Taxol, a powerful anti-cancer drug synthesized from the bark of the Pacific yew tree (Taxus brevifolia, Taxaceae), initially discovered by Monroe Wall, PhD, and Mansukh C. Wani, PhD, of the Research Triangle Institute in North Carolina,1 came to being in part due to Dr. Perdue’s insistence on cultivating the tree to ensure adequate supplies for testing. He did this despite resistance from the National Cancer Institute (NCI) for several years.
Dr. Perdue was born in Norfolk, Virginia, in 1924. He spent much of his youth, however, near his father’s side of the family in rural Pittsville, Maryland. Dr. Perdue’s father was a purser for 40 years on the Pennsylvania Railroad-operated ship that carried passengers and freight from Cape Charles to Norfolk, Virginia. His mother, Laura Taylor Perdue, was a milliner who was offered work in New York City before she met her husband.
Growing up, Dr. Perdue’s parents instilled in him the importance of reading. He became an avid non-fiction reader with a special interest in history. As a teenager, he helped tend the 5,000 chickens his family raised on the side, and later developed an interest in horticulture while working in a local plant nursery. Whether raising plants and animals or planning collecting trips for the Agricultural Research Service (ARS) of the US Department of Agriculture (USDA) later in life, Dr. Perdue was known for being exceptionally meticulous and thorough.
“One of the striking things about him was his super organization,” said Joseph Kirkbride, PhD, a former ARS colleague who was hired by Dr. Perdue in 1984 (oral communication, August 9, 2011). “Everything had its place, everything was in its place, and everything was properly labeled.”
Pharmacognosist Georgia Perdue, PhD, described her husband of 35 years as a kind and gentle man who didn’t let an opportunity or moment pass him by (oral communication, August 16, 2011). “He knew his work, and he was thoroughly honest,” she said. “He didn’t cut corners; he was too brilliant for that.”
As a young man in the early 1940s, Dr. Perdue was thrust into the harsh realities of a world at war. In 1944, after completing paratrooper jump school and officer candidate school, he was assigned to the US Army’s 506th Parachute Infantry Regiment, 101st Airborne Division, as 1st Lieutenant. Dr. Perdue, according to his wife, was never one to boast of his distinguished military service, despite having received 2 Purple Hearts and a Bronze Star.
“As he put it to me so many times, ‘I came home, put it out of my mind, put it behind me, and went on with life,’” said Georgia. It was only later that he became interested in exploring his military past when he and his wife traveled to Germany and Holland to retrace his steps during the war. He documented part of his experience in “Battle at Veghel Revisited,” a well-received article published in the British magazine After the Battle.
Fueled by his love of history, Dr. Perdue went on to publish Behind the Lines in Greece: The Story of OSS Operational Group II. The book recounts the story of 22 Greek-American soldiers on a successful mission during which they sabotaged an advancing German force by destroying railroad lines, trains, and bridges. While in Greece in 2005, their nephew Stavros Papageorgiou chauffeured the Perdues over 1,100 kilometers, tracing the paths that were forged on foot decades earlier by these soldiers. “We saw firsthand how very difficult and dangerous the mission was,” said Georgia.
In 1945, Dr. Perdue came home from the war, which made him one of the lucky ones. He didn’t, however, come home unscathed. He received a bullet wound to the knee during Operation Market Garden in Holland, and later—in Sturzelberg, Germany—he stepped on a landmine that permanently lodged shrapnel in his body. After recovering, Dr. Perdue was discharged, and he returned to study botany at the University of Maryland, where he received a bachelor’s degree in 1949. He then attended Harvard University, where he received his master’s degree in biology in 1951 and his doctorate in plant taxonomy in 1957.
Dr. Perdue’s scientific career began in 1951, when he joined the US Geological Survey in Washington, DC, as a botanist. There, he was responsible for mapping vegetation in China, India, and Thailand, among other countries. After a 3-year stint as an associate botanist at the Texas Research Foundation, Dr. Perdue accepted a job in 1957 at ARS in Beltsville, Maryland, where he spent the majority of his professional life.
Dr. Perdue held various titles during his 32 years with ARS. Initially, he was tasked to study various fibrous plants with the hope of finding a new source of paper pulp. He switched focuses in the early 1960s when he became the Chief of USDA’s Medicinal Plant Resources Laboratory. During this time, Dr. Perdue published what was to become one of the most important papers of his career. Georgia described her husband’s paper on giant reed (Arundo donax, Poaceae), the plant source of musical reeds, as “highly acclaimed in the ‘music world.’”
When President Richard Nixon declared war on cancer with the National Cancer Act of 1971, ARS coordinated with NCI in an effort to find plants in the United States and abroad with cancer-fighting properties. The goal of the interagency program was simple, but the logistics of the plant collecting trips could be overwhelmingly complicated. Dr. Kirkbride explained Dr. Perdue’s dedication to the program: “I think he most liked the hands-on field work, combined with his organizational skills and office skills [needed] to carry [it] out,” he said. “That’s what really appealed to him.”
Of all his professional accomplishments, Dr. Perdue was especially proud of his contribution to the development of new cancer-fighting drugs, said Dr. Kirkbride. “I think he would like to be remembered for having been involved in the cancer research program and having been involved in the discovery of Taxol,” he said.
