Inhibition of Microsomal Prostaglandin E2 Synthase Reduces Collagen Deposition in Melanoma Tumors and May Improve Immunotherapy Efficacy by Reducing T-cell Exhaustion

The arachidonic acid pathway participates in immunosuppression in various types of cancer. Our previous observation detailed that microsomal prostaglandin E2 synthase 1 (mPGES-1), an enzyme downstream of cyclooxygenase 2 (COX-2), limited antitumor immunity in melanoma; in addition, genetic depletion of mPGES-1 specifically enhanced immune checkpoint blockade therapy. The current study set out to distinguish the roles of mPGES-1 from those of COX-2 in tumor immunity and determine the potential of mPGES-1 inhibitors for reinforcing immunotherapy in melanoma. Genetic deletion of mPGES-1 showed different profiles of prostaglandin metabolites from that of COX-2 deletion. In our syngeneic mouse model, mPGES-1-deficient cells exhibited similar tumorigenicity to that of COX-2-deficient cells, despite a lower ability to suppress PGE2 synthesis by mPGES-1 depletion, indicating the presence of factors other than PGE2 that are likely to regulate tumor immunity. RNA-sequencing analysis revealed that mPGES-1 depletion reduced the expressions of collagen-related genes, which have been found to be associated with immunosuppressive signatures. In our mouse model, collagen was reduced in mPGES-1-deficient tumors, and phenotypic analysis of tumor-infiltrating lymphocytes indicated that mPGES-1-deficient tumors had fewer TIM3⁺ exhausted CD8⁺ T cells compared with COX-2-deficient tumors. CAY10678, an mPGES-1 inhibitor, was equivalent to celecoxib, a selective COX-2 inhibitor, in reinforcing anti-PD-1 treatment. Our study indicates that mPGES-1 inhibitors represent a promising adjuvant for immunotherapies in melanoma by reducing collagen deposition and T-cell exhaustion.

Significance

Collagen is a predominant component of the extracellular matrix that may influence the tumor immune microenvironment for cancer progression. We present here that mPGES-1 has specific roles in regulating tumor immunity, associated with several collagen-related genes and propose that pharmacologic inhibition of mPGES-1 may hold therapeutic promise for improving immune checkpoint-based therapies.

Abstract PS2-17: Identification of cell-free microRNA signatures in pre-operative plasma from breast cancer patients

Background: Breast cancer (BC) is a heterogeneous disease and difficult to treat once metastasis occurs. Thus, determining blood molecular biomarkers that allow for early diagnosis would help to identify BC patients at higher risk. MicroRNAs (miRs) are short sequences (18-22 base pairs) and promising candidates as biomarkers due to their high stability in blood. Using a direct blood cell-free miR (cfmiR) next generation sequencing (NGS) -based assay that requires no extraction, we assessed 2083 cfmiRs in plasma samples from BC patients. We hypothesize that specific cfmiR signatures detected in plasma from BC patients are associated with early BC diagnosis. Those cfmiRs represent unique patterns that may allow for monitoring BC tumor burden and early detection.Methods: Two cohorts of pre-operative plasma samples from BC patients (n= 158), one cohort of pre-operative plasma samples from patients with BC brain metastasis (BCBM, n= 5), and a cohort of female normal donors’ plasma samples (n=20) were assessed by HTG EdgeSeq miR whole transcriptome assay. All primary BC tumors were histopathology staged (TNM, AJCC 8th) after surgery and divided into two different cohorts: the BC-1 cohort (n= 80, including stage I= 39, II= 37, and III= 4 patients), and the BC-2 cohort (n= 78, including stage I= 42, II= 33, and III= 3 patients). All of the samples were analyzed using DESeq2 normalization and interrogated for differentially expressed (DE) miRs using a cut-off of 30 counts, FC>1.2 or <-1.2, and FDR (p<0.05). We utilized the BC-1 group as the training cohort and the BC-2 and the BCBM cohorts were used to validate the observations in BC-1.

Results: In a retrospective study the cfmiR profiles obtained from BC-1 patients were compared to the cfmiR profiles obtained from normal donors’ plasma samples. Briefly, 328 cfmiRs were DE in plasma samples from the BC-1 cohort compared to normal donors’ plasma samples, of which 184 were upregulated and 144 were downregulated. To validate our findings, we screened the plasma samples from the BC-2 cohort (n=78). The results showed that 181 of 361 DE cfmiRs were downregulated and 180 were upregulated. By comparing both BC cohorts we found 269 DE cfmiRs consistently changing, which included 82% and 74.5% of the cfmiRs identified in BC-1 and BC-2 cohorts, respectively. In addition, we compared the cfmiR expression of BCBM (n=5) and normal donors’ plasma samples. Of the 300 DE cfmiRs, 30 were downregulated and 270 were upregulated. By integrative analysis, a 59 cfmiR signature observed in BCBM plasma samples was consistently identified in both BC-1 and BC-2 cohorts. Also, 172 cfmiRs were found exclusively in BCBM and not in primary BC tumors. Receiving operative characteristic curve analysis showed that the 59 cfmiR signature was able to distinguish primary BC from female normal donors’ (BC-1 AUC= 0.910, p<0.05 and BC-2 AUC= 0.922, p<0.05, respectively). Using the 59 cfmiR signature, the first five components of the principal component analysis showed 85.26% and 85.27% mean cumulative variance for BC-1 and BC-2 respectively.Conclusions: Specific cfmiR patterns were associated with primary BC tumors and may have potential utility for early BC diagnosis, including disease recurrence. A 59 cfmiR signature detected in primary BC patients was able to detect BCBM and may have potential clinical utility in monitoring patients at higher risk of metastasis. Further analysis are in progress to validate our observations.

Citation Format: Matias Alberto Bustos, Negin Rahimzadeh, Xiaoqing Zhang, Kevin D. Tran, Grace Chang, Carol Nishikubo, Dave S.B. Hoon. Identification of cell-free microRNA signatures in pre-operative plasma from breast cancer patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS2-17.

Inter-Tumor Heterogeneity-Melanomas Respond Differently to GM-CSF-Mediated Activation

Granulocyte-monocyte colony stimulating factor (GM-CSF) is used as an adjuvant in various clinical and preclinical studies with contradictory results. These were attributed to opposing effects of GM-CSF on the immune or myeloid systems of the treated patients or to lack of optimal dosing regimens. The results of the present study point to inter-tumor heterogeneity as a possible mechanism accounting for the contrasting responses to GM-CSF incorporating therapies. Employing xenograft models of human melanomas in nude mice developed in our lab, we detected differential functional responses of melanomas from different patients to GM-CSF both in vitro as well as in vivo. Whereas cells of one melanoma acquired pro metastatic features following exposure to GM-CSF, cells from another melanoma either did not respond or became less malignant. We propose that inter-melanoma heterogeneity as manifested by differential responses of melanoma cells (and perhaps also of other tumor) to GM-CSF may be developed into a predictive marker providing a tool to segregate melanoma patients who will benefit from GM-CSF therapy from those who will not.

Downregulation of the Ubiquitin-E3 Ligase RNF123 Promotes Upregulation of the NF-κB1 Target SerpinE1 in Aggressive Glioblastoma Tumors

This study examined the role of the ubiquitin E3-ligase RNF123 in modulating downstream NF-κB1 targets in glioblastoma (GB) tumor progression. Our findings revealed an oncogenic pathway (miR-155-5p-RNF123-NF-κB1-p50-SerpinE1) that may represent a new therapeutic target pathway for GB patients with isocitrate dehydrogenase 1 and 2 (IDH) WT (wild type). Mechanistically, we demonstrated that RNF123 is downregulated in IDH WT GB patients and leads to the reduction of p50 levels. RNA-sequencing, reverse-phase protein arrays, and in vitro functional assays on IDH WT GB cell lines with RNF123 overexpression showed that SerpinE1 was a downstream target that is negatively regulated by RNF123. SERPINE1 knockdown reduced the proliferation and invasion of IDH WT GB cell lines. Both SerpinE1 and miR-155-5p overexpression negatively modulated RNF123 expression. In clinical translational analysis, RNF123, SerpinE1, and miR-155-5p were all associated with poor outcomes in GB patients. Multivariable analysis in IDH WT GB patients showed that concurrent low RNF123 and high SerpinE1 was an independent prognostic factor in predicting poor overall survival (p < 0.001, hazard ratio (HR) = 2.93, 95% confidence interval (CI) 1.7-5.05), and an increased risk of recurrence (p < 0.001, relative risk (RR) = 3.56, 95% CI 1.61-7.83).

Prospective Molecular Profiling of Circulating Tumor Cells from Patients with Melanoma Receiving Combinatorial Immunotherapy

BACKGROUND

Blood molecular profiling of circulating tumor cells (CTCs) can enable monitoring of patients with metastatic melanoma during checkpoint inhibitor immunotherapy (CII) and in combination with targeted therapies. We developed a microfluidics-based CTC platform to explore CTC profiling utility in CII-treated patients with melanoma using a melanoma messenger RNA (mRNA)/DNA biomarker panel.

METHODS

Blood samples (n = 213) were collected prospectively from 75 American Joint Committee on Cancer-staged III/IV melanoma patients during CII treatment and those enriched for CTCs. CTC profiling was performed using 5 known melanoma mRNA biomarkers and BRAF V600E DNA mutation. CTC biomarker status associations with clinical outcomes were assessed.

