This study extends the previous findings of a systemic treatment effect of a unique combination product, IGV-001, in recurrent GBM. As an autologous tumor cell treatment, results were postulated to be an immune response. This follow-on phase Ib trial for newly diagnosed GBM was designed to further test this hypothesis with broad entry criteria. While the primary objective remained safety, unexpected clinical and radiographic responses prompted termination of randomization and accrual only to the highest exposure cohort after patient 23. The protocol amendment also elevated analysis of clinical endpoints from exploratory objectives to clinical endpoint assessments joining the established radiographic assessments. The results of this trial reflect compelling improvement in PFS in the ITT population and for PFS, OS and PFS MGMT methylated subgroups who would have met entry criteria for current phase 3 newly-diagnosed GBM trials. These clinical endpoint improvements were accompanied by striking radiographic improvements with sustained meaningful quality of life.

Previous animal model experiments have shown a correlation between interferon gamma (IFN-␥) expression and both survival from infection with attenuated rabies virus (RABV) and reduction of neurological sequelae. Therefore, we hypothesized that rapid production of murine IFN-␥ by the rabies virus itself would induce a more robust antiviral response than would occur naturally in mice. To test this hypothesis, we used reverse engineering to clone the mouse IFN-␥ gene into a pathogenic rabies virus backbone, SPBN, to produce the recombinant rabies virus designated SPBN␥. Morbidity and mortality were monitored in mice infected intranasally with SPBN␥ or SPBN(؊) control virus to determine the degree of attenuation caused by the expression of IFN-␥. Incorporation of IFN-␥ into the rabies virus genome highly attenuated the virus. SPBN␥ has a 50% lethal dose (LD 50) more than 100-fold greater than SPBN(؊). In vitro and in vivo mouse experiments show that SPBN␥ infection enhances the production of type I interferons. Furthermore, knockout mice lacking the ability to signal through the type I interferon receptor (IFNAR ؊/؊ ) cannot control the SPBN␥ infection and rapidly die. These data suggest that IFN-␥ production has antiviral effects in rabies, largely due to the induction of type I interferons. IMPORTANCE Survival from rabies is dependent upon the early control of virus replication and spread. Once the virus reaches the central nervous system (CNS), this becomes highly problematic. Studies of CNS immunity to RABV have shown that control of replication begins at the onset of T cell entry and IFN-␥ production in the CNS prior to the appearance of virus-neutralizing antibodies.Moreover, antibody-deficient mice are able to control but not clear attenuated RABV from the CNS. We find here that IFN-␥ triggers the early production of type I interferons with the expected antiviral effects. We also show that engineering a lethal rabies virus to express IFN-␥ directly in the infected tissue reduces rabies virus replication and spread, limiting its pathogenicity in normal and immunocompromised mice. Therefore, vector delivery of IFN-␥ to the brain may have the potential to treat individuals who would otherwise succumb to infection with rabies virus. R abies virus (RABV) is the type species of the Lyssavirus genus in the Rhabdoviridae family. Its small, negative-stranded RNA genome contains only five true genes (1, 2). Although relatively simple, this zoonotic virus has a devastating impact worldwide. The majority of human rabies deaths occur in children in the developing world, and it is estimated that at least 55,000 humans die of rabies each year in Africa and Asia alone (3).Although RABV infection historically has been viewed as a death sentence once the virus reaches the brain, there is a small but growing number of humans who have survived rabies even though the virus entered the brain (4, 5). Due to such cases and to research using animal models of RABV infection (6-8), many believe that the immune system may be cap...

Immunotherapeutic strategies for malignant glioma have to overcome the immunomodulatory activities of M2 monocytes that appear in the circulation and as tumor associated macrophages (TAM). M2 cell products contribute to the growth-promoting attributes of the tumor microenvironment (TME) and bias immunity towards type 2, away from the type 1 mechanisms with anti-tumor properties. To drive type 1 immunity in CNS tissues we infected GL261 tumor-bearing mice with attenuated rabies virus (RABV). These neurotropic viruses spread to CNS tissues trans-axonally where they induce a strong type 1 immune response that involves Th1, CD8 and B cell entry across the blood brain barrier and virus clearance in the absence of overt sequelae. Intranasal infection with attenuated RABV prolonged the survival of mice bearing established GL261 brain tumors. Despite the failure of virus spread to the tumor, infection resulted in significantly enhanced tumor necrosis, extensive CD4 T cell accumulation and high levels of the proinflammatory factors IFNy, TNFa, and iNOS in the TME merely 4 days after infection, before significant virus spread or the appearance of RABV-specific immune mechanisms in CNS tissues. While the majority of g CD4 cells appeared functionally inactive, the proinflammatory changes in the TME later resulted in the loss of accumulating M2 and increased M1 TAM. Mice deficient in the Th1 transcription factor Tbet did not gain any survival advantage from RABV infection, exhibiting only limited tumor necrosis and no change in TME cytokines or TAM phenotype, highlighting the importance of type 1 mechanisms in this process.

Rabies remains a major public health issue worldwide, especially in developing countries where access to medical care can represent a real challenge. While there is still no cure for rabies, it is a vaccine-preventable disease with pre- and post-exposure prophylaxis regimens approved by the World Health Organization (WHO). However, many rabies-exposed individuals have limited access to vaccines and virus-neutralizing antibodies approved for post-exposure prophylaxis. Unfortunately, any delay in the administration of these reagents can have lethal consequences. This highlights the need to develop cost-effective immunological reagents with a greater window of efficacy. Live-attenuated vaccine strains of rabies virus presents a potential treatment in filling this gap. We show here that immunization with live-attenuated vaccines provide long-lasting rabies immunity, superior to the protection induced by inactivated vaccines. In the absence of an immunostimulatory adjuvant, vaccination with multiple doses of inactivated rabies virus induces a type-2 immune response. This type of immunity is highly effective at inducing neutralizing antibody but has limited efficacy in clearing the virus from central nervous system (CNS) tissues. In contrast, a single infection with live-attenuated rabies vaccine safely drives a type-1 immune response, associated with both the production of a neutralizing antibody and the clearance of wild-type rabies virus from CNS tissues. These results indicate that live-attenuated rabies strains have the potential to be more effective in post-exposure prophylaxis than conventional inactivated vaccines.

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