"Leukemias don't read textbooks," asserted Nicole Grieselhuber, MD, PhD, hematologist and researcher with The Ohio State University Comprehensive Cancer Center - Arthur G. James Cancer Hospital and Richard J. Solove Research Institute. "I am reminded of this fact every time I see a new patient. It may be said in literature that 'these two mutations do not occur together,' but then I see a patient in whom they do. It may be said that with a particular type of leukemia 'you will always see these surface markers by flow cytometry,' but sometimes I don't. Biology is a lot more complicated than anyone ever imagined."
Grieselhuber, a physician-scientist, described her research as focusing on "very basic biology-gene transcription and the regulation of gene expression chromatin." She noted that while this may sound far removed from diagnosing disease and treating patients, it is not true.
"The overarching theme of my work is exploring these basic biologic mechanisms and targeting them with novel drugs that have the potential to help patients. There is a whole world of biology behind developing a drug and finding new strategies for helping people. The clinic gives me an appreciation of the variability of leukemia. Seeing patients informs my research and is a motivating factor to develop new therapies."
Originally from Hamilton, Ohio, a small town between Cincinnati and Dayton, Grieselhuber said she had an interest in science from an early age. "At 8, I thought I wanted to be a veterinarian," she said, noting that her rural community encompassed farms and the animals that populated them.
"In high school, something happened that changed the course of my life. A high school science teacher encouraged me to apply to a summer research program for students to work in research labs at Cincinnati Children's Hospital. I did, and even though I knew nothing at all about lab research, I was selected. After spending that one summer in the lab, I was hooked on laboratory research. That same summer, I learned that MD/PhD programs were available and that I could do both lab research and clinical medicine. That sounded like an interesting career path to me."
Personal Appreciation of Research
Adding more motivation to the medical route was the fact that her father developed health problems due to familial hypercholesterolemia-a genetic disorder characterized by poor cholesterol metabolization resulting in very elevated levels of LDL and high rates of early heart attacks and heart disease.
"Some of my father's relatives died of heart attacks in their 30s. My father participated in clinical trials of cholesterol-lowering drugs during the earliest studies of statins," she said, adding that her father is now in his early 70s and living an active life. "Because of those trials, he probably exceeded his natural life expectancy by a good 20-30 years or more. I don't think he would be here today had it not been for the research and clinical trials. Observing his experiences gave me personal inspiration to pursue both science and medicine."
Grieselhuber earned her PhD and MD at Washington University where she worked with Timothy Ley, MD, an internationally recognized expert in genetics of acute myeloid leukemia (AML). "I did my thesis work with him. When I went back to medical school, I never found anything more interesting than hematology and leukemia, and I found I enjoyed taking care of that patient population."
Her lab efforts now focus on preclinical work in novel drugs to combat AML. She works with BET inhibitors. "The BET proteins bind to acetylated lysine on histones within open chromatin," detailed Grieselhuber. "They drive gene expression; AML cells seem to be really dependent on these particular proteins. These BET proteins are found fairly widely throughout different tissues of the body, and there are a lot of BET inhibitors in development. There is one (formulated as pills) where a clinical trial has been published (Lancet Haematol 2016; doi:10.1016/S2352-3026(15)00247-1). The side effects were surprisingly mild-nausea and diarrhea common to a lot of drugs in oncology-and tolerable when administered on an interrupted schedule, 2 weeks on, 1 week off. Continuous dosing was not tolerated."
Her specific interest is in combining BET inhibitors with other targeted therapies such as a drug called dinaciclib. "Published clinical trials suggest that when patients have a response to a single drug and go into remission, it tends not to be durable. We see that with the IDH inhibitors and the FLT3 inhibitors. It makes sense to me that leukemia cells are very complex beasts, so to speak, and it is unlikely that inhibiting one protein of the thousands of proteins that are in a leukemia cell will be enough to get rid of all of them.
"Can we combine these inhibitors in novel ways and make them work better? Are some mutations more responsive than others when a BET inhibitor combined with drug is used?"
The Power of Human Specimens
In looking for the answers, Grieselhuber takes smart advantage of blood and bone marrow samples that have been collected under research protocol from patients at Ohio State.
"We have a tissue banking protocol, called the Leukemia Tissue Bank, which does fairly extensive genetic testing on patient samples to describe what genetic mutations they have," she explained. "The bank processes the samples; the cells are frozen down and put into liquid nitrogen tanks. Then we can thaw them out, in some cases years after they were initially collected. When they are thawed out, the cells are still alive and can be used for studies of how the drugs affect the cells.
