Article Category: Research

Metastatic breast cancer has no cure and has proven stubbornly resistant to one of the most innovative and promising new cancer treatments: immunotherapy.

Now, researchers at Washington University School of Medicine in St. Louis have identified a way to treat the area surrounding breast tumors that have spread to bone so that such tumors become vulnerable to attack by the body’s immune system. When the researchers boosted the activity of certain immune cells, called T cells and macrophages, these immune cells worked together to clear metastatic breast tumors that had spread to the bones of mice, and continued to eliminate tumor cells that eventually returned.

The study is published March 8 in Cancer Discovery, a journal of the American Association for Cancer Research.

Macrophages are myeloid immune cells that attack cancer cells through the body’s innate immune response to general threats, such as tumors or viruses. Such macrophages further activate T cells by showing the T cells what they should be looking for, thereby harnessing the adaptive immune response as well. In this case, these macrophages present T cells with bits of recognizable tumor — called tumor antigens — from dead cancer cells, and the antigens direct the killing activities of T cells.

“After breast cancer has spread to other parts of the body, it becomes extraordinarily difficult to treat; current therapies can only try to slow it down,” said senior author Sheila A. Stewart, PhD, the Gerty Cori Professor of Cell Biology & Physiology. “About 70% of patients with metastatic breast cancer have tumors that have spread to their bones. Our study suggests we may be able to use two treatments — one to sensitize the myeloid tumor microenvironment to immunotherapy, and one to activate T cells — to target these bone metastases in a way that eliminates the tumor, prevents the cancer from returning and protects against bone loss in the process.”

Stewart, also a research member of Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine, and her colleagues found that blocking a molecule called p38MAPK reprograms the tumor microenvironment to become more vulnerable to attack by the immune system, including by immune cells and signaling molecules called anti-tumor cytokines. While a p38MAPK inhibitor alone reduced tumor size, it didn’t eliminate the tumor entirely. So, the researchers investigated whether adding another therapy that activates T cells and boosts their ability to find and destroy the tumor cells could be more effective at eliminating the metastatic cancer cells.

Common immunotherapies — called immune checkpoint inhibitors — are often described as “taking the brakes off” immune T cells, ushering them into battle against cancer. In this case, Stewart described the new approach as “hitting the gas” on T cells, supercharging them to be more effective against the cancer.

The researchers investigated two models of human metastatic breast cancer in mice and found that the metastatic tumors were eliminated in mice that received a p38MAPK inhibitor and an immune therapy called an OX40 agonist, which binds and activates T cells. All these mice were still alive and tumor-free at least 80 days after treatment. Among mice receiving either of the two treatments alone, only about half of them were still alive 60 days after treatment.

“If we targeted the microenvironment to make it more sensitive to T cells and simultaneously hit the gas on the T cells, all of the mice were cleared of the metastatic tumors,” Stewart said. “If we came back after two weeks and challenged the mice again with the same tumor cells, their immune systems could clear those cells as well. It appears that their immune systems developed long-term memory and knew to attack those returning cancer cells. The mice look like they’re basically vaccinated against the cancer.”

Three different OX40 agonists are being investigated in phase 2 clinical trials for cancer, including breast cancer. And p38MAPK inhibitors have been investigated in a number of inflammatory disorders, including rheumatoid arthritis and chronic obstructive pulmonary disease.

“We are hopeful that our study will interest companies that make these drugs, so that we can work toward developing a clinical trial that could investigate this strategy in patients with metastatic breast cancer,” Stewart said.

Jumping genes are short sections of DNA that have been incorporated randomly into the human genome over the long course of evolution. Also called transposable elements, these pieces of DNA have been implicated in the development of cancer.

But new research from Washington University School of Medicine in St. Louis suggests that transposable elements in various cancers potentially may be used to direct novel immunotherapies to tumors that don’t typically respond to immune-based treatments.

The study is available online in the journal Nature Genetics.

Immunotherapy is often most effective in tumors with numerous mutations, such as skin and lung cancers. Mutations in DNA cause cancer cells to produce unusual proteins that distinguish tumor cells from normal cells and serve as targets — called tumor antigens — for immunotherapies, such as antibodies, vaccines and genetically engineered CAR-T cell therapies. But many tumor types don’t contain large numbers of mutations and are therefore harder for the immune system to identify as a threat.

“Immunotherapy is an extremely promising approach for cancer treatment, but current therapies don’t work in many tumor types in which the mutation burden is low,” said senior author Ting Wang, PhD, the Sanford C. and Karen P. Loewentheil Distinguished Professor of Medicine. “We are excited about this research, because it opens up an entirely new way to identify tumor antigens in types of cancer that have previously been invisible to immunotherapy.”

