Genetic modification of clinical-grade T cells is undertaken to augment function, including redirecting specificity for desired antigen. We and others have introduced a chimeric antigen receptor (CAR) to enable T cells to recognize lineage-specific tumor antigen, such as CD19, and early-phase human trials are currently assessing safety and feasibility. However, a significant barrier to next-generation clinical studies is developing a suitable CAR expression vector capable of genetically modifying a broad population of T cells. Transduction of T cells is relatively efficient but it requires specialized manufacture of expensive clinical grade recombinant virus. Electrotransfer of naked DNA plasmid offers a cost-effective alternative approach, but the inefficiency of transgene integration mandates ex vivo selection under cytocidal concentrations of drug to enforce expression of selection genes to achieve clinically meaningful numbers of CAR +

Adoptive transfer of T cells expressing a CD19-specific chimeric antigen receptor (CAR) is being evaluated in multiple clinical trials. Our current approach to adoptive immunotherapy is based on a second generation CAR (designated CD19RCD28) that signals through a CD28 and CD3-ζ endodomain. T cells are electroporated with DNA plasmids from the Sleeping Beauty (SB) transposon/transposase system to express this CAR. Stable integrants of genetically modified T cells can then be retrieved when co-cultured with designer artificial antigen presenting cells (aAPC) in the presence of interleukin (IL)-2 and 21. Here, we reveal how the platform technologies of SB-mediated transposition and CAR-dependent propagation on aAPC were adapted for human application. Indeed, we have initiated clinical trials in patients with high-risk B-lineage malignancies undergoing autologous and allogeneic hematopoietic stem-cell transplantation (HSCT). We describe the process to manufacture clinical grade CD19-specific T cells derived from healthy donors. Three validation runs were completed in compliance with current good manufacturing practice for Phase I/II trials demonstrating that by 28 days of co-culture on γ-irradiated aAPC ∼1010 T cells were produced of which >95% expressed CAR. These genetically modified and propagated T cells met all quality control testing and release criteria in support of infusion.

Significance Patients with compromised T-cell function are at risk for opportunistic fungal infections. We have developed a novel approach to restore immunity by using a fungal pattern-recognition receptor Dectin-1 to redirect T-cell specificity to carbohydrate antigen in the fungal cell wall. We did so by genetically modifying T cells using the nonviral Sleeping Beauty gene-transfer system to enforce expression of a chimeric antigen receptor (CAR) that recapitulates the specificity of Dectin-1 (D-CAR). The D-CAR + T cells can be electroporated and propagated on artificial activating and propagating cells in a manner suitable for human application, enabling this immunology to be translated into immunotherapy. This approach has implications for genetically modifying T cells to express CARs with specificity for carbohydrate and thus broadening their application in the investigational treatment of pathogens and malignancies.

Optimal implementation of adoptive T-cell therapy for cancer will likely require multiple and maintained genetic modifications of the infused T-cells and their progeny so that they home to and recognize tumor cells, overcome tumor immune evasion strategies and remain safe. Retroviral vectors readily transduce T-cells and integrate into the host cell genome, but have a limited capacity for multigene insertion and co-transduction and are prohibitively expensive to produce at clinical grade. Genetic modification of T-cells using transposons as integrating plasmids is an attractive alternative due to the increased simplicity and cost of production. Of available transposons, piggyBac has the higher transposase activity and larger cargo capacity, and we now evaluate piggyBac for potential adoptive therapies with primary T cells. PiggyBac transposons mediated stable gene expression in ~20% of primary T-cells without selection. Treatment and maintenance of T-cells with IL-15 increased stable transgene expression up to ~40% and expression was sustained through multiple logs of expansion for over 9 weeks in culture. We demonstrate simultaneous integration of two independent transposons in 20% of T-cells, a frequency that could be increased to over 85% by selection of a transgenic surface marker (truncated CD19). PiggyBac could also deliver of transposons of up to 13 kb with 10,000 fold expansion of transduced T-cells in culture and finally we demonstrate delivery of a functional suicide gene (iCasp9). PiggyBac transposons may thus be used to express the multiple integrated transgenes that will likely be necessary for the broader success of T-cell therapy.

