An IL-2 proaerolysin fusion toxin that selectively eliminates regulatory t cells to enhance antitumor immune response.

BACKGROUND: Recent success with immune-checkpoint inhibitors in some tumor types has highlighted the power of the immune system to control and eradicate human cancer cells. However, these therapies have demonstrated a limited activity in prostate cancer, which has a more immunosuppressive microenvironment that can be because of the presence of a variety of inhibitory cell types, such as myeloid-derived suppressor cells, mesenchymal stem cells, and regulatory T cells (Tregs). One strategy to improve the efficacy of immune-based therapies for prostate cancer is to selectively eliminate these immunosuppressive cells within the tumor microenvironment. METHODS: We developed and characterized a chimeric protein consisting of the cytokine IL-2 fused to binding mutant of the highly toxic bacterial toxin proaerolysin (ie IL2-R336A). RESULTS: The IL2-R336A fusion protein selectively kills immunosuppressive Tregs that express the IL-2 receptor while having little to no effect on cells negative for this target. IL2-R336A depleted Tregs in both tumor bearing and nontumor bearing mice. Tumor bearing mice vaccinated with a GMCSF-expressing CT-26 GVAX vaccine had reduced tumor growth when given IL2-R336A before vaccination. IL2-R336A also enhanced immune response to a model hemagglutinin antigen (HA) in HA-tolerized mice. CONCLUSION: These results suggest that this IL2-R336A toxin may be a useful in improving the therapeutic efficacy of antitumor vaccines by enhancing the immune response against target tumor antigens.

A fine-needle aspirate-based vulnerability assay identifies polo-like kinase 1 as a mediator of gemcitabine resistance in pancreatic cancer.

This work aimed to discover targets for combination treatment with gemcitabine in pancreatic cancer. We selected 11 tumors from our live collection of freshly generated pancreatic cancer xenografts with known degrees of varying gemcitabine sensitivity. We briefly (6 h) exposed fine-needle aspiration material to control vehicle or gemcitabine (1 mumol/L) and compared the gene expression of the treated and untreated samples using a reverse transcription-PCR-based, customized low-density array with 45 target genes of therapeutic interest. The gene expression of the untreated sample (which can be considered a baseline/static readout) was not predictive of gemcitabine efficacy in these tumors. Altogether, the only gene that differentiated sensitive versus resistant cases was polo-like kinase 1 (Plk1), showing >50% downregulation in sensitive cases and no change in the resistant cases. Inhibition of Plk1 by either small interfering RNA gene knockdown or with the Plk1 pathway modulator (ON 01910.Na) synergized with gemcitabine in gemcitabine-refractory in vitro models providing mechanistic proof of concept. In vivo experiments in gemcitabine-resistant xenografts showed synergistic activity decreasing cell proliferation and tumor regressions. A quantitative gene expression-based vulnerability assay identified Plk1 as a relevant target dictating the susceptibility of pancreatic cancer to gemcitabine. Dynamic interrogation of cancer has the potential to provide key information about mechanisms of resistance and to enhance individualization of treatment.

Characterizing DNA methylation patterns in pancreatic cancer genome.

We performed a global methylation profiling assay on 1505 CpG sites across 807 genes to characterize DNA methylation patterns in pancreatic cancer genome. We found 289 CpG sites that were differentially methylated in normal pancreas, pancreatic tumors and cancer cell lines. We identified 23 and 35 candidate genes that are regulated by hypermethylation and hypomethylation in pancreatic cancer, respectively. We also identified candidate methylation markers that alter the expression of genes critical to gemcitabine susceptibility in pancreatic cancer. These results indicate that aberrant DNA methylation is a frequent epigenetic event in pancreatic cancer; and by using global methylation profiling assay, it is possible to identify these markers for diagnostic and therapeutic purposes in this disease.

A direct pancreatic cancer xenograft model as a platform for cancer stem cell therapeutic development.