Jumping genes — believed to have possibly originated from viruses — usually are found in parts of the genome that are inactive in adult tissues. But past work by Wang and his colleagues showed that these transposable elements sometimes can function as hidden on switches, forcing a gene to be turned on all the time, even though it should not be. As these stealthy on switches drive cancer growth, they also can churn out unusual pieces of proteins that are unique to the tumor and not present in normal cells.

In an analysis of 33 tumor types from the National Cancer Institute’s The Cancer Genome Atlas Program, the researchers identified 1,068 transposable element-derived transcripts — or sections of RNA made by the cancer cells — with the potential to produce tumor antigens that could serve as targets for new immunotherapies.

Wang and his colleagues determined that these possible tumor antigens were present on the surfaces of cancer cells, making them ideal for targeting with immunotherapies. Importantly, they found that almost 98% of the more than 10,000 tumors analyzed had at least one potential antigen target arising from a transposable element. Most tumors had from two to 75 possible antigens.

In another important finding, the researchers showed that many of the candidate proteins that could serve as antigens were present in multiple tumors and, in some cases, across tumor types. Wang and his colleagues speculated that this raises the possibility of a universal antigen-based therapy that could treat multiple tumors with a single cocktail targeting several of the most common tumor antigens that arise from jumping genes. For example, the data suggest that a vaccine with a combination of 20 of the most common protein targets could cover about 75% of patients across 27 cancer types.

“With this analysis, we can envision the design of a cancer vaccine that targets the top five or top 10 most common tumor proteins that are caused by transposable elements,” said Wang, also a research member of Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. “This type of vaccine is still just an idea, but we are excited about the potential, because these common targets could cover a large fraction of tumors. Much more work is necessary, but we are hopeful that this analysis can serve as a starting point for the development of effective immunotherapies across many more cancer types.”

Immunotherapy has transformed cancer care. In advanced melanoma, for example, the most fatal form of skin cancer, the five-year survival rate has risen from less than 10% to more than 50% since immunotherapy was introduced in 2011. Still, only about half of melanoma patients respond to immunotherapy, and those who do not respond face a difficult future.

Researchers at Washington University School of Medicine in St. Louis have discovered that the difference between people who do and do not respond to immunotherapy may have to do with an immune cell known as CD5+ dendritic cells because they bear the protein CD5 on their outer surfaces. Their research showed that people with a variety of kinds of cancers, including melanoma, lived longer if they had more CD5+ dendritic cells in their tumors, and that mice that lacked CD5 on their dendritic cells were unable to respond well to immunotherapy.

The findings, published Feb. 17 in the journal Science, suggest that a supplementary therapy designed to increase the number or activity of CD5+ dendritic cells potentially could extend the lifesaving benefits of immunotherapy to more cancer patients.

“Immunotherapy has revolutionized the field of cancer therapy, but there are a lot of patients with cancer who don’t benefit from it,” said senior author Eynav Klechevsky, PhD, an assistant professor of pathology & immunology and a researcher at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. “Part of the reason some people do not respond well to some forms of immunotherapy is because this population of dendritic cells is reduced dramatically. We’re developing some novel immune-based approaches to boost the activation of these CD5-expressing dendritic cells with a goal of helping more patients respond to immunotherapy.”

The immune system defends the body against cancer by activating immune cells known as T cells to recognize and kill tumor cells. In response, tumor cells manipulate the immune checkpoint system — a safeguard that prevents T cells from mistakenly attacking healthy cells — to hoodwink T cells into leaving them alone. Immune checkpoint blockade therapy works by thwarting tumor cells’ manipulations, thereby freeing T cells to recognize and destroy tumors. But even with therapy, some people’s T cells are unable to do their job effectively.

Klechevsky and colleagues — including first author Mingyu He, PhD, a staff scientist, and co-author Kate Roussak, MD, a postdoctoral researcher — suspected that people who don’t respond to immunotherapy may have a problem with their dendritic cells. If T cells are the players on a soccer field, dendritic cells are the coaches who get the players pumped up for the game and give them instructions. Without dendritic cells, T cells are subdued and aimless.

By analyzing data in The Cancer Genome Atlas — a public database with information on 20,000 tumors representing 33 cancer types — Klechevsky and colleagues discovered that patients with types of skin, lung, bone and soft tissue, breast and cervical cancers fared better if they had higher levels of CD5+ dendritic cells in their tumors.

Further experiments with human cells and mice showed that CD5+ dendritic cells are required for effective T cell activity against tumors. CD5+ dendritic cells from people powerfully induced T cells to activate and multiply. Mice with tumors responded only weakly to immunotherapy and failed to reject the tumors if they lacked CD5 on their dendritic cells.

