Purpose The multiple mechanisms used by solid tumors to suppress tumor-specific immune responses are a major barrier to the success of adoptively-transferred tumor-specific T-cells. Since viruses induce potent innate and adaptive immune responses, we hypothesized that the immunogenicity of viruses could be harnessed for the treatment of solid tumors if virus-specific T-cells (VSTs) were modified with tumor-specific chimeric antigen receptors (CARs). We tested this hypothesis using VZV-specific T-cells (VZVSTs) expressing a CAR for GD2, a disialoganglioside expressed on neuroblastoma and certain other tumors, since the live-attenuated VZV vaccine could be used for in vivo stimulation. Experimental Design We generated GMP-compliant, GD2.CAR-modified VZVSTs from healthy donors and cancer patients by stimulation with overlapping peptide libraries spanning selected VZV antigens, then tested their ability to recognize and kill GD2- and VZV antigen-expressing target cells. RESULTS Our choice of VZV antigens was validated by the observation that T-cells specific for these antigens expanded in vivo after VZV vaccination. VZVSTs secreted cytokines in response to VZV antigens, killed VZV infected target cells and limited infectious virus spread in autologous fibroblasts. However, while GD2.CAR-modified VZVSTs killed neuroblastoma cell lines on their first encounter, they failed to control tumor cells in subsequent cocultures. Despite this CAR-specific dysfunction, CAR-VZVSTs retained functional specificity for VZV antigens via their TCRs and GD2.CAR function was partially rescued by stimulation through the TCR or exposure to dendritic cell supernatants. CONCLUSION Vaccination via the TCR may provide a means to reactivate CAR-T-cells rendered dysfunctional by the tumor microenvironment. (NCT01953900).

This phase I trial reports the safety and activity of BPX101, a second-generation antigen-targeted autologous antigen presenting cell (APC) vaccine in men with metastatic castration-resistant prostate cancer (mCRPC). To manufacture BPX101, APCs collected in a single leukapheresis were transduced with adenoviral vector Ad5f35 encoding inducible human (ih)-CD40, followed by incubation with protein PA001, which contains the extracellular domain of human prostate-specific membrane antigen. The ih-CD40 represents a modified chimeric version of the dendritic cell (DC) co-stimulatory molecule, CD40, which responds to a bioinert membrane-permeable activating dimerizer drug, rimiducid (AP1903), permitting temporally controlled, lymphoid-localized, DC-specific activation. Eighteen men with progressive mCRPC following ≤1 prior chemotherapy regimen were enrolled to evaluate three doses of BPX101 (4 × 10, 12.5 × 10 and 25 × 10 cells) administered intradermally every 2-4 weeks followed by rimiducid (0.4 mg/kg) intravenous (IV) infusion 24 h after each BPX101 dose. There were no dose-limiting toxicities. Immune upregulation as well as anti-tumor activity was observed with PSA declines, objective tumor regressions and robust efficacy of post-trial therapy. This novel antigen-targeted and in vivo activated immunotherapy platform may warrant further development as monotherapy and as a component of rational combinations.