RESULTS

CTCs were detected in 88% of blood samples from patients with melanoma. CTC-derived biomarkers and clinical variables analyzed using classification and regression tree analysis revealed that a combination of lactate dehydrogenase, CTC-mRNA biomarkers, and tumor BRAF-mutation status was indicative of clinical outcomes for patients with stage IV melanoma (n = 52). The panel stratified low-risk and high-risk patients, whereby the latter had poor disease-free (P = 0.03) and overall survival (P = 0.02). Incorporation of a DNA biomarker with mRNA profiling increased overall CTC-detection capability by 57% compared to mRNA profiling only. RNA sequencing of isolated CTCs identified significant catenin beta 1 (CTNNB1) overexpression (P <0.01) compared to nondisease donor blood. CTC-CTNNB1 was associated with progressive disease/stable disease compared to complete-responder patient status (P = 0.02). Serial CTC profiling identified subclinical disease in patients who developed progressive disease during treatment/follow-up.

CONCLUSIONS

CTC-derived mRNA/DNA biomarkers have utility for monitoring CII, targeted, and combinatorial therapies in metastatic melanoma patients.

Abstract 3541: Epigenetic regulation of KPC1 ubiquitin ligase has a regulatory role on the NF-κB pathway in metastatic melanoma

Purpose: Abnormal activation of the NF-κB pathway promotes a more aggressive phenotype of cutaneous malignant melanoma. Understanding the mechanisms regulating the NF-κB pathway in melanoma is of critical importance. KPC1 (RNF123) is an E3 ubiquitin ligase that leads to proteasomal processing of precursor NF-κB1 p105 into mature p50, one of the most important steps in the NF-κB pathway regulation. We demonstrated novel epigenetic mechanisms affecting KPC1 expression that lead to an abnormal activation of the NF-κB pathway, which was significant during tumor progression in melanoma patients.

Experimental Design: Initially using melanoma cell lines, we investigated the functional interactions between KPC1 and NF-κB, and the epigenetic regulations of KPC1, including microRNA targeted interaction and DNA methylation. The clinical impact of KPC1 expression and these epigenetic regulations were further assessed in large cohorts of clinically well-annotated melanoma tissues (tissue micro-arrays; n=137, JWCI cohort; n=40) and melanoma TCGA database cohort (n=370). High-throughput RNA sequencing, reverse-phase protein array and human methylation 450k platform were utilized for comprehensive analyses.

Results: Initially using metastatic melanoma cell lines, we verified that KPC1 promotes processing of NF-κB1 p105 into p50, thereby modulates NF-κB-target gene expression and suppresses melanoma cell proliferation. Concordantly in melanoma tissue, KPC1 expression was down-regulated in AJCC stage IV melanoma compared to early stages (JWCI cohort stage I/II p=0.013, stage III p=0.004), whereby low KPC1 expression was significantly associated with poor overall survival in stage IV melanoma (tissue micro-arrays, n=137, Hazard Ratio 1.810, p=0.006). Furthermore, epigenetic mechanisms regulating KPC1, particularly miR-155-5p and

DNA methylation level at its promoter region, was shown to be significant in melanoma lines. This regulatory mechanism was validated in clinical melanoma tissues. High miR-155-5p expression, which is negatively regulated by its promoter DNA methylation level (melanoma TCGA database cohort; Pearson's r -0.455, p&lt;0.001), is significantly associated with KPC1 down-regulation (JWCI cohort; p=0.028, melanoma TCGA database cohort; p=0.003).

Conclusions: We identified miR-155-5p, which is epigenetically controlled by its promoter methylation, has a regulatory role on KPC1 expression. These interactions promote to down-regulation of KPC1 and abnormal NF-κB pathway activation, leading to highly proliferative melanoma cells and poor clinical outcomes. These findings suggest utility of KPC1 expression level for stratification of stage IV melanoma patients, and the importance of the miR-155-5p-KPC1-NF-κB-axis in controlling melanoma proliferation.

Citation Format: Yuuki Iida, Aaron Ciechanover, Diego M. Marzese, Keisuke Hata, Matias Bustos, Shigeshi Ono, Jinhua Wang, Matthew P. Salomon, Kevin Tran, Yelena Kravtsova-Ivantsiv, Gordon B. Mills, Michael A. Davies, Dave S.B. Hoon. Epigenetic regulation of KPC1 ubiquitin ligase has a regulatory role on the NF-κB pathway in metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3541.

Multiplex Gene Profiling of Cell-Free DNA in Patients With Metastatic Melanoma for Monitoring Disease

PURPOSE

Hotspot blood cell-free DNA (cfDNA) biomarker assays have limited utility in profiling tumor heterogeneity and burden and in capturing regional metastasis with low disease burden in patients with melanoma. We investigated the utility of a sensitive 54-cancer gene digital next-generation sequencing approach targeting blood cfDNA single nucleotide variants (SNVs) and copy number amplification for monitoring disease in patients with melanoma with regional or distant organ metastasis (DOM).

PATIENTS AND METHODS

A total of 142 blood samples were evaluated by digital next-generation sequencing across two patient cohorts. Cohort 1 contained 44 patients with stage II, III, or IV disease with matched tumor DNA at the time of surgery or DOM. Cohort 2 consisted of 12 overlapping patients who were longitudinally monitored after complete lymph node dissection to DOM.

RESULTS

In cohort 1, cfDNA SNVs were detected in 75% of patients. Tumor-cfDNA somatic SNV concordance was 85% at a variant allele fraction of ≥ 0.5%. An SNV load (number of unique SNVs detected) of greater than two SNVs and an SNV burden (total cumulative SNV VAF) of > 0.5% were significantly associated with worse overall survival (P < .05) in stage IV patients. In cohort 2, 98 longitudinal blood samples along with matched regional and distant metastases from 12 stage III patients were analyzed before complete lymph node dissection and throughout disease progression. cfDNA SNV levels correlated with tumor burden (P = .019), enabled earlier detection of recurrence compared with radiologic imaging (P < .01), captured tumor heterogeneity, and identified increasing SNVs levels before recurrence.

CONCLUSION

This study demonstrates significant utility for cfDNA profiling in patients with melanoma with regional and/or distant metastasis for earlier detection of recurrence and progression and in capturing tumor evolution and heterogeneity, thus impacting how patients with melanoma are monitored.

Abstract A10: Higher incidence of epigenomic alterations on BRAF and NRAS wild type melanoma brain metastases

Combined BRAF and NRAS gene mutations (mt) account for 70-80% of metastatic melanomas. Patients with BRAFmt benefit from novel targeted therapies; however, patients without this mutation lack effective targeted therapies. We have recently demonstrated that epigenetic alterations are alternative melanoma brain metastasis (MBM) drivers. Here, we propose that identifying epigenome-wide alterations on patients with MBM BRAF and NRAS wild type can identify novel epigenetic drug-based therapies. We performed targeted sequencing to cover the complete exon coverage of mutations of the BRAF and NRAS genes. Firstly, this analysis revealed a mutual exclusivity between BRAFmt and NRASmt. Of the 79% (100/127) of MBMs that carried BRAF or NRAS mutations, 57.5% (73/127) were BRAFmt and 21.2% (27/127) were NRASmt. The remaining 21.2% (27/127) were double wild type (BRAFwt/NRASwt). To identify genome-wide DNA methylation differences between MBMs harboring BRAFmt, NRASmt, or BRAFwt/NRASwt, we generated methylome maps of each MBM type using the Human methylation 450K BeadChip. BRAFwt/NRASwt MBMs presented a significantly higher methylation level (mean = 51% methylation level) than MBMs with NRASmt (mean = 48%) or BRAFmt (mean = 47% methylation level; P&lt;0.001), suggesting a higher influence of epigenetic alterations. 1,598 CpG sites were significantly differentially methylated in BRAFwt/NRASwt MBMs (FDR-corrected P&lt;0.05). Among the most affected genes, we identified significant enrichment on gene networks involved in oncogenic and pro-metastatic functions. These gene networks include apoptosis cascade, adhesion molecules, autophagy regulation, cell cycle regulation, ganglioside metabolism, homeotic and paralog genes (mainly from HOXA gene cluster, PAX6 and PAX7 genes), invasion mechanisms (including multiple metalloproteinase genes), oncogenic growth signaling (including BRAF, PI3K, RAC, and NOTCH pathways, among others), major master transcription factors (including MITF, SOX2, and SOX8), key tumor suppressor genes (including APC, ATM, BRCA1, RB1, and RUNX3, among others), and key epigenome regulatory factors, including DNA methyltransferases (DNMT3B and DNMT3L genes), histone deacetylases (HDAC2, HDAC3, HDAC4, HDAC5 genes) and lysine demethylases (KDM2A, KDM2B, KDM3A, KDM4B, KDM6B genes). Our study suggests the existence of a larger epigenomic alteration influence in double wild type (BRAFwt/NRASwt) MBMs than MBMs with driver mutations on BRAF or NRAS genes and provides the basis for the identification of novel and alternative epigenome-targeted therapies for melanoma patients with MBMs that cannot benefit from current targeted therapies.

Citation Format: Diego M. Marzese, Jamie L. Huynh, Sharon K. Huang, Garni Barkhoudarian, Daniel F. Kelly, and Dave S.B. Hoon. Higher incidence of epigenomic alterations on BRAF and NRAS wild type melanoma brain metastases. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A10.

