A measure of intrigue and discovery pertaining to head and neck cancer, spiked with compassion for patients struggling against treatment toxicities, helps quench the intellectual thirst of Yvonne Mowery, MD, PhD, Butler Harris Assistant Professor of Radiation Oncology at Duke University Medical Center, Durham, N.C.
Splitting time between the clinic and laboratory, Mowery is actively engaged in patient care as well as preclinical, translational, and clinical research. “I hope to get a better understanding of the biology of head and neck cancer and determine pathways that we can target to reduce metastatic spread of the disease and improve responsiveness to available treatments,” she told Oncology Times.
Long before reaching her current status as an award-winning investigator, Mowery grew up in Richmond, Va., in the midst of a “completely non-scientific” family. “I was an oddball,” she joked, while recalling her parents' patience with her backyard composting experiments that became so foul-smelling that the health department was contacted. As a kid, her idea of a great present was an encyclopedia of science, and the thing that caught her eye at the toy store was a junior chemistry set.
Science was clearly her path when she headed to the University of Virginia. In her sophomore year, Mowery began working in a genetics lab. That's where the lure of fruit flies took hold. “I looked at the development of their reproductive system and found that very interesting,” she recalled.
Nearing the completion of her undergraduate education, Mowery debated between attending medical school or graduate school. The eventual winner? Both. “I investigated physician-scientist training programs and arrived at Duke in 2004 to do a combined MD/PhD.” Today, Mowery spends 1 day a week in clinic where she sees patients, then moves to the lab for the remainder of the week to find strategies to improve patient care and develop therapies to deliver better outcomes for patients, both present and future.
“I treat cancers primarily of the head and neck—such as oral cavity, larynx, tonsils, base of tongue, sinuses—with radiation therapy. I think of head and neck cancers as being in a ‘very high-stakes real estate’ area,” she said, “because they are often close to saliva glands, vocal cords, etc. This requires intricate planning for radiation treatment. Visualization of the tumor through fiberoptic laryngoscopy allows me to see a tumor responding to radiation and chemotherapy during the weeks of treatment; it is gratifying to watch it happen with your own eyes.”
Mowery said toxicity associated with treatment of this area of the body can be severe, partially due to the fact that it is typically “...one of the longer courses of radiation that we do—about 7 weeks, 5 days a week,” she explained. “Patients typically require pain medicine to eat and drink a soft diet, lose their sense of taste, and experience very dry mouth, sometimes requiring a feeding tube for nutrition. In addition, the skin on their neck often falls off.” Comparing it to severe sunburn, Mowery said skin typically blisters and peels off, leaving behind a neck that is “red, angry, and very uncomfortable. It just comes with the territory.”
In addition to these side effects, Mowery said there is also an unusual biological aspect to head and neck cancers which figures largely in her work. “Something very interesting scientifically drew me to these cancers,” she informed. “There are two main causes of cancer in this area: tobacco use and human papillomavirus (HPV). Outcomes for patients with HPV-positive oropharynx cancers are excellent; even when the cancer is locally advanced about 80-90 percent of patients are cured. But the tobacco-induced cancers, by contrast, do much worse (about 60% or less survival rate for locally advanced disease). Even if the tumor size is the same and the number of involved lymph nodes are the same, the biology is completely different for the HPV-related and the HPV-unrelated disease.”
In fact, the staging system was changed at the beginning of this year so that HPV-related cancers and HPV-negative cancers are staged differently. “HPV-positive cancers that used to be staged at IVA may now be staged at I or II, but they remain at stage IVA if the cancer is HPV-negative,” Mowery detailed.
Asked why tobacco-related cancer behaves so badly, Mowery answered, “We do not have a good understanding of that; it is something I am studying. We do know, however, that HPV-negative tumors exhibit a loss of function of the p53 gene, [which] is really the king of all tumor suppressors. In HPV-related tumors, p53 is usually genetically still intact but its activity is affected by HPV.”
She also commented that people still actively smoking during treatment tend to do much worse, likely due in part to having lower oxygen levels in the tumor, which in turn causes the radiation to work less effectively. “If we can figure out ways to make HPV-negative tumors behave more like HPV-positive tumors, outcomes would improve.”
From Clinic to Research
These realities on the clinical side have informed and inspired some of Mowery's research efforts. One of her projects aims at reducing the toxicity of treatment while maintaining good outcomes in patients.
“A clinical trial that I am about to start will use PET/CT, a type of metabolic imaging, as an early litmus test to evaluate how patients are responding during treatment. If we find they are responding well, we will de-intensify and back off on the chemotherapy and radiation dose while still trying to achieve good outcomes,” Mowery explained.
