Preclinical evaluation of a MAGE-A3 vaccination utilizing the oncolytic Maraba virus currently in first-in-human trials.

Multiple immunotherapeutics have been approved for cancer patients, however advanced solid tumors are frequently refractory to treatment. We evaluated the safety and immunogenicity of a vaccination approach with multimodal oncolytic potential in non-human primates (NHP) (Macaca fascicularis). Primates received a replication-deficient adenoviral prime, boosted by the oncolytic Maraba MG1 rhabdovirus. Both vectors expressed the human MAGE-A3. No severe adverse events were observed. Boosting with MG1-MAGEA3 induced an expansion of hMAGE-A3-specific CD4+ and CD8+ T-cells with the latter peaking at remarkable levels and persisting for several months. T-cells reacting against epitopes fully conserved between simian and human MAGE-A3 were identified. Humoral immunity was demonstrated by the detection of circulating MAGE-A3 antibodies. These preclinical data establish the capacity for the Ad:MG1 vaccination to engage multiple effector immune cell populations without causing significant toxicity in outbred NHPs. Clinical investigations utilizing this program for the treatment of MAGE-A3-positive solid malignancies are underway (NCT02285816, NCT02879760).

Direct Lymph Node Vaccination of Lentivector/Prostate-Specific Antigen is Safe and Generates Tissue-Specific Responses in Rhesus Macaques.

Anti-cancer immunotherapy is emerging from a nadir and demonstrating tangible benefits to patients. A variety of approaches are now employed. We are invoking antigen (Ag)-specific responses through direct injections of recombinant lentivectors (LVs) that encode sequences for tumor-associated antigens into multiple lymph nodes to optimize immune presentation/stimulation. Here we first demonstrate the effectiveness and antigen-specificity of this approach in mice challenged with prostate-specific antigen (PSA)-expressing tumor cells. Next we tested the safety and efficacy of this approach in two cohorts of rhesus macaques as a prelude to a clinical trial application. Our vector encodes the cDNA for rhesus macaque PSA and a rhesus macaque cell surface marker to facilitate vector titering and tracking. We utilized two independent injection schemas demarcated by the timing of LV administration. In both cohorts we observed marked tissue-specific responses as measured by clinical evaluations and magnetic resonance imaging of the prostate gland. Tissue-specific responses were sustained for up to six months-the end-point of the study. Control animals immunized against an irrelevant Ag were unaffected. We did not observe vector spread in test or control animals or perturbations of systemic immune parameters. This approach thus offers an "off-the-shelf" anti-cancer vaccine that could be made at large scale and injected into patients-even on an out-patient basis.

Porcine dermatitis and nephropathy syndrome associated with porcine circovirus 2 infection in a Yorkshire pig.

We describe a case of porcine dermatitis and nephropathy syndrome (PDNS) in a 14-wk-old Yorkshire pig purchased from a commercial farm for research use. Physical examination of the affected animal upon arrival revealed multifocal, red, papular skin lesions on the rump, vulva, perineum, thighs, and lower hindlegs. At necropsy, gross lesions consisted of dermatitis, bilaterally enlarged kidneys and patchy pulmonary congestion. Histologic findings included multiorgan necrotizing vasculitis with prominent lesions in the skin, kidneys, lung, spleen, and liver. Immunohistochemical staining for porcine circovirus type 2 (PCV2) was strongly positive in affected areas of kidney and spleen. In light of the clinical assessment and gross and histologic findings, a diagnosis of PDNS was made. We emphasize the importance of considering PDNS as a differential diagnosis in laboratory swine with skin lesions.

Control of microbial contamination during surgical harvest of pig renal xenografts.

The pig has been identified as the most likely source of xenograft material for clinical use and studies are ongoing to overcome the immunological hurdles of pig-to-human transplantation. Attention is now being focussed on identifying and reducing the potential microbiological hazards associated with this technique. Studies have primarily addressed issues surrounding the production and health monitoring of xenograft source pigs and none have so far specifically evaluated the possible risks of microbial contamination during xenograft harvest. In this report, we evaluate the possible routes for contamination of a pig kidney xenograft during organ harvest and describe approaches to the control of these hazards, including the novel use of a custom designed airtight surgical canopy. A standard procedure for microbiological monitoring during xenograft harvest was devised and evaluated. This allowed the rapid identification and anti-microbial sensitivity testing of any isolated organisms. This would enable an early and appropriate pre-emptive treatment of infection because of transmission of pig micro-organisms.

The production of transgenic pigs for potential use in clinical xenotransplantation: baseline clinical pathology and organ size studies.

This report describes the results of hematology, serum biochemistry, growth, and organ weight studies undertaken on pigs from nine cohorts of qualified pathogen free (QPF) pigs reared within a high welfare bioexclusion facility as potential organ source animals. Confirmation of the high health status of the pigs was given through total leukocyte counts and serum globulin concentrations that fell below the expected reference range for conventional pigs. The calculated mean growth rate for QPF pigs was found to exceed target rates set for optimum genotype commercial pig herds. Body weights of QPF pigs were compared with kidney, heart and liver weights at necropsy.

The production of transgenic pigs for potential use in clinical xenotransplantation: microbiological evaluation.

Debate over the infection hazards of pig-to-human xenotransplantation has focused mainly on the porcine endogenous retroviruses (PERV). However, hazards of exogenous infectious agents possibly associated with the xenograft have also been evaluated (Xenotransplantation 2000; 7: 143). We report the results of a health monitoring program demonstrating the exclusion of more than 80 potential pathogens from nine cohorts of pigs reared in a high welfare bioexclusion facility as potential xenograft source animals. A dynamic bacterial flora of pigs reared under barrier conditions was characterized, emphasizing the significance of monitoring for multiresistant antimicrobial sensitivity patterns. Evidence was found for exclusion of two commonly residual exogenous viruses, porcine cytomegalovirus and porcine lymphotropic herpesviruses, among a proportion of the cohorts tested. Finally, there was histopathological evidence for low grade pneumonitis among sentinel pigs, likely to have been associated with the use of quaternary ammonium disinfectants during the production process, indicating a need for review of toxicology data for disinfectant agents used in such bioexclusion systems. Intensive health monitoring programs, based upon regularly updated recommendations from the microbiological research community, will enable significant reductions in the potential hazards associated with pig-to-human xenotransplantation.