The human tumor cloning assay in cancer drug development - A review

Animal studies with transplantable tumor cell lines suggested that the sensitivities of the in vitro tumor cultures to certain anticancer drugs agreed with the drug sensitivities of the same tumors in vivo. Soft agar cloning techniques have been established for human myeloma and ovarian cancer cells. Refinement of the techniques now permits cloning of most human malignancies. Drug sensitivity studies have been conducted measuring the reduction in the number of tumor colonies formed. Clinical trials showed that approximately one half of patients whose cells demonstrate in vitro sensitivity to a drug will obtain a clinical response to the same drug. Patients whose cells appear resistant to a certain drug in vitro rarely respond to the drug clinically. In vitro drug sensitivity testing may eventually allow some individualization of chemotherapy. In addition it already appears that these techniques may be excellent for screening new drugs with specific anticancer potentials.