Chimeric antigen receptor T cell (CAR T) therapy has delivered promising results, transforming the fight against various forms of cancer, but for many, the therapy comes with severe and potentially lethal side effects. Now, a research team led by Michael Mitchell of the School of Engineering and Applied Science has found a solution that could help CAR T therapies reach their full potential while minimizing severe side effects. (Image: iStock / Meletios Verras)
In recent years, cancer researchers have hailed the arrival of chimeric antigen receptor T cell (CAR T) therapy, which has delivered promising results, transforming the fight against various forms of cancer. The process involves modifying patients’ T-cells to target cancer cells, resulting in remarkable success rates for previously intractable forms of cancer.
Six CAR T cell therapies have secured FDA approval, and several more are in the pipeline. However, these therapies come with severe and potentially lethal side effects, namely cytokine release syndrome (CRS) and neurotoxicity. These drawbacks manifest as a range of symptoms—from high fever and vomiting to multiple organ failure and patient death—posing significant challenges to broader clinical application.
“Addressing CRS and neurotoxicity without compromising the therapeutic effectiveness of CAR T cells has been a complex challenge,” says Mitchell.
He says that unwanted interactions between CAR T and immune cells called macrophages drive the overactivation of macrophages, which in turn result in the release of toxic cytokines that lead to CRS and neurotoxicity.
“Controlling CAR T-macrophage interactions in vivo is difficult,” Mitchell says. “So, our study introduces a materials engineering-based strategy that involves incorporating a sugar molecule onto the surface of CAR T cells. These sugars are then used as a reactive handle to create a biomaterial coating around these cells directly in the body, which acts as a ‘suit of armor,’ preventing dangerous interactions with macrophages.”
First author Ningqiang Gong, a postdoctoral researcher in the Mitchell Lab, elaborates on the technique, “We attached this sugar molecule to the CAR T cells using metabolic labeling. This modification enables the CAR T cells to attack cancer cells without any hindrance.”
“When symptoms of CRS begin to manifest, we introduce another molecule—polyethylene glycol (PEG)—to create the suit of armor, which effectively blocks dangerous interactions between these engineered T cells, macrophages, and the tumor cells themselves,” Gong says.
Carl June, at the flash mob celebration of the FDA approval of the CAR T cell therapy he developed, in August 2017. (Image: Courtesy of Penn Medicine Magazine)
For most of modern medicine, cancer drugs have been developed the same way: by designing molecules to treat diseased cells. With the advent of immunotherapy, that changed. For the first time, scientists engineered patients’ own immune systems to recognize and attack diseased cells.
One of the best examples of this pioneering type of medicine is CAR T cell therapy. Invented in the Perelman School of Medicine by Carl June, the Richard W. Vague Professor in Immunotherapy, CAR T cell therapy works by collecting T cells from a patient, modifying those cells in the lab so that they are designed to destroy cancerous cells, and reinfusing them into the patient. June’s research led to the first FDA approval for this type of therapy, in 2017. Six different CAR T cell therapies are now approved to treat various types of blood cancers. Carl June, at the flash mob celebration of the FDA approval of the CAR T cell therapy he developed, in August 2017. (Image: Courtesy of Penn Medicine Magazine)
CAR T cell therapy holds the potential to help millions more patients—if it can be successfully translated to other conditions. June and colleagues, including Daniel Baker, a fourth-year doctoral student in the Cell and Molecular Biology department, discuss this potential in a perspective published in Nature.
In the piece, June and Baker highlight other diseases that CAR T cell therapy could be effective.
“CAR T cell therapy has been remarkably successful for blood cancers like leukemias and lymphomas. There’s a lot of work happening here at Penn and elsewhere to push it to other blood cancers and to earlier stage disease, so patients don’t have to go through chemo first,” June says. “Another big priority is patients with solid tumors because they make up the vast majority of cancer patients. Beyond cancer, we’re seeing early signs that CAR T cell therapy could work in autoimmune diseases, like lupus.”
As for which diseases to pursue as for possible future treatment, June says, “essentially it boils down to two questions: Can we identify a population of cells that are bad? And can we target them specifically? Whether that’s asthma or chronic diseases or lupus, if you can find a bad population of cells and get rid of them, then CAR T cells could be therapeutic in that context.”
