GM-CSF safety and effects in the management of advanced/refractory multiple myeloma patients: a phase I trial

Chimeric NKG2D receptor-expressing T cells as an immunotherapy for multiple myeloma

OBJECTIVE

Most myeloma tumor cells from patients express NKG2D ligands. We have reported the development of a chimeric NKG2D receptor (chNKG2D), which consists of the NKG2D receptor fused to the CD3zeta chain. T cells expressing this receptor kill and produce cytokines in response to NKG2D-ligand+ tumor cells. Therefore, we investigated whether human chNKG2D T cells respond against human myeloma cells.

MATERIALS AND METHODS

ChNKG2D T cells were generated from healthy donors and myeloma patients. The effector phase of chNKG2D T cells was analyzed by cell-surface marker expression and human myeloma cell lines were tested for expression of NKG2D ligands. Lysis of myeloma cell lines and cytokine secretion by chNKG2D T cells was determined. ChNKG2D T cells grown in serum-free media, or cyropreserved, were assessed for effector cell functions.

RESULTS

Myeloma cell lines expressed NKG2D ligands. ChNKG2D T cells from healthy donors and myeloma patients lysed myeloma cells, and secreted proinflammatory cytokines when cultured with myeloma cells or patient bone marrow, but not with peripheral blood mononuclear cells or normal bone marrow. Lysis of myeloma cells was dependent on chNKG2D T-cell expression of NKG2D and perforin. Additionally, chNKG2D T cells upregulated CD45RO, did not express CD57, and maintained expression of CD27, CD62L, and CCR7, indicating that the T cells were at an early effector stage. Finally, we showed that chNKG2D T cells generated with serum-free media, or when cryopreserved, maintained effector functions.

CONCLUSION

ChNKG2D T cells respond to human myeloma cells and can be generated using clinically applicable cell culture techniques.

Successful cancer vaccine therapy for carcinoembryonic antigen (CEA)-expressing colon cancer using genetically modified dendritic cells that express CEA and T helper-type 1 cytokines in CEA transgenic mice

This study was designed to determine whether the vaccination of genetically modified dendritic cells (DCs) simultaneously expressing carcinoembryonic antigen (CEA), granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 12 (IL-12) can overcome the peripheral T-cell tolerance to CEA and thereby elicit a therapeutic response in CEA transgenic mice. CEA transgenic mice were immunized once by subcutaneous injection with DCs adenovirally transduced with CEA and T helper-type 1 cytokine genes. The cytotoxic activity of spleen cells against CEA-expressing tumors, MC38-CEA, in the mice immunized with DCs expressing CEA (DC-AxCACEA) was higher than that in those immunized with DCs-AxCALacZ (p < 0.0001), and was augmented by the cotransduction with the GM-CSF/IL-12 gene (p < 0.05). The vaccination with DC-AxCACEA/GM-CSF/IL-12 could elicit a more potent therapeutic immunity than the vaccination with DC-AxCACEA in subcutaneous tumor models (p < 0.0001), and 4 of 5 mice showed a complete eradication of the subcutaneous tumors in these vaccination groups. Even in a large tumor model, this vaccination therapy completely eliminated the subcutaneous tumors in all mice. This antitumor activity mostly vanished with the depletion of CD8(+) T cells and NK cells in vivo and was completely abrogated with the depletion of CD4(+) T cells. A histopathological examination showed no evidence of an autoimmune reaction. No other adverse effects were observed. This vaccination strategy resulted in the generation of highly efficient therapeutic immune responses against MC38-CEA in the absence of autoimmune responses and demonstrated no adverse effects, and may therefore be useful for future clinical applications as a cancer vaccine therapy.

Nontraditional cytotoxic therapies for relapsed/refractory multiple myeloma

Multiple myeloma remains an incurable disease, with median survival rates of 4-6 years even with aggressive, high-dose chemotherapy, bone marrow transplantation, and intensive supportive care. Additionally, multiple myeloma is primarily a disease of the elderly, many of whom cannot tolerate aggressive chemotherapy. Thus, newer treatments with good safety profiles are needed to improve the quality of responses and, hopefully, to translate into prolonged progression and overall survival. The pathophysiology of multiple myeloma is complex, involving many pathways and interactions among cytokines, adhesion molecules, angiogenesis, and mechanisms of resistance, which, taken together, provide multiple targets for novel therapeutic modalities. Agents currently under investigation for treating multiple myeloma include thalidomide and its successors, PS-341, and arsenic trioxide. Thalidomide and immunomodulatory drugs both exhibit activity against multiple myeloma by affecting different levels of the immune system. PS-341 is a proteasome inhibitor that halts the cell cycle, resulting in apoptosis; it also inhibits a key transcription factor and may have antiangiogenic activity. Arsenic trioxide activates multicellular mechanisms to induce apoptosis, inhibit angiogenesis, and stimulate immune responses. Preclinical and early clinical data suggest that combination regimens should be pursued, given the different mechanisms of action of these compounds on the immune system and their non-overlapping toxicities at low dosages.