First-In-Human Clinical Trial Aims to Extend Remission for Children and Young Adults With Leukemia Treated With T-Cell Immunotherapy

Phase 1 pilot study utilizes T-cell antigen presenting cells to prolong the persistence of cancer-fighting chimeric antigen receptor (CAR) T cells, reduce the relapse rate

After phase 1 results of Seattle Children’s Pediatric Leukemia Adoptive Therapy (PLAT-02) trial have shown T-cell immunotherapy to be effective in getting  93 percent of patients with relapsed or refractory acute lymphoblastic leukemia (ALL) into complete initial remission, researchers have now opened a first-in-human clinical trial aimed at reducing the rate of relapse after the therapy, which is about 50 percent. The new phase 1 pilot study, PLAT-03, will examine the feasibility and safety of administering a second T-cell product intended to increase the long-term persistence of the patient’s chimeric antigen receptor (CAR) T cells that were reprogrammed to detect and destroy cancer.

The research team, led by Dr. Mike Jensen at the Ben Towne Center for Childhood Cancer Research at Seattle Children’s Research Institute, is exploring this strategy after discovering that of the patients who relapse in the PLAT-02 trial, about half of them have lost their CAR T cells. Lasting persistence of the CAR T cells is critical in combating a recurrence of cancer cells.

“While it’s promising that we’re able to get these patients who are very sick back into remission, we’re also seeing that the loss of the CAR T cells in some patients may be opening the door for the cancer to return,” said Dr. Colleen Annesley, an oncologist at Seattle Children’s and the lead investigator of the PLAT-03 trial. “We’re pleased to now be able to offer patients who have lost or are at risk of losing their cancer-fighting T cells an option that will hopefully lead to them achieving long-term remission.”

In the PLAT-03 trial, patients will receive “booster” infusions of a second T-cell product, called T antigen-presenting cells (T-APCs). The T-APCs have been genetically modified to express the CD19 target for the cancer-fighting CAR T cells to recognize. Patients will receive a full dose of T-APCs every 28 days for at least one and up to six doses. By stimulating the CAR T cells with a steady stream of target cells to attack, researchers hope the CAR T cells will re-activate, helping to ensure their persistence long enough to put patients into long-term remission.

PLAT-03 is now open to patients who first enroll in phase 2 of Seattle Children’s PLAT-02 trial and who are also identified as being at risk for early loss of their reprogrammed CAR T cells, or those who lose their reprogrammed CAR T cells within six months of receiving them.

The PLAT-03 trial is one of several trials that Seattle Children’s researchers are planning to open within the next year aimed at further improving the long-term efficacy of T-cell immunotherapy. In addition to the current T-cell immunotherapy trial that is open for children with neuroblastoma, researchers also hope to expand this promising therapy to other solid tumor cancers.

“We are pleased to be at a pivotal point where we are now looking at several new strategies to further improve CAR T-cell immunotherapy so it remains a long-term defense for all of our patients,” said Dr. Rebecca Gardner, Seattle Children’s oncologist and the lead investigator of the PLAT-02 trial. “We’re also excited to be working to apply this therapy to several other forms of pediatric cancer beyond ALL, with the hope that T-cell immunotherapy becomes a first line of defense, reducing the need for toxic therapies and minimizing the length of treatment to only weeks.”

To read about the experience of one of the patients in the PLAT-02 trial, please visit Seattle Children’s On the Pulse blog.

The T-cell immunotherapy trials at Seattle Children’s are funded in part by Strong Against Cancer, a national philanthropic initiative with worldwide implications for potentially curing childhood cancers. If you are interested in supporting the advancement of immunotherapy and cancer research, please visit Strong Against Cancer’s donation page.

For more information on immunotherapy research trials at Seattle Children’s, please call (206) 987-2106 or email immunotherapy@seattlechildrens.org.

Nanoparticles Reprogram Immune Cells to Fight Cancer

Researchers at Fred Hutchinson Cancer Research Center have developed biodegradable nanoparticles that can be used to genetically program immune cells to recognize and destroy cancer cells — while the immune cells are still inside the body.

In a proof-of-principle study to be published April 17 in Nature Nanotechnology, the team showed that nanoparticle-programmed immune cells, known as T cells, can rapidly clear or slow the progression of leukemia in a mouse model.

“Our technology is the first that we know of to quickly program tumor-recognizing capabilities into T cells without extracting them for laboratory manipulation,” said Fred Hutch’s Dr. Matthias Stephan, the study’s senior author. “The reprogrammed cells begin to work within 24 to 48 hours and continue to produce these receptors for weeks. This suggests that our technology has the potential to allow the immune system to quickly mount a strong enough response to destroy cancerous cells before the disease becomes fatal.”