The findings suggest that the amount of CD5+ dendritic cells inside tumors could be used to help doctors assess which patients are most likely to benefit from immunotherapy. They also suggest that increasing the numbers or the activity of such dendritic cells potentially could help more people benefit from immunotherapy. As part of this study, the researchers discovered that the immune protein IL-6 increases the amounts of CD5+ dendritic cells.

“We still don’t completely understand how immunotherapies work,” Klechevsky said. “This study indicates that there is more we can do to increase the efficacy of these treatments. I’m confident that if we can find ways to harness these cells or expand these cells in patients, we can help more people.”

A single drug compound simultaneously attacks hard-to-treat prostate cancer on several fronts, according to a new study in mice and human cells. It triggers immune cells to attack, helps the immune cells penetrate the tumor, and cuts off the tumor’s ability to burn testosterone as fuel, according to new research from Washington University School of Medicine in St. Louis. The drug may offer a promising new strategy for treating patients whose tumors don’t respond to standard therapy.

The study appears online in the journal Nature Communications.

Prostate cancer is notorious for eventually developing resistance to standard treatments that block or reduce testosterone, which fuels growth of these tumors. And like many solid tumors, prostate cancer also has proven stubbornly resistant to newer immunotherapies, which are intended to take the brakes off the immune system’s T cells to get them fighting cancerous invaders. Immunotherapies — most commonly, immune checkpoint inhibitors — can be extremely effective but only in certain cancers, such as melanoma.

“We need to develop better therapies for prostate cancer patients, because most of these tumors develop resistance to hormone-based therapies doctors rely on to treat these cancers,” said senior author Nupam P. Mahajan, PhD, a professor of surgery. “Immunotherapy is the newest and most promising type of therapeutic for cancer right now, but even so, immune checkpoint inhibitors have failed to do much against most solid tumors, including prostate cancer. This study was surprising because we found that this drug activates anti-cancer T cells in a novel way, and it also increases the T cells’ ability to penetrate the tumor. This could lead to a more effective strategy for patients whose cancers are hard to treat.”

The drug, called (R)-9b, is a small molecule that blocks an oncogene, a gene that drives cancer. The researchers initially attributed the drug’s success in mouse studies to its ability to reduce or eliminate androgen receptors in the prostate cancer cells. These receptors bind to testosterone and use the hormone to fuel tumor growth. The drug’s ability to eliminate the androgen receptor differs from standard drugs that reduce the amount of testosterone in the body, and other drugs that block the androgen receptor’s function as a transcription regulator.

But because the new drug was so effective, Mahajan and his colleagues suspected something more was going on. The drug blocks a gene called ACK1. The researchers developed a strain of mice that totally lacked this gene in order to study what happens when it’s missing. At first, the researchers were baffled by these mice. Mice missing an entire gene often have obvious problems. But these mice seemed fine. And when the researchers looked for tumor growth, they found very little. It was difficult to model cancer in these animals.

“In most of these mice, when we introduced cancer cells as we typically do, there was no trace of a tumor,” said Mahajan, also a research member of Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. “In the few that did develop tumors, the tumors were small compared to those of wild-type mice. This was the first clue that something important was happening in mice missing this gene. We found that they were able to mount a robust immune response against the cancer cells.”

When different mice — mice with this gene — were implanted with human prostate tumors and given the drug that blocks this gene, it had the same effect: taking the brakes off the immune system and producing increased levels of certain types of T cells known to attack cancer. The drug also increased signaling molecules that allow the T cells to penetrate the tumor and kill cancer cells more effectively. The tumors in these (R)-9b treated mice were much smaller than those of mice in control groups.

Given the drug’s success in tumor penetration, the researchers investigated whether adding immune checkpoint inhibitors to treatment with the drug would be even more effective, taking the brakes off T cells in more than one way at the same time — but there was no such improvement.

“Surprisingly, we found that the immune checkpoint inhibitor is activating ACK1, the very pathway we are shutting down with this drug compound,” Mahajan said. “It’s possible immune checkpoint inhibitors don’t work well in these tumors because they are turning on ACK1, which suppresses the immune response. Similar to prostate cancer, the ACK1 pathway activation also could be employed by other cancers that do not respond to checkpoint inhibitors. However, these cancers could respond to (R)-9b, so we would like to investigate this drug in other solid tumors as well.”

Mahajan said the drug spurs multiple responses because of the nature of the gene it blocks. Many genes have several roles in the body, and ACK1’s roles in expression of the androgen receptor and in reigning in the immune system make it an appealing target for cancer therapy, especially against solid tumors with a hormonal growth component, such as prostate and breast cancers.

Mahajan has worked with Washington University’s Office of Technology Management/Tech Transfer to file patents on the use of this drug in cancer treatment. His team is gathering data to apply for permission from the Food and Drug Administration to test the drug in a clinical trial for patients with prostate cancer.

