Abstract A54: Mithramycin inhibits cigarette smoke-mediated induction of ABCG2 in lung and esophageal cancer cells: Implications for targeting cancer stem cells in thoracic malignancies

Limited information is available regarding epigenetic mechanisms by which cigarette smoke mediates initiation and progression of thoracic malignancies. In order to examine this issue, lung and esophageal cancer cells (A549, Calu-6, NCI-SB-ESC1 and NCI-SB-ESC2), were cultured in normal media (NM) with or without cigarette smoke condensate (CSC) under clinically relevant exposure conditions. Microarray analysis revealed that five day CSC exposure significantly up-regulated ABCG2, encoding a xenobiotic pump highly expressed in cancer stem cells. Quantitative reverse transcription-PCR (qRT-PCR), western blot, and immunohistochemistry experiments confirmed up-regulation of ABCG2 in cultured cancer lines, but not normal small airway epithelial cells (SAEC) or immortalized esophageal squamous cells (HET1A) exposed to CSC. Flow cytometry experiments demonstrated that CSC increased the side population (SP) of cultured cancer cells. Transient transfection experiments using ABCG2 promoter reporter constructs revealed that deletion of xenobiotic response elements as well as SP-1 sites markedly attenuated ABCG2 induction by CSC. Chromatin immunoprecipitation (ChIP) experiments revealed that CSC-mediated induction of ABCG2 coincided with increased occupancy of aryl hydrocarbon receptor (AHR), SP-1, and Nrf2, as well as increased levels of RNA pol II and H3K9Ac within the ABCG2 promoter. Under conditions potentially achievable in clinical settings, mithramycin diminished basal as well as CSC-mediated increases in AHR, SP-1, and Nrf2 levels within the ABCG2 promoter, down-regulated ABCG2 expression, decreased S P, inhibited in-vitro proliferation of lung and esophageal cancer cells, and markedly diminished growth of established tumor xenografts. Microarray analysis revealed significant down-regulation of numerous stem-cell related pathways in lung cancer cells following mithramycin exposure. Collectively, these findings provide a potential mechanistic link between smoking status and outcome of patients with lung and esophageal cancers, and support clinical evaluation of mithramycin for targeting cancer stem cells in thoracic malignancies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A54.

Polycomb repressor complex-2 is a novel target for mesothelioma therapy

PURPOSE

Polycomb group (PcG) proteins are critical epigenetic mediators of stem cell pluripotency, which have been implicated in the pathogenesis of human cancers. This study was undertaken to examine the frequency and clinical relevance of PcG protein expression in malignant pleural mesotheliomas (MPM).

EXPERIMENTAL DESIGN

Microarray, quantitative reverse transcriptase PCR (qRT-PCR), immunoblot, and immunohistochemistry techniques were used to examine PcG protein expression in cultured MPM, mesothelioma specimens, and normal mesothelial cells. Lentiviral short hairpin RNA techniques were used to inhibit EZH2 and EED expression in MPM cells. Proliferation, migration, clonogenicity, and tumorigenicity of MPM cells either exhibiting knockdown of EZH2 or EED, or exposed to 3-deazaneplanocin A (DZNep), and respective controls were assessed by cell count, scratch and soft agar assays, and murine xenograft experiments. Microarray and qRT-PCR techniques were used to examine gene expression profiles mediated by knockdown of EZH2 or EED, or DZNep.

RESULTS

EZH2 and EED, which encode components of polycomb repressor complex-2 (PRC-2), were overexpressed in MPM lines relative to normal mesothelial cells. EZH2 was overexpressed in approximately 85% of MPMs compared with normal pleura, correlating with diminished patient survival. Overexpression of EZH2 coincided with decreased levels of miR-101 and miR-26a. Knockdown of EZH2 orEED, or DZNep treatment, decreased global H3K27Me3 levels, and significantly inhibited proliferation, migration, clonogenicity, and tumorigenicity of MPM cells. Common as well as differential gene expression profiles were observed following knockdown of PRC-2 members or DZNep treatment.

CONCLUSIONS

Pharmacologic inhibition of PRC-2 expression/activity is a novel strategy for mesothelioma therapy.

Liver resection and ablation for metastatic adrenocortical carcinoma

BACKGROUND

Adrenocortical carcinoma (ACC) is a rare disease without effective chemotherapy treated most appropriately with resection. The aim of this study was to evaluate our experience with liver resection for metastatic ACC.

METHODS

This study is a retrospective review of patients who underwent liver resection or radiofrequency ablation (RFA) for ACC from 1979 to 2009.

RESULTS

A total of 27 patients were identified. Of the 27, 19 underwent liver resection. Of the 19, 10 had a single liver lesion, and 18 of 19 were rendered free of disease in the liver, although only 11 of 19 were rendered completely free of disease because of extrahepatic disease (EHD). Of the 19, 13 had synchronous EHD. Also, 6 of 17 remained disease free in the liver at a median follow-up of 6.2 years (status of 2 of 19 was unknown). Of the 27 patients, 8 underwent RFA, 7 of 8 became free of disease in the liver, and 5 of 7 had EHD. No patients responded to prior chemotherapy. Median overall survival and survival of patients who underwent liver resection or RFA were both 1.9 years (0.2-12 + years); 5-year actuarial survivals were 29% and 29%, respectively. Disease-free interval (DFI) greater than 9 months from primary resection was associated with longer survival (median 4.1 vs 0.9 years; P = .013).

