David Tung

Intratumoral injection of Clostridium novyi-NT spores induces antitumor responses.

Clostridium novyi-NT targets aberrant tumor physiology and can produce a precise, robust, and reproducible antitumor response. Fighting Cancer with Clostridium Tumors are composed of necrotic, hypoxic, and well-oxygenated regions. Hypoxic tumor regions are more resistant to systemic anticancer agents and radiotherapy. However, they provide a fertile ground for the growth of anaerobic bacteria. Roberts et al. use an attenuated strain of the anaerobic, spore-forming bacterium Clostridium novyi (C. novyi-NT) and demonstrate precise, robust, and reproducible antitumor responses when C. novyi-NT spores were injected into tumors of rats, dogs, and one human patient. These results support the further development of intratumoral injections of C. novyi-NT spores as a therapeutic for patients with locally advanced, nonresectable cancers. Species of Clostridium bacteria are notable for their ability to lyse tumor cells growing in hypoxic environments. We show that an attenuated strain of Clostridium novyi (C. novyi-NT) induces a microscopically precise, tumor-localized response in a rat orthotopic brain tumor model after intratumoral injection. It is well known, however, that experimental models often do not reliably predict the responses of human patients to therapeutic agents. We therefore used naturally occurring canine tumors as a translational bridge to human trials. Canine tumors are more like those of humans because they occur in animals with heterogeneous genetic backgrounds, are of host origin, and are due to spontaneous rather than engineered mutations. We found that intratumoral injection of C. novyi-NT spores was well tolerated in companion dogs bearing spontaneous solid tumors, with the most common toxicities being the expected symptoms associated with bacterial infections. Objective responses were observed in 6 of 16 dogs (37.5%), with three complete and three partial responses. On the basis of these encouraging results, we treated a human patient who had an advanced leiomyosarcoma with an intratumoral injection of C. novyi-NT spores. This treatment reduced the tumor within and surrounding the bone. Together, these results show that C. novyi-NT can precisely eradicate neoplastic tissues and suggest that further clinical trials of this agent in selected patients are warranted.

Anti-inflammatory and immunomodulatory effects of bortezomib in various in vivo models.

Bortezomib (Velcade®) is a proteasome inhibitor that has been approved for the treatment of multiple myeloma and mantle cell lymphoma. It has been shown to inhibit the expression of cell adhesion molecules, co-stimulatory molecules, and NFĸB activation, to deplete alloreactive T lymphocytes, and to decrease Th1 cytokine production. The anti-inflammatory effects of bortezomib were further investigated in this current set of studies. Systemic treatment with bortezomib was efficacious in the thioglycolate-induced MCP-1 production model, and the dinitrofluorobenzene-induced delayed-type hypersensitivity model. Psoriasis is an autoimmune disease that affects about 2% of the world population. Many treatments have been reported with varying degrees of efficacy. A topical bortezomib formulation was developed to minimize systemic exposure. Its tolerability was investigated in a topical imiquimod (IMQ)-induced psoriasis model. Daily application of IMQ on mouse skin induced inflamed scaly skin lesions resembling plaque-type psoriasis. Fatality was observed in the 1-mg/ml dose group. At 0.1 and 0.01 mg/ml, bortezomib potentiated IMQ-induced erythema, scaling, skin thickening, and caused necrotic lesions. Lower doses had no effect on the clinical observations. Histologically, bortezomib dose-dependently increased parakeratosis, hyperkeratosis, acanthosis, and inflammatory cell infiltration. This study demonstrated that topical bortezomib is not suitable for the treatment of psoriasis.

Novel anti-inflammatory effects of repaglinide in rodent models of inflammation.

Background: Repaglinide is an FDA-approved treatment for type 2 diabetes mellitus. The anti-inflammatory effect of repaglinide in the absence of diabetes has not been reported previously. It is the objective of this set of studies to investigate the potential anti-inflammatory effects of repaglinide. Method: The in vivo anti-inflammatory effects of repaglinide were studied in two different models of delay type hyperreactivity (DTH) response induced by sheep red blood cells (sRBC) and 2,5′-dinitrofluorobenzene (DNFB), and in two different rodent models of lipopolysaccharide (LPS) challenge. Results: In mice systemically sensitized with sRBC, which subsequently received a local injection of sRBC in the footpad, local swelling occurred within 24 h after challenge. Repaglinide was efficacious in attenuating this response. In an orthogonal DTH model using DNFB as the antigen, the animals received topical sensitization with DNFB on their shaved backs, followed by topical challenge on the left ears. Repaglinide efficaciously downregulated the resulting ear swelling response. In mice challenged systemically or intratracheally with LPS, repaglinide significantly decreased serum tumor necrosis factor α level and bronchial alveolar lavage fluid MCP-1 levels, respectively. Conclusion: This set of data suggests novel anti-inflammatory effects of repaglinide in nondiabetic animals. However, the high dose required for an efficacious effect would make this application impractical in the clinic.

