The Adoptive Immunotherapy for Solid Tumors Using Modified Autologous CIK Cells

Cytokine-induced killer (CIK) cells exhibit high proliferation rate and cytotoxic activity in vitro. The major effector cells are the CD3+CD56+ subset. The cytolytic activity of CIK cells being independent of MHC restriction implies feasibility in using CIK cells allogeneic to the tumors. Experiments to block the MHC class-I and -II pathways on tumors-RNA transfected DCs showed that only MHC class-I blocking led to a significant reduction of heterogeneous CIK cells cytotoxicity after the co-culture. The safety of CIK cells was demonstrated by the lack of cytotoxicity toward autologous as well as allogeneic normal cells. Co-culture of CIK cells with dendritic cells (DCs) has been reported by us and others in a myriad of cancer (e.g., cholangiocarcinoma, osteosarcoma, glioblastoma multiforme, multiple myeloma, hepatocellular carcinoma, pancreatic carcinoma, renal \& colon carcinoma, murine leukemia \& lymphoma showing enhancement of anti-tumor cytotoxicity of CIK cell in all. The co-culture of CIK cells with DCs were reported to decrease the number of professional regulatory/ suppressor T cells (Treg, CD4+CD25+ cells) and decrease the secretion of IL-10, an immune suppressor cytokine, whereas the cytotoxic activity against target cells increased.

We have recently brought CIK cells through the preclinical phase (animal study) of human cholangiocarcinoma treatment. Cholangiocarcinoma (CCA), is a bile duct epithelial cancer endemic in the Northeast of Thailand, with an increasing incidence discernible in Europe and North America. Conventional treatments including surgery, chemotherapy, and radiation do not bring satisfactory survival due to anatomic location, presence of metastases, and high recurrent rates. These unsatisfactory outcomes urge to search innovative treatments such as immunotherapy. We reported the safety and efficacy of CIK cells in SCID mice model for cholangiocarcinoma. Several conditions of human CIK cells were examined using ex vivo cytotoxic assay and SCID mice pre-inoculated with human cholangiocarcinoma cells. We monitored the ex vivo cytotoxicity, tumor sizes and immunohistochemistry. Optimal tumor suppression was observed when CIK cells were pre-exposed to dendritic cells (DCs). Tumor-infiltrating human CD3+ cells were observed from day 2 - 14, but not in normal tissues elsewhere. These altogether indicated the specific homing of CIK cells to tumor mass. All animals did not exhibit any noticeable adverse reaction from the CIK treatments. The CD3+CD56+ cells are logical candidates for clinical trial while the DC-co-cultured CIK cells produced similar efficacy and more feasible for clinical application.

With a complete array of in vitro and in vivo study, the next rational step is moving forward to phase I/II clinical trials for a number of specified solid tumors (i.e., cholangiocarcinoma, osteosarcoma, and glioblastoma multiforme, nueroblastoma) using the optimized autologous CIK cells. Subjects without prior exposure to or weaned for at least 3 months from chemotherapy can be recruited to maintain the integrity of their immunological system, a critical factor for a successful immunotherapy.