Waksman isolated the first antibiotic shown to fight cancer

Person: Selman Waksman
Lived: 1888–1973
Field: Microbiology
From: Russian-American

The story

By the late 1930s Selman Waksman had spent two decades at Rutgers studying the microbes that live in soil and how they compete with one another. He was especially interested in the actinomycetes, a group of soil bacteria that includes the genus Streptomyces, and he suspected that some of the chemicals they produce to fight rival microbes might be turned into medicines.

In 1940 Waksman and his doctoral student H. Boyd Woodruff published a study of bacteria-killing substances produced by soil actinomycetes. Among them was actinomycin, isolated from fermentation products of Streptomyces. It was the first antibiotic Waksman's group discovered. Woodruff's doctoral work also produced streptothricin, and his methods helped guide the later search that led to streptomycin. Woodruff went on to a long career at Merck, developing industrial fermentation methods for vitamin B12 and other medicines.

At first actinomycin seemed too toxic to treat infections in people. But researchers later found that the compound had a remarkable property beyond killing bacteria. Actinomycin D was the first antibiotic shown to have anti-cancer activity, because it binds to DNA and stops cells from copying their genetic instructions into RNA, which halts the growth of rapidly dividing cancer cells.

Under the name dactinomycin, it was approved by the US Food and Drug Administration on December 10, 1964, and launched by Merck Sharp and Dohme under the trade name Cosmegen. It is still used as a chemotherapy medication for several cancers, including Wilms tumour, a kidney cancer of young children, as well as rhabdomyosarcoma, Ewing's sarcoma, gestational trophoblastic disease and certain testicular and ovarian cancers. It is often combined with other drugs, and it is also used to make tumours more sensitive to radiation therapy.

Dactinomycin is on the World Health Organization's List of Essential Medicines. Because it binds so readily to DNA, actinomycin D and a fluorescent relative have also become laboratory tools, used as stains to mark DNA in microscopy and to tell living cells from dead ones.

Why it matters

A drug that began in Waksman's soil studies has helped treat children and adults with cancer for six decades and is on the WHO's list of essential medicines.