The E6 and E7 oncoproteins of the high-risk HPV type16 represent ideal targets for HPV vaccine development, they being consistently expressed in cervical cancer lesions. Since HPV-16 is primarily transmitted through genital mucosal route, mucosal immune responses constitute an essential feature for vaccination strategies against HPV-associated lesions. We present here evidence showing that mucosal immunization of mice by the intranasal route with a mixture of peptides E7 44-62 and E6 43-57 from the E7 and E6 oncoproteins of HPV-16, respectively, using a mutant cholera toxin adjuvant (CT-2*), primed strong antigen-specific cellular immune responses in systemic and mucosal tissues. Significant levels of IFN-γ production by both CD4 and CD8 cells were observed along with CTL responses that were effective against both peptide-pulsed targets as well as syngeneic tumor cells (TC-1) expressing the cognate E6 and E7 proteins. Furthermore, mice immunized with the peptide mixture and CT-2* effectively resisted TC-1 tumor challenge. These results together with our earlier observations that T cell responses to these peptides correlate with recurrence-free survival in women after ablative treatment for HPV-associated cervical intraepithelial neoplasia, support the potential of these E6 and E7 peptides for inclusion in vaccine formulations.

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Infection of Indian-origin rhesus macaques by the simian human immunodeficiency virus (SHIV) is considered to be a suitable preclinical model for directly testing efficacy of vaccine candidates based on the HIV-1 envelope. We used this model for prophylactic vaccination with a peptide-cocktail comprised of highly conserved HIV-1 envelope sequences immunogenic/antigenic in macaques and humans. Separate groups of macaques were immunized with the peptide-cocktail by intravenous and subcutaneous routes using autologous dendritic cells (DC) and Freund's adjuvant, respectively. The vaccine elicited antigen specific IFN-gamma-producing cells and T-cell proliferation, but not HIV-neutralizing antibodies. The vaccinated animals also exhibited efficient cross-clade cytolytic activity against target cells expressing envelope proteins corresponding to HIV-1 strains representative of multiple clades that increased after intravenous challenge with pathogenic SHIV(KU2). Virus-neutralizing antibodies were either undetectable or present only transiently at low levels in the control as well as vaccinated monkeys after infection. Significant control of plasma viremia leading to undetectable levels was achieved in majority of vaccinated monkeys compared to mock-vaccinated controls. Monkeys vaccinated with the peptide-cocktail using autologous DC, compared to Freund's adjuvant, and the mock-vaccinated animals, showed significantly higher IFN-gamma production, higher levels of vaccine-specific IFN-gamma producing CD4(+) cells and significant control of plasma viremia. These results support DC-based vaccine delivery and the utility of the conserved HIV-1 envelope peptide-cocktail, capable of priming strong cell-mediated immunity, for potential inclusion in HIV vaccination strategies.

Purpose We have incorporated a positron emission tomography (PET) functionality in T cells expressing a CD19-specific chimeric antigen receptor (CAR) to non-invasively monitor the adoptively transferred cells. Procedures We engineered T cells to express CD19-specific CAR, firefly luciferase (ffLuc), and herpes simplex virus type-1 thymidine kinase (TK) using the non-viral-based Sleeping Beauty (SB) transposon/transposase system adapted for human application. Electroporated primary T cells were propagated on CD19+ artificial antigen-presenting cells. Results After 4 weeks, 90 % of cultured cells exhibited specific killing of CD19+ targets in vitro, could be ablated by ganciclovir, and were detected in vivo by bioluminescent imaging and PET following injection of 2′-deoxy-2′-[18F]fluoro-5-ethyl-1-β-D-arabinofuranosyl-uracil ([18F]FEAU). Conclusion This is the first report demonstrating the use of SB transposition to generate T cells which may be detected using PET laying the foundation for imaging the distribution and trafficking of T cells in patients treated for B cell malignancies.