Adam I. Riker

Phase I Trial of Interleukin-12 Plasmid Electroporation in Patients With Metastatic Melanoma

PURPOSE Gene-based immunotherapy for cancer is limited by the lack of safe, efficient, reproducible, and titratable delivery methods. Direct injection of DNA into tissue, although safer than viral vectors, suffers from low gene transfer efficiency. In vivo electroporation, in preclinical models, significantly enhances gene transfer efficiency while retaining the safety advantages of plasmid DNA. PATIENTS AND METHODS A phase I dose escalation trial of plasmid interleukin (IL)-12 electroporation was carried out in patients with metastatic melanoma. Patients received electroporation on days 1, 5, and 8 during a single 39-day cycle, into metastatic melanoma lesions with six 100-mus pulses at a 1,300-V/cm electric field through a penetrating six-electrode array immediately after DNA injection. Pre- and post-treatment biopsies were obtained at defined time points for detailed histologic evaluation and determination of IL-12 protein levels. RESULTS Twenty-four patients were treated at seven dose levels, with minimal systemic toxicity. Transient pain after electroporation was the major adverse effect. Post-treatment biopsies showed plasmid dose proportional increases in IL-12 protein levels as well as marked tumor necrosis and lymphocytic infiltrate. Two (10%) of 19 patients with nonelectroporated distant lesions and no other systemic therapy showed complete regression of all metastases, whereas eight additional patients (42%) showed disease stabilization or partial response. CONCLUSION This report describes the first human trial, to our knowledge, of gene transfer utilizing in vivo DNA electroporation. The results indicated this modality to be safe, effective, reproducible, and titratable.

MicroRNA-125b Confers the Resistance of Breast Cancer Cells to Paclitaxel through Suppression of Pro-apoptotic Bcl-2 Antagonist Killer 1 (Bak1) Expression

Paclitaxel (Taxol) is an effective chemotherapeutic agent for treatment of cancer patients. Despite impressive initial clinical responses, the majority of patients eventually develop some degree of resistance to Taxol-based therapy. The mechanisms underlying cancer cells resistance to Taxol are not fully understood. MicroRNA (miRNA) has emerged to play important roles in tumorigenesis and drug resistance. However, the interaction between the development of Taxol resistance and miRNA has not been previously explored. In this study we utilized a miRNA array to compare the differentially expressed miRNAs in Taxol-resistant and their Taxol-sensitive parental cells. We verified that miR-125b, miR-221, miR-222, and miR-923 were up-regulated in Taxol-resistant cancer cells by real-time PCR. We further investigated the role and mechanisms of miR-125b in Taxol resistance. We found that miR-125b was up-regulated in Taxol-resistant cells, causing a marked inhibition of Taxol-induced cytotoxicity and apoptosis and a subsequent increase in the resistance to Taxol in cancer cells. Moreover, we demonstrated that the pro-apoptotic Bcl-2 antagonist killer 1 (Bak1) is a direct target of miR-125b. Down-regulation of Bak1 suppressed Taxol-induced apoptosis and led to an increased resistance to Taxol. Restoring Bak1 expression by either miR-125b inhibitor or re-expression of Bak1 in miR-125b-overexpressing cells recovered Taxol sensitivity, overcoming miR-125-mediated Taxol resistance. Taken together, our data strongly support a central role for miR-125b in conferring Taxol resistance through the suppression of Bak1 expression. This finding has important implications in the development of targeted therapeutics for overcoming Taxol resistance in a number of different tumor histologies.

Interleukin-1 receptor antagonist decreases severity of experimental acute pancreatitis.