CONCLUSIONS

This study is a tertiary institution series of liver resection and RFA for ACC. Given the lack of effective systemic treatment options and the safety of resection and ablation, liver resection or RFA may be considered in selected patients with ACC metastatic to the liver especially with a long DFI.

Regional chemotherapy in locally advanced pancreatic cancer: RECLAP trial

BACKGROUND

Pancreatic cancer is the fourth leading cause of cancer death in the United States. Surgery offers the only chance for cure. However, less than twenty percent of patients are considered operative candidates at the time of diagnosis. A common reason for being classified as unresectable is advanced loco-regional disease.A review of the literature indicates that almost nine hundred patients with pancreatic cancer have received regional chemotherapy in the last 15 years. Phase I studies have shown regional administration of chemotherapy to be safe. The average reported response rate was approximately 26%. The average 1-year survival was 39%, with an average median survival of 9 months. Of the patients that experienced a radiographic response to therapy, 78 (78/277, 28%) patients underwent exploratory surgery following regional chemotherapy administration; thirty-two (41%) of those patients were amenable to pancreatectomy. None of the studies performed analyses to identify factors predicting response to regional chemotherapy.Progressive surgical techniques combined with current neoadjuvant chemoradiotherapy strategies have already yielded emerging support for a multimodality approach to treatment of advanced pancreatic cancer.Intravenous gemcitabine is the current standard treatment of pancreatic cancer. However, >90% of the drug is secreted unchanged affecting toxicity but not the cancer per se. Gemcitabine is converted inside the cell into its active drug form in a rate limiting reaction. We hypothesize that neoadjuvant regional chemotherapy with continuous infusion of gemcitabine will be well tolerated and may improve resectability rates in cases of locally advanced pancreatic cancer.

DESIGN

This is a phase I study designed to evaluate the feasibility and toxicity of super-selective intra-arterial administration of gemcitabine in patients with locally advanced, unresectable pancreatic adenocarcinoma. Patients considered unresectable due to locally advanced pancreatic cancer will receive super-selective arterial infusion of gemcitabine over 24 hours via subcutaneous indwelling port. Three to six patients will be enrolled per dose cohort, with seven cohorts, plus an additional six patients at the maximum tolerated dose; accrual is expected to last 36 months. Secondary objectives will include the determination of progression free and overall survival, as well as the conversion rate from unresectable to potentially resectable pancreatic cancer.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT01294358.

Paraneoplastic granulocytosis in metastatic melanoma

Paraneoplastic syndromes are an uncommon, yet well-described, phenomenon in cancer patients. The syndrome of granulocytosis caused by granulocyte colony-stimulating factor (G-CSF) production by tumors is rare and is difficult to diagnose in patients receiving treatment for metastatic disease. From January 2005 to May 2009, 626 patients were evaluated for treatment of metastatic melanoma. At initial evaluation or during the course of treatment, six patients had an elevated white blood cell count and no evidence of infection. All six had significantly elevated serum G-CSF. The level of serum G-CSF was directly correlated with the absolute neutrophil count. In-vitro assay of melanoma tumor from two patients showed elevated G-CSF in cell culture supernatant. The paraneoplastic syndrome of granulocytosis resulting from ectopic G-CSF production in patients with metastatic melanoma is rare. This diagnosis should be considered when common causes of granulocytosis have been ruled out.

Thoracic metastasectomy for adoptive immunotherapy of melanoma: a single-institution experience

OBJECTIVES

Although refractory to chemotherapy, metastatic melanoma may respond to adoptive immunotherapy. As novel treatments evolve, surgeons may be asked to perform metastasectomy not only for palliation or potential cure but also for isolation of tumor-infiltrating lymphocytes. This study was undertaken to examine outcomes of patients with melanoma undergoing thoracic metastasectomy in preparation for investigational immunotherapy.

METHODS

A retrospective review identified 107 consecutive patients who underwent 116 thoracic metastasectomy procedures from April 1998 to July 2009. Indications for surgical intervention included procurement of tumor-infiltrating lymphocytes, rendering of patients to no evaluable disease status, palliation, and diagnosis. Response Evaluation Criteria in Solid Tumors criteria were used to assess tumor response.

RESULTS

Thoracotomy, lobectomy, and video-assisted thoracoscopic surgery with nonanatomic resection were the most common procedures. Major complications included 1 death and 1 coagulopathy-induced hemothorax. Seventeen patients were rendered to no evaluable disease status. Virtually all patients with residual disease had tumor specimens cultured for tumor-infiltrating lymphocytes; approximately 70% of tumor-infiltrating lymphocyte cultures exhibited antitumor reactivity. Of the 91 patients with residual or recurrent disease, 24 (26%) underwent adoptive cell transfer of tumor-infiltrating lymphocytes, of whom 7 exhibited objective responses (29% response rate and 8% based on intent to treat). Rapid disease progression precluded tumor-infiltrating lymphocyte therapy in most cases. Actuarial 1- and 5-year survival rates for patients rendered to no evaluable disease status or receiving or not receiving tumor-infiltrating lymphocytes were 93% and 76%, 64% and 33%, and 43% and 0%, respectively.

