Systemic Therapy for Cutaneous Melanoma

Laying the groundwork for the Biobank of Rare Malignant Neoplasms at the service of the Hellenic Network of Precision Medicine on Cancer

Biobanks constitute an integral part of precision medicine. They provide a repository of biospecimens that may be used to elucidate the pathophysiology, support diagnoses, and guide the treatment of diseases. The pilot biobank of rare malignant neoplasms has been established in the context of the Hellenic Network of Precision Medicine on Cancer and aims to enhance future clinical and/or research studies in Greece by collecting, processing, and storing rare malignant neoplasm samples with associated data. The biobank currently comprises 553 samples; 384 samples of hematopoietic and lymphoid tissue malignancies, 72 samples of pediatric brain tumors and 97 samples of malignant skin neoplasms. In this article, sample collections and their individual significance in clinical research are described in detail along with computational methods developed specifically for this project. A concise review of the Greek biobanking landscape is also delineated, in addition to recommended technologies, methodologies and protocols that were integrated during the creation of the biobank. This project is expected to re‑enforce current clinical and research studies, introduce advances in clinical and genetic research and potentially aid in future targeted drug discovery. It is our belief that the future of medical research is entwined with accessible, effective, and ethical biobanking and that our project will facilitate research planning in the '‑omic' era by contributing high‑quality samples along with their associated data.

Bornyl cis-4-Hydroxycinnamate Suppresses Cell Metastasis of Melanoma through FAK/PI3K/Akt/mTOR and MAPK Signaling Pathways and Inhibition of the Epithelial-to-Mesenchymal Transition

Bornyl cis-4-hydroxycinnamate, a bioactive compound isolated from Piper betle stems, has the potential for use as an anti-cancer agent. This study investigated the effects of bornyl cis-4-hydroxycinnamate on cell migration and invasion in melanoma cells. Cell migration and invasion were compared in A2058 and A375 melanoma cell lines treated with/without bornyl cis-4-hydroxycinnamate (1–6 µM). To examine whether bornyl cis-4-hydroxycinnamate has a potential anti-metastatic effect on melanoma cells, cell migration and invasion assays were performed using a Boyden chamber assay and a transwell chamber in A2058 and A375 cells. Gelatin zymography was employed to determine the enzyme activities of MMP-2 and MMP-9. Cell lysates were collected for Western blotting analysis of matrix metalloproteinase (MMP)-2, MMP-9 and tissue inhibitors of metalloproteinase-1/2 (TIMP-1/2), as well as key molecules in the mitogen-activated protein kinase (MAPK), focal adhesion kinase (FAK)/ phosphatidylinositide-3 kinases (PI3K)/Akt/ mammalian target of rapamycin (mTOR), growth factor receptor-bound protein 2 (GRB2) signaling pathways. Our results demonstrated that bornyl cis-4-hydroxycinnamate is a potentially useful agent that inhibits melanoma cell migration and invasion, and altered melanoma cell metastasis by reducing MMP-2 and MMP-9 expression through inhibition of the FAK/PI3K/Akt/mTOR, MAPK, and GRB2 signaling pathways. Moreover, bornyl cis-4-hydroxycinnamate inhibited the process of the epithelial-to-mesenchymal transition in A2058 and A375 melanoma cells. These findings suggested that bornyl cis-4-hydroxycinnamate has potential as a chemotherapeutic agent, and warrants further investigation for its use in the management of human melanoma.

The Effect of Bornyl cis-4-Hydroxycinnamate on Melanoma Cell Apoptosis Is Associated with Mitochondrial Dysfunction and Endoplasmic Reticulum Stress

