Cancer Regression in Patients After Transfer of Genetically Engineered Lymphocytes

Abstract

Through the adoptive transfer of lymphocytes after host immunodepletion, it is possible to mediate objective cancer regression in human patients with metastatic melanoma. However, the generation of tumor-specific T cells in this mode of immunotherapy is often limiting. Here we report the ability to specifically confer tumor recognition by autologous lymphocytes from peripheral blood by using a retrovirus that encodes a T cell receptor. Adoptive transfer of these transduced cells in 15 patients resulted in durable engraftment at levels exceeding 10% of peripheral blood lymphocytes for at least 2 months after the infusion. We observed high sustained levels of circulating, engineered cells at 1 year after infusion in two patients who both demonstrated objective regression of metastatic melanoma lesions. This study suggests the therapeutic potential of genetically engineered cells for the biologic therapy of cancer.In the past two decades, fundamental advances in immunology have introduced opportunities for the development of cellular-based therapies for the treatment of cancer (1,2). After ex vivo expansion, transfer, and clonal repopulation in patients who have received lymphodepleting conditioning, autologous tumor-infiltrating lymphocytes (TILs) have been found to mediate objective cancer regression in a measurable proportion of patients with metastatic melanoma (3-5). A limitation of this approach is the requirement that patients have preexisting tumorreactive cells that can be expanded ex vivo. In addition, in many cancer patients, especially those with cancers other than melanoma, it is difficult to identify these tumor-reactive lymphocytes. To overcome this limitation, we set out to develop an approach to cancer immunotherapy based on the genetic modification of normal peripheral blood lymphocytes (PBLs).Tumor-associated antigens (TAAs) are recognized by the T cell receptor (TCR) on the T lymphocyte surface, which is composed of the TCR alpha and beta chains (6). The genes encoding the TCR that are specific for a variety of TAA have now been cloned, including the TCR-recognizing MART-1 and gp100 melanoma/melanocyte differentiation antigens, the NY-ESO-1 cancer-testis antigen that is present on many common epithelial cancers, and an epitope from the p53 molecule, which is expressed on the surface of approximately 50% of cancers of common epithelial origin (7-12). In each case, these antigens were detected by the TCR when they were presented as peptides by molecules encoded by the major histocompatibility complex protein human lymphocyte antigen (HLA)-A2. In vitro transcribed

Efficacy of IL‐2‐ versus IL‐15‐stimulated CD8 T cells in adoptive immunotherapy

“…In addition, the results of the present study might be helpful for the current efforts that utilize genetically engineered T cells [31][32][33] for adoptive immunotherapy.…”

Absence of retroviral vector-mediated transformation of gene-modified T cells after long-term engraftment in mice

“…Therefore, each 20 g mouse received approximately 2 Â 10 6 transduced T cells (1 Â 10 8 cells kg À1 ), which is comparable to the dose per kg of gene-modified T cells given to patients. 10,40,41 However, the absolute number of genemodified T cells was considerably less than that used in the clinic. Thus, although there is evidence that there can be close agreement between the transforming potential of retroviral vectors in mouse and human stem cells despite the delivery of much reduced absolute numbers of transduced stem cells in mice, 22,28 it should be noted that this may not be the case when considering T cells.…”

“…7 In addition, retrovirus has been used widely to transduce tumor cells and immune cells for cancer therapy. [8][9][10] Retroviral vectors have also been used successfully in human trials to correct gene deficiencies in diseases including ADA-SCID, [11][12][13][14] X-linked SCID 15,16 and chronic granulomatous disease. 17 Retroviruses insert their genes in a semirandom manner into host chromosomes, 18 and it is thought that retroviruses may integrate preferentially into transcriptionally active sites.…”

Mechanisms controlling titer and expression of bidirectional lentiviral and gammaretroviral vectors

“…[1][2][3][4] A number of applications, such as the cure of polygenetic diseases as well as adoptive T-cell transfer and generation of induced pluripotent stem cells require more complex vector architectures capable of coexpressing two or more transgenes from the same vector backbone. 5,6 The most commonly used coexpression strategies are based on 2A cleavage or internal ribosome entry sites (IRES). In both cases, a bicistronic RNA has to be generated from a single promoter and coexpression depends on the function of the interspersed element.…”