MUC16 and cancer: Since these antibodies bind tothe extracellular portion of MUC16 (i.e. CA125), the potential reasons for the failureof these antibodies are (i) binding of these antibodies to the circulating (shed) CA125,therefore, reducing the amount of antibodies available to target and kill the cancercells, (ii) the kinetics and dynamics of MUC16 cleavage/shedding from the tumor cells isnot well understood, therefore, the likelihood of shedding of cell-surface MUC16 wouldstill reduce the availability of these therapeutic antibodies to the cancer cells21.