"We can apply our combinations to the cells and see how they react. It is a really powerful tool to be able to investigate new drugs in patient samples," she continued. "In the lab we also have genetically engineered mouse models of leukemia, and those have their own uses. But they don't capture the full variability of different mutations seen in patients."
Patient cells are used both in vitro and in mice. "We use mice that are genetically engineered so that they do not have an immune system; the leukemia cells are injected into their veins," said Grieselhuber. "About half of the patient samples of leukemia cells will set up shop in the bone marrow of these animals. As they grow in the mice, we have the opportunity to give the drugs to the mice. We can see what happens to leukemia cells as well as what happens to the whole animal."
Additionally, leukemia cells generally do not survive more than a week in a petri dish; however, they survive in mice for up to 2 months. "That allows us to see more long-term effects," said Grieselhuber. "It lets us see what happens to the whole body."
Expanding Understanding
Among the emerging answers to Grieselhuber's hypothetical questions is the fact that some drug combinations have indeed proven successful in the mice.
"In the short term, one of the things we are interested in, particularly in combination with dinaciclib, is if there are specific mutations described in AML that make them more or less susceptible to that combination. While the cells may all look the same under the microscope, leukemia is not one disease; it is really a collection of diseases.
"It is important to get a sense of which particular patients might benefit from this combination. We are still testing and in some ways the challenge has been more in finding samples that do not respond. The combination of drugs seems to be pretty potent."
Grieselhuber's goals include moving one of these drug combinations to an early phase clinical trial, preferably under the auspices of the Leukemia Lymphoma Society Beat AML study. John Byrd, MD, Chief Medical Officer for the study, is also Grieselhuber's mentor. Beat AML is a basket study for elderly AML patients who are assigned to a therapy that fits their type of leukemia and the type of target their leukemia mutations have.
The ultimate payoffs, if drug combos are successful when moved to clinical trial, have the potential to be defined in different ways, said Grieselhuber. "We can define success by numbers: percentage of patients who achieve complete remission or an increased overall survival or progression-free survival-statistics all oncologists are familiar with. But there is also patient quality of life. Traditionally leukemia treatment has been done in a hospital setting and AML patients are often in a hospital weeks at a time when they are first diagnosed."
She added that it is known that when many AML patients look back on their medical experience they exhibit a sort of PTSD. "A lot of things happen fast-patients get diagnosed, put in the hospital, they don't have a chance to process anything as their lives change so quickly. In the hospital, they are completely removed from their daily life-school, work, friends, and family-all the things that make life worth living.
"Many of these new drugs can be given as pills or shorter IV infusions. So if we can develop treatments that can be given in outpatient settings that would be a huge improvement in quality of life for patients. That counts as a success.
"AML tends to be a disease of the elderly, and it is even harder on them," she continued. "Someone in their 80s statistically doesn't have that many years left. Patients don't want to choose between being with their family or treating their disease. Not having to do that would be a big benefit."
A recent recipient of a Conquer Cancer Young Investigator Award, Grieselhuber manages to get away from the tensions of research and clinical practice on the back of her beloved bay quarter horse, Breeze, who sports a lightning-shaped marking down her forehead. "Little girls at the stable where I keep her say it is her Harry Potter mark," laughed Grieselhuber, who has been riding since she was 8. "In a perfect world I would ride every day, but I usually manage three times a week if the weather is nice and all the stars are aligned."
Grieselhuber said her horse is actually a very accurate reporter of her stress levels and moods. "Breeze is a very sensitive animal-so if I am worried about something, it shows up in how she responds to me when I am riding her. I have to be able to clear my mind and let everything else go besides what is happening at the moment between me and my horse. So for me, riding provides both exercise and a mental benefit. My horse makes me let things go."
The physician-scientist exhibits her own sensitivity when she tells how working with patient samples has given her a new insight into human nature. "I am always amazed that patients consent to being part of this research. New AML patients are already feeling sick and have just been told they may have leukemia and need to have a bone marrow biopsy. It is a lot for people to take in," she detailed.
"On top of that we are asking if we can take some extra samples of blood and bone marrow for research. I wouldn't blame people if they said, 'I already have enough to deal with.' But a good percentage say, 'Yes, I want to help other people.' It is so important for patients and oncologists in the community to know that when someone consents to a study like this and we can use their [de-identified] samples, they help us to answer so many questions."
Valerie Neff Newitt is a contributing writer.
Spotlight on Young Investigators