In early 1947, Farber saw a 4-year-old girl with a rapidly progressing leukemia. As part of the study in Science, she received folic acid conjugates in hopes of inhibiting progression. After less than a month, Farber noted that “the patient appeared to be moribund.” Taking a risk, Farber requested a novel folic acid antagonist (aminopterin) from Lederle Laboratories, and began dosing the girl immediately.
Sadly, she died within a week, but postmortem biopsy showed a remarkable remission in the hematological profile of her bone marrow. Farber used her case to justify investigating folic acid antagonists in other patients, writing in the New England Journal of Medicine, “A change of this magnitude in such a short time has not been encountered in the marrow of leukemic children in our experience.” A clinical study followed where 16 children with acute leukemia received aminopterin; 10 went into temporary remission.