Brain metastasis is predetermined in early stages of cutaneous melanoma by CD44v6 expression through epigenetic regulation of the spliceosome

Melanoma brain metastasis (MBM) is frequent and has a very poor prognosis with no current predictive factors or therapeutic molecular targets. Our study unravels the molecular alterations of cell-surface glycoprotein CD44 variants during melanoma progression to MBM. High expression of CD44 splicing variant 6 (CD44v6) in primary melanoma (PRM) and regional lymph node metastases from AJCC Stage IIIC patients significantly predicts MBM development. The expression of CD44v6 also enhances the migration of MBM cells by hyaluronic acid and hepatocyte growth factor exposure. Additionally, CD44v6-positive MBM migration is reduced by blocking with a CD44v6-specific monoclonal antibody or knocking down CD44v6 by siRNA. ESRP1 and ESRP2 splicing factors correlate with CD44v6 expression in PRM, and ESRP1 knockdown significantly decreases CD44v6 expression. However, an epigenetic silencing of ESRP1 is observed in metastatic melanoma, specifically in MBM. In advanced melanomas, CD44v6 expression correlates with PTBP1 and U2AF2 splicing factors, and PTBP1 knockdown significantly decreases CD44v6 expression. Overall, these findings open a new avenue for understanding the high affinity of melanoma to progress to MBM, suggesting CD44v6 as a potential MBM-specific factor with theranostic utility for stratifying patients.

Abstract 402: Tumor necrosis factor-alpha and apoptosis induction in melanoma cells through histones modification by 3-deazaneplanocin A

Tumor necrosis factor-alpha (TNFα) is cytokine, which influences the tumor microenvironment. While melanoma is known to express variable levels of TNFα, its regulation is not well understood. The objective of the study was to investigate the epigenetic regulation of TNFα in melanoma cells. Melanoma cell lines were treated with 3-Deazaneplanocin A(DZNep), an inhibitor of polycomb-repressive complex 2(PRC2), and analyzed for its effect on the cell viability assay and apoptosis assay. PRC2 and histones H3K27me3, H3K4me2 and H3K9ac activity were assessed pre- and post-DZNep by Western blot on cell lines and tumors. ChIP-qPCR array, chromatin immunoprecipitation, and PCR array analysis of melanoma lines treated with DZNep. DZNep could induce apoptosis in melanoma cells, and up-regulate TNFα expression. Specific histones were associated with the upregulation of TNFα expression by ChIP-qPCR array. The repressive histone mark, H3K27me3, as well as the active histone marks, H3K4me2 and H3K9ac, were correlated with the regulation of TNFα expression. We demonstrated that DZNep can activate TNFα expression in melanoma through histone modification. These findings suggest that epigenetic agents targeting PRC2 can activate TNFα in melanoma cells. The DNA methylation, H3K27me3, H3K4me2, and H3K9ac modification, contribute to TNFα regulation.

Citation Format: Ryo Tanaka, Nicholas Donovan, Qiang Yu, Reiko Irie, Dave S.B. Hoon. Tumor necrosis factor-alpha and apoptosis induction in melanoma cells through histones modification by 3-deazaneplanocin A. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 402. doi:10.1158/1538-7445.AM2014-402

Molecular analysis of sentinel lymph nodes and search for molecular signatures of the metastatic potential of breast cancer

Molecular assays are a new and invaluable tool in the assessment of axillary lymph node status and metastatic potential of breast cancer. Many protocols for assessing the sentinel lymph node (SLN) status have been developed based on cytology and/or histology, showing that the rate of detection of metastasis increases with the number of histologic sections examined and with use of immunohistochemical staining in addition to conventional Hematoxylin & Eosin staining. However, full standardization of protocols for this procedure has not been achieved. Further attempts to increase sensitivity and specificity of sentinel node analysis include molecular biology-based techniques such as the real-time polymerase chain reaction (RT-PCR) and, more recently, one step nucleic acid amplification (OSNA). The latter technique, that has sensitivity close to 100% and extremely high specificity along with good reproducibility, allows analysis of the SLN in full with an intraoperative procedure in approximately 30 minutes. This highly standardized method permits to compare results between groups and predicts the probability of involvement of the remaining axillary lymph nodes based on the total tumor load of the SLN(s). Results of multicenter clinical trials suggest that OSNA allows a better personalization of patients' care based on the results of SLN analysis, because it offers criteria to select patient with metastatic SLN who will not receive additional benefit from axillary clearance. Due to the current controversy on the best treatment of the axilla after a positive SLN, the SLN copy number of CK19 mRNA can have a high impact on therapeutic decisions in this group of patients. Breast cancer is a highly heterogeneous group of diseases, characterized by remarkable differences in the histopathological features, response to treatment and clinical outcome. Most of the clinical and translational research efforts during the last decades aimed at identifying markers that would allow to predict the metastatic potential of early breast cancer, and hence to assess accurately its prognosis and to inform the choice of adjuvant systemic treatments. It is now clear that neoplastic transformation, tumor progression and response to treatment are driven and accompanied by the deregulated expression of hundred or thousand genes, whose status cannot be assessed by the currently established histopathological and immunohistochemical approach. The new molecular assays have elicited a great deal of expectations, and for the most part they have been enthusiastically welcomed as potentially offering new chances for a better and more personalized care of the patients. Many, however, are still reluctant to consider these assays ready for use in the clinical practice, and keep waiting for a confirmatory evidence of their utility when the results of ongoing clinical trials will be mature.

Pathologic Examination of Sentinel Lymph Node for Breast Carcinoma

Comprehensive pathologic evaluation of the sentinel lymph node using step sections and cytokeratin immunohistochemistry enhances detection of micrometastases and optimizes the staging of breast carcinoma. This review discusses our current understanding of the pathologic and molecular techniques for sentinel node examination.

Epigenome-wide DNA methylation landscape of melanoma progression to brain metastasis reveals aberrations on homeobox D cluster associated with prognosis

Melanoma brain metastasis (MBM) represents a frequent complication of cutaneous melanoma. Despite aggressive multi-modality therapy, patients with MBM often have a survival rate of <1 year. Alteration in DNA methylation is a major hallmark of tumor progression and metastasis; however, it remains largely unexplored in MBM. In this study, we generated a comprehensive DNA methylation landscape through the use of genome-wide copy number, DNA methylation and gene expression data integrative analysis of melanoma progression to MBM. A progressive genome-wide demethylation in low CpG density and an increase in methylation level of CpG islands according to melanoma progression were observed. MBM-specific partially methylated domains (PMDs) affecting key brain developmental processes were identified. Differentially methylated CpG sites between MBM and lymph node metastasis (LNM) from patients with good prognosis were identified. Among the most significantly affected genes were the HOX family members. DNA methylation of HOXD9 gene promoter affected transcript and protein expression and was significantly higher in MBM than that in early stages. A MBM-specific PMD was identified in this region. Low methylation level of this region was associated with active HOXD9 expression, open chromatin and histone modifications associated with active transcription. Demethylating agent induced HOXD9 expression in melanoma cell lines. The clinical relevance of this finding was verified in an independent large cohort of melanomas (n = 145). Patients with HOXD9 hypermethylation in LNM had poorer disease-free and overall survival. This epigenome-wide study identified novel methylated genes with functional and clinical implications for MBM patients.

Abstract 668: DNA methylation of apoptosis-related genes as clinical biomarker in rectal cancer

Background: To prevent over- and undertreatment of rectal cancer patients, there is a need for the development of new biomarkers that can complement the current staging system. We have previously shown that apoptosis plays an important role in local tumor recurrence after TME surgery. We studied the epigenetic regulation of several key apoptosis genes in rectal cancer tissues, using methylation-sensitive restriction enzymes.

Materials and methods: DNA was obtained from frozen specimens of 138 patients representative for the non-irradiated arm of the Dutch Total Mesorectal Excision (TME) trial. Isoschizomers HpaII (CpG methylation sensitive) and MspI (not sensitive) were used for restriction enzyme digestion of tumor DNA, followed by real-time PCR for apoptosis genes Apaf1, Bcl2, TrailR2, Fas and p53. A pilot series consisted of 50 patients with tumor stages I-III and 10 normal rectal tissues. For the validation study stage III patients (n=88) and 18 normal rectal tissues were selected.

Results: Single marker analyses showed a significant correlation between methylation status and apoptotic status (measured by immunohistochemical staining of M30) of Fas (p=0.005) and Apaf1 (p=0.052). Combining intrinsic pathway markers Apaf1, Bcl2 and p53, significant differences were observed between the methylation groups in survival and recurrence analyses (log rank test), with overall survival (p=0.054), cancer specific survival (p=0.014) and distant recurrence free survival (p=0.006).

Conclusion: Methylation of apoptosis genes is representative for the apoptotic status of a tumor and is correlated to survival and recurrence in rectal cancer patients. The apoptotic status of a tumor may be used to guide treatment strategies for individual patients.

[A.B. and E.C.M.Z contributed equally to this work.]

Citation Format: Anne Benard, Eliane C.M. Zeestraten, Inès J. Goossens-Beumer, Hein Putter, Christine Kuo, Cornelis J.H. van de Velde, Peter J.K. Kuppen, Dave S.B. Hoon. DNA methylation of apoptosis-related genes as clinical biomarker in rectal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 668. doi:10.1158/1538-7445.AM2013-668

Association between circulating tumor cells and prognosis in patients with stage III melanoma with sentinel lymph node metastasis in a phase III international multicenter trial

PURPOSE

The outcomes of patients with melanoma who have sentinel lymph node (SLN) metastases can be highly variable, which has precluded establishment of consensus regarding treatment of the group. The detection of high-risk patients from this clinical setting may be helpful for determination of both prognosis and management. We report the utility of multimarker reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) detection of circulating tumor cells (CTCs) in patients with melanoma diagnosed with SLN metastases in a phase III, international, multicenter clinical trial.