Bornyl cis-4-hydroxycinnamate, an active compound isolated from Piper betle stems, was investigated in terms of its effects on A2058 and A375 melanoma cell proliferation and protein expression in this study. We used flow cytometric analysis to examine the early stages of apoptosis induced by bornyl cis-4-hydroxycinnamate in the two melanoma cell lines and employed comparative proteomic analysis to investigate the effects of this compound on protein expression in A375 cells. Master maps generated by PDQuest software from two-dimensional electrophoresis (2-DE) analysis of A375 cells showed that the expression levels of 35 proteins were significantly altered, with 18 proteins upregulated and 17 downregulated. The proteomics study identified several proteins that are involved in mitochondrial dysfunction and endoplasmic reticulum stress (ER stress), in addition to apoptosis-associated proteins, including prohibitin, hypoxia-upregulated protein 1, stress 70 protein, 78 kDa glucose-regulated protein (GRP78), and protein deglycase DJ-1 (protein DJ-1) in melanoma cells exposed to bornyl cis-4-hydroxycinnamate. The treatment also resulted in a marked decline of the mitochondrial membrane potential, in cytochrome C release into the cytosol, in the activation of Bcl-2-associated X protein (Bax), Bcl-2-associated death promoter protein (Bad), caspase-3, and caspase-9, and in the decreased expression of p-Bad, B-cell lymphoma 2 (Bcl-2), Bcl-xl, and induced myeloid leukemia cell differentiation protein-1 (Mcl-1), indicating that apoptosis induced by bornyl cis-4-hydroxycinnamate was mediated by the mitochondria through the caspase-dependent pathway. Also, salubrinal (an eukaryotic initiation factor 2α inhibitor; eIF2α inhibitor) was able to protect the cells from bornyl cis-4-hydroxycinnamate-induced apoptosis. Bornyl cis-4-hydroxycinnamate-related cell death also implied that the protein kinase R-like endoplasmic reticulum kinase (PERK)–eIF2α–ATF4–CHOP signal pathways was activated upon bornyl cis-4-hydroxycinnamate treatment. Altogether, our results support the conclusion that bornyl cis-4-hydroxycinnamate-induced apoptosis in melanoma cells is associated with mechanisms correlated with the activation of caspase cascades, mitochondrial dysfunction, and endoplasmic reticulum stress, and indicate that this molecule has the potential to be developed as a chemotherapeutic agent for human melanoma.

Metastatic melanoma of the tongue: a case report with immunohistochemical profile

BACKGROUND

Melanoma of the skin is characterised by a high metastatic potential, but reports of metastasis to the tongue are rare. We report a case of skin melanoma with metastasis to the lymph nodes, tongue and brain.

OBJECTIVES

This report highlights the clinical and histological features of oral metastatic melanoma.

CASE REPORT

A 72-year-old man was seen with a nodule on the tongue. The differential diagnosis included salivary gland tumour, lymphoma and metastatic melanoma. His medical history revealed treatment for melanoma in the periumbilical region and micrometastases in the inguinal lymph nodes. An incisional biopsy was obtained and histological analysis showed the presence of a solid, epithelioid malignant tumour of monotonous appearance infiltrating the skeletal musculature. Immunohistochemistry showed reactivity of neoplastic cells to anti-HMB45, anti-melan A and anti-S100 antibodies and negativity for anti-PAN cytokeratin, confirming the diagnosis of metastatic melanoma.

CONCLUSION

The present findings highlight the importance of a complete medical evaluation of the patient by anamnesis to identify possible oral repercussions of primary diseases in other organs and/or systems.

Cutaneous Melanoma in Asians

Malignant melanoma is a rare disease in Asians but potentially the most aggressive form of skin cancer worldwide. It can occur in any melanocyte-containing anatomic site. Four main cutaneous melanoma subtypes are recognized: lentigo maligna melanoma, superficial spreading melanoma, acral lentiginous melanoma (ALM), and nodular melanoma. Generally, excessive exposure to ultraviolet (UV) radiation increases the risk of melanoma. The exception is ALM, which is the most common melanoma subtype in Asians and is not associated with UV radiation. ALM presents as dark brownish to black, irregular maculopatches, nodules, or ulcers on the palms, soles, and nails. The lesions may be misdiagnosed as more benign lesions, such as warts, ulcers, hematomas, foreign bodies, or fungal infections, especially in amelanotic acral melanomas where black pigments are absent. The aim of this brief review is to improve understanding and the rate of early detection thereby reducing mortality, especially regarding cutaneous melanoma in Asians.

