Special Guest Post: The Chemistry Professor & the Poisonous Tree

Today’s post is authored by my wonderful husband, Steve.  As I approach my last chemotherapy appointment this Friday (yay!), he shares the story of Taxol, the drug at work on me.

My wife sleeps in the reclining chair of the chemotherapy treatment room. A shawl knitted by her sister-in-law, herself a breast cancer survivor, is wrapped around her shoulders. A bright fuzzy blanket made by her mother lies across her lap and legs. Two plastic bags on the IV stand feed a clear liquid through the tangle of tubes to the port on her chest and then straight into her heart. The chemical in the liquid works in a unique way to halt cell division, which stops the cancer from growing. Drop by drop, minute by minute, it flows through her veins to poison the tumor that threatens her life.

I’ve spent my career as a forester, so I’m fascinated by this chemotherapy agent which was found in the bark of a tree. An unremarkable and slow-growing tree compared to its neighbors in the moist mountains of the Pacific Northwest, the Pacific yew, Taxus brevifolia, rarely reaches 50 feet tall. All parts of the tree, except for the fleshy aril surrounding its seed, are extremely poisonous.

Seven years before Sandee was born, botanist Arthur Barclay from the New Crops Research branch of the US Department of Agriculture and several graduate students were roaming the deep forests and steep slopes of the Gifford Pinchot National Forest in Washington. They collected samples of stem, fruit, and bark from a scraggly Pacific yew and sent them to labs for study. Researchers spent decades trying to identify the compound in the bark and its medicinal properties. It wasn’t until Sandee was in her mid-teens, however, that the drug derived from the yew bark, Taxol, entered clinical trials for cancer treatment. Only in 1991 was it shown to be effective against breast cancer.

But while life-saving for cancer patients, the production of Taxol could have been devastating to the yew trees.  In the early days of Taxol research, it took about 6 trees to produce the 25 pounds of bark needed to produce just one-half gram of Taxol, the amount required for a single patient. And removing the bark kills the trees. There simply were not enough of these trees to supply the needed quantities of bark; mass production of the drug could eradicate the species.

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In 1999, when I moved to Blacksburg, Virginia, I met David Kingston, a tall, lean Englishman with a penchant for bowties, born in London and educated at Cambridge University. He was an elder at the church I attended, and his earnest yet compassionate and thoughtful approach to preaching made his sermons some of the most impactful I have heard.

Dr. Kingston is also a chemistry professor at Virginia Tech. He was part of the research team that tackled the problem of synthesizing Taxol so that it could be produced sustainably. The Pacific yew has a cousin, the English or European yew (Taxus baccata), with its own long and storied history. English yew has been used to make bows for centuries, dating as far back, according to Homer, as the siege of Troy, and poet William Wordsworth spoke of a yew tree “of vast circumference and gloom profound.” The English yew is far more widespread than the Pacific yew, growing even as an ornamental shrub in the US, and its needles can be harvested without killing the tree. Dr. Kingston and his collaborators found a way to use a compound from the needles of the English yew to create the molecule needed to synthesize Taxol. It is this compound, hidden away in the bark and leaves of trees, decades in the making, that is coursing through Sandee’s veins while she sleeps.

I think of the times Sandee and I have hiked through forests, sharing our love for natural spaces. I remember the hike we took in the Cascade Mountains of Washington on a day off from her writers’ conference. We may have walked right by one of these Pacific yews. I recall the 370-year old English yew in the Oxford Botanical Garden we encountered a few years ago. I think of the millenia that people have used plant products for healing.

And I marvel at the decades of patient, persistent efforts of scientists and doctors who have overcome so many challenges to bring a compound from the bark of a poisonous tree into the very heart of my wife.  I’m honored to have known one of these scientists, but I am grateful to them all.