PATIENTS AND METHODS

Blood specimens were collected from patients with melanoma (n = 331) who were clinically disease-free after complete lymphadenectomy (CLND) before entering onto a randomized adjuvant melanoma vaccine plus bacillus Calmette-Guérin (BCG) versus BCG placebo trial from 30 melanoma centers (United States and international). Blood was assessed using a verified multimarker RT-qPCR assay (MART-1, MAGE-A3, and GalNAc-T) of melanoma-associated proteins. Cox regression analyses were used to evaluate the prognostic significance of CTC status for disease recurrence and melanoma-specific survival (MSS).

RESULTS

Individual CTC biomarker detection ranged from 13.4% to 17.5%. There was no association of CTC status (zero to one positive biomarkers v two or more positive biomarkers) with known clinical or pathologic prognostic variables. However, two or more positive biomarkers was significantly associated with worse distant metastasis disease-free survival (hazard ratio [HR] = 2.13, P = .009) and reduced recurrence-free survival (HR = 1.70, P = .046) and MSS (HR = 1.88, P = .043) in a multivariable analysis.

CONCLUSION

CTC biomarker status is a prognostic factor for recurrence-free survival, distant metastasis disease-free survival, and MSS after CLND in patients with SLN metastasis. This multimarker RT-qPCR analysis may therefore be useful in discriminating patients who may benefit from aggressive adjuvant therapy or stratifying patients for adjuvant clinical trials.

Cancer Cells Expressing Toll-like Receptors and the Tumor Microenvironment

Toll-like receptors (TLRs) play a crucial role in the innate immune response and the subsequent induction of adaptive immune responses against microbial infection or tissue injury. Recent findings show that functional TLRs are expressed not only on immune cells but also on cancer cells. TLRs play an active role in carcinogenesis and tumor progression during chronic inflammation that involves the tumor microenvironment. Damage-associated molecular patterns (DAMPs) derived from injured normal epithelial cells and necrotic cancer cells appear to be present at significant levels in the tumor microenvironment, and their stimulation of specific TLRs can foster chronic inflammation. This review discusses how carcinogenesis, cancer progression, and site-specific metastasis are related to interactions between cancer cells, immune cells, and DAMPs through TLR activation in the tumor microenvironment.

Quantitative Analysis of Methylation of Genomic Loci in Early-Stage Rectal Cancer Predicts Distant Recurrence

Purpose

There are no accurate prognostic biomarkers specific for rectal cancer. Epigenetic aberrations, in the form of DNA methylation, accumulate early during rectal tumor formation. In a preliminary study, we investigated absolute quantitative methylation changes associated with tumor progression of rectal tissue at multiple genomic methylated-in-tumor (MINT) loci sequences. We then explored in a different clinical patient group whether these epigenetic changes could be correlated with clinical outcome.

Patients and Methods

Absolute quantitative assessment of methylated alleles was used to assay methylation changes at MINT 1, 2, 3, 12, 17, 25, and 31 in sets of normal, adenomatous, and malignant tissues from 46 patients with rectal cancer. Methylation levels of these biomarkers were then assessed in operative specimens of 251 patients who underwent total mesorectal excision (TME) without neoadjuvant radiotherapy in a multicenter clinical trial.

Results

Methylation at MINT 2, 3, and 31 increased 11-fold (P = .005), 15-fold (P < .001), and two-fold (P = .02), respectively, during adenomatous transformation in normal rectal epithelium. Unsupervised grouping analyses of quantitative MINT methylation data of TME trial patients demonstrated two prognostic subclasses. In multivariate analysis of node-negative patients, this subclassification was the only predictor for distant recurrence (hazard ratio [HR], 4.17; 95% CI, 1.72 to 10.10; P = .002), cancer-specific survival (HR, 3.74; 95% CI, 1.4 to 9.43; P = .003), and overall survival (HR, 2.68; 95% CI, 1.41 to 5.11; P = .005).

Conclusion

Methylation levels of specific MINT loci can be used as prognostic variables in patients with American Joint Committee on Cancer stage I and II rectal cancer. Quantitative epigenetic classification of rectal cancer merits evaluation as a stratification factor for adjuvant treatment in early disease.

Association of circulating tumor cells with serum tumor-related methylated DNA in peripheral blood of melanoma patients

Although previous studies have separately shown the utility of circulating tumor cells (CTC) or cell-free tumor-related DNA in blood of cancer patients, there has been no investigation of their association and/or the prognostic value of combining these assessments. To date, the true source of tumor-related DNA in serum remains unknown. We hypothesized that CTC is a possible origin of serum tumor-related methylated DNA and their combination can predict disease outcome. To test this hypothesis, we obtained matched pairs of peripheral blood lymphocytes and serum specimens simultaneously from 50 American Joint Committee on Cancer stage IV melanoma patients before administration of biochemotherapy. Peripheral blood leukocytes were analyzed for three mRNA markers of CTC: MART-1, GalNAc-T, and MAGE-A3. Sera were analyzed for two methylated DNA markers: RASSF1A and RAR-beta2. CTC were detected in 13 of 15 (86%) patients with serum tumor-related methylated DNA and only in 13 of 35 (37%) patients without methylated DNA (P = 0.001). The number of CTC markers detected significantly correlated with methylated DNA (P = 0.008). CTC and methylated DNA were significantly correlated with biochemotherapy-treated patients' outcome. Patients with both CTC and methylated DNA showed significantly poorer response to biochemotherapy (P = 0.02) and worse time to progression and overall survival (P = 0.009 and 0.02, respectively). The correlation between CTC and serum tumor-related methylated DNA and the significant effect of this correlation on disease outcome indicate that a composite molecular assessment in blood may be a useful determinant of disease status and efficacy of systemic therapy for melanoma.

Estrogen receptor-alpha methylation predicts melanoma progression

The role of estrogen receptor alpha (ER-alpha) in melanoma is unknown. ER-alpha expression may be regulated in melanoma via hypermethylation of promoter CpG islands. We assessed ER-alpha hypermethylation in primary and metastatic melanomas and sera as a potential tumor progression marker. ER-alpha methylation status in tumor (n = 107) and sera (n = 109) from American Joint Committee on Cancer (AJCC) stage I to IV melanoma patients was examined by methylation-specific PCR. The clinical significance of serum methylated ER-alpha was assessed among AJCC stage IV melanoma patients receiving biochemotherapy with tamoxifen. Rates of ER-alpha methylation in AJCC stage I, II, and III primary melanomas were 36% (4 of 11), 26% (5 of 19), and 35% (8 of 23), respectively. Methylated ER-alpha was detected in 42% (8 of 19) of stage III and 86% (30 of 35) of stage IV metastatic melanomas. ER-alpha was methylated more frequently in metastatic than primary melanomas (P = 0.0003). Of 109 melanoma patients' sera in AJCC stage I, II, III, and IV, methylated ER-alpha was detected in 10% (2 of 20), 15% (3 of 20), 26% (5 of 19), and 32% (16 of 50), respectively. Serum methylated ER-alpha was detected more frequently in advanced than localized melanomas (P = 0.03) and was the only factor predicting progression-free [risk ratio (RR), 2.64; 95% confidence interval (95% CI), 1.36-5.13; P = 0.004] and overall survival (RR, 2.31; 95% CI, 1.41-5.58; P = 0.003) in biochemotherapy patients. Hypermethylated ER-alpha is a significant factor in melanoma progression. Serum methylated ER-alpha is an unfavorable prognostic factor.

Microphthalmia transcription factor as a molecular marker for circulating tumor cell detection in blood of melanoma patients

PURPOSE

Microphthalmia transcription factor (Mitf), which is important in melanocyte development and melanoma growth, was assessed using real-time quantitative reverse transcription-PCR assay to investigate its expression as a marker for circulating melanoma cells in blood and determine the correlation with disease stage and survival in melanoma patients.

EXPERIMENTAL DESIGN

In optimization studies for Mitf, we tested 15 melanoma cell lines, 41 peripheral blood lymphocytes from healthy volunteers, and 21 metastatic melanoma tissues. Blood specimens were procured from 90 patients with stage I (n = 20), stage II (n = 20), stage III (n = 28), and stage IV (n = 22) melanoma. Blood specimens were also obtained at four bleed intervals from 58 patients enrolled in a prospective multicenter trial of biochemotherapy before and after surgical treatment of American Joint Committee on Cancer stage III melanoma.

RESULTS

Under the optimized conditions, Mitf was negative in healthy peripheral blood lymphocytes and positive in all melanoma cell lines and 18 (86%) melanoma tissues. In the 90 patients, the rate of Mitf detection was higher with increasing American Joint Committee on Cancer stage (P < 0.0001). In the 58 patients treated with biochemotherapy and surgery, Mitf detection decreased with treatment (P = 0.019). Mitf detection after treatment was associated with a significantly lower relapse-free (P < 0.0001) and overall (P = 0.001) survival and was a significant independent prognostic factor for relapse-free (risk ratio, 5.63; P = 0.0004) and overall (risk ratio, 5.36; P = 0.005) survival.

CONCLUSIONS

Mitf detection in blood can indicate subclinical metastatic disease and predict treatment outcome in melanoma patients.

