The incidence of
choriocarcinoma has decreased over time and therapeutic results have improved about 90% complete remission in patients without extensive
metastasis. However, some
choriocarcinomas metastasize to other organs and show resistance to
chemotherapy, having a poor prognosis despite multidisciplinary treatment. Better methods of early diagnosis for recurrence or
micrometastasis, and treatment against cases with intractable
gestational trophoblastic neoplasia (GTN) are needed to improve the prognosis.
Human chorionic gonadotropin (hCG) is a
glycoprotein hormone composed of two dissimilar subunits and a
tumor marker to make a diagnosis and monitor
therapeutic effect in GTN. Even when hCG levels in the serum become too low to measure with the
hCG beta-
CTP system which is the most sensitive assay, there are estimated to be approximately 10,000 trophoblastic cells in the body. Residual trophoblast cells may cause symptoms such as
bleeding or undergo malignant transformation to
choriocarcinoma. Since most
monoclonal antibodies developed so far are murine, administration creates human anti-mouse
antibodies, resulting in clinical failure. More recent mouse/human chimeric
antibodies or
humanized antibodies still possess substantial immunogenicity that makes repeated administration difficult. In the present study, KM mice that can produce completely human
monoclonal antibodies were used to prepare hCG-specific human
monoclonal antibody. This yielded 8-1A, a human
monoclonal antibody capable of reacting with intact hCG. In the future, new diagnostic techniques and treatments for chorionic diseases may be developed using this kind of human
monoclonal antibody.