“What’s exciting is it’s not just theoretical at this point. There have been clinical reports in other autoimmune diseases, including myasthenia gravis and inflammatory myopathy,” Baker says. “But we are seeing early evidence that CAR T cell therapy will be successful beyond cancer. And it’s really opening the minds of people in the field to think about how else we could use CAR T. For example, there’s some pioneering work at Penn from the Epstein lab for heart failure. The idea is that you could use CAR T cells to get rid of fibrotic tissue after a cardiac injury, and potentially restore the damage following a heart attack.”
Baker adds, “there’s no question that over the last decade, CAR T cell therapy has revolutionized cancer. I’m hoping to play a role in bringing these next generation therapies to patients and make a real impact over the next decade. I think there’s potential for cell therapy to be a new pillar of medicine at large, and not just a new pillar of oncology.”
Perelman School of Medicine’s Maayan Levy, and Christoph Thaiss. (Image: Courtesy of Penn Medicine News)
When we hear about gut bacteria, we may think about probiotics and supplements marketed to help with digestion, about how taking antibiotics might affect our intestinal tract, or perhaps about trendy diets that aim to improve gut health.
But two researchers at Penn Medicine think that understanding the microbiome, the entirety of microbial organisms associated with the human body, might be the key to deciphering the fundamental mechanisms that make our bodies work. They think these microbes may work like a call center switchboard, making connections to help different organs, biological systems, and the brain communicate. Maayan Levy, and Christoph Thaiss, both assistant professors of microbiology at the Perelman School of Medicine, argue that the microbiome is instrumental to revealing how signals from the gastrointestinal tract are received by the rest of the body—which may hold the key to understanding inter-organ communication in general. Perelman School of Medicine’s Maayan Levy, and Christoph Thaiss. (Image: Courtesy of Penn Medicine News)
While the gut sends signals to all parts of the body to initiate various biological processes, the mechanisms underlying this communication—and communication between different organs involved in these processes—is relatively unknown.
“The more we learn about the role the microbiome plays in a wide range of diseases— from cancer to neurodegenerative diseases to inflammatory diseases—the more important it becomes to understand what exactly its role is,” says Thaiss. “And hopefully once we understand how it works, we can use the microbiome to treat these diseases.”
Levy and Thaiss joined the faculty at Penn Medicine after completing their graduate studies in 2018. Here, they continue to investigate the role of the microbiome in various biological processes.
In his lab, Thaiss focuses on the impact of the microbiome on the brain. He recently identified species of gut-dwelling bacteria that activate nerves in the gut to promote the desire to exercise. Most recently, Thaiss published a study that identified the cells that communicate psychological stress signals from the brain to the gastrointestinal tract, and cause symptoms of inflammatory bowel disease.
Meanwhile, in her lab, Levy examines how the microbiome influences the development of diseases, like cancer, and other conditions throughout the body.
A recent publication authored by Levy suggested that the ketogenic diet (high fat, low carbohydrate) causes the production of a metabolite called beta-hydroxybutyrate (BHB), that suppresses colorectal cancer in small animal models.
Now, Levy is collaborating with Bryson Katona, an assistant professor of Medicine in the division of gastroenterology who specializes in gastrointestinal cancers, to investigate whether BHB has the same effect in patients with Lynch syndrome, which causes individuals to have a genetic predisposition to many different kinds of cancer, including colon cancer. These efforts are part of a growing emphasis at Penn on finding methods to intercept cancer in its earliest stages.
“It’s remarkable that we were able to quickly take the findings from our animal models and rapidly design a clinical trial,” Levy says. “One of the most exciting aspects of our work is not only making discoveries about how our bodies work on a biological level, but then being able to work with the world’s leading clinical experts to translate these discoveries into therapies for patients.”
Further, studies led by Levy and Thaiss often utilize human samples and data from the Penn Medicine BioBank, to validate animal model findings in the tissue of human patients suffering from the diseases which they are investigating.