Glucose, a common sugar in food, is one of the most important nutrients in the body. Cancer cells tend to consume it at an astounding pace. At first glance, that seems to make good sense because cancer cells have a lot of synthesis to do. After all, as tumors grow rapidly, each cell has to replicate its entire contents.

But here’s the catch. Cancer cells don’t use the glucose very efficiently. Instead of sucking all of the energy they can out of glucose, they release most of it as a waste material.

“To extract the maximum amount of energy from glucose, cells must transport its transformation products into mitochondria,” said Gary Patti, the Michael and Tana Powell Professor of Chemistry in Arts & Sciences and of genetics and of medicine at the School of Medicine. Patti, a member of Siteman Cancer Center at Barnes-Jewish Hospital and the School of Medicine, is senior author of the new study

“There are certain biochemical rules that metabolism is supposed to follow. It’s been interesting to think about why tumors might be allowed to break them,” Patti said. “However, the findings we report here demonstrate that cancer cells do follow conventional principles.”

Overflowing

Mitochondria are tiny compartments inside cells, often referred to as the cell’s power plants or powerhouses. What goes in and out of them is tightly controlled.

As a bit of backstory, a famous biochemist named Otto Warburg first discovered the wasteful nature of tumors in the 1920s. To explain why more energy isn’t harvested from glucose, he postulated that mitochondria are damaged in cancer cells.

“We now know that this is not true. Mitochondria are functional and, in fact, active in most cancers,” Patti said. But that leaves a persistent and vexing question unanswered: Why do cancer cells metabolize so little of the glucose they consume in mitochondria?

“I think what has been confounding is that there has been this notion that cancer cells prefer not to oxidize glucose in their mitochondria,” Patti said. “Perhaps as a legacy of Warburg’s original thinking or maybe because it happens so extensively, the assumption has often been that cancer cells want to use glucose wastefully.”

All sorts of explanations have been offered as to why cancer cells might want to be wasteful with their glucose. However, Patti and his team contend that these rationalizations may be unnecessary. In the end, cancer metabolism may not be as unusual as scientists thought.

Cancer cells really do want to metabolize glucose in their mitochondria, and they do so. Until they can’t.

“When we restrict the amount of glucose taken up by cancer cells, almost all of it makes its way into mitochondria,” Patti said. “But as glucose consumption is increased, the speed of moving glucose-derived molecules into mitochondria can’t keep up.”

In other words, cancer cells only waste glucose away because transport into mitochondria is too slow.

Imagine a bathtub faucet that is spitting out water faster than the drain can remove it. Eventually, the water overflows onto the floor.

“This is not a radically new metabolic paradigm. Most cells do prefer to oxidize glucose in mitochondria rather than excrete it as waste,” Patti said. “Our data suggest that cancer cells are not an exception. They appear to follow the same biochemical patterns as other cells.”

Saturated

The Patti team’s discovery was made possible by a powerful technology called metabolomics.

“During the past decade, advances in the field of metabolomics and mass spectrometry have been extraordinary,” Patti noted. “We have now reached a point where measuring molecules in single cells is even possible.”

In this study, the researchers combined metabolomics with stable isotope tracers. This allowed them to tag different parts of glucose so that they could track it inside of cells, watching the speed at which things entered mitochondria or were excreted from cells. That is how the scientists discovered that the normal pathways for transporting fuel were getting outpaced, or saturated, in cancer cells.

The rate at which tumors consume glucose has been exploited by doctors in the clinic for decades as a way to diagnose cancer and identify its stage. It also has led some to believe that limiting glucose uptake with drugs or by eating a sugar-free diet might “starve” the cancer cells to death.

This study’s findings raise questions about such a strategy.

“We may need to rethink how best to target glucose metabolism in cancer,” Patti said. “If cancer cells take up more glucose than they need, and using it wastefully is not a driver of disease, then glucose metabolism may not be as attractive of a therapeutic target as we had hoped.”

Pancreatic cancer is one of the most aggressive and deadly tumor types and notorious for its resistance to virtually all types of treatment, including newer immunotherapies.

A new study — in mice — from Washington University School of Medicine in St. Louis suggests that blocking a major inflammatory pathway that is activated in pancreatic cancer makes the tumors sensitive to chemotherapy and a type of immunotherapy that prompts the immune system’s T cells to attack the cancer cells. The therapy more than doubled survival in a mouse model of pancreatic cancer.

The study’s results, published March 7 in the journal Gastroenterology, lend additional support for the rationale behind a new national clinical trial that will evaluate the same treatment strategy in patients with pancreatic ductal adenocarcinoma — the most common malignant tumor of the pancreas. The researchers plan to enroll about 50 patients nationwide.