Systemic chemotherapy is modulated by platelet-activating factor-receptor agonists

Chemotherapy is used to treat numerous cancers including melanoma. However, its effectiveness in clinical settings is often hampered by various mechanisms. Previous studies have demonstrated that prooxidative stressor-mediated generation of oxidized lipids with platelet-activating factor-receptor (PAF-R) agonistic activity induces systemic immunosuppression that augments the growth of experimental melanoma tumors. We have recently shown that treatment of murine B16F10 melanoma cells in vitro or tumors implanted into syngeneic mice and treated intratumorally with various chemotherapeutic agents generated PAF-R agonists in a process blocked by antioxidants. Notably, these intratumoral chemotherapy-generated PAF-R agonists augmented the growth of secondary (untreated) tumors in a PAF-R dependent manner. As both localized and systemic chemotherapies are used based on tumor localization/stage and metastases, the current studies were sought to determine effects of PAF-R agonists on systemic chemotherapy against experimental melanoma. Here, we show that systemic chemotherapy with etoposide (ETOP) attenuates the growth of melanoma tumors when given subsequent to the tumor cell implantation. Importantly, this ETOP-mediated suppression of melanoma tumor growth was blocked by exogenous administration of a PAF-R agonist, CPAF. These findings indicate that PAF-R agonists not only negatively affect the ability of localized chemotherapy but also compromise the efficacy of systemic chemotherapy against murine melanoma.

Immunologic responses to xenogeneic tyrosinase DNA vaccine administered by electroporation in patients with malignant melanoma

Background

Prior studies show that intramuscular injection and particle-mediated epidermal delivery of xenogeneic melanosomal antigens (tyrosinase or Tyr, gp100) induce CD8⁺ T cell responses to the syngeneic protein. To further define the optimal vaccination strategy, we conducted a phase I study of in vivo electroporation (EP) of a murine Tyr DNA vaccine (pINGmuTyr) in malignant melanoma patients.

Methods

Human leukocyte antigen (HLA)-A1, A2, A24 or B35 stage IIb-IV melanoma patients received up to five doses of the mouse tyrosinase DNA vaccine by EP every three weeks at dose levels of 0.2 mg, 0.5 mg, or 1.5 mg per injection. Peripheral blood mononuclear cells (PBMC) were collected, cultured with a peptide pool containing eight HLA class I-restricted Tyr-specific T-cell epitopes, and analyzed by HLA-A*0101-restricted tetramers and intracellular cytokine staining (ICS).

Results

Twenty-four patients received ≥1 dose of the pINGmuTyr vaccine; PBMCs from 21 patients who completed all five doses were available for Tyr immune assays. The only common toxicity was grade 1 injection site reaction. Six of 15 patients (40%) in the 1.5 mg dose cohort developed Tyr-reactive CD8⁺ T cell responses following stimulation, defined as a ≥3 standard deviation increase in baseline reactivity by tetramer or ICS assays. No Tyr-reactive CD8⁺ T cell response was detected in the 0.2 mg and 0.5 mg dose cohort patients. Epitope spreading of CD8⁺ T cell response to NY-ESO-1 was observed in one patient with vitiligo. One patient subsequently received ipilimumab and developed an enhanced Tyr-reactive response with polyfunctional cytokine profile. After a median follow-up of 40.9 months, median survival has not been reached.

Conclusions

A regimen of five immunizations with pINGmuTyr administered by EP was found to be safe and resulted in Tyr-reactive immune responses in six of 15 patients at 1.5 mg dose cohort.

Trial registration

ClinicalTrials.gov NCT00471133

Proteomic investigation of the sinulariolide-treated melanoma cells A375: effects on the cell apoptosis through mitochondrial-related pathway and activation of caspase cascade

Sinulariolide is an active compound isolated from the cultured soft coral Sinularia flexibilis. In this study, we investigated the effects of sinulariolide on A375 melanoma cell growth and protein expression. Sinulariolide suppressed the proliferation and migration of melanoma cells in a concentration-dependent manner and was found to induce both early and late apoptosis by flow cytometric analysis. Comparative proteomic analysis was conducted to investigate the effects of sinulariolide at the molecular level by comparison between the protein profiles of melanoma cells treated with sinulariolide and those without treatment. Two-dimensional gel electrophoresis (2-DE) master maps of control and treated A375 cells were generated by analysis with PDQuest software. Comparison between these maps showed up- and downregulation of 21 proteins, seven of which were upregulated and 14 were downregulated. The proteomics studies described here identify some proteins that are involved in mitochondrial dysfunction and apoptosis-associated proteins, including heat shock protein 60, heat shock protein beta-1, ubiquinol cytochrome c reductase complex core protein 1, isocitrate dehydrogenase (NAD) subunit alpha (down-regulated), and prohibitin (up-regulated), in A375 melanoma cells exposed to sinulariolide. Sinulariolide-induced apoptosis is relevant to mitochondrial-mediated apoptosis via caspase-dependent pathways, elucidated by the loss of mitochondrial membrane potential, release of cytochrome c, and activation of Bax, Bad and caspase-3/-9, as well as suppression of p-Bad, Bcl-xL and Bcl-2. Taken together, our results show that sinulariolide-induced apoptosis might be related to activation of the caspase cascade and mitochondria dysfunction pathways. Our results suggest that sinulariolide merits further evaluation as a chemotherapeutic agent for human melanoma.

