Highly efficient procedure for production of human monoclonal antibodies: establishment of hybrids between Epstein-Barr virus-transformed B lymphocytes and heteromyeloma cells by use of GIT culture medium

Strategies of targeting the extracellular domain of RON tyrosine kinase receptor for cancer therapy and drug delivery. J Cancer Res Clin Oncol. 2016;142:2429-2446. [PMID: 27503093 DOI: 10.1007/s00432-016-2214-4]

PURPOSE

Cancer is one of the most important life-threatening diseases in the world. The current efforts to combat cancer are being focused on molecular-targeted therapies. The main purpose of such approaches is based on targeting cancer cell-specific molecules to minimize toxicity for the normal cells. RON (Recepteur d'Origine Nantais) tyrosine kinase receptor is one of the promising targets in cancer-targeted therapy and drug delivery.

METHODS

In this review, we will summarize the available agents against extracellular domain of RON with potential antitumor activities.

RESULTS

The presented antibodies and antibody drug conjugates against RON in this review showed wide spectrum of in vitro and in vivo antitumor activities promising the hope for them entering the clinical trials.

CONCLUSION

Due to critical role of extracellular domain of RON in receptor activation, the development of therapeutic agents against this region could lead to fruitful outcome in cancer therapy.

Nucleotide sequence analysis of a human monoclonal antibody TONO-1 with cytotoxic potential for T-leukemia/lymphoma cells

A human monoclonal antibody (HuMab) TONO-1 (IgM, lambda) recognizes cell surface antigens associated primarily with human T-leukemia/lymphoma cells. In this study, we investigated the reactivity against T-leukemia/lymphoma cells in detail, cytotoxic potential and primary nucleotide and deduced amino acid sequences of the rearranged heavy and light chains of the HuMab TONO-1. Expression of the molecules (TONO-1 Ags) detected by a HuMab TONO-1 was significantly heterogeneous even in the same T-leukemia/lymphoma cell lines HPB-MLT and MOLT-4F. The flow cytometric curves showed an unusual broad-based spread of fluorescence intensity. HuMab TONO-1 was shown to have the ability to kill the T-leukernia/lymphoma cells efficiently in the presence of rabbit complements. However, HuMab TONO-1 did not demonstrate significant antibody-dependent cellular cytotoxic activity. Furthermore, HuMab TONO-1 heavy and light chain variable regions were cloned, sequenced and analyzed. HuMab TONO-1 uses a V(H) gene member of the V(H)IV gene family V(H)71-4, and is productively rearranged with the germ line D(H) gene D(XP')1, and the germ line J(H)5 gene with multiple somatic mutations. HuMab TONO-1 Vlambda belongs to the lambda light chain variable subgroup I family and is derived from the Vlambdalc germ line gene Humlv1042, and germ line gene Jlambda1 without somatic mutations. The results reveal that the production of HuMab TONO-1, with cytotoxic potential for human T-leukemia/lymphoma cells, is achieved by rearrangement of the V(H)71-4/Humlv1042 germ line variable region gene combination, that is associated with the autoimmune repertoire.

A new and efficient method to generate human IgG monoclonal antibodies reactive to cancer cells using SCID-hu mice

Human monoclonal antibodies (mAbs) are very useful for treatment of cancer, but they are difficult to obtain since immunization of humans is not a practical proposition at present. As an approach to circumvent this problem, we have simultaneously inoculated cancer tissues and regional lymph node cells obtained from lung cancer patients into SCID mice to allow in vivo stimulation of human lymphocytes against autologous cancer tissues. Human immunoglobulins, especially IgG, were observed in the SCID-hu sera, and some showed high reactivity to lung cancer cell lines. Testing of human B-lymphoblastoid cell lines obtained from SCID-hu spleen and thymus for antibody activity revealed 16-45% of them to be reactive to lung cancer cells. These percentages are high as compared with previous reports. Furthermore, we could establish 4 human IgG mAbs reactive to lung cancer cell lines. These results indicate successful stimulation of specific human lymphocytes in vivo, which thereby enables efficient generation of human monoclonal antibodies using SCID-hu mice.

Construction of a human B cell line, TKHMY, suitable for production of stable human hybridomas

In order to produce stable hybridomas for generation of human monoclonal antibodies (HMAbs), an attempt was made to construct a suitable human parental B cell line with double selection markers, the strategy being to produce HMAbs by fusing a parental B cell line with EBV-transformed B cells producing specific antibodies. The resultant TKHMY cell line, constructed by transfecting the Blasticidin S resistant (bsr) gene into the HAT sensitive human B cell line LTR 228 could be used as a fusion partner for very efficient production of human hybridomas. Secretion of IgG monoclonal antibodies to antigens on lung cancer cells by one such hybridoma was very stable, indicating that this TKHMY cell line has practical advantage in the area of antibody production.

A novel human monoclonal antibody directed to a tumor-associated antigen

Twelve human monoclonal antibodies (HuMAb) were established by the fusion of (mouse x human) heteromyeloma cells with B-lymphoblastoid cells derived from the regional lymph nodes of three patients with squamous cell carcinoma of the lung. They were tested for reactivity to two kinds of proteins (purified protein derivatives and bovine serum albumin) by ELISA, Sq-19 (squamous cell carcinoma) culture cells by indirect membrane immunofluorescence tests, and Sq-19 tumor xenograft by immunohistological study. Among them, one HuMAb 904F (IgM, lambda) was selected. In indirect membrane immunofluorescence tests, this 904F antibody reacted with various kinds of cell lines, e.g. lung cancer, esophageal cancer, endometrial cancer, and stomach cancer. It did not react with malignant hematopoietic and diploid fibroblast cell lines. Immunohistologically, it stained the tumor nests of squamous cell carcinoma, adenocarcinoma, and large cell carcinoma of the lung. It also stained those of esophagus and colon, but not those of small cell carcinoma of lung, or stomach. On frozen-section specimens of normal tissues from various organs, it showed only limited areas of positive staining. Limited positive findings were observed at a reticular zone of the adrenal gland, at the esophagus as weak staining, and at islets of the pancreas as very weak staining. Western blotting analysis demonstrated that it recognized a 54 kDa trypsin-sensitive molecule which is expressed on the surface of tumor cells. These results suggest the 904F monoclonal antibody detects a novel tumor-associated antigen which is recognized by the human immune system.

A simple and improved method to generate human hybridomas

By improving our previous method for production of human hybridomas, we developed a simple and remarkably efficient method for production of human hybridomas. We reformed our previous method in the following three points: (1) we added irradiated (30 Gy) myeloma cells as feeder cells to culture of fusion cells; (2) ouabain concentration in the selective medium was reduced from 2 x 10(-6) M to 1 x 10(-6) M; (3) selective medium (GIT-HAT-OL) was added to the culture after overnight cultivation of fusion cells. Consequently, we obtained higher fusion frequency (1/700 vs. 1/5500) compared with our previous method. By our present method, only so small number of human B cells (EBV-LCL) is required, so that the time necessary to establish human hybridomas is reduced.