“There were several plants that were his babies, so to speak,” said Georgia. In addition to the Pacific yew, Dr. Perdue felt a special connection with the Chinese happy tree (Camptotheca acuminata, Nyssaceae) and Maytenus buchananii (Celastraceae).2
In 1963, a chemical compound in the fruit, stems, and leaves of the Chinese happy tree was found to have strong anti-tumor capabilities. With the supply of happy trees in the United States dwindling, Dr. Perdue insisted that NCI plant seedlings to secure future materials. The NCI, however, ignored his request. The tree was eventually cultivated in California, due in part to Dr. Perdue’s tenacity. C. acuminata is the source of 2 cancer drugs today—Topotecan® and Irinotecan®.
The fate of M. buchananii was also decided, in part, by Dr. Perdue. “Without Perdue’s imagination, initiative, and positive approach to a formidable task, it is doubtful maytansine would have been available in sufficient amounts for clinical trial,” wrote the late biologist Jonathan Hartwell of the cancer-fighting chemical compound derived from M. buchananii (G. Perdue, e-mail, August 25, 2011). (Hartwell is the author of the pioneering series of articles eventually published as a book called Plants Used Against Cancer [1982] in which he compiled a massive list of plants around the world that, based on ethnobotanical information, were believed to have some type of anti-tumor effect. This compilation formed the basis of NCI’s search for plants with potential cancer-fighting compounds.)
Georgia, who would occasionally travel with her husband, recalled one collecting trip in Kenya in which Dr. Perdue lined up what she referred to as “probably the only wood chipper in the country” for their collecting purposes. “I was with Bob when he collected 35-40,000 pounds of Maytenus,” Georgia said of the plant, which was approved for sampling and designated a “protected species” by the Kenya Forest Service. “It was the most organized and coordinated effort I have ever seen. But that was Bob!”
In an effort to give back to Kenya, Dr. Perdue coordinated with the pharmaceutical company Eli Lilly to donate 2 well-known anti-cancer drugs, vincristine and vinblastine, to a major hospital in Nairobi. With conservation in mind, he was also responsible for planting 35,000 M. buchananii cuttings near Mombasa, Kenya. “He felt like he had to do something for Kenya,” said Georgia. “[It] shows the generous spirit, the kindness for which Perdue was known worldwide.’
Today, derivatives of maytansine are still being transformed into cancer-fighting drugs. “Conjugates have been made with a variety of antibodies targeting colon, breast, lung, pancreatic, and other solid tumors,” said Gordon Cragg, PhD, who retired from NCI in 1996. (G. Perdue, e-mail communication, August 24, 2011). “Fourteen are in preclinical or clinical development,” he added.
Despite the limited success of the cancer screening program, Georgia hopes that her husband’s countless plant collecting trips, including earlier collections in the United States, will eventually lead to other useful cancer drugs.
“Bob was extremely involved in obtaining the botanicals for cancer drugs in the US,” said Freddie Ann Hoffman, MD, president of the natural products consulting firm Heterogeneity, LLC, where Dr. Perdue worked during the final years of his life (oral communication, August 8, 2011). “It was all I could do to keep Bob from hopping on the plane and going to the far end of the world to take a look at these plants even though he was in his 80s. He worked up until the day he died.”
Dr. Perdue retired from ARS in 1989 to form his own company, Ver-Tech International, Inc., based in North Bethesda. At Ver-Tech, he established Vernonia galamensis (Asteraceae), an oilseed plant he serendipitously came across in Ethiopia, as an industrial crop in Central America. Today, more than 125 laboratories in the United States and abroad have found a variety of uses for this oil, including as paint dilutant that does not produce volatile organic compounds, which mix with nitrogen in the atmosphere to produce the greenhouse gas ozone.3
“He was a goal setter, a detailed manager, who vigorously attached and accomplished such goals,” said retired economic botanist, noted author, and ABC Board of Trustee (emeritus) Jim Duke, PhD, who temporarily replaced Dr. Perdue as the head of the cancer screening program at ARS (J. Duke, e-mail communication, August 10, 2011). “Bob efficiently led the huge Cancer Screening Program of the New Crops Programs for years.”
Although Dr. Hoffman worked with Dr. Perdue for a only few years, she understood the importance of his past work. “The impact of his career touched many around the world in places you can’t even imagine,” she said.
Dr. Perdue is survived by his wife Georgia; his children Robert E. Perdue III, Susan Sherwin, and Holly Boyle; stepsons R. Craig, John, Mark, and Nels Bergstrom; a nephew and 2 great nieces; 10 grandchildren; and 9 great grandchildren.
—Tyler Smith
References
1. Noted cancer researcher Mansukh Wani closes the books on 44-Year career. RTI International website. www.rti.org/news.cfm?nav=6&objectid=026FAA96-2D85-4212-912BE7E3887433E7. Accessed September 1, 2011.
2. Species: Camptotheca acuminata (Happy tree). Uniprod Taxonomy website. www.uniprot.org/taxonomy/16922. Accessed August 29, 2011.
3. Persinos G. Vernonia Galamensis: herbal cure for the greenhouse dffect? HerbalGram. 1994; 24:14-15.