Induction of apoptosis by 11-dehydrosinulariolide via mitochondrial dysregulation and ER stress pathways in human melanoma cells

In this study the isolated compound 11-dehydrosinulariolide from soft coral Sinularia leptoclados possessed anti-proliferative, anti-migratory and apoptosis-inducing activities against A2058 melanoma cells. Anti-tumor effects of 11-dehydrosinulariolide were determined by MTT assay, cell migration assay and flow cytometry. Growth and migration of melanoma cells were dose-dependently inhibited by 2–8 μg/mL 11-dehydrosinulariolide. Flow cytometric data indicated that 11-dehydrosinulariolide induces both early and late apoptosis in melanoma cells. It was found that the apoptosis induced by 11-dehydrosinulariolide is relevant to mitochondrial-mediated apoptosis via caspase-dependent pathways, elucidated by loss of mitochondrial membrane potential (∆Ψm), release of cytochrome C, activation of caspase-3/-9 and Bax as well as suppression of Bcl-2/Bcl-xL. The cleavage of PARP-1 suggested partial involvement of caspase-independent pathways. Immunoblotting data displayed up-regulations of PERK/eIF2α/ATF4/CHOP and ATF6/CHOP coupling with elevation of ER stress chaperones GRP78, GRP94, calnexin, calreticulin and PDI, implicating the involvement of these factors in ER stress-mediated apoptosis induced by 11-dehydrosinulariolide. The abolishment of apoptotic events after pre-treatment with salubrinal indicated that ER stress-mediated apoptosis is also induced by 11-dehydrosinulariolide against melanoma cells. The data in this study suggest that 11-dehydrosinulariolide potentially induces apoptosis against melanoma cells via mitochondrial dysregulation and ER stress pathways.

Proteomic investigation of anti-tumor activities exerted by sinularin against A2058 melanoma cells

The extracts from soft corals have been increasingly investigated for biomedical and therapeutic purposes. The aim of this study is to examine and analyze the anti-tumor effects of the genus Sinularia extract sinularin on A2058 melanoma cells using MTT assay, cell migration assay, wound healing assay, flow cytometric analysis, and proteomic analysis. Sinularin dose-dependently (1-5 μg/mL) inhibited melanoma cell proliferation while the treatment at identical concentrations suppressed cell migration. Sinularin dose-dependently enhanced apoptotic melanoma cells and caused tumor cell accumulation at G2/M phase, indicating that sinularin exerts apoptosis-induced and cell cycle-delayed activities in A2058 melanoma cells. Comparative proteomic analysis was conducted to investigate the effects of sinularin at the molecular level by comparison between the protein profiling of melanoma cells treated with sinularin and without the treatment. Thirty-five differential proteins (13 upregulated and 22 downregulated) concerning the treatment were identified by liquid chromatography-tandem mass spectrometry. Proteomic data and Western blot displayed the levels of several tumor inhibitory or apoptosis-associated proteins including annexin A1, voltage-dependent anion-selective channel protein 1 and prohibitin (upregulated), heat shock protein 60, heat shock protein beta-1, and peroxiredoxin-2 (downregulated) in A2058 melanoma cells exposed to sinularin. Increased expression of p53, cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9, p21, and Bax and decreased expression of Bcl-2 in sinularin-treated melanoma cells suggest that the anti-tumor activities of sinularin against melanoma cells are particularly correlated with these pro-apoptotic factors. These data provide important information for the mechanisms of anti-tumor effects of sinularin on melanoma cells and may be helpful for drug development and progression monitoring of human melanoma.

