The discovery of Tamoxifen

Tamoxifen is a medication used in the treatment of breast cancer and has one of the greatest serendipitous drug discovery stories. It was an accidental discovery that has gone on to save the lives of half a million people, and improved the prognosis of millions of others.

Figure 1: Structure of Tamoxifen

A small group of research scientists found that the drug candidate they were working on was completely ineffective for the originally intended biological target. Dr Dora Richardson was the chemist on the project, and an early-career pharmacologist Dr V Craig Jordan conducted structure-activity relationship studies that showed the drug could potentially be effective against breast cancer.

Jordan's eventual animal studies proved that Tamoxifen not only had an anti-tumor effect in breast cancer but could be prescribed indefinitely to prevent breast cancer in high-risk patients.

Tamoxifen is now the oldest and most-prescribed hormone therapy medication for hormone-receptor-positive, early, locally advanced and widespread metastatic breast cancer.

Figure 2: Tamoxifen is sold under the brand name Nolvadex, amongst others

Discovered in 1966 - but its full therapeutic potential not realized until the late 1970s - it has been prescribed for more than 40 years in the prevention and treatment of breast cancer. Structure-activity studies based on Tamoxifen's structure and pharmacological properties has also produced Tamoxifen derivatives that provide effective alternatives in the treatment of hormone-responsive cancers.

Although a structured and rational approach to drug design is vital, the role of human scientists and their curiosity underpins pharmaceutical innovation and the discovery of some of the world's best-selling medicines.