BACKGROUND Fulminant acute pancreatitis is a disease of complex origin that results in activation of several of the proinflammatory cytokines. Because interleukin-1 (IL-1) is an integral early component of the acute inflammatory process, the use of an IL-1 receptor antagonist (IL-1ra) was investigated in experimental acute pancreatitis to determine the therapeutic potential of proximal cytokine blockade and to further establish the role of inflammatory cytokines in the pathogenesis of acute pancreatitis. METHODS IL-1ra was administered in escalating doses either before or after acute edematous, necrotizing pancreatitis was induced in adult male mice by injection of cerulein. The severity of pancreatitis was quantified by serum amylase, lipase, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) levels, pancreatic wet weight, and blinded histologic grading. RESULTS Administration of medium (10 mg/kg) and high (100 mg/kg) doses of IL-1ra either before or after the induction of pancreatitis significantly decreased the expected rise in pancreatic wet weight, lipase, IL-6, and TNF-alpha (all, p < 0.01). Serum amylase was significantly reduced when IL-1ra was administered in either dosage before (p < 0.05), but not after, induction of pancreatitis. Pancreatic edema, necrosis, and inflammatory cell infiltrate were significantly diminished (p < 0.05) by histologic grading in all animals receiving medium or high doses of IL-1ra. Low doses of IL-1ra (1.0 mg/kg) had modest effects if given before, but no effect if given after, induction of pancreatitis. CONCLUSIONS The proinflammatory cytokines IL-6 and TNF-alpha are elevated during experimental acute pancreatitis and correlate well with the severity of local pancreatic destruction. Blockade of the cytokine cascade at the level of the IL-1 receptor before or soon after induction of pancreatitis significantly attenuates the rise in these cytokines and is associated with decreased severity of pancreatitis and reduced intrinsic pancreatic damage.

Warburg effect in chemosensitivity: Targeting lactate dehydrogenase-A re-sensitizes Taxol-resistant cancer cells to Taxol

BackgroundTaxol is one of the most effective chemotherapeutic agents for the treatment of patients with breast cancer. Despite impressive clinical responses initially, the majority of patients eventually develop resistance to Taxol. Lactate dehydrogenase-A (LDH-A) is one of the predominant isoforms of LDH expressed in breast tissue, which controls the conversion of pyruvate to lactate and plays an important role in glucose metabolism. In this study we investigated the role of LDH-A in mediating Taxol resistance in human breast cancer cells.ResultsTaxol-resistant subclones, derived from the cancer cell line MDA-MB-435, sustained continuous growth in high concentrations of Taxol while the Taxol-sensitive cells could not. The increased expression and activity of LDH-A were detected in Taxol-resistant cells when compared with their parental cells. The downregulation of LDH-A by siRNA significantly increased the sensitivity of Taxol-resistant cells to Taxol. A higher sensitivity to the specific LDH inhibitor, oxamate, was found in the Taxol-resistant cells. Furthermore, treating cells with the combination of Taxol and oxamate showed a synergistical inhibitory effect on Taxol-resistant breast cancer cells by promoting apoptosis in these cells.ConclusionLDH-A plays an important role in Taxol resistance and inhibition of LDH-A re-sensitizes Taxol-resistant cells to Taxol. This supports that Warburg effect is a property of Taxol resistant cancer cells and may play an important role in the development of Taxol resistance. To our knowledge, this is the first report showing that the increased expression of LDH-A plays an important role in Taxol resistance of human breast cancer cells. This study provides valuable information for the future development and use of targeted therapies, such as oxamate, for the treatment of patients with Taxol-resistant breast cancer.

Immune selection after antigen-specific immunotherapy of melanoma

BACKGROUND Melanoma antigen (MA)-specific vaccination strongly enhances antitumor reactivity in vivo and is capable of producing strong cytotoxic T lymphocyte responses in vitro. Furthermore, specific human leukocyte antigen-restricted T cell activation is hypothesized to occur in response to peptide-based immunotherapy, which may lead to the preferential killing of tumor cells bearing the relevant MA. The development of melanoma antigen-loss variants may subsequently occur in vivo. METHODS Analysis of 532 melanoma lesions from 204 patients was performed on fine-needle aspiration biopsy specimens. Lesions were graded for the expression of the MAs gp100 and MART-1 with use of immunocytochemistry. A total of 351 melanoma lesions were divided into cohorts on the basis of the treatment received. The pretreatment group (n = 175) consisted of lesions obtained before any form of gp100 immunotherapy, with the posttreatment group (n = 176) consisting of lesions obtained after vaccination with a modified gp100 epitope, gp209-2M +/- interleukin 2 (IL-2). RESULTS The percentage of lesions not expressing the gp100 antigen is greater than the percentage not expressing MART-1 (26% vs 14%). The frequency of lesions with high expression (> 75%) of gp100 significantly decreased with therapy (47% vs 34%) and conversely negative lesions increased (18% vs 29%). Treatment of lesions with peptide alone (no IL-2) revealed a significant decrease in gp100 expression (47% vs 32%), enhanced with the addition of IL-2 to therapy (47% vs 35%). The expression of MART-1 remained essentially unchanged unless IL-2 was added (54% vs 54%, MART-1 peptide alone, 54% vs 43%, MART-1 peptide + IL-2). Of 94 patients (181 lesions) assessed for gp100 expression before treatment, 10 patients responded to therapy. Pretreatment lesions in responding patients expressed some level of gp100 in all cases compared with 27% of nonresponding lesions, which were negative for gp100 expression. CONCLUSIONS. This study indirectly demonstrates that vaccination with an MA-derived peptide can result in immune selection in vivo. Furthermore, it provides strong immunologic evidence for the specificity of MA vaccines and to the relevance of MA expression in predicting the response to vaccination.