While Levy and Thaiss pursue different research interests with their labs, they also collaborate often, building on their previous research into what the microbiome does, and its role in the biological processes that keep us healthy. Their long-term goal is to learn about the mechanisms by which the gastrointestinal tract influences disease processes in other organs to treat various diseases of the body using the gastrointestinal tract as a noninvasive entry point to the body.
“Some of the most common and devastating diseases in humans—like cancer or neurodegeneration—are difficult to treat because they are no existing therapies that can reach the brain,” says Thaiss. “If we can understand how the gastrointestinal tract interacts with other organs in the body, including the brain, we might be able to develop treatments that ‘send messages’ to these organs through the body’s natural communication pathways.”
“Obviously there is a lot more basic biology to be uncovered before we get there,” adds Levy. “Most importantly, we want to map all the different routes by which the gastrointestinal tract interacts with the body, and how that communication happens.”
Christopher Thaiss is Assistant Professor in Microbiology in the Perelman School of Medicine. He is a member of the Penn Bioengineering Graduate Group.
A research team led by engineers at the University of Pennsylvania and Northwestern University scientists has created a new synthetic biology approach, or a “QR code for cancer cells,” to follow tumor cells over time, finding there are meaningful differences in why a cancer cell dies or survives in response to anti-cancer therapies.
Remarkably, what fate cancer cells choose after months of therapy is “entirely predictable” based on seemingly small, yet important, differences that appear even before treatment begins. The researchers also discovered the reason is not genetics, contrary to beliefs held in the field.
The study outlined the team’s new technology platform that developed a QR code for each of the millions of cells for scientists to find and use later — much like tagging swans in a pond. The QR code directs researchers to a genome-wide molecular makeup of these cells and provides information about how they’ve reacted to cancer treatment.
“We think this work stands to really change how we think about therapy resistance,” said Arjun Raj, co-senior author and Professor in Bioengineering in the School of Engineering and Applied Science at the University of Pennsylvania. “Rather than drug-resistant cells coming in just one flavor, we show that even in highly controlled conditions, different ‘flavors’ can emerge, raising the possibility that each of these flavors may need to be treated individually.”
In the study, the lab and collaborators sought to apply synthetic biology tools to answer a key question in cancer research: What makes certain tumors come back a few months or years after therapy? In other words, could the lab understand what causes some rare cells to develop therapeutic resistance to a drug?
“There are many ways cells become different from each other,” said Yogesh Goyal, the co-senior author at Northwestern University. “Our lab asks, how do individual cells make decisions? Understanding this in the context of cancer is all the more exciting because there’s a clinically relevant dichotomy: A cell dies or becomes resistant when faced with therapies.”
Using the interdisciplinary team, the scientists put the before-and-after cloned cells through a whole genome sequencing pipeline to compare the populations and found no systematic underlying genetic mutations to investigate the hypothesis. Raj and Goyal helped develop the QR code framework, FateMap, that could identify each unique cell that seemed to develop resistance to drug therapy. “Fate” refers to whether a cell dies or survives (and if so, how), and the scientists “map” the cells across their lifespan, prior to and following anti-cancer therapy. FateMap is the result of work from several research institutions, and it applies an amalgamation of concepts spanning several disciplines, including synthetic biology, genome engineering, bioinformatics, machine learning and thermodynamics.
“Some are different by chance — just as not all leaves on a tree look the same — but we wanted to determine if that matters,” Goyal said. “The cell biology field has a hard time defining if differences have meaning.”
Rather than being the single disease class many people refer to, “cancer” is a blanket term that covers more than 100 distinct diseases, many of which have little in common aside from originating with rapidly dividing cells. Since different cancers demand different treatments, it follows that any given new therapy emerging from any institution would be likely to be a new cancer treatment.
But why so many in just this five-year period?
The volume of new cancer treatments makes sense, says Abramson Cancer Center (ACC) director Robert Vonderheide, attributing the flurry of new cancer drug approvals to a recent “explosion” in knowledge about cancer biology.
“Much of that knowledge is about the immune system’s ability to attack cancer, which people seriously doubted until about 20 years ago. As soon as we had a clinical validation for this Achilles heel in cancer, the dam burst for ideas about other ways to exploit that vulnerability to come forward,” he says. “The first drug that came out to activate the immune system inspired the rest of the field to find the next drug, and the one after that. We as a field have moved from serendipity and empiricism to science-driven drug design.”