Washington University researchers at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine will lead the national trial that is part of the National Cancer Institute’s (NCI) Experimental Therapeutics Clinical Trials Network, a collaboration of industry, academic medical centers and researchers focused on early clinical investigations of innovative cancer therapies. The network includes more than 30 clinical sites in the U.S. and Canada.

“Washington University has a lot of strengths in bringing science from the lab to the clinic,” said senior author Kian-Huat Lim, MD, PhD, an associate professor of medicine and principal investigator for translational science on the national trial. “With this therapy, we are going after a pathway that we know is involved in driving the aggressiveness of pancreatic cancer. The results of this study are promising in that it showed a way to break through the defenses of this tumor type, making it susceptible to our therapeutics, including combinations of chemotherapy and newer immunotherapies that stimulate T cells to fight the cancer.”

The researchers, including first author Vikas Somani, PhD, a postdoctoral research associate in Lim’s lab in the Division of Oncology in the Department of Medicine, found that a protein called IRAK4 drives inflammation in pancreatic tumors and leads to T cell exhaustion, meaning the T cells can’t function as they should to attack harmful cells, including cancer. The researchers tested an IRAK4 inhibitor, called CA-4948, and found that the treatment reduced inflammatory signaling in the tumors in mice and improved the ability of T cells to infiltrate the tumors and kill pancreatic cancer cells. The therapy also sensitized the tumors to a type of immunotherapy called checkpoint immunotherapy, which “take the brakes off” T cells, improving their ability to attack tumor cells.

The researchers found that the IRAK4 inhibitor shuts down a key pathway called NF-kappaB, which has long been known for its roles in driving cancer. Much research is focused on shutting down this pathway and its downstream effects after it becomes activated. A novel element of this therapy is that the IRAK4 inhibitor prevents the harmful pathway from becoming activated in the first place.

In mice with a common aggressive model of pancreatic cancer, the researchers found that the IRAK4 inhibitor alone increased survival compared with a placebo or chemotherapy. In combination, the IRAK4 inhibitor plus chemotherapy increased survival further compared with placebo or chemotherapy alone. In addition, when combined with two immunotherapies, the IRAK4 inhibitor significantly extended survival from an average of 25 days with the inhibitor alone to an average of 46 days with the inhibitor plus immunotherapy combination. Some of the mice survived as long as 100 days on the combination therapy.

The IRAK4 inhibitor is already in national clinical trials investigating its use against blood cancers.

“We look forward to beginning the national clinical trial of this drug in patients with pancreatic cancer — the trial is a direct translation of this particular paper,” said Haeseong Park, MD, an associate professor of medicine and principal investigator of the new trial. “We are excited to be working with the NCI and clinical sites in the Experimental Therapeutics Clinical Trials Network so that we can harness our innovative homegrown science and bring it to the national level.”

Soon, Park’s team also will begin a single-center trial at Siteman Cancer Center to test the safety and efficacy of the IRAK4 inhibitor CA-4948 in gastric cancer.

Glioblastoma, an aggressive cancer in the brain or spinal cord, has proven stubbornly resistant to newer immunotherapies. And radiation and chemotherapy, the standard treatment for glioblastoma, result in fewer than 10% of patients surviving longer than five years after diagnosis.

But a new study from researchers at Washington University School of Medicine in St. Louis shows that treatment with an immune-boosting protein called interleukin 7 (IL-7) in combination with radiation improves survival in mice with glioblastoma. The new mouse study shows that IL-7 increases the number of T cells in the tumor and other immune organs. Such immune cells can then attack the cancer cells and improve survival.

The findings are published Jan. 14 in Clinical Cancer Research, a journal of the American Association for Cancer Research.

The study in mice suggests promise for a phase 1/2 clinical trial at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis that is investigating a long-acting type of IL-7 in patients with glioblastoma.

Radiation in combination with chemotherapy is the standard of care for various cancers including glioblastoma. Although beneficial against cancer, these treatments also can impair patients’ T cells, known as lymphocytes, that are important for fighting infections. Many glioblastoma patients have low levels of T cells. Glioblastoma patients who have chronically low lymphocyte counts don’t survive as long as patients with higher numbers of these T cells.

“Previously, a multicenter study from the American Brain Tumor Consortium showed a six-month shorter survival for patients with low versus normal numbers of T cells,” said first author Jian L. Campian, MD, PhD, who conducted the research at Washington University School of Medicine and the Brain Tumor Center at Siteman. “We knew that glioblastoma patients with low lymphocytes surprisingly also have low IL-7, which is a growth factor that supports T cells. Normally, people with low T cells should have a high level of IL-7. We wanted to find out if giving IL-7 to patients could increase the numbers of T cells and, in the process, have a positive impact on survival.”

