Zheng Cui is a biochemist currently serving as an Associate Professor of Pathology (Tumor Biology) at Wake Forest University. Last year his research into granulocyte therapy made headlines by achieving a complete cure for all types of cancer tested in mice. As an oncologist and a cancer researcher he has proposed that certain individuals (estimated at 10% to 15% of the human population) naturally produce a special kind of white blood cell that contains an inherent resistance to cancer. These white blood cells could potentially be extracted from donors and given to cancer victims, thus endowing them with cancer resistance.
The following transcript of Zheng Cui’s presentation at the Methuselah Foundation conference entitled ”Understanding Aging: Biomedical and Bioengineering Approaches” has not been approved by the speaker. Video is also available.
Natural Cancer Resistance in Mice and in Humans
First of all, I would like to thank Aubrey for inviting me again. I spoke at the SENS 3 conference last year. I think this project will attract a lot of public attention. In recent days I have had to deal with a lot of media interviews. Tomorrow morning you may read something in the newspaper, and some sites I believe have already posted their report on this talk. The main purpose for today’s talk is to announce the opening of this clinical trial.
We already have a website, live today, as we talk. Perhaps you can go to the website and look at some details if you do not have the chance to get everything in the next twenty minutes. After last year’s conference in Cambridge, I was invited by the Chinese government to give a talk on Christmas, but the very next day I realized it was a very close call for me.
If you don’t read Chinese, you might not realize this is a public execution of violent criminals, so I was that close to getting myself into a lot of trouble. It gives you a similar sentiment that this is a very controversial project in terms of a basic science approach. We believe it is based on observations—some people call us phenomenologists. We proudly accept that name.
The main concept for this project is very simple. This idea, that we may have natural resistance to cancer present in our body at all times, is not a new idea. It has been proposed for over a hundred years. In other words, the reason that we are sitting here cancer-free is not because we’re lucky, it is because we may have an innate system in our body to protect us—in other words, to get rid of cancer cells. As we get older, this protection may get weaker. That balance between the generation of cancer cells on a continuous basis can overtake the ability of your body to get rid of them.
Where do we find evidence for this? When we look at the literature there is almost no direct evidence, but when we look a little bit harder we realize there are some really courageous experiments done in the 1950′s. If you read some of the older reports, you see that Dr. Chester Southam was injecting human subjects with live cancer cells. It was a very clear message intended to persuade the general public that there is a cancer resistance naturally present in our body, especially in healthy individuals. However, in cancer patients, this ability was lost. Because of all the legal and ethical problems of this entire line of study, it was shut down and almost disappeared. However, the scientific message was profound. A lot of people followed this idea, but there is no way that you can do a similar experiment.
In 1999, we did not design anything specifically to look for cancer resistance. It was merely a laboratory accident that led us to this interesting phenomenon. At the time we were trying to collect antibodies, so it was routine to introduce very aggressive cancer cells, which will kill the host in three to four weeks. No single mouse ever survived.
However, this mouse came along. We thought we forgot to inject this mouse. After several attempts, with increasing doses, he still remained healthy. That really surprised us. We thought this must be a very dramatic event because if no other mice survived, and he survived, there must be something there… but it is only one mouse.
It is very fortunate that this kind of survivability against cancer cells can be passed on to the next generation. That was ten years ago, and we still have a very large colony in our facility. It is 25 generations and several thousand mice later that it passed on with a dominant inherited trait. We also noticed that someone here was presenting on high throughput sequencing—this might be a great project for them. It is genetic, it’s inheritable, but we do not know what caused it. Perhaps these newer technologies can help us to answer this question in a very definitive way.
This is a picture of the original mouse a few weeks before he passed on of natural causes after a long and productive life. It makes me very jealous, but their life is measured in numbers—ours is not. We also realized before long that the reason for cancer resistance is because their immune cells are doing something to the cancer cells.
If you look at the wild type mice, cancer cells grow like crazy. However, if you look at the resistant mice, you put these cancer cells in them and in a few hours the cancer cells are in a lot of trouble. First you see these cells being surrounded, and second they are ruptured. This seems to be a typical immunological reaction. If you look at the EM, you can see that the cell interaction between the immune cells of the resistant host and the cancer cells is very tight. The immune cell latches onto the cancer cells and there is a surface erosion of these cells.
Physical contact is very important. If you block this physical contact, you can actually prevent this killing event. That suggests to us that cell-to-cell contact is very important. The cell has to get there and interact at the cell surface.
This is a picture of cell surface erosion. It also surprised us, there are two effector cells. If you are a cell biologist or a pathologist, you will immediately notice, this is macrophage, this is neutrophil. What are they doing there? It is a very interesting question. It is not supposed to be the cells that kill the cancer cells. Cancer immunologists are all about T cells and B cells, but what are these cells doing there?
