Adjuvant therapy for patients with high-risk malignant melanoma

Exploiting dendritic cells for active immunotherapy of cancer and chronic infections

Dendritic cells (DCs) are important antigen-presenting cells (APCs) that can prime naive T cells and control adaptive immune responses with respect to magnitude, memory and self-tolerance. Understanding the biology of these cells is central to the development of new generation immunotherapies for cancer and chronic infections. This review presents a brief overview of DC biology and of the preparation and use of DC-based vaccines.

Phenotypic and functional changes of human melanoma xenografts induced by DNA hypomethylation: immunotherapeutic implications

Emerging in vitro evidence points to an immunomodulatory activity of DNA hypomethylating drugs in human malignancies. We investigated the potential of 5-aza-2'-deoxycytidine (5-AZA-CdR) to modulate the expression of cancer testis antigens (CTA) and of HLA class I antigens by melanoma xenografts, and the resulting modifications in immunogenicity of neoplastic cells. Three primary cultures of melanoma cells, selected for immune phenotype and growth rate, were grafted into BALB/c nu/nu mice that were injected intraperitoneally with different dose- and time-schedules of 5-AZA-CdR. Molecular analyses demonstrated a de novo long-lasting expression of the CTA MAGE-1, -2, -3, -4, -10, GAGE 1-6, NY-ESO-1, and the upregulation of MAGE-1, MAGE-3, and NY-ESO-1 levels in melanoma xenografts from 5-AZA-CdR-treated mice. Serological and biochemical analyses identified a de novo expression of NY-ESO-1 protein and a concomitant and persistent upregulation of HLA class I antigens and of HLA-A1 and -A2 alleles. Immunization of BALB/c mice with 5-AZA-CdR-treated melanoma cells generated high titer circulating anti-NY-ESO-1 antibodies. Altogether, the data obtained identify an immunomodulatory activity of 5-AZA-CdR in vivo and strongly suggest for its clinical use to design novel strategies of CTA-based chemo-immunotherapy for melanoma patients.

Defining the mechanism by which IFN-β dowregulates c-myc expression in human melanoma cells: pivotal role for human polynucleotide phosphorylase (hPNPaseold-35)

Type I interferons (IFN-alpha/-beta) are capable of suppressing c-myc mRNA expression by modulating post-transcriptional processing. However, the molecular mechanism of this phenomenon is poorly understood. We previously established that human polynucleotide phosphorylase (hPNPase(old-35)), a type I IFN-inducible 3',5' exoribonuclease involved in mRNA degradation, induces G1 cell cycle arrest and eventually apoptosis by specifically degrading c-myc mRNA. We now demonstrate a close association between IFN-beta-induced hPNPase(old-35) upregulation and c-myc downregulation in human melanoma cells. Employing stable melanoma cell clones expressing hPNPase(old-35) small inhibitory RNA, we demonstrate that hPNPase(old-35) is a key molecule coupled with IFN-beta-mediated downregulation of c-myc mRNA. Inhibition of hPNPase(old-35) or overexpression of c-myc protects melanoma cells from IFN-beta-mediated growth inhibition, emphasizing the importance of hPNPase(old-35) upregulation and consequent c-myc downregulation in IFN-beta-induced growth inhibition and apoptosis induction. In these contexts, targeted overexpression of hPNPase(old-35) might be a novel therapeutic strategy for c-myc-overexpressing and IFN-resistant tumors, such as melanomas.

Cost effectiveness and cost utility of adjuvant interferon alpha in cutaneous melanoma: a review

Although interferon alpha (IFN) has been approved since 1995 in the US as adjuvant therapy for high-risk melanoma patients, its cost effectiveness and economic value have only been recently addressed. There are very few papers that address the overall cost and cost components of treating melanoma patients, all of them focusing on the US. These studies showed the large cost of treatment of stage III and IV patients (around $US40,000-60,000 [1997/8 values]). Chemotherapy and adjuvant immunomodulators comprised a large part of this cost. Cost-effectiveness studies performed for the US, Spain and Italy have been largely based on the results of the pivotal Eastern Cooperative Oncology Group (ECOG) 1684 trial using high-dose (10-20 Megaunits [MU]/m(2)) IFN in mainly stage III patients. Incremental cost-effectiveness ratios for adjuvant IFN versus observation from these studies fall in the range of $US13,000-40,000 per life-year gained (1998 values), depending on the time horizon, discount rate and cost of IFN, with an extrapolated life-gain over lifetime ranging between 1.9 and 3 years. Only one study, the French Cooperative Melanoma Group trial in stage IIA/B patients, used low-dose (3 MU(2)) IFN and yielded a quite favourable incremental cost effectiveness ratio (cost per life-year gained) ranging from $US12,954 over 5 years (survival gain 3 months) to $US1,544 over a lifetime (extrapolated survival gain 2.6 years) [1995 values]. Although these results could be seen as supporting the more widespread use of adjuvant IFN in melanoma, it should be stressed that they were based on the only two positive clinical trials out of a total of ten. Moreover, the impact on survival was lost in both positive trials at > or = 8 years' follow-up and thus the costs assessments are likely to be overly optimistic. The eight negative high-dose (HDI) and low-dose (LDI) IFN trials have failed to show an impact on survival (HDI: ECOG 1690 and North Central Cancer Treatment Group [NCCTG]; LDI: ECOG 1690, WHO-16, UK Coordinating Committee on Cancer Research [UKCCRC] and Austrian, Scottish and European Organisation for Research and Treatment of Cancer trials). Mature results from more recent trials are pending. A definitive appraisal of the cost effectiveness of IFN in melanoma patients will have to await these results and their economic analyses.

Characterization of methylthioadenosin phosphorylase (MTAP) expression in malignant melanoma

Homozygous deletions of human chromosomal region 9p21 occur frequently in malignant melanoma and are associated with the loss of the tumor suppressor genes p16(INK4a) and p15(INK4b). In the same chromosomal region the methylthioadenosine phosphorylase (MTAP) gene is localized and therefore may also serve as a tumor suppressor gene. The aim of this study was to analyze MTAP mutations and expression patterns in malignant melanomas. To examine the MTAP gene and expression of MTAP protein we screened 9 human melanoma cell lines and primary human melanocytes by reverse transcriptase-polymerase chain reaction, sequencing, and immunoblotting. Analyzing the melanoma cell lines we found significant down-regulation of MTAP mRNA expression. In only one cell line, HTZ19d, this was due to homozygous deletion of exon 2 to 8 whereas in the other cell lines promoter hypermethylation was detected. MTAP expression was further analyzed in vivo by immunohistochemical staining of 38 tissue samples of benign melanocytic nevi, melanomas, and melanoma metastases. In summary, we demonstrate significant inverse correlation between MTAP protein expression and progression of melanocytic tumors as the amount of MTAP protein staining decreases from benign melanocytic nevi to metastatic melanomas. Our results suggest an important role of MTAP inactivation in the development of melanomas. This finding may be of great clinical significance because recently an association between MTAP activity and interferon sensitivity has been suggested.