The first CAR T cell therapy approval invigorated Penn faculty interested in finding new ways to harness the immune system to fight cancer.
“An approval like that makes what you’re working on more of a reality,” says Avery Posey, an assistant professor of systems pharmacology and translational therapeutics in the Perelman School of Medicine, whose lab team spends much of its time trying to identify more specific antigens for solid tumors and also studies ways to optimize engineered donor T cells. “It brings a new perspective, showing that your work is more than basic research and can actually become drugs that impact patients’ lives. That’s a real motivator to keep pushing forward.”
Honing new immunotherapies is a priority among Penn researchers, but not every recently approved new cancer treatment or detection tool developed at the institution engages the immune system. Faculty have explored and introduced widely varying approaches to improving the standard of care for cancer patients.
Myeloma cells producing monoclonal proteins of varying types, created by Scientific Animations under the Creative Commons Attributions-Share Alike International 4.0 License
Multiple myeloma is an incurable bone marrow cancer that kills over 100,000 people every year. Known for its quick and deadly spread, this disease is one of the most challenging to address. As these cancer cells move through different parts of the body, they mutate, outpacing possible treatments. People diagnosed with severe multiple myeloma that is resistant to chemotherapy typically survive for only three to six months. Innovative therapies are desperately needed to prevent the spread of this disease and provide a fighting chance for those who suffer from it.
Michael Mitchell, J. Peter and Geri Skirkanich Assistant Professor of Innovation in Bioengineering (BE), and Christian Figueroa-Espada, doctoral student in BE at the University of Pennsylvania School of Engineering and Applied Science, created an RNA nanoparticle therapy that makes it impossible for multiple myeloma to move and mutate. The treatment, described in their study published in PNAS, turns off a cancer-attracting function in blood vessels, disabling the pathways through which multiple myeloma cells travel.
By shutting down this “chemical GPS” that induces the migration of cancer cells, the team’s therapy stops the spread of multiple myeloma, helping to eliminate it altogether.
“Macrophages killing cancer cell” photographed by Susan Arnold.
By silencing the molecular pathway that prevents macrophages from attacking our own cells, Penn Engineers have manipulated these white blood cells to eliminate solid tumors.
Cancer remains one of the leading causes of death in the U.S. at over 600,000 deaths per year. Cancers that form solid tumors such as in the breast, brain or skin are particularly hard to treat. Surgery is typically the first line of defense for patients fighting solid tumors. But surgery may not remove all cancerous cells, and leftover cells can mutate and spread throughout the body. A more targeted and wholistic treatment could replace the blunt approach of surgery with one that eliminates cancer from the inside using our own cells.
Dennis Discher, Robert D. Bent Professor in Chemical and Biomolecular Engineering, Bioengineering, and Mechanical Engineering and Applied Mechanics, and postdoctoral fellow, Larry Dooling, provide a new approach in targeted therapies for solid tumor cancers in their study, published in Nature Biomedical Engineering. Their therapy not only eliminates cancerous cells, but teaches the immune system to recognize and kill them in the future.
“Due to a solid tumor’s physical properties, it is challenging to design molecules that can enter these masses,” says Discher. “Instead of creating a new molecule to do the job, we propose using cells that ‘eat’ invaders – macrophages.”
Macrophages, a type of white blood cell, immediately engulf and destroy – phagocytize – invaders such as bacteria, viruses, and even implants to remove them from the body. A macrophage’s innate immune response teaches our bodies to remember and attack invading cells in the future. This learned immunity is essential to creating a kind of cancer vaccine.
But, a macrophage can’t attack what it can’t see.
“Macrophages recognize cancer cells as part of the body, not invaders,” says Dooling. “To allow these white blood cells to see and attack cancer cells, we had to investigate the molecular pathway that controls cell-to-cell communication. Turning off this pathway – a checkpoint interaction between a protein called SIRPa on the macrophage and the CD47 protein found on all ‘self’ cells – was the key to creating this therapy.”