Melanoma Patients with Positive Sentinel Nodes Who Did Not Undergo Completion Lymphadenectomy: A Multi-Institutional Study

BackgroundCompletion lymph node dissection (CLND) is considered the standard of care in melanoma patients found to have sentinel lymph node (SLN) metastasis. However, the therapeutic utility of CLND is not known. The natural history of patients with positive SLNs who do not undergo CLND is undefined. This multi-institutional study was undertaken to characterize patterns of failure and survival rates in these patients and to compare results with those of positive-SLN patients who underwent CLND.MethodsSurgeons from 16 centers contributed data on 134 positive-SLN patients who did not undergo CLND. SLN biopsy was performed by using each institution’s established protocols. Patients were followed up for recurrence and survival.ResultsIn this study population, the median age was 59 years, and 62% were male. The median tumor thickness was 2.6 mm, 77% of tumors had invasion to Clark level IV/V, and 33% of lesions were ulcerated. The primary melanoma was located on the extremities, trunk, and head/neck in 45%, 43%, and 12%, respectively. The median follow-up was 20 months. The median time to recurrence was 11 months. Nodal recurrence was a component of the first site of recurrence in 20 patients (15%). Nodal recurrence–free survival was statistically insignificantly worse than that seen in a contemporary cohort of patients who underwent CLND. Disease-specific survival for positive-SLN patients who did not undergo CLND was 80% at 36 months, which was not significantly different from that of patients who underwent CLND.ConclusionsThis study underscores the importance of ongoing prospective randomized trials in determining the therapeutic value of CLND after positive SLN biopsy in melanoma patients.

Significance of Sentinel Lymph Node Micrometastases in Human Breast Cancer

BACKGROUND The significance of micrometastatic disease in the sentinel lymph nodes (SLN) of patients with invasive breast cancer has been questioned. The objective of our study was to review the impact of micrometastatic carcinoma detected by SLN biopsy. STUDY DESIGN Between January 1997 and May 2004, 2,408 patients with invasive breast cancer and an SLN with micrometastatic (N0[i+], N1mi) or no metastatic (N0[i-]) disease were identified through our breast database. Slide review was performed and reclassified by the 6(th) edition of the American Joint Committee on Cancer Staging Manual. Of these, 27 were excluded from analysis because of evidence of macrometastatic disease on slide review or enrollment in the American College of Surgeons Oncology Group Z10 study. RESULTS Of 2,381 patients, 2,108 were N0(i-), 151 were N0(i+), and 122 were N1mi. Overall and disease-free survivals of patients with an N1mi SLN were substantially worse than those in patients with an N0(i-) SLN (p < 0.001 and p=0.006, respectively). Additional positive non-SLNs were identified in 15.5% (15 of 97) of N1mi patients and 9.3% (10 of 107) of N0(i+) patients undergoing completion axillary lymph node dissection. Overall survival of the N0(i+) SLN patients not undergoing axillary dissection was substantially less than those undergoing axillary dissection (p=0.02). CONCLUSIONS Detection of micrometastatic carcinoma (N1mi) in the SLNs of invasive breast cancer patients is a major indicator of poorer survival compared with N0(i-) patients. Although survival of patients with an N0(i+) SLN does not statistically differ from that of N0(i-) patients, 9.3% of these patients had additional axillary nodal disease on axillary dissection, and N0(i+) patients had a decreased survival when axillary dissection was omitted.