Survivin expression by metastatic melanoma predicts poor disease outcome in patients receiving adjuvant polyvalent vaccine

Survivin and livin are members of the inhibitor of apoptosis protein (IAP) family. We hypothesized that elevated expression levels of these 2 IAP genes in resected advanced-stage metastatic melanoma lesions would be associated with poor disease outcome in patients receiving a polyvalent therapeutic cancer vaccine (Canvaxintrade mark). A quantitative real-time RT-PCR (qRT) assay for survivin and livin genes was used to assess mRNA expression in 63 metastatic melanomas obtained during cytoreductive surgery of American Joint Committee on Cancer (AJCC) stage IV melanoma. Nineteen of 63 metastatic melanoma patients received Canvaxin pre- and postoperatively, and 37 patients received only postoperative Canvaxin. Expression of survivin and livin protein was assessed by immunohistochemistry (IHC) and then correlated with mRNA. Survivin mRNA was detected in 62 of 63 (98%) melanoma specimens ranging from 0-5.96 x 10(4) mRNA copies of total RNA. Lower mRNA copy levels of survivin significantly correlated with improved overall survival among the 37 patients who received Canvaxin postoperatively but not preoperatively (log-rank test, p = 0.023). Among patients with low survivin mRNA copies, those who received postoperative Canvaxin did significantly better than patients who received pre- and postoperative Canvaxin (p = 0.003). Livin mRNA was detectable in 60 of 63 (95%) metastatic melanoma specimens but had no significant prognostic utility. These studies demonstrate that lower levels of survivin in recurrent metastatic melanomas are associated with significantly improved survival in patients receiving postoperative adjuvant immunotherapy. Overall, the study indicates survivin expression in metastatic melanomas can significantly influence disease outcome and patient responses to immunotherapy.

Multimarker quantitative real-time PCR detection of circulating melanoma cells in peripheral blood: relation to disease stage in melanoma patients

BACKGROUND

Detection of melanoma cells in circulation may be important in assessing tumor progression. The objective of this study was to develop a specific, reliable multimarker quantitative real-time reverse transcription-PCR (qRT) assay for detecting melanoma cells in patients' blood.

METHODS

We developed qRT assays for the mRNA of four melanoma-associated markers: MART-1, GalNAc-T, PAX-3, and MAGE-A3. In optimization studies, we tested 17 melanoma cell lines and 49 peripheral blood leukocyte (PBL) samples from volunteers. We performed RNA and melanoma cell dilution studies to assess the detection limits and imprecision of the assays. We measured the mRNAs in blood specimens from 94 melanoma patients [American Joint Committee on Cancer (AJCC) stage I, n = 20; II, n = 20; III, n = 32; IV, n = 22].

RESULTS

All markers were frequently detected in melanoma cell lines, whereas none of the markers was detected in PBLs from volunteers. The qRT assay could detect 1 melanoma cell in 10(7) PBLs in the melanoma cell-dilution studies. Markers were detected in 15%, 30%, 75%, and 86% of melanoma patients with AJCC stage I, II, III, and IV disease, respectively. The number of positive markers and AJCC stage were significantly correlated (Spearman correlation coefficient = 0.58; P < 0.0001).

CONCLUSIONS

Multimarker qRT can detect circulating melanoma cells in blood. Measurement of the studied molecular markers in blood may be useful in detection of metastasis and monitoring treatment response of melanoma patients.

Detection of occult metastatic breast cancer cells in blood by a multimolecular marker assay: correlation with clinical stage of disease

Currently, molecular markers offer the unique opportunity to identify occult metastasis in early stage cancer patients not otherwise detected with conventional staging techniques. To date, well-characterized molecular tumor markers to detect occult breast cancer cells in blood are limited. Because breast tumors are heterogeneous in tumor marker expression, we developed a "multimarker" reverse transcription-PCR assay combined with the highly sensitive electrochemiluminescence automated detection system. Breast cancer cell lines (n = 7), primary breast tumors (n = 25), and blood from normal donors (n = 40) and breast cancer patients [n = 65; American Joint Committee on Cancer (AJCC) stages I-IV] were assessed for four mRNA tumor markers: beta-human chorionic gonadotropin (beta-hCG), oncogene receptor (c-Met), beta 1-->4-N-acetylgalactosaminyl-transferase, and a tumor-associated antigen (MAGE-A3). None of the tumor markers were expressed in any normal donor bloods. Breast cancer cell lines and primary breast tumors expressed beta-hCG, c-Met, beta 1-->4-N-acetylgalactosaminyl-transferase, and MAGE-A3 mRNA. Of the 65 breast cancer patient blood samples assessed, 2, 3, 15, 49, and 31% expressed 4, 3, 2, 1, and 0 of the mRNA tumor markers, respectively. At least two markers were expressed in 20% of the blood specimens. The addition of a combination of markers enhanced detection of systemic metastasis by 32%. In patient blood samples, the MAGE-A3 marker correlated significantly with tumor size (P = 0.0004) and AJCC stage (P = 0.007). The combination of beta-hCG and MAGE-A3 mRNA markers correlated significantly with tumor size (P = 0.04), and the marker combination c-Met and MAGE-A3 showed a significant correlation with tumor size (P = 0.005) as well as AJCC stage (P = 0.018). A multimarker reverse transcription-PCR assay that correlates with known clinicopathological prognostic parameters may have potential clinical utility by monitoring tumor progression with a blood test.

Detection of MAGE-A3 in breast cancer patients' sentinel lymph nodes

The detection of occult metastatic breast cancer cells by RT-PCR is limited by the poor specificity of most tumour mRNA markers. MAGE-A3 is a highly specific tumour mRNA marker that is not expressed in non-cancer cells. This study assesses MAGE-A3 mRNA as a molecular marker for the detection of tumour cells in the sentinel lymph nodes (SLN) of breast cancer patients. Serial frozen sections of SLN (n = 121) were obtained from 77 AJCC (American Joint Committee on Cancer) Stage I-IIIA breast cancer patients. MAGE-A3 mRNA analysis of SLN was performed by RT-PCR and Southern blot analysis. Tumour cells were detected in 48 of 121 (40%) SLN from 77 patients by H&E or IHC staining, and 35 of 77 (45%) patients, overall, had histopathologically (H&E and/or IHC) positive SLN. Among histopathologically negative SLN, 28 of 73 (38%) SLN were MAGE-A3 mRNA positive by RT-PCR. Overall, 41 of 77 (53%) patients and 50 of 121 (41%) SLN were positive for MAGE-A3. MAGE-A3 mRNA expression in the SLN occurred more frequently with infiltrating lobular carcinoma (P < 0.001) than with infiltrating ductal carcinoma, adding further evidence of possible phenotypic differences between these 2 subtypes of breast cancer. Due to its high specificity, MAGE-A3 mRNA is a potentially useful marker for detecting breast cancer cells in the SLN. One half of breast tumours expressed MAGE-A3 mRNA, which has important potential implications for antigen-specific targeted immunotherapy.

Microsatellite alterations detected in the serum of early stage breast cancer patients

Breast cancer is the most common malignancy affecting women. Advances in screening have resulted in an increasing trend towards detecting earlier stage tumors associated with a longer disease-free survival. Because of this prolonged latency period, it is critical to identify patients early in their disease course who are at increased risk for recurrence, whereby treatment decisions may be altered accordingly based on more precise information. Molecular markers that demonstrate prognostic importance as well as utility for assessing subclinical disease progression offer one such approach. Specifically, circulating microsatellite alterations that reflect those genetic events occurring in tumors and that can be serially assessed through a minimally invasive procedure are a logistically practical method. In this study, serum was collected preoperatively from 56 patients with early stage breast cancer (AJCC stages I/II) and assessed for loss of heterozygosity (LOH) using 8 microsatellite markers. Twelve (21%) of 56 patients demonstrated LOH in their serum for at least one marker. Histopathologic correlation revealed an association between the presence of circulating LOH in serum and those tumors with increased proliferation indices as characterized by an increased diploid index, elevated MIB-1 fraction, and abnormal ploidy. These findings demonstrate the presence of circulating microsatellite alterations in the serum from patients with early stage breast cancer. The association of known poor prognostic features found in tumors with increased nuclear activity not only suggests a possible etiology for their presence, but also offers a potential blood-based surrogate marker for this disease that may demonstrate clinical utility in long-term follow-up studies.

Molecular detection of metastatic melanoma cells in cerebrospinal fluid in melanoma patients

Melanoma frequently metastasizes to the central nervous system (CNS). The diagnosis of CNS metastases typically is made following the onset of clinical symptoms. Thus, more sensitive diagnostic approaches are needed to identify subclinical CNS metastases. Currently, standard cytologic analysis of the cerebrospinal fluid (CSF) is limited by its poor sensitivity. A more sensitive assay was therefore developed using multiple reverse transcriptase-polymerase chain reaction (RT-PCR) markers. CSF was collected and assessed by RT-PCR for three known melanoma-associated markers (MAGE-3, MART-1, and tyrosinase) to detect occult metastatic melanoma cells in the CSF of 37 American Joint Committee on Cancer (AJCC) stage IV melanoma patients. Cytologic analysis of CSF was performed on all patients, and immunohistochemistry (IHC) analysis was performed on 33 CSF samples using anti-S100 and anti-HMB-45 antibodies. Only one patient (3%) had tumor-positive CSF cytology and IHC upon entry into the study, whereas 12 patients (32%) were positive for at least one RT-PCR marker. The correlation between CSF RT-PCR positivity of MART-1 and/or MAGE-3 and the development of CNS metastases at 3 mo was significant (p = 0.04). Fifteen of 37 patients (41%) had either positive MRI and/or positive RT-PCR results. Multimarker RT-PCR is more informative and sensitive than cytology/IHC in assessing the CSF of melanoma patients.

