The immune system is the ultimate yin and yang, explains Anthony D. Sandler, M.D., senior vice president and surgeon-in-chief of the Joseph E. Robert Jr. Center for Surgical Care at Children’s National in Washington, D.C. With an ineffective immune system, infections such as the flu or diarrheal illness can run unchecked, causing devastating destruction. But on the other hand, excess immune activity leads to autoimmune diseases, such as lupus or multiple sclerosis. Thus, the immune system has “checks and balances” to stay controlled.
Cancer takes advantage of “the checks and balances,” harnessing the natural brakes that the immune system puts in place to avoid overactivity. As the cancer advances, molecular signals from tumor cells themselves turn on these natural checkpoints, allowing cancers to evade immune attack.
Several years ago, a breakthrough in pharmaceutical science led to a new class of drugs called checkpoint inhibitors. These medicines take those proverbial brakes off the immune system, allowing it to vigorously attack malignancies. However, Dr. Sandler says, these drugs have not worked uniformly and in some cancers, they barely work at all against the cancer.
One of these non-responders is high risk neuroblastoma, a common solid tumor found outside the skull in children. About 800 U.S. children are diagnosed with this cancer every year. And kids who have the high-risk form of neuroblastoma have poor prognoses, regardless of which treatments doctors use.
However, new research could lead to promising ways to fight high-risk neuroblastoma by enabling the immune system to recognize these tumors and spark an immune response. Dr. Sandler and colleagues recently reported on these results in the Jan. 29, 2018, PLOS Medicine using an experimental model of the disease.
The researchers created this model by injecting the preclinical models with cancer cells from an experimental version of neuroblastoma. The researchers then waited several days for the tumors to grow. Samples of these tumors showed that they expressed a protein on their cell surfaces known as PD-L1, a protein that is also expressed in many other types of human cancers to evade immune system detection.
To thwart this protective feature, the researchers made a cancer vaccine by removing cells from the experimental model’s tumors and selectively turning off a gene known as Id2. Then, they irradiated them, a treatment that made these cells visible to the immune system but blocked the cells from dividing to avoid new tumors from developing.
They delivered these cells back to the experimental models, along with two different checkpoint inhibitor drugs – antibodies for proteins known as CLTA-4 and PD-L1 – over the course of three treatments, delivered every three days. Although most checkpoint inhibitors are administered over months to years, this treatment was short-term for the experimental models, Dr. Sandler explains. The preclinical models were completely finished with cancer treatment after just three doses.
Over the next few weeks, the researchers witnessed an astounding turnaround: While experimental models that hadn’t received any treatment uniformly died within 20 days, those that received the combined vaccine and checkpoint inhibitors were all cured of their disease. Furthermore, when the researchers challenged these preclinical models with new cancer cells six months later, no new tumors developed. In essence, Dr. Sandler says, the preclinical models had become immune to neuroblastoma.
Further studies on human patient tumors suggest that this could prove to be a promising treatment for children with high-risk neuroblastoma. The patient samples examined show that while tumors with a low risk profile are typically infiltrated with numerous immune cells, tumors that are high-risk are generally barren of immune cells. That means they’re unlikely to respond to checkpoint inhibiting drugs alone, which require a significant immune presence in the tumor microenvironment. However, Dr. Sandler says, activating an immune response with a custom-made vaccine from tumor cells could spur the immune response necessary to make these stubborn cancers respond to checkpoint inhibitors.
Dr. Sandler cautions that the exact vaccine treatment used in the study won’t be feasible for people. The protocol to make the tumor cells immunogenic is cumbersome and may not be applicable to gene targeting in human patients. However, he and his team are currently working on developing more feasible methods for crafting cancer vaccines for kids. They also have discovered a new immune checkpoint molecule that could make this approach even more effective.
“By letting immune cells do all the work we may eventually be able to provide hope for patients where there was little before,” Dr. Sandler says.
In addition to Dr. Sandler, study co-authors include Priya Srinivasan, Xiaofang Wu, Mousumi Basu and Christopher Rossi, all of the Joseph E. Robert Jr. Center for Surgical Care and The Sheikh Zayed Institute for Pediatric Surgical Innovation (SZI), at Children’s National in Washington, D.C.
Financial support for research described in this post was provided by the EVAN Foundation, the Catherine Blair foundation, the Michael Sandler Research Fund and SZI.