Identification of novel epigenetically modified genes in human melanoma via promoter methylation gene profiling

The inactivation of tumor‐related genes through the aberrant methylation of promoter CpG islands is thought to contribute to tumor initiation and progression. We therefore investigated promoter methylation events involved in cutaneous melanoma by screening 30 genes of interest for evidence of promoter hypermethylation, examining 20 melanoma cell lines and 40 freshly procured melanoma samples. Utilizing quantitative methylation‐specific PCR, we identified five genes (SOCS1, SOCS2, RAR‐beta 2, TNFSF10C, and TNFSF10D) with hypermethylation frequencies ranging from 50% to 80% in melanoma cell lines as well as freshly procured tissue samples. Eighteen genes (LOX, RASSF1A, WFDC1, TM, APC, TFPI2, TNFSF10A, CDKN2A, MGMT, TIMP3, ASC, TPM1, IRF8, CIITA‐PIV, CDH1, SYK, HOXB13, and DAPK1) were methylated at lower frequencies (2–30%). Two genes (CDKN1B and PTEN), previously reported as methylated in melanoma, and five other genes (RECK, IRF7, PAWR, TNFSF10B, and Rb) were not methylated in the samples screened here. Daughter melanoma cell lines showed identical methylation patterns when compared with original samples from which they were derived, as did synchronous metastatic lesions from the same patient. We identified four genes (TNFSF10C, TNFSF10D, LOX, and TPM1) that have never before been identified as hypermethylated in melanoma, with an overall methylation frequency of 60, 80, 50, and 10%, respectively, hypothesizing that these genes may play an important role in melanoma progression.

The hedgehog pathway transcription factor GLI1 promotes malignant behavior of cancer cells by up-regulating osteopontin.

The role of Hedgehog (Hh) signaling as a developmental pathway is well established. Several recent studies have implicated a role for this pathway in multiple cancers. In this study we report that expression of GLI1 and osteopontin (OPN) increase progressively with the progression of melanoma from primary cutaneous cancer to metastatic melanoma in clinically derived specimens. We have further determined that OPN is a direct transcriptional target of GLI1. We have observed that OPN expression is stimulated in the presence of Hh ligands and inhibited in the presence of the Smoothened (SMO) inhibitor, cyclopamine. Transcriptional silencing of GLI1 negatively impacts OPN expression and compromises the ability of cancer cells to proliferate, migrate, and invade in vitro and interferes with their ability to grow as xenografts and spontaneously metastasize in nude mice. These altered attributes could be rescued by re-expressing OPN in the GLI1-silenced cells, suggesting that OPN is a critical downstream effector of active GLI1 signaling. Our observations lead us to conclude that the GLI1-mediated up-regulation of OPN promotes malignant behavior of cancer cells.

Comparative methodologies of regulatory T cell depletion in a murine melanoma model.

There has been recent interest in the depletion of regulatory T cells (Tregs) as part of a multi-faceted approach to the immunotherapy of melanoma patients. This is in part due recent findings that convincingly show that Tregs are an integral part of regulating and even suppressing an immune response to growing tumor cells. We therefore compared three methods of Treg depletion and/or elimination, utilizing low dose cyclophosphamide (CY), a specific antibody directed against the IL-2 receptor found on Tregs (PC61) and the use of denileukin diftitox (DD), which is a fusion protein designed to have a direct cytocidal action on cells which express the IL-2 receptor. We show that CY administration resulted in the highest reduction in Tregs among the three reagents. However, the reduction in Tregs with CY was also associated with the concomitant reduction of CD8(+) T cells and a lack of tumor antigen priming. Utilization of DD resulted in a >50% Treg cell reduction without parallel cytocidal effects upon other T cell subsets but did not enhance anti-tumor immunity against B16 melanoma. Lastly, the PC61 showed a moderate reduction of Tregs that lasted longer than the other reagents, without a reduction in the total number of CD8(+) T cells. Furthermore, PC61 treatment did not abrogate tumor antigen-specific immunity elicited by dendritic cells (DC). We therefore conclude that PC61 administration was the most effective method of reducing Tregs in a murine melanoma model in addition to providing evidence of a synergistic effect when combined with DC-based immunotherapy.