What can you do with a liberal arts degree? Native New Yorker Daniel Heller, PhD, majored in history, added in some basic science courses, and started his working life as a middle school science teacher. After taking some additional chemistry coursework during non-teaching hours, Heller parlayed it all into a doctorate in chemistry from the University of Illinois. Today he is a biomedical engineer at Memorial Sloan Kettering Cancer Center (MSKCC), New York City, where his Cancer Nanomedicine Laboratory team invents new technologies that can assist health care in helping human kind.
Heller chuckled when mentioning his circuitous life path and some of the stops along the way: performing as a wizard at a Renaissance Fair (“...liquid nitrogen turns into a pretty impressive potion...”), trying to master the Argentine tango, appreciating his brother's equally non-traditional path as a drummer in heavy metal bands, and happily settling into married life with his wife who is a primary care physician.
In recent years, he has also managed to garner solid industry credentials in the form of awards, including the NSF CAREER Award (2018), Pershing Square Sohn Prize for Young Innovators in Cancer Research (2017), and NIH Director's New Innovator Award (2012), among others.
“I like inventing,” Heller stated simply. “In my lab, we often think of ourselves as biomedical engineers whose primary goal is invent new technologies to improve cancer research, diagnosis, and therapy. Only when I arrived at MSKCC did I realize how far that is from the way biologists think. I was trained that our goal is to invent, and to learn new science along the way, while a biologist's goal is to understand nature and develop tools mainly as a means to an end. I didn't have a huge biomedical background coming in, but by talking to the people around me at Sloan Kettering and Weill Cornell Medicine [where he is an Assistant Professor], I have learned a great deal.”
As detailed on his laboratory website (www.mskcc.org/research-areas/labs/daniel-heller), Heller and team are “... developing nanomedicines to target precision agents to disease sites, including to metastatic cancers. We are also addressing the problem of the early detection of cancer and other diseases by building implantable nanosensors. To enable the discovery of new medicines, we also are inventing new nanosensors and imaging tools to accelerate drug development and biomedical research.”
Nanoparticles in Treatment
Heller told Oncology Times that it all begins with interaction and collaboration. “We are lucky because we get to dig deep with the clinicians, clinician/scientists, and biologists to understand exactly what might be wrong with a particular mode of therapy,” said Heller of his development process. “An oncologist might talk to us about a drug or class of therapies that have particular problems and specific side effects, such as dose-limiting toxicity that prevents people from getting enough of a therapy to adequately inhibit the target in the tumor.”
He added that problems often stem from the fact that a drug negatively affects tissue that is not part of the tumor. “Can we avoid that one vulnerable tissue that will really mess up the use of this drug for treating the tumor? Can we prevent the drug from getting into that tissue?” asked Heller rhetorically. Clearly, he believes it is possible with the help of nanoparticles.
He noted that people erroneously think of nanoparticles as being “the smallest of the small.” But small molecule drugs, and even protein drugs, are much smaller than nanoparticles. Most drugs can diffuse all over the body. “But if we put the drug into a larger nanoparticle, we can keep it from spraying out over all the tissues,” detailed Heller.
His team also must consider how to deliver the nanoparticle containing the drug to a precise location in the tumor site, and whether there is a target that can lead it to that tumor site. “Most of the targets we are looking for are not on the tumor cells themselves, but on the blood vessels that are feeding the tumor,” said Heller. “Our targets are not drug targets, but rather gateways to the tumor, molecules on blood vessels in tumors sites, or sites of inflammation. Then we make sure that the nanoparticle has a molecule on the outside of it that can stick to those targets.”
The research takes the engineering team into the realms of vascular biology, vascular transport, and an understanding of how materials can get across the blood, across the blood/brain barrier, across the tumor barrier. “We are also exploring signaling pathways,” said Heller. “When trying to deliver a kinase inhibitor, for example, we must consider the target we are hitting, where else that target is in the body, and if there any other off-target proteins elsewhere in the body that the drug will hit. We also have to think about resistance mechanisms and compensatory pathways. So as a team we have been learning a lot of physiology.”
Heller says his 5-year-old laboratory contains requisite benches, a tissue culture room, and a studio equipped with lasers and optics for work on sensors. In the basement reside the all-important mice, critical to preclinical development and testing. Looking at target proteins in the body of a mouse, the team is able to determine if a drug encased in a nanoparticle hits the target, if it works better in a nanoparticle, and if it has the same side effects.