Multiple members in the biophysical engineering lab lead by Dennis Discher, including co-lead author and postdoctoral fellow and Penn Bioengineering alumnus Jason Andrechak and Bioengineering Ph.D. student Brandon Hayes, contributed to this study. The research was funded by grants from the National Heart, Lung, and Blood Institute and the National Cancer Institute, including the Physical Sciences Oncology Network, of the US National Institutes of Health.
They will conduct research, pursue graduate degrees, or teach English in Belgium, Brazil, Colombia, Denmark, Ecuador, Estonia, France, Germany, Guatemala, India, Israel, Latvia, Mexico, Nepal, New Zealand, the West Bank-Palestine territories, South Korea, Spain, Switzerland, Taiwan, and Thailand.
The Fulbright Program is the United States government’s flagship international educational exchange program, awarding grants to fund as long as 12 months of international experience.
Among the Penn Fulbright grant recipients for 2023-24 is Ella Atsavapranee, from Cabin John, Maryland, who graduated in May with a bachelor’s degree in bioengineering from the School of Engineering and Applied Science and a minor in chemistry from the College. She was offered a Fulbright to conduct research at the École Polytechnique Fédérale de Lausanne in Switzerland.
At Penn, Atsavapranee worked with Michael Mitchell, J. Peter and Geri Skirkanich Assistant Professor in Bioengineering, engineering lipid nanoparticles to deliver proteases that inhibit cancer cell proliferation. She has also worked with Shan Wang, Leland T. Edwards Professor in the School of Engineering and Professor of Electrical Engineering at Stanford University, using bioinformatics to discover blood biomarkers for cancer detection. To achieve more equitable health care, she worked with Lisa Shieh, Clinical Professor in Medicine at the Stanford School of Medicine, to evaluate an AI model that predicts risk of hospital readmission and study how room placement affects patient experience.
Outside of research, Atsavapranee spread awareness of ethical issues in health care and technology as editor-in-chief of the Penn Bioethics Journaland a teaching assistant for Engineering Ethics (EAS 2030). She was also a Research Peer Advisor for the Penn Center for Undergraduate Research & Fellowships (CURF), a student ambassador for the Office of Admissions, and a volunteer for Service Link, Puentes de Salud, and the Hospital of the University of Pennsylvania. She plans to pursue a career as a physician-scientist to develop and translate technologies that are more affordable and accessible to underserved populations.
Read the full list of Penn Fulbright grant recipients for 2023-24 in Penn Today.
Neil Sheppard, Adjunct Associate Professor of Pathology and Laboratory Medicine in the Perelman School of Medicine, and David Mai, a Bioengineering graduate student in the School of Engineering and Applied Science, explained the findings of their recent study, which offered a potential strategy to improve T cell therapy in solid tumors, to the European biotech news website Labiotech.
The Solomon R. Pollack Award for Excellence in Graduate Bioengineering Research is given annually to the most deserving Bioengineering graduate students who have successfully completed research that is original and recognized as being at the forefront of their field. This year, the Department of Bioengineering at the University of Pennsylvania recognizes the stellar work of four graduate students in Bioengineering.
Margaret Billingsley
Dissertation: “Ionizable Lipid Nanoparticles for mRNA CAR T Cell Engineering”
Maggie Billingsley
Margaret earned a bachelor’s degree in Biomedical Engineering from the University of Delaware where she conducted research in the Day Lab on the use of antibody-coated gold nanoparticles for the detection of circulating tumor cells. She conducted doctoral research in the lab of Michael J. Mitchell, J. and Peter Skirkanich Assistant Professor in Bioengineering. After defending her thesis at Penn in 2022, Margaret began postdoctoral training at the Massachusetts Institute of Technology (MIT) in the Hammond Lab where she is investigating the design and application of polymeric nanoparticles for combination therapies in ovarian cancer. She plans to use these experiences to continue a research career focused on drug delivery systems.
“Maggie was an absolutely prolific Ph.D. student in my lab, who pioneered the development of new mRNA lipid nanoparticle technology to engineer the immune system to target and kill tumor cells,” says Mitchell. “Maggie is incredibly well deserving of this honor, and I am so excited to see what she accomplishes next as a Postdoctoral Fellow at MIT and ultimately as a professor running her own independent laboratory at a top academic institution.”
