owing to the decreased magnitude of TCR-proximal signaling. We provide evidence that the differences in Lck constitutive activity between CD8+ TCM and TEM are due to differential regulation by SH2 domain-containing phosphatase-1 (Shp-1) and C-terminal Src kinase, and we use modeling of early TCR signaling to reveal the significance of these differences. We show that inhibition of Shp-1 results in increased constitutive Lck activity in TCM to levels similar to TEM, as well as increased cytotoxic effector function in TCM Collectively, this work demonstrates a role for constitutive Lck activity in controlling Ag sensitivity, and it suggests that differential activities of TCR-proximal signaling components may contribute to establishing the divergent effector properties of TCM and TEM. This work also identifies Shp-1 as a potential target to improve the cytotoxic effector functions of TCM for adoptive cell therapy applications.

PURPOSE: The identification of personalized germline markers with biological relevance for the prediction of cutaneous melanoma (CM) prognosis is highly demanded but to date it has been largely unsuccessful. As melanoma progression is controlled by host immunity, here we present a novel approach interrogating immunoregulatory pathways using the genome-wide maps of expression quantitative trait loci (eQTL) to reveal biologically relevant germline variants modulating CM outcomes. EXPERIMENTAL DESIGN: Using whole genome eQTL data from a healthy population, we identified 385 variants -significantly impacting the expression of 268 immune-relevant genes. The 40 most significant eQTLs were tested in a prospective cohort of 1,221 CM patients for their association with overall (OS) and recurrence-free survival using Cox regression models. RESULTS: We identified highly significant associations with better melanoma OS for rs6673928, impacting IL19 expression (HR 0.56, 95% CI 0.41-0.77; P= 0.0002) and rs6695772, controlling the expression of BATF3 (HR 1.64, 95% CI 1.19-2.24; P= 0.0019). Both associations map in the previously suspected melanoma prognostic locus at 1q32. Furthermore, we show that their combined effect on melanoma OS is substantially enhanced reaching the level of clinical applicability (HR 1.92, 95% CI 1.43-2.60; P= 2.38e-5). CONCLUSIONS: Our unique approach of interrogating lymphocyte-specific eQTLs reveals novel and biologically relevant immunomodulatory eQTL predictors of CM prognosis that are independent of current histopathological markers. The significantly enhanced combined effect of identified eQTLs suggests the personalized utilization of both SNPs in a clinical setting, strongly indicating the promise of the proposed design for the discovery of prognostic or risk germline markers in other cancers.

Endothelin-1 (ET-1) is a vasoactive peptide that also plays a role in the tanning response of the skin. Animal and cell culture studies have also implicated ET-1 in melanoma progression, but no association studies have been performed to link ET-1 expression and melanoma in humans. Here, we present the first in-vivo study of ET-1 expression in pigmented lesions in humans: an ET-1 immunohistochemical screen of melanocytic nevi, melanoma in situ lesions, invasive melanomas, metastatic melanomas, and blue nevi was performed. Twenty-six percent of melanocytic nevi and 44% of melanoma in situ lesions demonstrate ET-1 expression in the perilesional microenvironment, whereas expression in nevus or melanoma cells was rare to absent. In striking contrast, 100% of moderately to highly pigmented invasive melanomas contained numerous ET-1-positive cells in the tumor microenvironment, with 79% containing ET-1-positive melanoma cells, confirmed by co-staining with melanoma tumor marker HMB45. Hypopigmented invasive melanomas had reduced ET-1 expression, suggesting a correlation between ET-1 expression and pigmented melanomas. ET-1-positive perilesional cells were CD68-positive, indicating macrophage origin. Sixty-two percent of highly pigmented metastatic melanomas demonstrated ET-1 expression in melanoma cells, in contrast to 28.2% of hypopigmented specimens. Eighty-nine percent of benign nevi, known as blue nevi, which have a dermal localization, were associated with numerous ET-1-positive macrophages in the perilesional microenvironment, but no ET-1 expression was detected in the melanocytes. We conclude that ET-1 expression in the microenvironment increases with advancing stages of melanocyte transformation, implicating a critical role for ET-1 in melanoma progression, and the importance of the tumor microenvironment in the melanoma phenotype.