She noted that because HPV-positive and HPV-negative cancers are still treated exactly the same way when not on a clinical trial, investigators also hope to find out if treatment can be de-intensified for the HPV-positive patients who tend to have more successful outcomes by virtue of their cancer type, thus allowing them to avoid some of the severe side effects.
“Of course, even in HPV-positive cancers, not every patient is cured,” cautioned Mowery, “so we want to see if we can identify, early on, who is going to do well and who, in contrast, still needs that full 7-week intensive course of radiation therapy and chemotherapy.”
Another clinical trial ongoing at Duke in which Mowery is involved is testing a drug called BMX-001 given to patients through a subcutaneous injection during radiation. “We hope the drug will reduce the mucositis—the inflammation and irritation of the lining of the mouth and throat during radiation—and dry mouth,” she said.
Mowery is also busy in lab with intensive work in developing new mouse models of both HPV-related and HPV-unrelated squamous cell carcinoma of the head and neck. “My objective is to develop a platform in which I can develop radiation with immunotherapy, as well as with chemotherapy and various novel systemic agents, to try to improve outcomes particularly for HPV-negative disease,” noted Mowery, also the winner of a 2017 Conquer Cancer Young Investigator Award. “I want to discover if there are ways that we can make our bodies and our immune system realize that these cells are not ‘self’ and activate the immune system to attack and eliminate them.”
Tobacco-related cancer is induced in mice by giving them a carcinogen present in tobacco, “... causing them to become like a tobacco chewer or smoker,” Mowery explained. “Having that exposure causes mutations in cells in the lining of their mouth.”
Mowery further said her research is taking advantage of large sequencing projects in which various head and neck tumors have been sequenced. These data are publicly available and published primarily by The Cancer Genome Atlas organization. “I have been able to see which genes are most commonly mutated and then can genetically engineer mice to have those mutations. In other words, I can specifically knock out certain genes in the head and neck to model the cancer in mice.”
This is extremely important because it allows Mowery and team to interrogate the biology of the mutations, and determine which genetic changes and pathways lead to the cancer spreading from its site of origin to the lymph nodes or the lungs. “It helps us to develop therapies to block the cancer and keep it at bay, and to determine if there are better ways to sensitize the cancer to radiation and chemotherapy,” she detailed. “And we have an opportunity to test drugs that we hope will help with side effects of radiation. We must make sure that drugs protecting normal tissue are not also protecting the tumor. Having great animal models of human cancer is really important to making progress.”
As if her work in head and neck cancer were not enough, Mowery is continuing an earlier effort begun in the lab of her research mentor David G. Kirsch, MD, PhD, by acting as radiation oncology principal investigator for a multi-site, international prospective randomized clinical trial investigating the combination of the immune checkpoint inhibitor pembrolizumab (anti-PD-1 antibody) and radiation therapy for patients with high-risk soft tissue sarcoma of the extremities. The researchers are also examining the biology behind the effects of radiation combined with pembrolizumab in a co-clinical trial using primary mouse models of sarcoma.
“We saw promising results combining them in this model. Our hope is by using this combination during the early stage of disease we may be able to eliminate those cells that have escaped the primary tumor before they cause a problem.”
Who Has Time for Hobbies?
Asked about her life outside of the clinic and lab, Mowery admitted that little time is left for hobbies. “I used to play tennis, but now I just enjoy watching it,” she said through a chuckle. “I splurged on a Labor Day vacation to the U.S. Open in New York. In my off time, I mostly read and spend time with my family. I am married; my wife is a nurse at Duke working in bone marrow transplant. We have no children.”
But the couple does have the patter of little feet in their midst. “We have two small dogs, Heidi and Cassie, a Maltese and a Maltese Shih Tzu mix—both less than 10 lbs.,” Mowery offered. “We live in downtown Durham, N.C., which is a burgeoning area. It's kind of cool, and a little bit grungy—but in a good way. I love going for walks and checking out new restaurants. And I love food,” she added brightly.
After a brief pause, Mowery turned her thoughts again to patients. “There is one other clinical trial we've recently opened in the head and neck space. We are looking at financial toxicity of patients,” she said. “We are very concerned about the bills patients incur for cancer care and how that affects their quality of life.
“Unfortunately, some people just can't afford to fill their whole prescription. Some take their drugs every other day because they are worried about cost. Some patients just do not follow through on therapy. We need to get a better sense of how much of that is going on and if there are early warning signs we can detect allowing us to intervene.”
Mowery added that better communications between health care providers and patients are needed to help patients better understand costs they face and identify resources that can help them.
“We just opened this survey-based pilot trial in June. We hope to have data next year and be able to develop a follow-up plan to employ the strategies that we find,” said Mowery. “There are a lot of ways we can try to help our patients.”
Valerie Neff Newitt is a contributing writer.
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