Prognostic significance of circulating microsatellite markers in the plasma of melanoma patients

PURPOSE

Multiple genetic alterations including loss of heterozygosity (LOH) occur commonly in melanoma tumors. We demonstrated previously free-circulating DNA microsatellites with LOH in the blood of melanoma patients. These LOH markers in plasma may be useful as surrogates for subclinical disease progression. The purpose of this study was to determine whether the presence of circulating tumor microsatellite markers in the preoperative blood from patients with melanoma has prognostic utility.

EXPERIMENTAL DESIGN

Plasma was analyzed for the presence of LOH at six chromosome regions, which are common for allelic loss in melanoma tumors, in 57 patients undergoing surgical resection of all of the clinically apparent disease.

RESULTS

LOH was detected in 32 of 57 patients (56%). Both LOH incidence and frequency correlated with advancing American Joint Committee on Cancer stage. In patients with American Joint Committee on Cancer stage III, the presence of LOH as an independent variable in preoperative plasma was significantly associated (P = 0.05) with an increased risk of death. Furthermore, LOH at microsatellite marker D1S228 in the plasma of patients with advanced disease correlated significantly (P = 0.0009) with a poorer survival after surgical resection. LOH commonly found in melanoma tumors can be successfully identified in the plasma of a patient, providing a potentially less invasive route for following genetic changes that serve as molecular surrogates for assessing subclinical disease progression.

CONCLUSIONS

This study provides evidence that blood testing for circulating tumor genetic markers may provide valuable prognostic information and guide future therapy.

Ganglioside GM2/GD2 synthetase mRNA is a marker for detection of infrequent neuroblastoma cells in bone marrow

GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-4Glcbeta1-Cer (GM2)/GalNAcbeta1-4(NeuAcalpha2-8NeuAcalpha2-3)Galbeta1-4Glcbeta1-1Cer (GD2) synthetase [beta-1,4-N-acetyl-galactosaminyl transferase (GalNAc-T)] mRNA, which encodes a key glycosyltransferase for ganglioside GD2 synthesis, was assessed as a molecular marker for detecting metastatic neuroblastoma cells in bone marrow (BM). GalNAc-T mRNA expression by neuroblastoma cell lines (n = 15), primary untreated neuroblastoma tumors (n = 29), morphologically normal BM (n = 22), peripheral blood stem cells (n = 10) from patients with cancers other than neuroblastoma, and blood mononuclear cells from normal donors (n = 17) was assessed by using reverse transcriptase-polymerase chain reaction (RT-PCR) and electrochemiluminescence detection assay (RT-PCR/ECL). BM harvested from 15 neuroblastoma patients was tested before and after ex vivo immunomagnetic bead purging, and results were compared to immunocytological analysis of the same specimens. All neuroblastoma cell lines (mean, 653 x 10(3) ECL units) and primary tumors (mean, 683 x 10(3) ECL units) were positive for significant expression of GalNAc-T mRNA compared to normal blood and BM cells. The RT-PCR/ECL assay could detect GalNAc-T mRNA in 100 pg of total RNA, and in a mixture of one neuroblastoma cell among 10(7) normal BM or blood cells. Eight of 15 autologous BM cells harvested from patients with neuroblastoma had tumor cells detectable by immunocytology, and all 15 were positive for GalNAc-T mRNA. After ex vivo purging, none of the BM cells was immunocytology-positive, but six remained positive by the RT-PCR/ECL assay. GalNAc-T mRNA provides a specific and sensitive molecular marker for RT-PCR/ECL detection of infrequent neuroblastoma cells in BM.

Tumor-reactive T helper lymphocytes recognize a promiscuous MAGE-A3 epitope presented by various major histocompatibility complex class II alleles

The development of effective T cell-based immunotherapy for cancer requires the identification of antigens capable of inducing both CTL and T helper immune responses. Although CTLs will participate in the antitumor response mainly by exerting their lytic activity on the tumor cells, helper T lymphocytes will be critical for the induction and maintenance of the CTLs. Thus, effective subunit therapeutic vaccines should include both CTL and T helper epitopes from antigens expressed on the tumor cells. The product of the MAGE-A3 gene is an attractive candidate for tumor immunotherapy because it is expressed in the majority of melanomas and in a great proportion of other solid tumors. Although numerous CTL epitopes for the MAGE-A3 antigen have been reported, only a few have been described for helper T cells. Here we show that a synthetic peptide derived from the MAGE-A3 sequence (MAGE-A3(146-160)) was effective in inducing in vitro T helper responses in the context of HLA-DR4 and HLA-DR7 alleles. Most significantly, the peptide-reactive helper T lymphocytes were capable of recognizing various forms of MAGE-A3 antigen (tumor cell lysates, dead/apoptotic tumor cells, or recombinant MAGE-A3 protein), indicating that the T-cell epitope represented by peptide MAGE-A3(146-160) is naturally processed by antigen-presenting cells. These studies are relevant for the design of multi-epitope vaccines for treating MAGE-A3-expressing tumors through the simultaneous stimulation of CTL and T helper lymphocytes.

Molecular clonality of in-transit melanoma metastasis

In-transit melanoma is characterized by an aggressive pattern of recurrence that is associated with a poorer prognosis. Because in-transit melanoma is considered to result from the intralymphatic trapping of melanoma cells between the primary tumor and regional lymph nodes, it provides an excellent model to assess genetic events associated with early metastasis. The hypothesis of this study was to determine whether in-transit metastases are clonal in origin and therefore, may have specific genetic alterations uniquely associated with this disease and the development of early metastasis. This was assessed using loss of heterozygosity (LOH) analysis for specific DNA microsatellite loci. Seventy-nine paraffin-embedded in-transit melanoma lesions from 25 patients (range, 2 to 9 lesions per patient; average, 3.4 lesions per patient) were assessed for LOH using eight microsatellite DNA markers on six chromosomes. In 19 of 25 patients (76%) LOH was demonstrated for at least one marker. The most frequent microsatellite marker demonstrating LOH was D9S157 (56%). Using LOH microsatellite markers to assess intertumor heterogeneity, six of 79 tumors (7.6%) demonstrated different profiles when compared to other lesions from the same patient. In-transit metastases from those patients demonstrating intertumor heterogeneity were further assessed using laser capture microdissection and DNA analysis, and revealed no significant intratumor heterogeneity. In conclusion, LOH was frequently observed in in-transit melanoma metastasis. Based on LOH analysis, in-transit metastases are clonal in origin. The establishment of clinically successful in-transit melanoma metastasis requires specific genetic events that seem to be unique and homogeneous for each patient.

Molecular strategy for detecting metastatic cancers with use of multiple tumor-specific MAGE-A genes

BACKGROUND

The human melanoma-associated antigen family A (MAGE-A) has high specificity and expression in various malignancies, but individual family members are expressed at low frequency in any one particular type of cancer. We therefore developed a method to detect mRNAs from multiple MAGE-A genes in a single reaction.

METHODS

Universal MAGE-A (uMAGE-A) primers and probe were designed to reverse-transcribe, amplify, and detect by electrochemiluminescence (ECL) MAGE-A mRNAs on the Origen Analyzer. The assay was performed on total RNA of melanoma (n = 9 cell lines and 24 tumors), breast cancer (n = 7 and 26), and colorectal cancer (CRC; n = 5 and 12). We also evaluated blood from melanoma (n = 50), breast cancer (n = 16), and CRC (n = 21) patients.

RESULTS

The uMAGE-A mRNA was detectable in 0.01-1 ng of cell line RNA. The identity of the uMAGE-A cDNA products was confirmed by sequencing and polyacrylamide gel electrophoresis. The uMAGE-A assay increased detection of melanoma, breast cancer, and CRC tumor by 13%, 31%, and 25%, respectively, compared with a MAGE-A1 assay, and by 17%, 19%, and 25%, respectively, compared with a MAGE-A3 assay. The uMAGE-A assay detected circulating tumor cells in the blood of melanoma (24%), breast cancer (25%), and CRC (29%) patients.

CONCLUSIONS

The uMAGE-A reverse transcription-PCR/ECL assay provides a practical and sensitive approach for detection of various metastatic cancers in tissues and blood.

Molecular staging of early colon cancer on the basis of sentinel node analysis: a multicenter phase II trial

PURPOSE

Approximately 30% of patients with American Joint Committee on Cancer stage I or II colorectal cancer (CRC) develop systemic disease. We hypothesized that multimarker reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of sentinel lymph nodes (SNs) draining a primary CRC could detect micrometastases not detected by conventional histopathologic analysis.

PATIENTS AND METHODS

In a multi-institutional study, 40 patients with primary CRC underwent dye-directed lymphatic mapping at the time of colon resection. Each dye-stained SN was tagged, and the tumor and regional nodes were resected en bloc. All lymph nodes were examined by conventional hematoxylin and eosin (HE) staining. In addition, each SN was cut into multiple sections for cytokeratin immunohistochemical (CK-IHC) staining and for RT-PCR and electrochemiluminescent detection of three markers: beta-chain human chorionic gonadotropin, hepatocyte growth factor receptor, and universal melanoma-associated antigen. Whenever possible, RT-PCR assay was also performed on primary tumor tissue. The detection sensitivity of individual markers was 10(-3) to 10(-4) microg of RNA and one to five tumor cells in 10(7) lymphocytes of healthy donors.

