Phenotypic and functional attributes of lentivirus-modified CD19-specific human CD8+ central memory T cells manufactured at clinical scale.

A key determinant of the therapeutic potency of adoptive T-cell transfer is the extent to which infused cells can persist and expand in vivo. Ex vivo propagated virus-specific and chimeric antigen receptor (CAR)-redirected antitumor CD8 effector T cells derived from CD45RA(-) CD62L(+) central memory (TCM) precursors engraft long-term and reconstitute functional memory after adoptive transfer. Here, we describe a clinical scale, closed system, immunomagnetic selection method to isolate CD8(+) T(CM) from peripheral blood mononuclear cells (PBMC). This method uses the CliniMACS device to first deplete CD14(+), CD45RA(+), and CD4(+) cells from PBMC, and then to positively select CD62L(+) cells. The average purity and yield of CD8(+) CD45RA(-) CD62L TCM obtained in full-scale qualification runs were 70% and 0.4% (of input PBMC), respectively. These CD8(+) T(CM) are responsive to anti-CD3/CD28 bead stimulation, and can be efficiently transduced with CAR encoding lentiviral vectors, and undergo sustained expansion in interleukin (IL)-2/IL-15 over 3-6 weeks. The resulting CD8(+) T(CM)-derived effectors are polyclonal, retain expression of CD62L and CD28, exhibit CAR-redirected antitumor effector function, and are capable of huIL-15-dependent in vivo homeostatic engraftment after transfer to immunodeficient NOD/Scid IL-2RgCnull mice. Adoptive therapy using purified T(CM) cells is now the subject of a Food and Drug Administration-authorized clinical trial for the treatment of CD19(+) B-cell malignancies, and 3 clinical cell products expressing a CD19-specific CAR for IND #14645 have already been successfully generated from lymphoma patients using this manufacturing platform.

Adoptive transfer of chimeric antigen receptor re-directed cytolytic T lymphocyte clones in patients with neuroblastoma.

Metastatic neuroblastoma is a poor-prognosis malignancy arising during childhood that overexpresses the L1-cell adhesion molecule (CD171). We have previously described a tumor L1-cell adhesion molecule-specific, single chain antibody-derived, chimeric antigen receptor designated CE7R for re-directing the antigen-specific effector functioning of cytolytic T lymphocytes. Here, we report on the feasibility of isolating, and the safety of infusing, autologous CD8(+) cytolytic T lymphocyte clones co-expressing CE7R and the selection-suicide expression enzyme HyTK in children with recurrent/refractory neuroblastoma. The cytolytic T lymphocyte products were derived from peripheral blood mononuclear cells that were subjected to polyclonal activation, plasmid vector electrotransfer, limiting dilution hygromycin selection, and expansion to numbers sufficient for adoptive transfer. In total, 12 infusions (nine at 10(8) cells/m(2), three at 10(9) cells/m(2)) were administered to six patients. No overt toxicities to tissues known to express L1-cell adhesion molecule (e.g., central nervous system, adrenal medulla, and sympathetic ganglia) were observed. The persistence of cytolytic T lymphocyte clones in the circulation, measured by vector-specific quantitative polymerase chain reaction, was short (1-7 days) in patients with bulky disease, but significantly longer (42 days) in a patient with a limited disease burden. This first-in-humans pilot study sets the stage for clinical trials employing adoptive transfer in the context of minimal residual disease.