CONCLUSIONS

Relatively few patients currently having thoracic metastasectomy undergo adoptive cell transfer. Continued refinement of tumor-infiltrating lymphocyte expansion protocols and improved patient selection might increase the number of patients with melanoma benefiting from these interventions.

Liver resection for metastatic melanoma with postoperative tumor-infiltrating lymphocyte therapy

BACKGROUND

Patients with metastatic melanoma to the liver (MML) have a median survival of 4 to 6 months. This study evaluated patients who underwent liver resection with intent to receive postoperative tumor-infiltrating lymphocyte (TIL) therapy.

METHODS

Retrospective analysis of a prospective database identified patients with MML who underwent liver resection from 1980 to 2008.

RESULTS

A total of 539 patients had MML, and 39% (204 of 539) had tumor collected for TIL. A total of 17% (35 of 204) underwent liver resection for TIL. The 3-year overall survival was 53%. Lack of extrahepatic disease (P = .026), negative margin (P = .056), and single hepatic metastasis (P = .04) predicted survival after univariate analysis. Only lack of extrahepatic disease remained a significant predictor of survival after multivariate analysis (P = .043). A total of 31% (11 of 35) underwent complete resection without TIL, and 69% (24 of 35) underwent resection with synchronous intrahepatic and extrahepatic disease with intent to receive TIL. For 9 of 11 patients (2 of 11 excluded for gene therapy), 3-year survival was 80%. A total of 4 (44%) of 9 experienced recurrence, with a median disease-free survival of 1.2 years. For 24 patients (69%) with residual disease, 3-year survival was 51% (2 of 24 excluded for gene therapy). A total of 63% (15 of 24) received postoperative TIL (3-year survival 65%), and 29% (7 of 24) did not. A total of 40% (6 of 15) had disease that partially responded to TIL; the disease of 67% (4 of 6) had not progressed at median follow-up of 55 months (range, 42-197+ months). The seven patients who did not receive TIL had a median survival of 4.6 months.

CONCLUSIONS

Resection of MML with TIL should be considered because it can result in prolonged survival in a highly selected group of patients.

Streptococcus milleri infections of the pleural space: operative management predominates

BACKGROUND

Management of patients with thoracic empyema ranges from tube thoracostomy drainage, with or without fibrinolytics, to operative intervention, with the optimal intervention remaining uncertain. Streptococcus milleri, typically a benign bacterium colonizing the oropharynx, has recently been reported as a potential pathogen in pneumonia and pleural space disease. Our initial experience indicated this infection, when in the pleural space, was particularly tenacious and often required major operative intervention to eradicate. Therefore, we hypothesized that patients with S milleri pleural space infections often require operative intervention as definitive treatment.

METHODS

We reviewed all patients from June 17, 1999 to April 15, 2005 with S milleri infections at our level I academic trauma/acute care surgery department at a safety-net hospital. S milleri infections were diagnosed by thoracentesis, bronchoalveolar lavage, tube thoracostomy fluid, or intraoperative culture.

RESULTS

Over the 70-month period evaluated, of 697 patients with S milleri infections, 39 patients had S milleri infections of the pleural space; 26 (67%) patients underwent operative intervention. The majority (72%) were men with a mean age of 46 (range 22 to 63); the underlying etiology in those patients requiring operation was pneumonia (26 patients; 67%), trauma (9 patients; 23%), postoperative infection (2 patients), foreign body ingestion (1 patient), and malignancy (1 patient). The vast majority of patients in the operative group were treated preoperatively with tube thoracostomy (88%) and antibiotics (96%). The average duration of chest tube drainage prior to operation was 4.4 days (95% confidence interval [CI] 2.6 to 6.2) and antibiotic treatment was 6.0 days (95% CI 3.8 to 8.2). Thirteen patients (50%) underwent video-assisted thoracoscopic surgery (VATS) and 13 patients required thoracotomy. VATS was performed more often when operative intervention occurred early (average hospital day 6.2) compared to initial thoracotomy or conversion from VATS to thoracotomy (average hospital day 9.8). Hospital length of stay was less in the operative group (average 24 days; 95% CI 17 to 31) than in the nonoperative group (34 days; 95% CI 19 to 49), discharge to home was greater in the operative group (77% vs. 16%), and mortality was less in operative group (0% vs. 23%).

CONCLUSIONS

Despite attempts at nonoperative management, the majority of patients with a S milleri pleural space infection require operative intervention for definitive therapy. Patients diagnosed with S milleri empyema should be considered for early operative intervention due to the unrelenting nature of their infection. Operative treatment is associated with a shorter hospital length of stay, increased discharge to home, and decreased mortality.