Despite major advances in the treatment of metastatic melanoma, treatment failure is still inevitable in most cases. Manipulation of key epigenetic regulators, including inhibition of Bromodomain and extra-terminal domain (BET) family members impairs cell proliferation in vitro and tumor growth in vivo in different cancers, including melanoma. Here, we investigated the effect of combining the BET inhibitor JQ1 with the BRAF inhibitor Vemurafenib in in vitro and in vivo models of BRAF-mutant melanoma. We performed cytotoxicity and apoptosis assays, and a xenograft mouse model to determine the in vitro and in vivo efficacy of JQ1 in combination with Vemurafenib against BRAF-mutant melanoma cell lines. Further, to investigate the molecular mechanisms underlying the effects of combined treatment, we conducted antibody arrays of in vitro drug-treated cell lines and RNA sequencing of drug-treated xenograft tumors. The combination of JQ1 and Vemurafenib acted synergistically in BRAF-mutant cell lines, resulting in marked apoptosis in vitro, with upregulation of proapoptotic proteins. In vivo, combination treatment suppressed tumor growth and significantly improved survival compared to either drug alone. RNA sequencing of tumor tissues revealed almost four thousand genes that were uniquely modulated by the combination, with several anti-apoptotic genes significantly down-regulated. Collectively, our data provide a rationale for combined BET and BRAF inhibition as a novel strategy for the treatment of melanoma.

PURPOSE: The application of pan-cancer next generation sequencing panels in the clinical setting has facilitated the identification of low frequency somatic mutations and the testing of new therapies in solid tumors using the 'basket trial' scheme. However, little consideration has been given to the relevance of non-synonymous germline variants which are likely to be uncovered in tumors and germline and which may be relevant to prognostication and prediction -of treatment response. EXPERIMENTAL DESIGN: We analyzed matched tumor and normal DNA from 34 melanoma patients using an Ion Torrent cancer-associated gene panel. We elected to study the germline variant Q472H in the kinase insert domain receptor (KDR), which was identified in 35% of melanoma patients in both a pilot and an independent 1,223 patient cohort. Using patient-derived melanoma cell lines and human samples, we assessed proliferation, invasion, VEGF levels and angiogenesis by analyzing tumor microvessel density using anti-CD34 antibody. RESULTS: Serum VEGF levels and tumor microvessel density were significantly higher in Q472H versus KDR wild-type patients. Primary cultures derived from melanomas harboring the KDR variant were more proliferative and invasive than KDR wild-type. Finally, using a VEGFR2 antibody, we showed that KDR Q472H cells were sensitive to targeted inhibition of VEGFR2, an effect that was not observed in KDR WT cells. CONCLUSION: Our data support the integration of germline analysis into personalized treatment decision-making and suggest that patients with germline KDR variant might benefit from anti-angiogenesis treatment.

Exosomes are produced by cells to mediate intercellular communication, and have been shown to perpetuate diseases, including cancer. New tools are needed to understand exosome biology, detect exosomes from specific cell types in complex biological media, and to modify exosomes. Our data demonstrate a cellular pathway whereby membrane-bound scavenger receptor type B-1 (SR-B1) in parent cells becomes incorporated into exosomes. We tailored synthetic HDL-like nanoparticles (HDL NP), high-affinity ligands for SR-B1, to carry a fluorescently labeled phospholipid. Data show SR-B1-dependent transfer of the fluorescent phospholipid from HDL NPs to exosomes. Modified exosomes are stable in serum and can be directly detected using flow cytometry. As proof-of-concept, human serum exosomes were found to express SR-B1, and HDL NPs can be used to label and isolate them. Ultimately, we discovered a natural cellular pathway and nanoparticle-receptor pair that enables exosome modulation, detection, and isolation.

