Deletion of key gene regulatory factors fortifies T cell attack on melanoma cells
A decade ago researchers announced development of a cancer immunotherapy called CAR (for chimeric antigen receptor)-T, in which a patient is re-infused with their own genetically modified T cells equipped to mount a potent anti-tumor attack.
Chimeric antigen receptor therapy. CAR molecules (light blue) bind to CD19 molecules on a cancer cell leading to segregation of granzyme vesicles (yellow) that activate apoptosis.
Credit: La Jolla Institute for Immunology
Usage Restrictions: Only in conjunction with articles describing this research.
Since then CAR T approaches (one of several strategies collectively known as "adoptive T cell transfer") have made headlines as a novel cellular immunotherapy tool, most successfully against so-called "liquid cancers" like leukemias and lymphomas.
Sarcomas and carcinomas have proven more resistant to these approaches, in part because engineered T-cells progressively lose tumor-fighting capacity once they infiltrate a tumor. Immunologists call this cellular fatigue T cell "exhaustion" or "dysfunction."
In efforts to understand why, La Jolla Institute for Immunology (LJI) investigators Anjana Rao, Ph.D., and Patrick Hogan, Ph.D., have published a series of papers over the last years reporting that a transcription factor that regulates gene expression, called NFAT, switches on "downstream" genes that weaken T cell responses to tumors and thus perpetrates T cell exhaustion.
One set of these downstream genes encodes transcription factors known as NR4A, and a previous graduate student, Joyce Chen, showed that genetic elimination of NR4A proteins in tumor-infiltrating CAR T cells improved tumor rejection. However, the identity of additional players cooperating with NFAT and NR4A in that pathway has remained unknown.
Now a paper published in this week's online edition of the Proceedings of the National Academy of Sciences (PNAS) from the Rao and Hogan labs provides a more complete list of participants in an extensive gene expression network that establishes and maintains T cell exhaustion.
The study employs a mouse model to show that genetically eliminating two new factors, TOX and TOX2, also improves eradication of "solid" melanoma tumors in the CAR T model. This work suggests that comparable interventions to target NR4A and TOX factors in patients may extend the use of CAR T-based immunotherapy to solid tumors.
The group began by comparing gene expression profiles in samples of normal versus "exhausted" T cells, searching for factors upregulated in parallel with NR4A as co-conspirators in T cell dysfunction. "We found that two DNA binding proteins called TOX and TOX2 were consistently highly expressed along with NR4A transcription factors," says Hyungseok Seo, Ph.D., a postdoctoral fellow in the Rao lab and the study's first author. "This discovery suggested that factors like NFAT or NR4A may control expression of TOX."
The group then recapitulated a CAR T protocol in mice by first inoculating animals with melanoma tumor cells to establish a tumor, and then a week later infusing mice with one of two collections of T cells: a "control" sample from a normal mouse, versus a sample derived from mouse genetically engineered to lack TOX and TOX2 expression in T cells.
Remarkably, mice infused with TOX-deficient CAR T cells showed more robust regression of melanoma tumors than did mice infused with normal cells. Moreover, mice treated with TOX-deficient CAR T cells exhibited dramatically increased survival, suggesting that loss of TOX factors combats T cell exhaustion and allows T cells to destroy tumor cells more effectively.
Additional analysis led the investigators down a pathway ending with a well-known immune adversary. The researchers showed that TOX factors join forces with both NFAT and NR4A to promote expression of an inhibitory receptor called PD-1, which decorates the surface of exhausted T cells and sends immunosuppressive signals.
PD-1 is blocked by numerous monoclonal antibodies called checkpoint inhibitors, which combat immunosuppression and activate an innate anti-cancer immune response. Convergence of TOX, NFAT, and NR4A on PD-1 makes molecular and immunological sense and puts it at the convergence of both cellular and antibody immunotherapy approaches.
"Currently, CAR T cell therapy shows amazing effects in patients with "liquid tumors" such as leukemia and lymphoma," says Seo. "But they still do not work well in patients with solid tumors due to T cell exhaustion. If we could inhibit TOX or NR4A by treating CAR T cells with a small molecule, this strategy might show a strong therapeutic effect against solid cancers such as melanomas."
The study was funded by NIH grants AI109842, AI040127, AI108651 and AI140095, GM007752, S10OD016262 and S10 RR027366. Other support came from an AACR-Genentech Immuno-oncology Research, a Donald J. Gogel Cancer Research Irvington Fellowship, a PhRMA Foundation Paul Calabresi Medical Student Research Fellowship and graduate student fellowships from CONACYT/UCMEXUS.
Full citation: Hyungseok Seo, Joyce Chena, Edahí Gonzàlez Avalosa, Daniela Samaniego Castruitaa, Arundhoti Dasg, Yueqiang H. Wang, Isaac F. López Moyadoa, Romain Georgesa, Wade Zhanga, Atsushi Onoderaa, Cheng-Jang Wuk, Li-Fan Luk, Patrick G. Hogan, Avinash Bhandoola and Anjana Rao. TOX and TOX2 cooperate with NR4A transcription factors to impose CD8+T cell exhaustion. PNAS, 2019. doi.: 10.1073/pnas.201905675
About La Jolla Institute
The La Jolla Institute for Immunology is dedicated to understanding the intricacies and power of the immune system so that we may apply that knowledge to promote human health and prevent a wide range of diseases. Since its founding in 1988 as an independent, nonprofit research organization, the Institute has made numerous advances leading toward its goal: life without disease.
Gina Kirchweger | EurekAlert!
First SARS-CoV-2 genomes in Austria openly available
03.04.2020 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften
Do urban fish exhibit impaired sleep? Light pollution suppresses melatonin production in European perch
03.04.2020 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Drops of water falling on or sliding over surfaces may leave behind traces of electrical charge, causing the drops to charge themselves. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz have now begun a detailed investigation into this phenomenon that accompanies us in every-day life. They developed a method to quantify the charge generation and additionally created a theoretical model to aid understanding. According to the scientists, the observed effect could be a source of generated power and an important building block for understanding frictional electricity.
Water drops sliding over non-conducting surfaces can be found everywhere in our lives: From the dripping of a coffee machine, to a rinse in the shower, to an...
90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous
An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...
The bacteria that cause tuberculosis need iron to survive. Researchers at the University of Zurich have now solved the first detailed structure of the transport protein responsible for the iron supply. When the iron transport into the bacteria is inhibited, the pathogen can no longer grow. This opens novel ways to develop targeted tuberculosis drugs.
One of the most devastating pathogens that lives inside human cells is Mycobacterium tuberculosis, the bacillus that causes tuberculosis. According to the...
An international team with the participation of Prof. Dr. Michael Kues from the Cluster of Excellence PhoenixD at Leibniz University Hannover has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.
A 15-member research team from the UK, Germany and Japan has developed a new method for generating and detecting quantum-entangled photons at a wavelength of...
Together with their colleagues from the University of Würzburg, physicists from the group of Professor Alexander Szameit at the University of Rostock have devised a “funnel” for photons. Their discovery was recently published in the renowned journal Science and holds great promise for novel ultra-sensitive detectors as well as innovative applications in telecommunications and information processing.
The quantum-optical properties of light and its interaction with matter has fascinated the Rostock professor Alexander Szameit since College.
02.04.2020 | Event News
26.03.2020 | Event News
23.03.2020 | Event News
03.04.2020 | Materials Sciences
03.04.2020 | Life Sciences
03.04.2020 | Life Sciences