Cellular immunotherapies have shown promise in clinical trials, but challenges remain to making them more widely available and to being able to deploy them quickly. At present, it typically takes a couple of weeks to prepare these treatments: the T cells must be removed from the patient and  genetically engineered and grown in special cell processing facilities before they are infused back into the patient. These new nanoparticles could eliminate the need for such expensive and time consuming steps.

Although his T-cell programming method is still several steps away from the clinic, Stephan imagines a future in which nanoparticles transform cell-based immunotherapies — whether for cancer or infectious disease — into an easily administered, off-the-shelf treatment that’s available anywhere.

“I’ve never had cancer, but if I did get a cancer diagnosis I would want to start treatment right away,” Stephan said. “I want to make cellular immunotherapy a treatment option the day of diagnosis and have it able to be done in an outpatient setting near where people live.”

The body as a genetic engineering lab

Stephan created his T-cell homing nanoparticles as a way to bring the power of cellular cancer immunotherapy to more people.

In his method, the laborious, time-consuming T-cell programming steps all take place within the body, creating a potential army of “serial killers” within days.

As reported in the new study, Stephan and his team developed biodegradable nanoparticles that turned T cells into CAR T cells, a particular type of cellular immunotherapy that has delivered promising results against leukemia in clinical trials.

The researchers designed the nanoparticles to carry genes that encode for chimeric antigen receptors, or CARs, that target and eliminate cancer. They also tagged the nanoparticles with molecules that make them stick like burrs to T cells, which engulf the nanoparticles. The cell’s internal traffic system then directs the nanoparticle to the nucleus, and it dissolves.

The study provides proof-of-principle that the nanoparticles can educate the immune system to target cancer cells. Stephan and his team designed the new CAR genes to integrate into chromosomes housed in the nucleus, making it possible for T cells to begin decoding the new genes and producing CARs within just one or two days.

Once the team determined that their CAR-carrying nanoparticles reprogrammed a noticeable percent of T cells, they tested their efficacy. Using a preclinical mouse model of leukemia, Stephan and his colleagues compared their nanoparticle-programming strategy against chemotherapy followed by an infusion of T cells programmed in the lab to express CARs, which mimics current CAR-T-cell therapy.

The nanoparticle-programmed CAR-T cells held their own against the infused CAR-T cells. Treatment with nanoparticles or infused CAR-T cells improved survival 58 days on average, up from a median survival of about two weeks.

The study was funded by Fred Hutch’s Immunotherapy Initiative, the Leukemia & Lymphoma Society, the Phi Beta Psi Sorority, the National Science Foundation and the National Cancer Institute.

Next steps and other applications

Stephan’s nanoparticles still have to clear several hurdles before they get close to human trials. He’s pursuing new strategies to make the gene-delivery-and-expression system safe in people and working with companies that have the capacity to produce clinical-grade nanoparticles. Additionally, Stephan has turned his sights to treating solid tumors and is collaborating to this end with several research groups at Fred Hutch.

And, he said, immunotherapy may be just the beginning. In theory, nanoparticles could be modified to serve the needs of patients whose immune systems need a boost, but who cannot wait for several months for a conventional vaccine to kick in.

“We hope that this can be used for infectious diseases like hepatitis or HIV,” Stephan said.  This method may be a way to “provide patients with receptors they don’t have in their own body,” he explained.  “You just need a tiny number of programmed T cells to protect against a virus.”

Penn Team Tracks Rare T Cells in Blood to Better Understand Annual Flu Vaccine

For most vaccines to work the body needs two cell types – B cells and T helper cells – to make antibodies. B cells are the antibody factories and the T helper cells refine the strength and accuracy of antibodies to home and attack their targets. A technique that identifies these helper immune cells could inform future vaccine design, especially for vulnerable populations.

Flu vaccines work by priming the immune system with purified proteins from the outer layer of killed flu viruses. An antibody is a protein that recognizes a unique pathogen molecule called an antigen that is specific for a particular strain. Antibodies bind to their targets with precision in the best of circumstances. In doing so, the antibody blocks a harmful microbe from replicating or marks it to be killed by other immune cells.

The level of antibodies in the blood tells immunologists how well a vaccine is working, specifically, how many antibodies are made and how strongly they disable microbes. The relatively scarce circulating T follicular helper cells, or cTfh for short, are key to antibody strength. Without Tfh, effective antibodies cannot be made, yet very little is known about cTfh cells in humans after vaccination.

