New Tool Predicts Response to Immunotherapy in Lung Cancer Patients
Posted on by Douglas M. Sheeley, Sc.D., NIH Common Fund
With just a blood sample from a patient, a promising technology has the potential to accurately diagnose non-small cell lung cancer (NSCLC), the most-common form of the disease, more than 90 percent of the time. The same technology can even predict from the same blood sample whether a patient will respond well to a targeted immunotherapy treatment.
This work is a good example of research supported by the NIH Common Fund. Many Common Fund programs support development of new tools that catalyze research across the full spectrum of biomedical science without focusing on a single disease or organ system.
The emerging NSCLC prediction technology was developed as part of our Extracellular RNA Communication Program. The program develops technologies to understand RNA circulating in the body, known as extracellular RNA (exRNA). These molecules can be easily accessed in bodily fluids such as blood, urine, and saliva, and they have enormous potential as biomarkers to better understand cancer and other diseases.
When the body’s immune system detects a developing tumor, it activates various immune cells that work together to kill the suspicious cells. But many tumors have found a way to evade the immune system by producing a protein called PD-L1.
Displayed on the surface of a cancer cell, PD-L1 can bind to a protein found on immune cells with the similar designation of PD-1. The binding of the two proteins keeps immune cells from killing tumor cells. One type of immunotherapy interferes with this binding process and can restore the natural ability of the immune system to kill the tumor cells.
However, tumors differ from person to person, and this form of cancer immunotherapy doesn’t work for everyone. People with higher levels of PD-L1 in their tumors generally have better response rates to immunotherapy, and that’s why oncologists test for the protein before attempting the treatment.
Because cancer cells within a tumor can vary greatly, a single biopsy taken at a single site in the tumor may miss cells with PD-L1. In fact, current prediction technologies using tissue biopsies correctly predict just 20 – 40 percent of NSCLC patients who will respond well to immunotherapy. This means some people receive immunotherapy who shouldn’t, while others don’t get it who might benefit.
To improve these predictions, a research team led by Eduardo Reátegui, The Ohio State University, Columbus, engineered a new technology to measure exRNA and proteins found within and on the surface of extracellular vesicles (EVs) . EVs are tiny molecular containers released by cells. They carry RNA and proteins (including PD-L1) throughout the body and are known to play a role in communication between cells.
As the illustration above shows, EVs can be shed from tumors and then circulate in the bloodstream. That means their characteristics and internal cargo, including exRNA, can provide insight into the features of a tumor. But collecting EVs, breaking them open, and pooling their contents for assessment means that molecules occurring in small quantities (like PD-L1) can get lost in the mix. It also exposes delicate exRNA molecules to potential breakdown outside the protective EV.
The new technology solves these problems. It sorts and isolates individual EVs and measures both PD-1 and PD-L1 proteins, as well as exRNA that contains their genetic codes. This provides a more comprehensive picture of PD-L1 production within the tumor compared to a single biopsy sample. But also, measuring surface proteins and the contents of individual EVs makes this technique exquisitely sensitive.
By measuring proteins and the exRNA cargo from individual EVs, Reátegui and team found that the technology correctly predicted whether a patient had NSCLC 93.2 percent of the time. It also predicted immunotherapy response with an accuracy of 72.2 percent, far exceeding the current gold standard method.
The researchers are working on scaling up the technology, which would increase precision and allow for more simultaneous measurements. They are also working with the James Comprehensive Cancer Center at The Ohio State University to expand their testing. That includes validating the technology using banked clinical samples of blood and other bodily fluids from large groups of cancer patients. With continued development, this new technology could improve NSCLC treatment while, critically, lowering its cost.
The real power of the technology, though, lies in its flexibility. Its components can be swapped out to recognize any number of marker molecules for other diseases and conditions. That includes other cancers, neurodegenerative diseases, traumatic brain injury, viral diseases, and cardiovascular diseases. This broad applicability is an example of how Common Fund investments catalyze advances across the research spectrum that will help many people now and in the future.
 An immunogold single extracellular vesicular RNA and protein (AuSERP) biochip to predict responses to immunotherapy in non-small cell lung cancer patients. Nguyen LTH, Zhang J, Rima XY, Wang X, Kwak KJ, Okimoto T, Amann J, Yoon MJ, Shukuya T, Chiang CL, Walters N, Ma Y, Belcher D, Li H, Palmer AF, Carbone DP, Lee LJ, Reátegui E. J Extracell Vesicles. 11(9):e12258. doi: 10.1002/jev2.12258.
Video: Unlocking the Mysteries of Extracellular RNA Communication (Common Fund)
Extracellular RNA Communication Program (ERCC) (Common Fund)
Upcoming Meeting: ERCC19 Research Meeting (May 1-2, 2023)
Eduardo Reátegui Group for Bioengineering Research (The Ohio State University College of Engineering, Columbus)
Note: Dr. Lawrence Tabak, who performs the duties of the NIH Director, has asked the heads of NIH’s Institutes, Centers, and Offices to contribute occasional guest posts to the blog to highlight some of the interesting science that they support and conduct. This is the 27th in the series of NIH guest posts that will run until a new permanent NIH director is in place.