Novel Anti-Inflammatory Effects of Doxazosin in Rodent Models of Inflammation

Background: Doxazosin is an α1-adrenergic receptor antagonist for the treatment of high blood pressure and benign prostatic hyperplasia. Peripheral α-adrenergic receptors have been implicated in inflammation. Aim: To examine the anti-inflammatory effects of doxazosin in rodent models of inflammation. Method: The anti-inflammatory properties of doxazosin were investigated in 4 models. In all studies, drug treatment was administered 15 min prior to challenge. In the lipopolysaccharide (LPS)-induced systemic inflammation model, LPS was injected systemically at 0.25 mg/kg. At 90 min after challenge, blood samples were collected for analysis. In the LPS-induced pulmonary inflammation model, LPS was instilled intranasally. Four hours after challenge, the lungs were harvested for monocyte chemoattractant protein-1 (MCP-1) analysis. In a delayed-type hypersensitivity model, the mice were injected intravenously with sheep red blood cells, and rechallenged in the left footpad 7 days later. Drug treatment was given on day 6 and 7 just prior to the rechallenge. The thickness of hind footpads was measured at 15 min after rechallenge. In the thioglycollate-induced peritoneal monocyte infiltration model, mice were challenged with 3% thioglycollate, and 2 h later peritoneal lavage fluid was collected for MCP-1 analysis. Results: In animals challenged systemically and intranasally with LPS, doxazosin inhibited TNF-α and MCP-1 production, respectively. In the delayed-type hypersensitivity model, footpad swelling was inhibited by doxazosin. Doxazosin decreased the level of MCP-1 release in the peritoneal cavity of thioglycollate-stimulated animals, though this effect was not statistically significant. Conclusion: This is the first set of studies that reports the novel anti-inflammatory effects of doxazosin.

Possible Therapeutic Effect of Trilostane in Rodent Models of Inflammation and Nociception

Background Trilostane was identified in an in vivo screen of compounds in a lipopolysaccharide model of inflammation to support a repurposing effort. There is no previous documentation of any anti-inflammatory effects of trilostane. Objective The aim of this study was to elucidate the novel pharmacologic activity of trilostane in a series of inflammation and nociception signal-finding models. Methods Anti-inflammatory effects of trilostane were evaluated in lipopolysaccharide-induced systemic and lung inflammation models and in a 2,4-dinitrofluorobenzene–induced delayed-type hypersensitivity (DTH) model in the mouse ear. The analgesic activities of trilostane were evaluated in a hot plate nociception model as a function of paw-withdrawal latency and in the formalin-induced nociception model with a behavioral end point. In all studies, trilostane was administered 15 minutes before challenge. In the DTH model, the animals were given a second dose 24 hours after the first dose. Results Trilostane inhibited tumor necrosis factor-α and monocyte chemoattractant protein-1 production in the lipopolysaccharide-induced systemic and pulmonary inflammation models. It also significantly reduced ear swelling in the 2,4-dinitrofluorobenzene–induced DTH model. In the hot plate nociception model, trilostane increased the latency of paw-licking behavior. Trilostane also significantly reduced the duration of pain behaviors in the late phase of the formalin-induced inflammatory pain model. Conclusions These signal-finding studies suggest that trilostane has novel anti-inflammatory and analgesic properties.

Identification of immunologic and clinical characteristics that predict inflammatory response to C. Novyi-NT bacteriolytic immunotherapy

BackgroundClostridium novyi-NT (CNV-NT), has shown promise as a bacterolytic therapy for solid tumors in mouse models and in dogs with naturally developing neoplasia. Factors that impact the immunologic response to therapy are largely unknown. The goal of this pilot study was to determine if plasma immune biomarkers, immune cell function, peripheral blood cytological composition and tumor characteristics including evaluation of a PET imaging surrogate of tumor tissue hypoxia could predict which dogs with naturally developing naïve neoplasia would develop an inflammatory response to CNV-NT.ResultsDogs that developed an inflammatory response to CNV-NT had a higher heart rate, larger gross tumor volume, greater tumor [64Cu]ATSM SUVMax, increased constitutive leukocyte IL-10 production, more robust NK cell-like function and greater peripheral blood lymphocyte counts compared to dogs that did not develop an inflammatory response to CNV-NT. Of these, unstimulated leukocyte IL-10 production, heart rate, and gross tumor volume appeared to be the best predictors of which dogs will develop an inflammatory response to CNV-NT.ConclusionsDevelopment of inflammation in response to CNV-NT is best predicted by pretreatment unstimulated leukocyte IL-10 production, heart rate, and gross tumor volume.

Evaluation of 1-(2-deoxy-2-fluoro-1-d-arabinofuranosyl)-5-iodouracil (FIAU) as an ex vivo bacterial detection agent

The nucleoside analogue, 1-(2-deoxy-2-fluoro-1-d-arabinofuranosyl)-5-iodouracil (FIAU) is a substrate for thymidine kinase (TK), which is commonly expressed in bacteria. It is currently being investigated in clinical studies as an in vivo bacterial infection detection agent. In developing countries where imaging facilities are not readily available, deploying such technology can be a big hurdle. However, a portable ex vivo system might provide a good alternative. In an in vitro system, [125I]-FIAU incubated with bacteria is phosphorylated by TK, and is trapped within the bacteria, which can be detected by radioscintography. The suitability of this agent to be utilized as part of an ex vivo bacterial detection system was evaluated. In the first part of this report, the optimization of the incubation and detection condition using E. coli as a test case is described. Samples were incubated in a growth promoting medium containing the label, then after filtering and washing, the amount of radioactivity trapped on the filter was quantitated by a scintillation counter. As a proof of concept demonstration, blinded urine samples from urinary tract infection (UTI) patients and normal donors were tested in the FIAU system. Of the 13 UTI positive and 15 normal urine samples tested, there were 2 false negatives and 1 false positive, respectively. Potential explanations for the false positive and negatives as well as the commercialization possibility of this system will be discussed.