The researchers found that mice with glioblastoma tumors treated with a combination of chemotherapy, radiation and IL-7 lived longer than mice that received only chemotherapy and radiation. On average, control mice that received no treatment lived about 20 days after tumor implantation. The mice that received IL-7 alone lived about 30 days, and those that received radiation alone lived about 35 to 40 days. The mice that received a combination of radiation and IL-7 lived at least 40 days, and many were still alive at 90 days. The longest survival was in the mice that received the triple combination of chemotherapy, radiation and IL-7, most of which lived at least 45 days, with many still alive at the 90-day mark.

“It’s difficult to know how these increases in survival in mice might translate to people,” said co-senior author Milan Chheda, MD, an associate professor of medicine. “If many of these mice are surviving at least three months by adding IL-7, we’re hoping to see some type of improvement in our patients who are treated with IL-7. As a basis for comparison, the chemotherapy given for glioblastoma is called temozolomide, and it was first approved because it improved patient survival by an average of slightly over two months.”

In addition to increasing T cell numbers in the tumor and the tumor’s environment, IL-7 treatment increased T cells in the blood and immune organs, including the thymus, spleen and lymph nodes, the investigators found. The therapy also reduced T regulatory cells, which are known to suppress the immune system in the microenvironment of brain tumors.

“We are encouraged by the results we are seeing in the mice,” said senior author Dinesh Thotala, PhD, an associate professor of radiation oncology. “We also see evidence that IL-7 could be considered as a replacement for temozolomide, especially among the nearly 70% of patients who have a type of tumor that does not respond well to this chemotherapy.”

The researchers explained that current immunotherapies called immune checkpoint inhibitors work by taking the brakes off immune cells that are already present. Since so many glioblastoma patients have depleted T cell numbers, it is perhaps not surprising that immune checkpoint inhibitors have not proven effective.

“If we are able to increase the number of T cells by giving IL-7, we would like to find out if adding immune checkpoint inhibitors would then increase T cell activity against the cancer cells,” said Chheda, who treats patients at Siteman Cancer Center.

Campian, who is now with the Mayo Clinic, said the researchers have plans to launch a follow-up study in glioblastoma patients at Washington University and the Mayo Clinic to determine whether combining immune checkpoint inhibitors with long-acting IL-7 boosts survival.

An immunotherapy based on supercharging the immune system’s natural killer cells has been effective in treating patients with recurrent leukemia and other difficult to treat blood cancers. Now, researchers at Washington University School of Medicine in St. Louis have shown in preclinical studies conducted in mice and human cells that this type of cell-based immunotherapy also could be effective against solid tumors, starting with melanoma, a type of skin cancer that can be deadly if not caught early.

The study is published June 29 in Clinical Cancer Research, a journal of the American Association for Cancer Research.

In recent years, an immunotherapy called immune checkpoint inhibitors has revolutionized treatment for advanced melanoma. In one well-known example, this immunotherapy was successfully used to treat former President Jimmy Carter, whose melanoma had spread to his liver and brain.

But the therapy only works in about half of such patients. And even among those who respond well to the initial therapy, about half go on to develop resistance to it. Consequently, researchers have been seeking different ways to harness the immune system to attack melanoma cells. One possibility is to use natural killer (NK) cells, a part of the immune system’s first line of defense against dangerous cells, whether cancer cells or invading bacteria.

Todd A. Fehniger, MD, PhD, a professor of medicine, and his team have had success in clinical trials treating recurrent leukemia with a patient’s own natural killer cells or those from a donor. The NK cells are harvested from the patient’s or a donor’s blood and exposed to a set of chemical signals called cytokines that activate the cells and prime them to remember this activation. When these “cytokine-induced memory-like” NK cells are given to the patient, they are more potent in attacking the cancer because they already have been revved up, as Fehniger puts it.

“These ‘revved-up’ memory-like NK cells attack blood cancers quite well,” said Fehniger, the study’s co-senior author and an oncologist who treats patients at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. “But relatively little work has been done on whether these cells can be used against solid tumors. This is an unmet need in solid tumor oncology. Our study provides proof of principle that memory-like NK cells respond better than normal NK cells against melanoma, and it serves as a stepping stone to a first-in-human clinical trial of these cells in advanced melanoma.”

Added co-senior author Ryan C. Fields, MD, the Kim and Tim Eberlein Distinguished Professor of Surgical Oncology: “We hope this is also a step toward harnessing NK cells against multiple solid tumors. Melanoma was a good place to start because we know it responds to immune therapy. But because many patients don’t respond or develop resistance, we felt that targeting a different aspect of the immune system was a promising strategy to pursue.”

The standard checkpoint inhibitor immunotherapy that works well in some melanoma patients targets T cells, another type of immune cell that also frequently is harnessed against different forms of cancer. According to the researchers, patients who don’t respond well or stop responding to the T cell-based standard therapy and have no other options would be good candidates for NK cell therapy.