New Target for Cancer Immunotherapy: Exosomes
Posted on by Dr. Francis Collins
It was once a central tenet of biology that RNA molecules did their work inside the cell. But it’s now clear that RNA molecules are also active outside the cell, with potentially major implications for our health. To learn more about these unrecognized roles, the NIH Common Fund has launched the Extracellular RNA (exRNA) Communication Program.
This month, members of this research consortium described their latest progress in unraveling the secrets of exRNA in a group of 18 papers in the Cell family of journals. And it’s not just RNA that the consortium is studying, it’s also proteins. Among the many exciting results just published is the serendipitous discovery that proteins carried inside tiny, bubble-like vesicles, called exosomes, may influence a cancer’s response to immunotherapy . The work sheds light on why certain cancers are resistant to immunotherapy and points to new strategies for unleashing the immune system in the fight against cancer.
The new findings center on a type of immunotherapy drugs known as checkpoint inhibitors. They are monoclonal antibodies produced by industry that can boost the immune system’s ability to attack and treat cancer.
One of those antibodies specifically targets a protein, called PD-1, on the surface of certain immune cells. When PD-1 binds a similarly named protein, called PD-L1, on the surface of another cell, the interaction prevents immune cells from attacking. Some tumors seem to have learned this and load up on PD-L1 to evade the immune system.
That’s where checkpoint inhibitors come in. By blocking the interaction between PD-1 and PD-L1, the treatment removes a key check on the immune system, allowing certain immune cells to wake up and attack the tumor.
Checkpoint inhibitors work better in some cancer types than in others. In melanoma, for example, up to about 30 percent of patients respond to checkpoint inhibitor therapy. But in prostate cancer, response rates are in the single digits.
Researchers led by Robert Blelloch, a member of the exRNA consortium and a scientist at the University of California, San Francisco, wanted to know why. He and his team looked for clues in RNA within the cells taken from immunotherapy-resistant prostate cancers.
As published in Cell, the researchers got their first hint of something biologically intriguing in an apparent discrepancy in their data. As they expected from prior work, PD-L1 protein was present in the treatment-resistant cancers. But the PD-L1 messenger RNAs (mRNA), which serve as templates for producing the protein, told an unexpected story. The resistant cancer cells made far more PD-L1 mRNAs than needed to produce the modest levels of PD-L1 proteins detected inside the cells.
Where was the missing PD-L1? Blelloch’s team found it in exosomes. The cancer cells were packaging large quantities of the protein inside exosomes and secreting them out of the cell to other parts of the body.
In additional studies with a mouse model of prostate cancer, the researchers found that those PD-L1-packed exosomes travel through the blood and lymphatic systems to lymph nodes, the sites where immune cells become activated. Once there, PD-L1-laden exosomes put the immune system to sleep, preventing certain key cells from locating and attacking the cancer, including the primary tumor and places where it may have spread.
In important follow up studies, the researchers edited two genes in cancer cells to prevent them from producing exosomes. And, in the absence of exosomes, the cells no longer formed tumors. Importantly, both edited and unedited cells still produced PD-L1, but only those that exported PD-L1 in exosomes disarmed the immune system. Studies in a mouse model of immunotherapy-resistant colorectal cancer yielded similar results.
The new evidence suggests that blocking the release of PD-L1 in exosomes, even temporarily, might allow the immune system to launch a successful and sustained attack against a cancer.
Blelloch notes that many intriguing questions remain. For example, it’s not yet clear why antibodies that target PD-L1 on cancer cells don’t disable PD-L1 found in exosomes. The good news is that the new findings suggest it may be possible to find small molecules that do target PD-L1-packed exosomes, unleashing the immune system against cancers that don’t respond to existing checkpoint inhibitors. In fact, Blelloch’s team is already screening for small molecules that might fit the bill.
Since its launch about five years ago, the exRNA Communication Program has published an impressive 480 peer-reviewed papers, including the latest work in the Cell family of journals. I’d encourage readers to click on some of the other excellent work. I hear that another batch of papers will be published later this year.
 Suppression of exosomal PD-L induces systemic anti-tumor immunity and memory. Poggio M, Hu T, Pai CC, Chu B, Belair CD, Chang A, Montabana E, Lang UE, Fu Q, Fong L, Blelloch R. Cell. 2019 Apr 4;177(2):414-427.
Video: Unlocking the Mysteries of RNA Communication (Common Fund/NIH)
Immunotherapy to Treat Cancer (National Cancer Institute/NIH)
Blelloch Lab (University of California, San Francisco)
NIH Support: Common Fund; National Cancer Institute; National Center for Advancing Translational Sciences; National Heart, Lung, and Blood Institute; National Institute on Drug Abuse
exRNA: Helping Cells Get Their Message Out
Posted on by Dr. Francis Collins
When your email is interrupted or blocked, it creates havoc. Messages remain undelivered, stalling interactions between you and your friends, family, and colleagues at work. Likewise when communication fails between your body’s cells, disease can result. Scientists recently discovered a new group of molecules called extracellular RNA (exRNA) that appears to travel between cells to help them communicate. Now, NIH is encouraging researchers to explore the potential of these newly discovered messengers.