Antioestrogens in Treatment of Breast Cancer: Value of Nafoxidine in 52 Advanced Cases

The synthetic non-steroidal antioestrogen nafoxidine (U-11, 100A) was given by mouth to 52 women with locally advanced or metastatic breast cancer, in 85% of whom the disease had become resistant to, or relapsed after, previous endocrine treatment. The objective response rate (complete or partial regression of disease) among 48 cases treated for at least four weeks was 37%. Tumours in soft tissue seemed to respond better than skeletal metastases. The patients in all but one of the 52 cases were postmenopausal. Those who had had an objective response to previous hormone treatment had a greater chance of deriving benefit from nafoxidine than those who had been resistant to hormone treatment. Side effects of nafoxidine were dryness of skin, increased loss of scalp hair, and heightened sensitivity to sunlight. None were serious, and they could be lessened by protection from solar radiation or a decrease in dosage. No obvious depression of thyroid or adrenal function or obvious water retention or masculinization was seen. Cataract was a possible complication. This clinical trial was preceded by laboratory studies in which a transplantable oestrogen-dependent tumour in the Syrian hamster was notably inhibited by the administration of nafoxidine. This experimental model may prove useful in screening potentially useful antioestrogenic agents against breast cancer before a human trial.