The spectrum of immunohistochemical reactivity of monoclonal antibody DS6 in nongynecologic neoplasms

DS6 is a murine monoclonal antibody that was developed using ovarian serous adenocarcinoma as immunogen. DS6 reacts immunohistochemically with a tumor-associated antigen, CA6, which has only a limited range of expression in normal human tissues. CA6 is most characteristically expressed in type II pneumocytes, fallopian tube epithelium, and urothelium, but lacks expression in mesothelium. The authors recently reported the spectrum of reactivity of DS6 with a wide variety of neoplasms of the gynecologic tract and found DS6 to be highly characteristic of serous neoplasms. CA6 is also expressed in other müllerian-derived epithelial neoplasms of the gynecologic tissues, but is not typically expressed by ovarian intestinal-type mucinous neoplasms, mesothelioma, mesenchymal neoplasms, ovarian germ cell tumors, or sex cord-stromal neoplasms. In this study, the authors tested the monoclonal antibody DS6 with 1,202 nongynecologic neoplasms to characterize the full range of expression of antigen CA6. This study has shown that CA6 is highly expressed by many carcinomas of breast, pancreas, and urothelium, and also shows expression in some carcinomas of renal and pulmonary origin, and some neoplasms of other sites. DS6 immunoreactivity is not seen in the majority of neoplasms with hematopoietic, mesenchymal, or germ cell differentiation.