Despite significant advances in melanoma therapy, melanoma remains the deadliest form of skin cancer, with a 5-year survival rate of only 15%. Thus, novel treatments are required to address this disease. Notch and ERBB are evolutionarily conserved signaling cascades required for the maintenance of melanocyte precursors. We show that active Notch1 (Notch1(NIC)) and active (phosphorylated) ERBB3 and ERBB2 correlate significantly and are similarly expressed in both mutated and wild-type BRAF melanomas, suggesting these receptors are co-reactivated in melanoma to promote survival. Whereas blocking either pathway triggers modest effects, combining a ?-secretase inhibitor to block Notch activation and a tyrosine kinase inhibitor to inhibit ERBB3/2 elicits synergistic effects, reducing cell viability by 90% and hampering melanoma tumor growth. Specific inhibition of Notch1 and ERBB3 mimics these results, suggesting these are the critical factors triggering melanoma tumor expansion. Notch and ERBB inhibition blunts AKT and NF?B signaling. Constitutive expression of NF?B partially rescues cell death. Blockade of both Notch and ERBB signaling inhibits the slow cycling JARID1B-positive cell population, which is critical for long-term maintenance of melanoma growth. We propose that blocking these pathways is an effective approach to treatment of melanoma patients regardless of whether they carry mutated or wild-type BRAF.

Melanoma lacks a clinically useful blood-based biomarker of disease activity to help guide patient management. To determine whether measurements of circulating, cell-free, tumor-associated BRAFmutant and NRASmutant DNA (ctDNA) have a higher sensitivity than LDH to detect metastatic disease prior to treatment initiation and upon disease progression we studied patients with unresectable stage IIIC/IV metastatic melanoma receiving treatment with BRAF inhibitor therapy or immune checkpoint blockade and at least 3 plasma samples obtained during their treatment course. Levels of BRAFmutant and NRASmutant ctDNA were determined using droplet digital PCR (ddPCR) assays. Among patients with samples available prior to treatment initiation ctDNA and LDH levels were elevated in 12/15 (80%) and 6/20 (30%) (p = 0.006) patients respectively. In patients with RECIST scores <5 cm prior to treatment initiation, ctDNA levels were elevated in 5/7 (71%) patients compared to LDH which was elevated in 1/13 (8%) patients (p = 0.007). Among all disease progression events the modified bootstrapped sensitivities for ctDNA and LDH were 82% and 40% respectively, with a median difference in sensitivity of 42% (95% confidence interval, 27%-58%; P < 0.001). In addition, ctDNA levels were elevated in 13/16 (81%) instances of non-RECIST disease progression, including 10/12 (83%) instances of new brain metastases. In comparison LDH was elevated 8/16 (50%) instances of non-RECIST disease progression, including 6/12 (50%) instances of new brain metastases. Overall, ctDNA had a higher sensitivity than LDH to detect disease progression, including non-RECIST progression events. ctDNA has the potential to be a useful biomarker for monitoring melanoma disease activity.

OBJECTIVES: The impact of ethnicity and the socioeconomic status (SES) among Caucasians is not well studied. Here, we examine the impact of income on melanoma presentation and prognosis within a Caucasian cohort, accounting for ethnicity, as some reports suggest increased melanoma incidence in Ashkenazi Jewish (AJ) BRCA mutation carriers. METHODS: We studied prospectively enrolled primary melanoma patients at New York University. SES data were estimated using United States' Census Bureau data and patient zip codes. We evaluated associations between ethnicity, SES, and baseline characteristics using the x03C7;2 test and multivariate logistic regression. We compared survival distributions using Kaplan-Meier curves, log-rank tests, and Cox proportional hazard ratios. RESULTS: Of the 1,339 enrolled patients, AJ represented 32% (n = 423). Apart from AJ being older at presentation (p < 0.001), no significant differences were observed in baseline characteristics between ethnic groups. Patients with a median household income (MHI) lower than the median of the cohort were significantly more likely to present with advanced stages (p < 0.001) compared to patients with a higher MHI. Shorter overall (p = 0.016) and post-recurrence survival (p = 0.042) was also observed in patients from lower-income households. CONCLUSION: Data suggest that disparities in melanoma presentation in Caucasians stratify according to income independent of ethnic background.