RESULTS

One to three SNs were identified in each patient. An average of 15 nodes were removed from each CRC specimen. No nonsentinel (untagged) node contained evidence of tumor if all tagged (sentinel) nodes in the same specimen were histopathology tumor-negative. HE staining of SNs identified tumor in 10 patients (25%), and CK-IHC of SNs identified occult micrometastases in four patients (10%) whose SNs were negative by HE. Of the remaining 26 patients with no evidence of SN involvement by HE or CK-IHC, 12 (46%) had positive RT-PCR results. The number of markers expressed in each SN correlated (P <.04) with the T stage of the primary tumor. There was 79% concordance in marker expression for the respective pairs (n = 38) of primary tumor and histopathologically positive SNs, and 86% (12 of 14) concordance between RT-PCR positive and histopathologically positive SNs.

CONCLUSION

Identification and focused examination of the SN is a novel method of staging CRC. CK-IHC and RT-PCR identified occult micrometastases in 53% of patients whose SNs were negative by conventional staging techniques. These ultrasensitive assays of the SN can identify patients who may be at high risk for recurrence of CRC and therefore are more likely to benefit from systemic adjuvant therapy.

The clinical utility of multimarker RT-PCR in the detection of occult metastasis in patients with melanoma

Cutaneous melanoma is characterized by a high propensity for metastasis. Currently, surgical intervention remains the mainstay of therapy. This approach has proven most beneficial when the diagnosis is of early stage primary lesions. Likewise, patients undergoing resection for a solitary site of metastasis have shown a survival advantage. Identification of metastatic disease depends predominantly on radiographic techniques requiring the presence of significant tumor burdens for successful imaging. However, at that time, the role of surgery and/or biochemotherapy may be of limited value. Techniques to identify minimal disease states may permit more accurate assessment of prognosis. The detection of occult tumor cells by RT-PCR in the blood, lymph nodes, and bone marrow of melanoma patients provides one such approach to monitor tumor progression. Single-marker RT-PCR has been used as one such approach but is noted to have limitations in sensitivity and specificity based on the heterogeneity of tumor marker expression among tumors as well as within an individual tumor lesion or among multiple lesions in individual patients. We employed a multimarker reverse transcriptase polymerase chain reaction assay that demonstrates improved sensitivity over a single-marker approach. Currently, the consequences of detecting systemic subclinical metastasis remain unknown pending longer-term follow-up. The detection of occult melanoma cells using molecular techniques in conjunction with known clinicopathologic prognostic factors may provided a novel and efficient approach in monitoring tumor progression and further identify high-risk patients diagnosed early in the disease course.

Functional interleukin-4 receptor and interleukin-2 receptor common gamma chain in human gastric carcinoma: a possible mechanism for cytokine-based therapy

Interleukin (IL)-2 and IL-4 play a critical role in the regulation of the immune response. Yet both of the receptors for these cytokines have been found on nonhematopoietic cells, including human gastric carcinoma cell lines and tissue specimens. IL-4 causes G1 phase cell cycle arrest of gastric carcinoma; the effect directly correlates with the expression of IL-4 receptor (IL-4R) and is seen within 48 hours after treatment. Cells lacking IL-4R are unaffected by IL-4. We examined signal transduction pathways employed by IL-4 that may account for cell cycle arrest of an established human gastric carcinoma cell line, CRL 1739. Western blot analysis was performed on CRL 1739 cultured in the presence of IL-4 (500 U/ml). Cells were lysed, protein extracted, and electroblotted; blots were then probed with murine mono-clonal antibodies to specific intracellular proteins. Western blotting of CRL 1739 with antiphosphotyrosine antibody (4G10) demonstrated multiple (140 kDa and 65 kDa) phosphoproteins seen only in IL-4-treated CRL 1739. Immunoprecipitation and blotting of CRL 1739 with specific secondary antibodies demonstrated that the 140 kDa phosphoprotein was IL-4R", the 65kDa phosphoprotein was IL-2Rgc, the 130 kDa phosphoprotein was Janus kinase (JAK1), and the 116 kDa phosphoprotein was JAK3. Reverse transcription-polymerase chain reaction with specific primers demonstrated that multiple human gastric tumor specimens expressed IL-4R" and IL-2Rgc but did not express the leukocyte marker CD45. These results suggest that human gastric carcinomas may express functional cytokine receptors, including the IL-2Rgc commonly found in association with the lymphocyte IL-2R. These receptors may represent novel targets for directing cytokine-based therapy.

Microsatellite analysis of melanoma lesions using (CA)13 oligonucleotides as an internal probe

The accurate assessment of microsatellite loci on specific chromosome regions for loss of heterozygosity (LOH) is important to identify potential tumor suppressor gene locations and recently correlations to clinicopathology of tumors. Analysis of microsatellite markers usually requires performing polymerase chain reaction (PCR) with labeled primers. This often leads to spurious PCR products that make interpretations of specific PCR bands difficult. Assessment of LOH by radiolabeled PCR is not always easy to interperet when there are multiple bands present, multiple markers and specimens are being assessed, and in multiplex LOH PCR. We describe an approach to accurately verify PCR-based LOH in which labeled PCR primers are not needed to detect allele expression. Specificity is determined by using a digoxigenin-labeled oligonucleotide (CA)13 as an internal specific probe for hybridization. Because the majority of di-nucleotide microsatellite markers contain the sequence of (CA)n or (GT)n repeats, this (CA)n probe is highly versatile. Forty cutaneous melanoma biopsies from advanced stage patients were assessed using the oligonucleotide probe at five chromosome regions (1q, 6q, 9p, 10q, 11q). The LOH frequency in informative cases varied from 33% to 47% in which chromosome 6q was the highest followed closely by 11q. We observed a higher frequency of LOH in the 6q (47%) and 11q (41%) compared to previously reported studies using the probe technique. This new approach was also demonstrated to be efficient in multiplex-PCR to detect LOH in melanomas. Using the probe hybridization approach it was demonstrated that in advanced cutaneous melanomas LOH are quite frequently expressed on 5 different chromosome regions.

Induction of melanoma-associated antigen systemic immunity upon intratumoral delivery of interferon-gamma retroviral vector in melanoma patients

A total of 17 patients with metastatic melanoma were treated with intratumoral interferon-gamma (IFN-gamma) retroviral vector in a phase I clinical trial. A cycle of treatment consisted of five daily injections every 2 weeks. Patients were divided into two treatment arms that involved a single course (one cycle) of treatment (group I; n = 9) and multiple cycles (six cycles) of treatment (group II; n = 8). Patients received intratumoral injections of IFN-gamma (10(7) plaque-forming units/mL administered at 0.3, 0.5, and 1.0 mL per cohort of patients). All patients receiving multiple injections either maintained stable disease (n = 5) or achieved a partial or complete response (n = 3) of the injected lesion, whereas in patients receiving a single cycle of treatment, only one of nine patients had a response. Patients were assessed for immunoglobulin G antibody (Ab) responses to the melanoma-associated antigens (MAA) tyrosinase, gp100, TRP-2, and MAGE-A1 by affinity enzyme-linked immunosorbent assay. Anti-MAGE-A1 and tyrosinase Ab were significantly elevated from baseline (day 0) to week 16 during treatment (P = .005; P = .002, respectively) in patients who received multiple injections. Patients undergoing treatment who had a clinical response (stable disease or better) also had significantly more elevated Ab responses to a greater number of MAA (P = .0004). The induction of systemic Ab responses to multiple MAA also correlated with systemic clinical responses. These studies suggest that multiple anti-MAA Ab responses are associated with clinical responses to IFN-gamma retroviral treatment and may be used as surrogate response markers.

Molecular markers in blood as surrogate prognostic indicators of melanoma recurrence

Improvement is needed in the ability to evaluate the prognosis of melanoma patients who are clinically disease-free but likely to develop recurrent metastatic disease. The detection of circulating melanoma cells in blood is a potential surrogate marker of subclinical residual disease. We assessed the prognostic clinical utility of a multimarker melanoma reverse transcriptase-PCR (RT-PCR) assay using blood of 46 patients who were clinically disease-free. All patients were followed up for more than 4 years for disease recurrence. There was a significant correlation between number of RT-PCR markers present in blood and American Joint Committee on Cancer stage (P = 0.009). The number of RT-PCR markers detected in blood was an independent prediction factor of disease recurrence in a Cox proportional hazard model (P = 0.02). A risk factor model using American Joint Committee on Cancer stage and number of positive RT-PCR markers significantly predicted disease recurrence in 2, 3, and 4 years of follow-up. These studies demonstrate that molecular detection of circulating melanoma cells may be of significant prognostic value in determining early disease recurrence and may be useful for stratifying patients for adjuvant therapy.

Molecular detection of metastatic pancreatic carcinoma cells using a multimarker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

The diagnosis of pancreatic carcinoma is often associated with a poor prognosis, because most patients already have advanced disease. A highly sensitive assay to detect the progression of pancreatic carcinoma would be of significant clinical utility. The authors developed multiple tumor mRNA markers for reverse transcriptase-polymerase chain reaction (RT-PCR) to detect metastatic tumor cells in the blood and tissue of patients with American Joint Committee on Cancer (AJCC) Stage II/III or IV pancreatic carcinoma.