The researchers studied human NK cells from both healthy people and from patients with melanoma and found that the cytokine-induced memory-like NK cells could effectively treat mice harboring human melanoma tumors. Tumors shrank to the point of being almost undetectable in many of the mice, and the memory-like NK cells prevented the tumors from returning in most cases for the duration of the 21-day experiment. While normal NK cells also reduced and controlled melanoma tumors, they did not do so to the same degree.

“We are currently designing a clinical trial to evaluate these NK cells in patients with advanced melanoma who have exhausted all other treatment options,” Fehniger said. “We would like to investigate NK cells from a donor and, separately, a patient’s own NK cells to see if the cytokine-induced memory-like NK cells offer an effective treatment option for patients with this aggressive skin cancer.”

The NK cell-based immunotherapy is potentially safer than other cell-based immunotherapies because the NK cells do not trigger a cytokine storm, as is seen sometimes in CAR-T cell therapy, which often is used for blood cancers, nor do the NK cells cause graft-versus-host disease, which sometimes follows a stem cell transplant.

“Even 10 years ago, we had no effective therapies for advanced melanoma — much like the lack of therapies for glioblastoma or advanced pancreatic cancer today,” said Fields, a surgeon who treats patients at Siteman. “Checkpoint immunotherapy has revolutionized melanoma treatment, but we’re still not satisfied with the 50% response rate. We want to do better, and this NK cell therapy is a promising approach. And in the future, we may be able to combine an NK cell-based therapy with checkpoint inhibition for an even better response.”

Fehniger and his colleagues have worked with Washington University’s Office of Technology Management to license the cytokine-induced memory-like NK cell technology to a company called Wugen. Fehniger is a co-founder of Wugen and serves on its scientific advisory board.

A blood test developed at Washington University School of Medicine in St. Louis could help determine next steps for patients whose prostate cancer has spread despite treatment.

The test is designed to help doctors determine if a patient’s disease can’t be effectively treated with a newer therapy called androgen receptor (AR) targeted therapy. Knowing this, a patient could decide whether to pursue a more traditional, and potentially more beneficial, therapy.

Results of a study evaluating whether the test can accurately predict treatment resistance suggest the technology is promising, and the researchers are continuing to refine it.

Second leading cause of cancer death

Prostate cancer is the second leading cause of cancer death in American men, and it is estimated that one in every 41 will die of prostate cancer. The most deadly form of the disease is treatment-resistant metastatic prostate cancer, which grows despite treatment and may not be sensitive to drugs that target the androgen receptor pathway. One way to identify these high-risk patients is by tracking an alteration in the blood called AR-V7.

“Although noninvasive, this previous approach has suboptimal sensitivity, meaning that it missed some patients with treatment-resistant metastatic disease,” Chaudhuri said.

The current research builds on prior work by Chaudhuri, and by Dang and Maher. Chaudhuri previously showed that cell-free DNA-based liquid biopsies can detect minimal areas of cancer that remain, after treatment. Dang and Maher showed that advanced prostate cancers have distinct tumor genomic profiles. Together, they embarked to develop a test combining their expertise, which resulted in EnhanceAR-Seq.

“We believe our strategy significantly advances the field by monitoring the most impactful mutations to predict treatment response while maximizing the patient population that may benefit from EnhanceAR-Seq,” Maher said.

The researchers compared results from EnhanceAR-Seq with the AR-V7 blood test and showed that EnhanceAR-Seq was far more sensitive.

“While the clinical blood test for AR-V7 was an important advancement in the prostate cancer biomarker world, our EnhanceAR-Seq really takes liquid biopsies to the next level,” Pachynski said. “With vastly improved sensitivity and specificity over the current standard-of-care AR-V7 test, we are able to better detect resistance to treatment earlier.”

“EnhanceAR-Seq was good at detecting secondary resistance too,” Chauhan said. “Sensitivity of detection went up further as we monitored some patients over time, suggesting this could really help the clinician.”

The researchers believe that their method, which requires a simple blood draw, could be made even simpler in the future.

“EnhanceAR-Seq could potentially be adapted to urine too, something we are investigating in the lab,” Chaudhuri said.

“Ultimately, our goal with this is to personalize prostate cancer treatment choices at the earliest time points, to improve outcomes for these patients,” Pachynski said. “I see EnhanceAR-Seq as playing an important role, though future studies need to be done to validate our work here and show that it improves clinical decision-making for our high-risk metastatic patients.”

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Participant samples were analyzed as part of the “Circulating Tumor DNA (ctDNA) for Early Treatment Response Assessment of Solid Tumors” study (ClinicalTrials.gov Identifier: NCT04354064). This work is supported by the Alvin J. Siteman Cancer Research Fund, National Cancer Institute, Cancer Research Foundation, an American Cancer Society Institutional Research Grant, a Sidney Kimmel Scholar Award, the Galen Hoskin and Dina Wolkoff Giving Fund and the Prostate Cancer Foundation.

