Secondary drug failure occurring during chronic treatment with LHRH: appearance of an antibody

Secondary drug failure with regard to subjective and hormonal responses occurred in a patient treated chronically with LHRH. This failure of response to hormone therapy was correlated with increased binding of 125I-LHRH by the patient's sera. Also, competitive displacement of 125I-LHRH by unlabelled LHRH was demonstrated. Affinity constants and titers of order appropriate for antibody were obtained. These data support strongly a report of antibody formation to exogenous LHRH in man.