The association of N-palmitoylethanolamine with the FAAH inhibitor URB597 impairs melanoma growth through a supra-additive action

Background

The incidence of melanoma is considerably increasing worldwide. Frequent failing of classical treatments led to development of novel therapeutic strategies aiming at managing advanced forms of this skin cancer. Additionally, the implication of the endocannabinoid system in malignancy is actively investigated.

Methods

We investigated the cytotoxicity of endocannabinoids and their hydrolysis inhibitors on the murine B16 melanoma cell line using a MTT test. Enzyme and receptor expression was measured by RT-PCR and enzymatic degradation of endocannabinoids using radiolabeled substrates. Cell death was assessed by Annexin-V/Propidium iodine staining. Tumors were induced in C57BL/6 mice by s.c. flank injection of B16 melanoma cells. Mice were injected i.p. for six days with vehicle or treatment, and tumor size was measured each day and weighted at the end of the treatment. Haematoxylin-Eosin staining and TUNEL assay were performed to quantify necrosis and apoptosis in the tumor and endocannabinoid levels were quantified by HPLC-MS. Tube formation assay and CD31 immunostaining were used to evaluate the antiangiogenic effects of the treatments.

Results

The N-arachidonoylethanolamine (anandamide, AEA), 2-arachidonoylglycerol and N- palmitoylethanolamine (PEA) reduced viability of B16 cells. The association of PEA with the fatty acid amide hydrolase (FAAH) inhibitor URB597 considerably reduced cell viability consequently to an inhibition of PEA hydrolysis and an increase of PEA levels. The increase of cell death observed with this combination of molecules was confirmed in vivo where only co-treatment with both PEA and URB597 led to decreased melanoma progression. The antiproliferative action of the treatment was associated with an elevation of PEA levels and larger necrotic regions in the tumor.

Conclusions

This study suggests the interest of targeting the endocannabinoid system in the management of skin cancer and underlines the advantage of associating endocannabinoids with enzymatic hydrolysis inhibitors. This may contribute to the improvement of long-term palliation or cure of melanoma.

Towards new therapeutic approaches for malignant melanoma

Recent progress in understanding the molecular mechanisms of the initiation and progression of melanoma has created new opportunities for developing novel therapeutic modalities to manage this potentially lethal disease. Although at first glance, melanoma carcinogenesis appears to be a chaotic system, it is indeed, arguably, a deterministic multistep process involving sequential alterations of proto-oncogenes, tumour suppressors and miRNA genes. The scope of this article is to discuss the most recent and significant advances in melanoma molecular therapeutics. It is apparent that using single agents targeting solely individual melanoma pathways might be insufficient for long-term survival. However, the outstanding results on melanoma survival observed with novel selective inhibitors of B-RAF, such as PLX4032 give hope that melanoma can be cured. The fact that melanoma develops acquired resistance to PLX4032 emphasises the importance of simultaneously targeting several pathways. Because the most striking feature of melanoma is its unsurpassed ability to metastasise, it is important to implement newer systems for drug delivery adapted from research on stem cells and nanotechnology.

A cyclopalladated complex interacts with mitochondrial membrane thiol-groups and induces the apoptotic intrinsic pathway in murine and cisplatin-resistant human tumor cells

Background

Systemic therapy for cancer metastatic lesions is difficult and generally renders a poor clinical response. Structural analogs of cisplatin, the most widely used synthetic metal complexes, show toxic side-effects and tumor cell resistance. Recently, palladium complexes with increased stability are being investigated to circumvent these limitations, and a biphosphinic cyclopalladated complex {Pd₂ [S_(-)C², N-dmpa]₂ (μ-dppe)Cl₂} named C7a efficiently controls the subcutaneous development of B16F10-Nex2 murine melanoma in syngeneic mice. Presently, we investigated the melanoma cell killing mechanism induced by C7a, and extended preclinical studies.

Methods

B16F10-Nex2 cells were treated in vitro with C7a in the presence/absence of DTT, and several parameters related to apoptosis induction were evaluated. Preclinical studies were performed, and mice were endovenously inoculated with B16F10-Nex2 cells, intraperitoneally treated with C7a, and lung metastatic nodules were counted. The cytotoxic effects and the respiratory metabolism were also determined in human tumor cell lines treated in vitro with C7a.

