Publications by authors named "Arnold Leonard"

The ultimate goal of bacterial based cancer therapy is to achieve non-toxic penetration and colonisation of the tumour microenvironment. To overcome this efficacy-limiting toxicity of anticancer immunotherapy, we have tested a therapy comprised of systemic delivery of a vascular disrupting agent to induce intratumoral necrotic space, cannabidiol to temporarily inhibit angiogenesis and acute inflammation, and a strain of Typhimurium that was engineered for non-toxic colonisation and expression of immunomodulators within the tumour microenvironment. This combination treatment strategy was administered to transgenic mice burdened with autochthonous mammary gland tumours and demonstrated a statistically significant 64% slower tumour growth and a 25% increase in mean survival time compared to control animals without treatment.

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Much of the bacterial anticancer therapy being developed relies on the ability of bacteria to specifically colonise tumours. Initial attempts to translate promising Typhimurium (. Typhimurium) preclinical results to the clinical setting failed, primarily due to lack of tumour colonisation and the significant toxicities from systemically administered Gram-negative bacteria.

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Salmonella has been shown to preferentially colonize solid tumors. It is known that toxicity limits the systemic administration of immunomodulatory cytokines that have a significant anticancer effect. Therefore, we tested a unique cancer treatment strategy comprised of oral delivery of Saltikva, an attenuated strain of Salmonella typhimurium that contain the human gene for interleukin-2.

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Background: Immunotherapies for cancer treatment have demonstrated substantial promise even though toxicities and development of tumor resistance limit their effectiveness. A combinatorial approach using immunotherapy with other treatment modalities may decrease side effects while maintaining maximal therapeutic effect. We aimed to determine if bacterial immunotherapy in combination with a chemotherapeutic would be efficacious and less toxic than conventional chemotherapy in an established, preclinical, autochthonous tumor model.

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Background/aim: Cancer treatment with attenuated Salmonella enterica Typhimurium (S. Typhimurium) has gained momentum in recent years. However, the effectiveness of this treatment has not been explored in autochthonous models.

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Programmed death ligand 1 (PD-L1), is an important regulator of T-cell activation and has emerged as an important target for cancer immunotherapy. Single chain variable fragments (scFvs) have several desirable characteristics and are an attractive alternative to monoclonal antibodies for experimental or therapeutic purposes. Three chickens were immunized against murine PD-L1, and mRNA isolated from their spleens was used to generate an immunized immunoglobulin variable region library.

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Fruit seeds high in antioxidants have been shown to have anticancer properties and enhance host protection against microbial infection. Recently we showed that a single oral dose of Salmonella enterica serovar Typhimurium expressing a truncated human interleukin-2 gene (SalpIL2) is avirulent, immunogenic, and reduces hepatic metastases through increased natural killer cell populations in mice. To determine whether antioxidant compounds enhance the antitumor effect seen in SalpIL2-treated animals, we assayed black cumin (BC), black raspberry (BR), and milk thistle (MT) seed oils for the ability to reduce experimental hepatic metastases in mice.

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Salmonella enterica serovar Typhimurium preferentially colonizes tumors in vivo and has proven to be an effective biologic vector. The attenuated S. enterica Typhimurium strain chi4550 was engineered to express truncated human interleukin-2 and renamed SalpIL2.

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Purpose: The current management of osteosarcoma (OS) entails an aggressive preoperative and postoperative chemotherapeutic regimen with limb salvage surgery. Despite these efforts, relapse-free survival is less than 60% in patients with classic OS, whereas most patients relapse with pulmonary metastases. In these studies, we sought to prevent the establishment of pulmonary metastases from OS with a single oral dose of SalpIL2.

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Historically, osteosarcoma has been a problematic metastatic disease, with 40-80% of patients developing pulmonary metastasis after primary tumor resection. Recent treatment advancements have reduced the occurrence of metastatic lesions to less than 30%. Using attenuated Salmonella typhimurium, we previously demonstrated regression in tumor burden in murine solid tumor and metastatic models.

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Introduction: We have previously shown that Salmonella elicits an antitumor response against hepatic adenocarcinomatous metastases. In vitro studies have demonstrated both intracellular invasion and proliferation of Salmonella within cultured neuroblastoma cells. We sought to demonstrate in vivo invasion, proliferation, and a potential antitumor response.

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Background/purpose: Attenuated Salmonella typhimurium, a facultative intracellular parasite that colonizes the liver, has been shown to accumulate within extrahepatic malignancies. The authors sought to define a mechanism for attenuated Salmonella accumulation within cancer cells compared with hepatocytes.

Methods: Invasion and intracellular proliferation of attenuated Salmonella was assessed through an in vitro assay performed on neuroblasoma, osteosarcoma, hepatoma, and colon adenocarcinoma cell lines and compared with freshly isolated mouse hepatocytes.

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Purpose: The authors investigated the utility of attenuated Salmonella typhimurium for preventing the establishment of hepatic metastases in a murine model.

Methods: A single, oral 10(8) cfu dose of attenuated S typhimurium was given 8 days before the establishment of a model of unresectable hepatic metastases. Animals were assessed for hepatic tumor number and volume, hepatic lymphocyte population analysis, and survival.

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Introduction: Oral inoculation with a nontoxic, attenuated strain of Salmonella typhimurium reduces tumor burden and improves survival in a mouse model of metastatic colon cancer. These effects are likely mediated by S. typhimurium-induced increases in hepatic natural killer leukocytes.

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The spectrum of surgical diseases in patients with cystic fibrosis (CF) has not been comprehensively studied. A retrospective review of 792 consecutive patients with CF presenting over a 25 year period (1970-1994) was made to determine the incidence of operations, procedures performed, complications encountered, and impact on physical development and pulmonary function tests (PFTs). A total of 191 operations were performed on 130 (16%) of the 792 patients; 98 operations (51%) were abdominal, 58 (30%) thoracic, and 31 (16%) hernias; 64 were male, and 66 female; average age was 14 +/- 10 years.

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