Victoria Muir
Dissertation: “Designing Hyaluronic Acid Granular Hydrogels for Biomaterials Applications”
Victoria Muir
Victoria is currently a Princeton University Presidential Postdoctoral Research Fellow in the lab of Sujit S. Datta, where she studies microbial community behavior in 3D environments. She obtained her Ph.D. in 2022 as an NSF Graduate Research Fellow at Penn Bioengineering under the advisement of Jason A. Burdick, Adjunct Professor in Bioengineering at Penn and Bowman Endowed Professor in Chemical and Biological Engineering at the University of Colorado, Boulder. She received a B.ChE. in Chemical Engineering from the University of Delaware in 2018 as a Eugene DuPont Scholar. Outside of research, Victoria is highly active in volunteer and leadership roles within the American Institute of Chemical Engineers (AIChE), currently serving as Past Chair of the Young Professionals Community and a member of the Career and Education Operating Council (CEOC). Victoria’s career aspiration is to become a professor of chemical engineering and to lead a research program at the interaction of biomaterials, soft matter, and microbiology.
“Victoria was a fantastic Ph.D. student,” says Burdick. “She worked on important projects related to granular materials from the fundamentals to applications in tissue repair. She was also a leader in outreach activities, a great mentor to numerous undergraduates, and is already interviewing towards an independent academic position.”
Sadhana Ravikumar
Dissertation: “Characterizing Medial Temporal Lobe Neurodegeneration Due to Tau Pathology in Alzheimer’s Disease Using Postmortem Imaging”
Sadhana Ravikumar
Sadhana completed her B.S. in Electrical Engineering at the University of Cape Town, South Africa in 2014 and her M.S. in Biomedical Engineering from Carnegie Mellon University in 2017. Outside of the lab, she enjoys spending time in nature and exploring restaurants in Philadelphia with friends. She focused her doctoral work on the development of computational image analysis techniques applied to ex vivo human brain imaging data in the Penn Image Computing and Science Laboratory of Paul Yushkevich, Professor of Radiology at the Perelman School of Medicine and member of the Penn Bioengineering Graduate Group. She hopes to continue working at the intersection of machine learning and biomedical imaging to advance personalized healthcare and drug development.
“Dr. Sadhana Ravikumar’s Ph.D. work is a tour de force that combines novel methodological contributions crafted to address the challenge of anatomical variability in ultra-high resolution ex vivo human brain MRI with new clinical knowledge on the contributions of molecular pathology to neurodegeneration in Alzheimer’s disease,” says Yushkevich. “I am thrilled that this excellent contribution, as well as Sadhana’s professionalism and commitment to mentorship, have been recognized through the Sol Pollack award.”
Hannah Zlotnick
Dissertation: “Remote Force Guided Assembly of Complex Orthopaedic Tissues”
Hannah Zlotnick
Hannah was a Ph.D. candidate in the lab of Robert Mauck, Mary Black Ralston Professor in Orthopaedic Surgery and in Bioengineering. She successfully defended her thesis and graduated in August 2022. During her Ph.D., Hannah advanced the state-of-the-art in articular cartilage repair by harnessing remote fields, such as magnetism and gravity. Using these non-invasive forces, she was able to control cell positioning within engineered tissues, similar to the cell patterns within native cartilage, and enhance the integration between cartilage and bone. Her work could be used in many tissue engineering applications to recreate complex tissues and tissue interfaces. Hannah earned a B.S. in Biological Engineering from the Massachusetts Institute of Technology (MIT) in 2017 during which time she was also a member of the women’s varsity soccer team. At Penn, Hannah was also involved in the Graduate Association of Bioengineers (GABE) intramurals & leadership, and helped jumpstart the McKay DEI committee. Since completing her Ph.D., Hannah has begun her postdoctoral research as a Schmidt Science Fellow in Jason Burdick’s lab at the University of Colorado Boulder where she looks to improve in vitro disease models for osteoarthritis.
“Hannah was an outstanding graduate student, embodying all that is amazing about Penn BE – smart, driven, inventive and outstanding in every way,” says Mauck. “ I can’t wait to see where she goes and what she accomplishes!”
Congratulations to our four amazing 2023 Sol Pollack Award winners!
A research team led by engineers at the 