METHODS

An RT-PCR plus Southern blot assay was used to detect mRNA of tumor markers in blood and tissues. mRNA expression of the tumor progression markers MET (hepatocyte growth factor receptor gene c-met), GalNAc-T (beta1,4- N-acetyl-galactosaminyl-transferase), and beta-hCG (beta-human chorionic gonadotropin) was evaluated in 9 pancreatic carcinoma cell lines, 13 tumor biopsy specimens, 5 nonmalignant pancreatic tissue specimens, and blood from 33 pancreatic carcinoma patients and 32 healthy donors.

RESULTS

The detection limit of the assay was 1 rhog, 10 rhog, and 10 rhog for MET, GalNAc-T, and beta-hCG mRNA expression, respectively. The pancreatic carcinoma cell lines expressed all three mRNA markers. Of blood specimens from 17 patients with AJCC Stage IV pancreatic carcinoma, 82%, 65%, and 76% were MET, GalNAc-T, and beta-hCG mRNA positive, respectively. Of blood specimens from 16 patients with AJCC Stage II/III disease, 88% were positive for at least 1 mRNA marker.

CONCLUSIONS

A multiple molecular marker assay was developed to detect cancer cells in blood and tissue from patients with different stages of pancreatic carcinoma. The detection of cancer cells in the blood may be used as a marker of pancreatic tumor progression and may be useful in monitoring response to therapy.

PTEN / MMAC1 mutation and frequent loss of heterozygosity identified in chromosome 10q in a subset of hepatocellular carcinomas

Frequent allelic losses on chromosome 10q have been reported in several types of cancers, suggesting the presence of a putative tumor suppressor gene(s) on the chromosomal arm. We examined loss of heterozygosity (LOH) on chromosome 10q in 37 hepatocellular carcinomas (HCC) using eleven dinucleotide microsatellite markers, spanning the entire chromosome arm of 10q. Twelve (32%) out of 37 informative cases showed allelic losses of at least one locus on 10q and eight tumors showed a partial deletion of 10q. Analysis of deletion mapping of these eight cases identified two commonly deleted regions within the distal part of 10q (10q24-q26), a 20-cM interval flanked by D10S597 and D10S216 and a 24-cM interval flanked by D10S216 and D10S590. Moreover, we detected a somatic missense mutation (Met --> Val) of a candidate tumor suppressor gene PTEN / MMAC1, located at 10q23.3, in one HCC with LOH of 10q. Our findings indicated the presence of putative tumor suppressor gene(s) in the distal region of 10q that might be involved in the development and progression of HCC. Inactivation of PTEN / MMAC1 gene located outside the commonly deleted region of 10q might also play an important role in a subset of HCCs.

Molecular detection of metastatic pancreatic carcinoma cells using a multimarker reverse transcriptase-polymerase chain reaction assay

BACKGROUND

The diagnosis of pancreatic carcinoma is often associated with a poor prognosis, because most patients already have advanced disease. A highly sensitive assay to detect the progression of pancreatic carcinoma would be of significant clinical utility. The authors developed multiple tumor mRNA markers for reverse transcriptase-polymerase chain reaction (RT-PCR) to detect metastatic tumor cells in the blood and tissue of patients with American Joint Committee on Cancer (AJCC) Stage II/III or IV pancreatic carcinoma.

METHODS

An RT-PCR plus Southern blot assay was used to detect mRNA of tumor markers in blood and tissues. mRNA expression of the tumor progression markers MET (hepatocyte growth factor receptor gene c-met), GalNAc-T (beta1,4- N-acetyl-galactosaminyl-transferase), and beta-hCG (beta-human chorionic gonadotropin) was evaluated in 9 pancreatic carcinoma cell lines, 13 tumor biopsy specimens, 5 nonmalignant pancreatic tissue specimens, and blood from 33 pancreatic carcinoma patients and 32 healthy donors.

RESULTS

The detection limit of the assay was 1 rhog, 10 rhog, and 10 rhog for MET, GalNAc-T, and beta-hCG mRNA expression, respectively. The pancreatic carcinoma cell lines expressed all three mRNA markers. Of blood specimens from 17 patients with AJCC Stage IV pancreatic carcinoma, 82%, 65%, and 76% were MET, GalNAc-T, and beta-hCG mRNA positive, respectively. Of blood specimens from 16 patients with AJCC Stage II/III disease, 88% were positive for at least 1 mRNA marker.

CONCLUSIONS

A multiple molecular marker assay was developed to detect cancer cells in blood and tissue from patients with different stages of pancreatic carcinoma. The detection of cancer cells in the blood may be used as a marker of pancreatic tumor progression and may be useful in monitoring response to therapy.

Functional interleukin 4 receptor and interleukin 2 receptor common gamma-chain on human non-small cell lung cancers: novel targets for immune therapy

OBJECTIVE

The interleukin 4 receptor has been demonstrated on the surface of human non-small cell lung carcinoma cell lines and tumor specimens. Interleukin 4 causes G1-phase cell-cycle arrest of non-small cell lung cancer cell lines expressing the interleukin 4 receptor; the effect directly correlates with the expression of the interleukin 4 receptor and is seen within 48 hours after treatment. We examined signal transduction pathways used by the interleukin 4 receptor that may account for growth arrest of the cell line LUst but had no effect on another non-small cell lung cancer cell line, SK-MES-1.

METHODS

Western blot analysis was performed on both LUst and SK-MES-1 cell lines cultured in the presence of interleukin 4 (500 U/mL). Cells were lysed, protein extracted, and electroblotted; blots were then probed with murine monoclonal antibodies to specific intracellular proteins.

RESULTS

Western blotting of the cell lines with antiphosphotyrosine antibody (4G10) demonstrated multiple (140 kd, 100-130 kd, and 65 kd) phosphoproteins seen only in the interleukin 4-treated LUst cell line and not observed in the SK-MES-1 cell lines. Immunoprecipitation and blotting of the LUst cell line with specific secondary antibodies demonstrated that the 140-kd phosphoprotein was the interleukin 4 receptor, the 130-kd phosphoprotein was Janus kinase 1, the 116-kd phosphoprotein was Janus kinase 3, and the 65-kd phosphoprotein was the interleukin 2 receptor gamma-chain. Specific binding was not observed in the non-small cell lung cancer cell line SK-MES-1, suggesting that a functional interleukin receptor gamma-chain was not present. Southern blotting with complementary DNA probes to interleukin 2 receptor gamma-chain confirmed the absence of this receptor on cell line SK-MES-1.

CONCLUSIONS

These results suggest that non-small cell lung cancer cells may express functional cytokine receptors, including the interleukin 2 receptor gamma-chain commonly found in association with the lymphocyte interleukin 2 receptor. These receptors may be novel targets for directing cytokine-based immune therapy.

RNA melanoma vaccine: induction of antitumor immunity by human glycoprotein 100 mRNA immunization

An RNA melanoma vaccine was investigated to induce protective immunity in a mouse-melanoma model. LacZ mRNA was synthesized in vitro by pSFV3 expression vector and introduced into the spleen of mice, using HVJ-liposomes. A high level of beta-galactosidase activity was detected for 10 days in mouse spleen. The human melanoma-associated antigen gp100 mRNA was synthesized in vitro by pSFV3 vector and encapsulated in HVJ-liposomes. Immunization by direct injection of the gp100 mRNA HVJ-liposomes into mouse spleen induced both anti-gp100 Ab and CTL responses against B16 melanoma. Immunization by administration of gp100 mRNA into the spleen delayed tumor growth and significantly prolonged survival compared with control treated mice. These preclinical studies demonstrate that an RNA tumor antigen vaccine strategy has potential application for human cancer treatment and prevention.

Prognostic significance of occult metastases detected by sentinel lymphadenectomy and reverse transcriptase-polymerase chain reaction in early-stage melanoma patients

PURPOSE

Detection of micrometastases in the regional tumor-draining lymph nodes is critical for accurate staging and prognosis in melanoma patients. We hypothesized that a multiple-mRNA marker (MM) reverse transcriptase-polymerase chain reaction (RT-PCR) assay would improve the detection of occult metastases in the sentinel node (SN), compared with hematoxylin and eosin (H&E) staining and immunohistochemistry (IHC), and that MM expression is predictive of disease relapse.

PATIENTS AND METHODS

Seventy-two consecutive patients with clinical early-stage melanoma underwent sentinel lymphadenectomy (SLND). Their SNs were serially sectioned and assessed for MAGE-3, MART-1, and tyrosinase mRNA expression by RT-PCR, in parallel with H&E staining and IHC, for melanoma metastases. MM expression in the SNs was correlated with H&E and IHC assay results, standard prognostic factors, and disease-free survival.

RESULTS

In 17 patients with H&E- and/or IHC-positive SNs, 16 (94%) expressed two or more mRNA markers. Twenty (36%) of 55 patients with histopathologically negative SNs expressed two or more mRNA markers. By multivariate analysis, patients at increased risk of metastases to the SN had thicker lesions (P =.03), were 60 years of age or younger (P <.05), and/or were MM-positive (P <.001). Patients with histopathologically melanoma-free SNs who were MM-positive, compared with those who were positive for one or fewer mRNA markers, were at increased risk of recurrence (P =.02). Patients who were MM-positive with histopathologically proven metastases in the SN were at greatest risk of disease relapse (P =. 01).

CONCLUSION

H&E staining and IHC underestimate the true incidence of melanoma metastases. MM expression in the SN more accurately reflects melanoma micrometastases and is also a more powerful predictor of disease relapse than are H&E staining and IHC alone.