A new study that reveals the dozens of molecular changes that bring about endometrial cancer offers insight into how physicians might be able to better identify which patients will need aggressive treatment and why a common treatment is not effective for some patients.

The study appears Feb. 13 in the journal Cell.

Funded by the National Cancer Institute, the study also suggests a potential role for already approved drugs that target proteins newly implicated in this disease also commonly known as uterine cancer.

“This study reveals a new dimension of endometrial cancer and moves us closer to identifying new therapeutic targets,” said co-senior author Li Ding, PhD, a professor of medicine at Washington University School of Medicine in St. Louis and a research member of Siteman Cancer Center. “Cancer mutations affect proteins, which are the functional units inside cells. We now have the capacity to understand in detail what the genetic mutations are doing inside the cancer cells, and that can serve as a basis for new treatment strategies.”

The paper builds on work by The Cancer Genome Atlas (TCGA) which identified the genetic underpinnings of the disease in 2013.

“This is like the Google Earth of endometrial cancer,” said Karin Rodland, PhD, of the Department of Energy’s Pacific Northwest National Laboratory (PNNL). “It’s a very comprehensive portrait of this particular cancer type. We tried to measure everything we possibly could. Then we searched for patterns.”

Ding and Rodland are two of five corresponding authors of the paper; David Fenyo, PhD, of New York University School of Medicine is the senior corresponding author. Other corresponding authors are with the Baylor College of Medicine and PNNL. Overall, scientists from more than a dozen institutions contributed to the project.

The team studied 95 uterine tumors and 49 normal uterine tissue samples. Scientists measured the abundance, modifications and locations of many vital molecular players, including genes, proteins, messenger RNAs, circular RNAs, micro RNAs, and evidence of what scientists call “post-translational modifications.” The latter are key to determining when and where proteins, the molecular workhorses of cells, are turned on or off.

The scientists developed a promising new way to identify tumors that are classified incorrectly as not aggressive but that turn out to be just as invasive as a type of tumor that grows quickly and is more likely than other tumors to kill patients.

Currently, the aggressiveness of an endometrial tumor is assessed largely by viewing its cells under a microscope. The team explored a new method that shows how the activity levels of certain proteins clearly differentiate aggressive from less-aggressive tumors.

One analysis, led by co-first author Daniel Cui Zhou, a doctoral student at Washington University, showed how the protein beta-catenin, a well-known actor in many types of cancer, interacts with an important signaling pathway to evade detection and spur cells to grow out of control.

“This is the first delineation of the entire beta-catenin complex in a specific disease,” said Ding, also a research member of The McDonnell Genome Institute at Washington University. “We know it plays roles in endometrial cancer and colorectal cancer, so this is a major step forward in understanding the details of this important cancer driver.”

The team also found that a process that involves packing and unpacking genes happens more often than expected in tumor cells. With more than six feet of DNA squeezed into nearly every human cell, the body must pack it efficiently, but it also needs to unspool the DNA so that other molecular machinery can access it. Analysis led by co-author Alla Karpova, a doctoral student in Ding’s lab, found that a key part of the unspooling process, known as histone acetylation, is very active in endometrial cancer.

“Histone acetylation tends to activate genes, which can drive cancer growth,” Ding said. “In theory, we could use information about histone acetylation to predict how aggressive a tumor is likely to be.”

The team also discovered that small, often overlooked molecules known as circular RNAs seem to be involved in the transformation that cells undergo when they gain the ability to spread. The process is called the endothelial-to-mesenchymal transition and is what makes endometrial cancer deadly.

In addition, the team created a new way to determine which patients are most likely to benefit from a treatment known as checkpoint therapy, in which drugs such as pembrolizumab and nivolumab are used to dodge the barriers that some cancer cells use to evade the immune system. It’s one of many ways scientists are exploring immunotherapy to spur the body’s natural defenses to fight cancer.

Currently in endometrial cancer, physicians use a measurement known as “tumor mutation burden” to determine which patients are most likely to benefit from checkpoint therapy. Based on the measurements of immune activity in this study, the scientists have proposed a new measure focused on how well a patient’s body flags cancer cells and presents them to the body’s immune system for destruction — a key function for checkpoint inhibitors to be effective.

Better insight into exactly who would benefit from the drugs would allow physicians to avoid their use in patients who are unlikely to benefit, sparing them unnecessary side effects.

“Now that we have this insight into proteins, we can start thinking about better therapeutic options at the molecular level for patients who have endometrial cancer,” Ding said. “Drugs target proteins, so this was not possible before we acquired this understanding of tumor proteins. We are much closer to effective personalized treatment with this new study.”