Children’s urologist Michael H. Hsieh, M.D., Ph.D., knew from age 10 that he would become a doctor. Proof is at his parents’ home. For an elementary school art project, students were instructed to fashion a coat of arms out of clay. In addition to panels for truth, justice and Taiwan, in the shield’s M.D. panel, a snake twists around a rod, like the staff for Asclepius, a Greek god associated with healing.
“I liked science. When I can use it to help patients, that is very rewarding,” says Dr. Hsieh, the first doctor in his family.
Tinker/tailor is shorthand for the mystery drama, “Tinker Tailor Solider Spy,” he explains, adding that the “tinker” part also refers “to the fact that I am always questioning things, and science is about experimentation, trying to seek answers to questions.”
While still in medical school during a rotation Dr. Hsieh saw a bladder operation on a young child and thought it was “amazing.” That experience in part inspired Dr. Hsieh to become a urologist and bladder scientist. His training in immunology and study of the bladder naturally led him to study urinary tract infections and parasitic worms that affect the urinary tract. In addition, thanks to R01 funding from the National Institutes of Health (NIH), Dr. Hsieh is co-principal investigator with Axel Krieger, University of Maryland, and Jin U. Kang, Johns Hopkins, on a project to develop imaging robots for supervised autonomous surgery on soft tissue.
The $1 million in NIH funding pushes the boundaries on amazing by using multi-spectral imaging technology and improved techniques to reduce surgical complications.
Anastomosis is a technique used by surgeons to join one thing to another, whether it’s a vascular surgeon suturing blood vessels, an orthopedic surgeon joining muscles or a urologist stitching healthy parts of the urinary tract back together. Complications can set in if their stitching is too tight, prompting scar tissue to form, or too loose, letting fluid seep out.
“The human eye can see a narrow spectrum of electromagnetic radiation. These multi-spectral imaging cameras would see across greater set of wavelengths,” he says.
The project has three aims: figuring out the best way to place sutures using multi-spectral imaging, accurately tracking soft tissue as they model suturing and comparing the handicraft of a robot against anastomosis hand-sewn by surgeons.
“I like challenges, and I like new things. I am definitely not interested in doing permutations of other people’s work,” Dr. Hsieh explains. “I would much rather go on a path that hasn’t been tread. It is more difficult in some ways, but on a day-to-day basis, I know I am making a contribution.”
In another innovative research project, Dr. Hsieh leveraged a protein secreted by a parasitic worm, Schistosoma haematobium, that suppresses inflammation in hosts as a new therapeutic approach for chemotherapy-induced hemorrhagic cystitis, a form of inflammation of the bladder.
Watching his first surgery nearly 30 years ago, he had no idea robots might one day vie to take over some part of that complicated procedure, or that parasite proteins could be harnessed as drugs. However, he has a clear idea which innovations could be on the horizon for urology in the next three decades.
“My hope is 30 years from now, we will have a solid UTI vaccine and more non-antibiotic therapies. UTIs are the second-most common bacterial infection in childhood and, in severe cases, can contribute to kidney failure,” he says.
Globally, parasitic worms pose an ongoing challenge, affecting more than 1 billion worldwide – second only to malaria. People persistently infected by schistosome worms fail to reach their growth potential, struggle academically and lack sufficient energy for exercise or work.
“There is a feeling that the infection prevalence might be decreasing globally, but not as quickly as everyone hopes. In 30 years perhaps with more mass drug administration and additional drugs – including a vaccine – we’ll have it close to eliminated globally. It would become more like polio, casting a slim shadow with small pockets of infection here or there, rather than consigning millions to perpetual poverty.”
Craig Sable, M.D., associate chief of the division of cardiology and director of echocardiography at Children’s National Health System, earned a lifetime achievement award, formally known as the 2018 Cardiovascular Disease in the Young (CVDY) Meritorious Achievement Award, on Nov. 10 at the American Heart Association’s Scientific Sessions 2018.
The CVDY Council bestows the prestigious award to individuals making a significant impact in the field of cardiovascular disease in the young. The CVDY Council supports the mission to improve the health of children and adults with congenital heart disease and acquired heart disease during childhood through research, education, prevention and advocacy.
Dr. Sable is recognized for his entire body of research, education and advocacy focused on congenital and acquired heart disease, but especially for his rheumatic heart disease (RHD) research in Uganda.
