1962

British chemists patent tamoxifen, originally invented as a birth control pill, but found to have the opposite effect of shutting off estrogen in many tissues (i.e., an estrogen antagonist); in 1973, it was found to destroy breast cancer cells in those patients whose cancer cells expressed the estrogen receptor (ER-positive cancer cells): These patients’ cancer cells were dependent on estrogen for survival, unlike those with ER-negative cancer cells (Mukherjee, 215-217). “For the first time in the history of cancer, a drug, its target, and a cancer cell had been conjoined by a core molecular logic” (217).