The beginnings of the modern era of cancer chemotherapy can be traced directly to the German introduction of chemical warfare during World War I. Among the chemical agents used, mustard gas was particularly devastating.  Although banned by the Geneva Protocol in 1925, the advent of World War II caused concerns over the possible re-introduction of chemical warfare. Such concerns led to the discovery of nitrogen mustard, a chemical warfare agent, as an effective treatment for some types of cancer. Two pharmacologists from the Yale School of Medicine, Louis S. Goodman and Alfred Gilman, were recruited by the US Department of Defense to investigate potential therapeutic applications of chemical warfare agents. Goodman and Gilman observed that mustard gas was too volatile an agent to be suitable for laboratory experiments. They exchanged a nitrogen molecule for sulfur and had a more stable compound in nitrogen mustard. A year into the start of their research, a German air raid in Bari, Italy led to the exposure of more than 1000 people to the SS John Harvey's secret cargo composed of mustard gas bombs. Dr. Stewart Francis Alexander, a lieutenant colonel who was an expert in chemical warfare, was subsequently deployed to investigate the aftermath.  Autopsies of the victims suggested that profound lymphoid and myeloid suppression had occurred after exposure. In his report, Dr. Alexander theorized that since mustard gas all but ceased the division of certain types of somatic cells whose nature was to divide fast, it could also potentially be put to use in helping to suppress the division of certain types of cancerous cells.
Using that information, Goodman and Gilman reasoned that this agent could be used to treat lymphoma, a tumor of lymphoid cells. They first set up an animal model by establishing lymphomas in mice and demonstrated they could treat them with mustard agents. Next, in collaboration with a thoracic surgeon, Gustaf Lindskog, they injected a related agent, mustine (the prototype nitrogen mustard anticancer chemotherapeutic), into a patient with non-Hodgkins lymphoma. The patient, a Polish immigrant to Connecticut known in literature only as JD, received his first injections on August 27, 1942 at 10 a.m. The doctors observed a dramatic reduction in the patients tumor masses. Although the effect lasted only a few weeks, and the patient had to return for another set of treatment, that was the first step to the realization that cancer could be treated by pharmacological agents. The patient ultimately died of cancer on December 1, 1942, 96 days after his first dose. Publication of the first clinical trials was reported in 1946 in The New York Times.