Over the past 15 years, Dr. Sable has brought more than 100 doctors and medical staff to Kampala, the capital and largest city in Uganda, partnering with more than 100 local doctors and clinicians to develop a template for a sustainable infrastructure to diagnose, treat and prevent both RHD and congenital heart disease.
RHD is a result of damage to the heart valves after acute rheumatic fever (ARF). The process starts with a sore throat from streptococcal infection, which many children in the United States treat with antibiotics.
“For patients who develop strep throat, their body’s reaction to the strep throat, in addition to resolving its primary symptoms, can result in attacking the heart,” says Dr. Sable. “The initial damage is called acute rheumatic fever. In many cases this disease is self-limited, but if undetected, over years, it can lead to long-term heart valve damage called rheumatic heart disease. Unfortunately, once severe RHD develops the only treatment is open-heart surgery.”
In 2017, Sable and the researchers published a study in the New England Journal of Medicine about the global burden of RHD, which is often referred to as a disease of poverty.
RHD is observed more frequently in low- and middle-income countries as well as in marginalized communities in high-income countries. RHD has declined on a global scale, but it remains the most significant cause of morbidity and mortality from heart disease in children and young adults throughout the world.
In 2017 there were 39.4 million causes of RHD, which resulted in 285,000 deaths and 9.4 million disability-adjusted life-years.
In 2018 the World Health Organization issued a referendum recognizing rheumatic heart disease as an important disease that member states and ministries of health need to prioritize in their public health efforts.
The common denominator that drives Dr. Sable and the global researchers, many of whom have received grants from the American Heart Association to study RHD, is the impact that creating a scalable solution, such as widespread adoption of vaccines, can have on entire communities.
“The cost of an open-heart surgery in Uganda is $5,000 to $10,000, while treatment for a child with penicillin for one year costs less than $1,” says Dr. Sable. “Investment in prevention strategies holds the best promise on a large scale to eradicate rheumatic heart disease.”
Sable and the team have screened more than 100,000 children and are conducting the first randomized controlled RHD trial, enrolling nearly 1,000 children, to examine the effectiveness of using penicillin to prevent progression of latent or subclinical heart disease, the earliest form of RHD.
During the Thanksgiving holiday weekend, Dr. Sable and a team of surgeons will fly back to Uganda to operate on children affected by RHD, while also advancing their research efforts to produce a scalable solution, exported on a global scale, to prevent RHD in its earliest stages.
Dr. Sable and colleagues from around the world partner on several grant-funded research projects. Over the next few years, the team hopes to answer several important questions, including: Does penicillin prevent the earliest form of RHD and can we develop a vaccine to prevent RHD?
To view the team’s previously-published research, visit Sable’s PubMed profile.
To learn about global health initiatives led by researchers at Children’s National, visit www.GHICN.org.
Despite being the most common extracranial solid tumor found in children and having multiple modes of therapy, neuroblastoma continues to carry a poor prognosis. However, a recent cutting-edge pre-clinical study, PD-L1 checkpoint inhibition and anti-CTLA-4 whole tumor cell vaccination counter adaptive immune resistance: A mouse neuroblastoma model that mimics human disease, published in PLOS Medicine shows the first signs of success in treating high-risk neuroblastoma, a promising step not only for neuroblastoma patients, but potentially for other types of cancer and solid tumors as well. While the research was conducted on mouse models and is in the early stages, the lead author of the study, Anthony Sandler, M.D., senior vice president and surgeon-in-chief of the Joseph E. Robert, Jr., Center for Surgical Care at Children’s National, believes these findings are an encouraging development for the field.
The treatment method combines a novel personalized vaccine and a combination of drugs that target checkpoint inhibitors enabling the immune system to identify and kill cancer cells. When these checkpoints are blocked, it’s similar to taking the brakes off the immune system so that the body’s T cells can be primed by the vaccine, identify the tumor and allow for targeted tumor cell killing. The vaccine then brings in reinforcements to double down on the attack, helping to eradicate the tumor. The vaccine could also be used as a way to prevent recurrence of disease. After a patient has received the vaccine, the T cells would live in the body, remembering the tumor cells, and attack reemerging cancer in a similar way that a flu vaccine helps fight off the flu virus.
“Treatment options like these that help the body use its own immune system to fight off cancer are incredibly promising, and we look forward to continuing this work to understand how we can best help our patients and their families,” said Dr. Sandler.
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