Results

Cyclopalladated complex interacts with thiol groups on the mitochondrial membrane proteins, causes dissipation of the mitochondrial membrane potential, and induces Bax translocation from the cytosol to mitochondria, colocalizing with a mitochondrial tracker. C7a also induced an increase in cytosolic calcium concentration, mainly from intracellular compartments, and a significant decrease in the ATP levels. Activation of effector caspases, chromatin condensation and DNA degradation, suggested that C7a activates the apoptotic intrinsic pathway in murine melanoma cells. In the preclinical studies, the C7a complex protected against murine metastatic melanoma and induced death in several human tumor cell lineages in vitro, including cisplatin-resistant ones. The mitochondria-dependent cell death was also induced by C7a in human tumor cells.

Conclusions

The cyclopalladated C7a complex is an effective chemotherapeutic anticancer compound against primary and metastatic murine and human tumors, including cisplatin-resistant cells, inducing apoptotic cell death via the intrinsic pathway.

Efficient in vivo microRNA targeting of liver metastasis

Targeting oncogenic microRNAs (miRNAs) is emerging as a promising strategy for cancer therapy. In this study, we provide proof of principle for the safety and efficacy of miRNA targeting against metastatic tumors. We tested the impact of targeting miR-182, a pro-metastatic miRNA frequently overexpressed in melanoma, the in vitro silencing of which represses invasion and induces apoptosis. Specifically, we assessed the effect of anti-miR-182 oligonucleotides synthesized with 2' sugar modifications and a phosphorothioate backbone in a mouse model of melanoma liver metastasis. Luciferase imaging showed that mice treated with anti-miR-182 had a lower burden of liver metastases compared with control. We confirmed that miR-182 levels were effectively downregulated in the tumors of anti-miR-treated mice compared with tumors of control-treated mice, both in the liver and in the spleen. This effect was accompanied by an upregulation of multiple miR-182 direct targets. Transcriptional profiling of tumors treated with anti-miR-182 or with control oligonucleotides revealed an enrichment of genes controlling survival, adhesion and migration modulated in response to anti-miR-182 treatment. These data indicate that in vivo administration of anti-miRs allows for efficient miRNA targeting and concomitant upregulation of miRNA-controlled genes. Our results demonstrate that the use of anti-miR-182 is a promising therapeutic strategy for metastatic melanoma and provide a solid basis for testing similar strategies in human metastatic tumors.

Immunologic response to xenogeneic gp100 DNA in melanoma patients: comparison of particle-mediated epidermal delivery with intramuscular injection

PURPOSE

Prior studies show that i.m. injection of xenogeneic orthologues of melanosomal antigens (tyrosinase, gp100) induces CD8(+) T-cell responses to the syngeneic protein. To further define the optimal vaccination strategy, we conducted a pilot clinical trial comparing i.m. injection with particle-mediated epidermal delivery (PMED).

EXPERIMENTAL DESIGN

Human leukocyte antigen (HLA)-A*0201(+) disease-free melanoma patients were randomized to the PMED or i.m. arm, receiving eight vaccinations over 4 months. Patients received 4 microg or 2,000 microg per injection, respectively, of mouse gp100 DNA. Peripheral blood mononuclear cells were collected, cultured with gp100 peptides, and analyzed by tetramer and intracellular cytokine staining for responses to HLA-A*0201-restricted gp100 epitopes [gp100(209-217) (ITDQVPFSV) and gp100(280-288) (YLEPGPVTA)].

RESULTS

Twenty-seven patients with stage IIB-IV melanoma were analyzable for immune response. The only common toxicity was grade 1 injection site reaction in nine patients with no intergroup difference, and one dose-limiting toxicity of acute hypersensitivity occurred in a PMED patient with undiagnosed gold allergy. Four of 27 patients produced gp100 tetramer(+)CD8(+) T cells, all carrying the CCR7(lo)CD45RA(lo) effector-memory phenotype. Five of 27 patients generated IFN-gamma(+)CD8(+) T cells, one who was also tetramer-positive. Overall, vaccination induced a response in 30% of patients, which was not significantly associated with study arm or clinical outcome. However, the PMED group showed a trend toward increased IFN-gamma(+)CD8(+) T-cell generation (P = 0.07).

CONCLUSION

A comparable efficacy and safety profile was shown between the i.m. and PMED arms, despite a significantly decreased dose of DNA used for PMED injection.