There is an enormous gap between the antiproliferative and in vivo antitumor efficacy of gemcitabine in cell line-based models and its clinical efficacy. This may be due to insensitiveness of the precursor, cancer stem cell (CSC) compartment to cytotoxic agents. The hedgehog pathway is associated with CSC signaling and control. We used a direct xenograft model of pancreatic cancer and a two-stage approach was used to test the hypotheses that targeting CSC could increase the efficacy of gemcitabine. Tumors from a gemcitabine-sensitive xenograft were treated with gemcitabine first, and randomized, after tumor regression to continuing treatment with gemcitabine, a hedgehog inhibitor alone or in combination with gemcitabine. We tested markers described as associated with CSC such as CD24, CD44, ALDH, nestin, and the hedgehog pathway. After induction with gemcitabine, treated tumor showed an enrichment in CSC markers such as ALDH and CD24. Subsequently, a release from gemcitabine prompted a repopulation of proliferating cells and a decrease in such markers to equilibrate from pretreatment levels. Combined treatment with gemcitabine and cyclopamine induced tumor regression and decrease in CSC markers and hedgehog signaling. Cytoplasmic CD24 and ALDH were inversely and strongly associated with growth and were expressed in a minority of cells that we propose constitute the CSC compartment. Hedgehog inhibitors as part of a dual compartment therapeutic approach were able to further reduce tumor growth and decreased both static and dynamic markers of CSC. Direct tumor xenografts are a valid platform to test multicompartment therapeutic approaches in pancreatic cancer.

Meanings and political implications of "psychopathology" in a gender identity clinic: a report of 10 cases.

Beginning in August 2007, we committed ourselves to a clinical review the co-morbid diagnostic patterns of the last 10 patients interviewed by our Gender Identity Clinic. We found 90% of these diverse patients had at least one other significant form of psychopathology. This finding seems to be in marked contrast to the public, forensic, and professional rhetoric of many who care for transgendered adults. Much of this rhetoric sounds remarkably certain about the long-term value of gender transition, hormones, and sex reassignment surgery in improving the lives of those with Gender Identity Disorder (GID). Such clinical certainty would have to be based on carefully established sophisticated follow-up findings. These are lacking. The psychopathologies in this series included problems of mood and anxiety regulation and adapting in the world. Two of the 10 have had persistent significant regrets about their previous transitions. In discussing management decisions, civil rights, and ethics, we planned to separately briefly present the 10 patients. However, our decision to seek patients' permission proved so upsetting to three of the first six patients that we altered the structure of this report. Our attempt to follow the ethical principle of informed consent caused us to violate the principle of nonmalfiescence. This distressing experience only illustrates, however, the disadvantage of discussing professional concepts with lay audiences. Emphasis on civil rights is not a substitute for the recognition and treatment of associated psychopathology. Gender identity specialists, unlike the media, need to be concerned about the majority of patients, not just the ones who are apparently functioning well in transition.

Antitumor activity and molecular effects of the novel heat shock protein 90 inhibitor, IPI-504, in pancreatic cancer.

Targeting Hsp90 is an attractive strategy for anticancer therapy because the diversity and relevance of biological processes are regulated by these proteins in most cancers. However, the role and mode of action of Hsp90 inhibitors in pancreatic cancer has not been studied. This study aimed to assess the antitumor activity of the Hsp90 inhibitor, IPI-504, in pancreatic cancer and to determine the biological effects of the agent. In vitro, we show that pharmacologic inhibition of Hsp90 by IPI-504 exerts antiproliferative effects in a panel of pancreatic cancer cells in a dose- and time-dependent manner. In pancreatic cancer xenografts obtained directly from patients with pancreas cancer, the agent resulted in a marked suppression of tumor growth. Although known Hsp90 client proteins were significantly modulated in IPI-504-treated cell line, no consistent alteration of these proteins was observed in vivo other than induction of Hsp70 expression in the treated xenografted tumors. Using a proteomic profiling analysis with isotope tags for relative and absolute quantitation labeling technique, we have identified 20 down-regulated proteins and 42 up-regulated proteins on IPI-504 treatment.tumor growth Identical changes were observed in the expression of the genes coding for these proteins in a subset of proteins including HSPA1B, LGALS3, CALM1, FAM84B, FDPS, GOLPH2, HBA1, HIST1H1C, HLA-B, and MARCKS. The majority of these proteins belong to the functional class of intracellular signal transduction, immune response, cell growth and maintenance, transport, and metabolism. In summary, we show that IPI-504 has potent antitumor activity in pancreatic cancer and identify potential pharmacologic targets using a proteomics and gene expression profiling.