Now, a team led by researchers from the Perelman School of Medicine at the University of Pennsylvania has found a way to identify the small population of cTfh present in the blood after an annual flu vaccine to monitor their contribution to antibody strength. They published their findings in Science Immunology this week. The studies, led by Ramin Herati, MD, an instructor of Infectious Disease, used high dimensional immune-cell profiling and specific genomic tests to identify and track these rare cells over time.

“The poor understanding of cTfh function is, in part, because these cells spend most of their time waiting in lymph nodes for the next infection, and not circulating in the blood,” said senior author E. John Wherry, PhD, a professor of Microbiology and director of the Institute of Immunology at Penn. “To get a handle on how well these cells are doing their job following vaccination, we have needed a way to measure their responses without gaining direct access to lymph nodes. Because of the central role of circulating T follicular helper cells in antibody development, new vaccine development strategies will benefit from a better understanding of the properties of these essential cells in the immune response.”

Molecular Bar Codes
Every T cell has a unique receptor on its outer surface. After receiving a vaccine, the result is one T cell with this unique bar code of sorts that replicates, making thousands of clones with identical copies of the same bar code. After vaccination this expansion of T cells dies down and a few clones remain behind. These memory cells wait it out in lymph nodes and other organs for the next time the infection or vaccine enters the body. These clones can then be called into action to protect the individual or help boost the vaccine immunity.

In the current study, the team was able to track circulating helper T cells because the unique bar code they possessed is specific to the strains used in an annual flu vaccine. Wherry and colleagues traced antibody production in 12 healthy subjects, aged 20 to 45 for three years from 2013 to 2105. The circulating subset of helper follicular T cells expressed different transcription factors and cytokines — Bcl-6, c-Maf, and IL-21 – compared to other T-cell subpopulations in the blood. The number of the cTfh cells sharply increased at seven days after a subject received a flu shot.

Repeated vaccination of the study participants brought back genetically identical clones of cTfh cells in successive years, indicating robust cTfh memory to the flu vaccine. These responses are a proxy for specific antibodies to the flu vaccine each year. In addition, these results measure the dynamics of vaccine-induced cTfh memory and recall over time, allowing investigators to monitor the key human-vaccine-induced cTfh responses and gain insights into why responses to flu vaccines are suboptimal in many people.

The ability to track these cTfh responses in the blood, instead of accessing lymph nodes in humans, allows for real-time monitoring of key cellular mechanisms involved in vaccination. Such knowledge should allow further optimization of vaccines for hard-to-treat diseases like the flu, but also HIV, and other infections in which inducing potent vaccines has been a challenge.

“These cTfh are a missing piece of being able to truly monitor and predict their ability to induce the desired magnitude and quality of immune memory, and therefore protection by vaccines,” Wherry said. The team next intends to look at elderly populations in which vaccines are not as effective and ask what role cTfh cell populations play in that part of the human population.

Co-authors are Alexander Muselman, Laura Vella, Bertram Bengsch, Kaela Parkhouse, Daniel Del Alcazar, Jonathan Kotzin, Susan A. Doyle, Pablo Tebas, Scott E. Hensley, Laura F. Su, and Kenneth E. Schmader.

 

Researchers Identify Possible Pathway to Reboot Immune System After Bone-Marrow Transplants

New research has shown how a cell surface molecule, Lymphotoxin β receptor, controls entry of T-cells into the thymus; and as such presents an opportunity to understanding why cancer patients who undergo bone-marrow transplant are slow to recover their immune system.

The study, published in the Journal of Immunology, used mouse models to reveal an in vivo mechanism that researchers believe might also represent a novel pathway for immunotherapeutic targeting to support patients following transplantation.

The thymus, which sits in front of the heart and behind the sternum, imports T-cell precursors from the bone marrow and supports their development into mature T-cells that fight off dangerous diseases.

T-cells are often the last cells to recover in cancer patients receiving bone marrow transplants. Though the cancer is cured, patients are often left with an impaired immune system that can take years to recover.

The Birmingham team, supported by US-based collaborators at The Sanford Burnham Medical Research Institute and The Trudeau Institute, found that Lymphotoxin β receptor was required to allow the entry of T-cell progenitors to the thymus both in a healthy state, and during immune recovery following bone-marrow transplantation.

Significantly, the team also found that antibody-mediated stimulation of Lymphotoxin β receptor in murine models enhanced initial thymus recovery and boosted the number of transplant derived T-cells.