The eventual goal is to translate this understanding and these emerging technologies to clinical use and human patients. But it is a long row to hoe. “Once a technology is developed, it must go through the full ‘investigational new drug’ FDA process,” Heller lamented. “Even if a known compound is inside the particle, the whole particle is treated as a new drug. That means we can't just give it to clinicians to trial in patients; first the FDA must allow us to start a clinical trial.” Though regulatory delays are a frustration, the researcher said enthusiasm remains high because the potential of the new technologies is so powerful.
Nanoparticles in Detection
The Cancer Nanomedicine Laboratory also maintains an interest in developing innovative approaches to cancer detection that is “... easier and more predictive. We found that we can detect some cancers earlier by measuring certain biomarkers in a person without having to take blood or biofluids to do it,” said Heller.
Instead, a tiny sensor made of carbon nanotubes is inserted inside a person. The nanotubes give off infrared light that can pass through tissues. “We can implant nanomaterial in a body, shoot light into it from outside the body, and then get a reading externally,” detailed Heller. “These nanomaterials are very sensitive to certain stimuli. We can put an antibody onto the surface of the nanotube and when it binds to an antigen we can see a signal change—a shift in the wavelength of the nanotube fluorescence—through the tissue.” (The team successfully detected ovarian cancer signaling changes in a mouse model. This work was detailed in a paper, Non-Invasive Ovarian Cancer Biomarker Detection via an Optical Nanosensor Implant, coauthored by Heller in Science Advances [2018;4(4):eaaq1090]).
Implications for future use of this technology in humans are significant. Heller said the first possible application could be in people with risk factors for certain diseases. “We could implant a biomarker or panel of biomarkers in people to detect early stage cancer, to measure cancer recurrence, or to monitor treatment and have earlier warning when therapy stops working.”
Asked how early the signaling changes would become apparent, Heller said it depends on the level of a given marker in the tissue. “With ovarian cancer, we would look at the technology as an intrauterine device, placed near the source of the cancer. If we were to wait for biomarkers to reach a high enough level to be detected in the blood, we likely would be dealing with late-stage cancer. If we can measure that biomarker right next to the ovaries or fallopian tube, we would see signal changes at an even earlier point in the life cycle of the cancer.”
Looking downstream of this work, Heller said the team is already questioning if it might be possible to insert a small sensor under the skin, in the blood, or even in a tattoo to measure all kinds of biomarkers, then report a whole panel in real time, at early stages, back to a wearable Fitbit-like device. “The long-term hope is to find super easy ways to measure lots of biomarkers in real time,” said Heller.
Nanoparticles in Discovery
A third aspect of the work underway in Heller's lab focuses on making research tools, specifically using carbon nanotubes as sensors in drug discovery assays. Heller believes the sensors will be able to measure things that have not been measurable before, or measured in ways that could not be accomplished before, such as in living cells and living tissue. “By measuring an analyte inside living cells or living tissue in mice, we gain the ability to do studies that cannot be done otherwise. This will allow us to address new hypotheses, and it will be helpful for drug development and for basic researchers at institutions such as MSKCC.”
Heller stressed that it is exactly institutions like MSKCC that can lead the way in helping biomedical engineers interact more fully with biomedical researchers. “Even though both of these concepts have the word ‘biomedical’ in them, ‘biomedical engineering’ departments come from engineering schools, while ‘biomedical research’ comes from places that often do not have engineering schools. So there is a disconnect,” said Heller. “I realize how valuable it is to me as an engineering researcher to be in a biomedical institution and come in contact with the people who study biomedical questions and understand the medical problems. Biomedical institutions would benefit greatly from organized efforts to bring in engineering researchers whose goal it is to understand and make new technologies to address their problems.”
Heller laughed at the suggestion that some of the things he makes sound like cinematic props from the vintage sci-fi flick, The Incredible Voyage. “Sometimes people think we are the science fiction lab of Memorial Sloan Kettering,” he admitted with humor. And when asked if the younger history student/middle school teacher/or physical scientist in him ever thinks, “I can't believe I am doing this kind of stuff,” he answered without hesitation, “Yeah, all the time. I think I have gotten to where I am by not defining myself. It's important to be flexible. Where does it stop? It doesn't. If you keep changing you can aspire to do anything you want.”
Valerie Neff Newitt is a contributing writer.
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