Mesothelin is a cell-surface molecule over-expressed on a large fraction of carcinomas, and thus is an attractive target of immunotherapy. A molecularly targeted therapy for these cancers was created by engineering T cells to express a chimeric receptor with high affinity for human mesothelin. Lentiviral vectors were used to express a single-chain variable fragment that binds mesothelin and that is fused to signaling domains derived from T-cell receptor zeta, CD28, and CD137 (

HIV’s phenomenal capacity to vary its HLA-I-restricted peptide antigens allows it to escape from host cytotoxic T-lymphocytes (CTLs). Nevertheless, therapeutics able to target HLA-I-associated antigens, with specificity for the spectrum of preferred CTL escape mutants, could prove effective. Here we use phage display to isolate and enhance a T-cell receptor (TCR) originating from a patient CTL line and specific for the immunodominant HLA-A*02-restricted, HIVgag-specific peptide SLYNTVATL (SL9). High affinity (KD <400pM) TCRs were produced that bound with a half-life in excess of three hours, retained specificity, targeted HIV-infected cells and recognized all common escape variants of this epitope. CD8 T-cells transduced with supraphysiologic TCR produced a greater range of soluble factors and more IL2, than those transduced with natural SL9-specific TCR, and effectively controlled wildtype and mutant strains of HIV at effector-to-target ratios that could be achieved by T-cell therapy.

Human T helper 17 (TH17) cells regulate host defense, autoimmunity, and tumor immunity. Although cytokines that control human TH17 cell development have been identified, the costimulatory molecules important for TH17 cell generation are unknown. Here, we found that the inducible costimulator (ICOS) was critical for the differentiation and expansion of human TH17 cells. Human cord blood contained a subset of CD161+CD4+T cells that were recent emigrants from the thymus, expressed ICOS constitutively, and were imprinted as TH17 cells through ICOS signaling. ICOS stimulation induced c-MAF, RORC2, and T-bet expression in these cells, leading to increased secretion of interleukin-21 (IL-21), IL-17, and interferon-γ (IFN-γ) compared with cells stimulated with CD28. Conversely, CD28 ligation abrogated ICOS costimulation, dampening RORC2 expression while promoting the expression of the aryl hydrocarbon receptor, which led to reduced secretion of IL-17 and enhanced production of IL-22 compared with cells stimulated with ICOS. Moreover, ICOS promoted the robust expansion of IL-17+IFN-γ+ human T cells, and the antitumor activity of these cells after adoptive transfer into mice bearing large human tumors was superior to that of cells expanded with CD28. The therapeutic effectiveness of ICOS-expanded cells was associated with enhanced functionality and engraftment in vivo. These findings reveal a vital role for ICOS signaling in the generation and maintenance of human TH17 cells and suggest that components of this pathway could be therapeutically targeted to treat cancer or chronic infection and, conversely, that interruption of this pathway may have utility in multiple sclerosis and other autoimmune syndromes. These findings have provided the rationale for designing new clinical trials for tumor immunotherapy.

To facilitate the therapeutic application of antigen-presenting cells (APCs), we have developed a cell-based artificial APC (aAPC) system by engineering K562 cells with lentiviruses to direct the stable expression and secretion of a variety of co-stimulatory molecules and cytokines. Here we report the use of a combinatorial lentiviral gene transfer approach to achieve long-term stable expression of at least seven genes in the K562 parental cell line. Expression of various combinations of genes on the aAPC enables the precise determination of human T-cell activation requirements, such that aAPCs can be tailored for the optimal propagation of T-cell subsets with specific growth requirements and distinct functions. The aAPCs support ex vivo growth and long-term expansion of functional human CD8 T cells without requiring the addition of exogenous cytokines, in contrast to the use of natural APCs. Distinct populations of T cells can be expanded with aAPCs expressing CD137L (4-1BBL) and/or CD80. Finally, the aAPCs provide an efficient platform to expand genetically modified T cells and to maintain CD28 expression on CD8 T cells. Therefore, K562-based aAPCs have therapeutic potential for adoptive immunotherapies and vaccinations.