Professor Graham Anderson, from the University of Birmingham, explained, “The thymus is often something of an ignored organ, but it plays a crucial role in maintain an effective immune system.”

“Post-transplantation, T-cell progenitors derived from the bone marrow transplant can struggle to enter the thymus, as if the doorway to the thymus is closed. Identifying molecular regulators that can ‘prop open’ the door and allow these cells to enter and mature, could well be a means to help reboot the immune system.”

Beth Lucas, also at the University of Birmingham, added, “This is just one piece of the puzzle. It may be that there are adverse effects to opening the door to the thymus, but identifying a pathway that regulates this process is a significant step.”

Following these positive findings the team aim to move towards in-vitro samples of human thymus to examine the role that Lymphotoxin  receptor might play in regulation of thymus function in man.

The research was funded by the Medical Research Council (MRC) and Cancer Research UK (CRUK), together with support from the Biotechnology and Biological Sciences Research Council (BBSRC) and Arthritis Research UK (ARUK).

St. Jude Researchers Reveal How Two Types of Immune Cells Can Arise From One

The fates of immune cells can be decided at the initial division of a cell. Researchers at St. Jude Children’s Research Hospital have discovered that the production of daughter cells with different roles in the immune system is driven by the lopsided distribution of the signaling protein c-Myc. Nudging c-Myc in one direction or the other could make vaccines more effective or advance immunotherapies for cancer treatment. The research appears online today in the scientific journal Nature.

Asymmetric cell division generates two types of cells with distinct properties. This type of cell division is essential for producing various cell types and plays an important role in development. Rather than producing two identical daughter cells, the cells undergoing asymmetric division produce daughter cells that are fated for vastly different roles. In the case of activated T cells, researchers knew that one daughter cell became the rapidly dividing effector T cells that launch the immediate attack on infectious agents and other threats. The other daughter cell became the slowly dividing memory T cells that function like sentries to provide long-term protection against recurring threats. Until now, the mechanism underlying the process was unknown.

“Our study shows that the way in which the regulatory protein c-Myc distributes during asymmetric cell division directly influences the fate and roles of activated T cells,” said corresponding author Douglas Green, Ph.D., St. Jude Department of Immunology chair. “We also show how this asymmetry is established and sustained.”

The researchers worked with cells growing in the laboratory and in mice. Scientists showed that during asymmetric cell division of activated T cells, high levels of c-Myc accumulated in one daughter cell. There, c-Myc functioned like a shot of caffeine to launch and sustain the rapid proliferation of effector T cells, including those in mice infected with the influenza virus. In contrast, the daughter cells with low levels of c-Myc functioned like memory T cells, proliferating to mount an immune response a month later when mice were again exposed to the virus.

Researchers also identified the metabolic and signaling pathways that serve as a positive feedback loop to sustain the high levels of c-Myc that effector T-cells require to maintain their identities and function. The scientists showed that disrupting certain components of the system disturbed c-Myc production, which altered the fate of T cells and caused effector T cells to operate like memory T cells.

“Our work suggests that it may be possible to manipulate the immune response by nudging production of c-Myc in one direction or the other,” Green said. “Potentially that could mean more effective vaccines or help to advance T-cell immune therapy for cancer treatment.”

c-Myc is an important transcription factor that regulates expression of a variety of genes and plays a pivotal role in cell growth, differentiation and death via apoptosis (programmed cell death). Excessive or inappropriate production of c-Myc is a hallmark of a wide variety of cancers. Previous research from Green and his colleagues showed that c-Myc also drives metabolic changes following T cell activation. The metabolic reprogramming fuels proliferation of effector T cells. “Activated T cells divide every four to six hours. There is no other cell in adults that can divide that fast, not even cancer cells,” Green explained.

In this study, the researchers observed several metabolic changes that arose from the way c-Myc partitioned in the cell. These metabolic changes help regulate the way the cells divide, proliferate and differentiate. In a series of experiments, researchers showed how manipulating that system could affect T cell fate following asymmetric cell division by modifying production of c-Myc. “While daughter cells of activated T cells seem to have very different fates, we showed their behavior could be altered by manipulating these metabolic and regulatory pathways to increase or decrease c-Myc levels.” Green said.

Asymmetric cell division is an important driver of other fundamental processes in cells, including early embryonic development and the self-renewal of stem cells.

“Similar control mechanisms exist in other cells that divide asymmetrically, including stem cells in the digestive and nervous systems,” he added.