This is a quick review of the two systems that we have and our mice have. We have an innate immune system that is rapid and ferocious. It is involved in cells such as natural killer cells, macrophages and neutrophils, and they can act within hours. The other is a more dedicated system. It is very low level, compared to the innate immune system, but very specific. Usually they require weeks, if not months.
Here is a quick review of our immune system. Granulocytes and neutrophils are a major component of this. 50 to 70% of our cells belong to this class of neutrophil, and there are other classes of granulocytes. The lymphocytes make up about 10% of white blood cells. 10 to 15% of the other cells are something we call monocytes. When they get into tissues they are called macrophages.
We realized that in these mice the macrophage and neutrophil keep popping up. The other thing is you can see that we challenged them four times, hoping to get an idea of what type of cells are involved in this cancer killing mechanism. We knew that this was an innate immune response. It is very rapid—within a few hours it can complete its task.
I still call myself a phenomenologist, because I have to be visually convinced of this kind of event. This is an experiment injecting cancer cells into these mice, and then, using time lapse microscopy, seeing what happened to them. In this case, the large cells are cancer cells. By the end of this video, all the cancer cells are captured by the immune cells. They form very large cell aggregates, where we know there is something happening. This is how the rosettes form, because you can even see how the turbidity in the test tube changes. The next event occurred after the immune cells captured the cancer cells. You see the cells rupture, almost like a balloon.
After I saw this, I was convinced that we were dealing with something I never saw before. This is my favorite video, which I call the “magic bullet.” This immune cells finds the cancer cell, and it pops. After you see this video, you have to believe that something is happening.
There are many requests from cancer patients and their families to move into human trials. Who cares if a mouse gets cancer? This is perhaps a transition we can make to human cancer. We have devised this cell killing assay, simply to mix immune cells collected from individuals and mix them with cancer cells. After a certain time of incubation, we count how many cancer cells were alive compared with controls.
Wild type mice have almost no cancer killing activity. Resistant mice have some activity even in human cancer cells. The resistance can cross species to kill human cancer cells. We can update this graph now that we have a lot more points, but the basic message is still the same. It looks like a normal distribution. Some people are high, some people are low, and most are in between. For people who are a little bit older, the average is lower. If you look at cancer patients, the trend is even lower.
This was an open label study. People challenged us to do a double blinded study. We said okay, so here is the double blinded. In a healthy subject, the ratio of cells are different there, but the point is very clear. The older you are, most people cannot maintain this number. In cancer patients the number is a lot lower. Even lower are dogs. Humans have an overall mortality rate of 25% due to cancer. For mice, it is about 80%. For dogs it is about 50%, so right in between human and mice populations.
The next questions was where this activity is. Is it in the agranulocytes or granulocytes? We realized that most activity is in the granulocytes. That was a big surprise to us. If you look at the granulocyte count in individuals, it can range from 50% to 75% of white cells. If you calculate that and compound them together, most of the cancer killing activity is in the granulocyte fraction. Is that broad spectrum or is it specific to one type of cancer? We realized that in cervical cancer, breast cancer, prostate cancer and sarcoma, all are killed to a relatively high degree similar to each other.
Here is another serendipitous discovery. We always run into the assay problem when winter comes. When Thanksgiving and Christmas comes around, I would say to the graduate students who do these assays, “You must be distracted by all the holidays. Keep working on the system until it starts to work.” They would go back to the lab, changing everything along the way, and after several months things would start to work again. However, we realized after several years that this always happened at the same time. We realized that it may be more than just making mistakes.
Beginning in 2005, we stopped changing things. We said, if we don’t change anything and it still goes through this pattern, it might be something else. We realized after messing around with all these different components, waters and assay solutions, it retained this pattern. It became very clear to us that this was a seasonality. Our immune function has a winter low and a summer high. It was quite a surprise to us, but it was very clear.
What’s wrong with winter? Our ancestors in the pre-technology era had to conserve energy during the winter, because they have no food availability like we have right now. The only way that our ancestors could survive winter was to reduce their metabolic rate. They would sleep a lot more, eat a lot less, and do a lot fewer things than they would otherwise during the summer.
If someone wanted to do this experiment, it would not be that difficult. If the seasons have such a profound impact on our anti-cancer immunity, what about areas that do not experience seasonal changes, like equatorial regions? This is World Health Organization data, and it shows that all the countries with a low incidence rate for cancer is near the equatorial region where there is no seasonal change. We were surprised to find this kind of correlation. Whether it is directly related, we don’t know. We hope that someday we can figure it out.
In humans, you can see that it is similar to the mouse. When there is this killing activity, the cancer cells are surrounded by neutrophils and macrophages. A student made another video to show whether human cancer cells can actually be killed by these isolated, highly purified granulocytes. You can see apoptosis and rupturing. The point is that whatever happened in mice whose cancer cells were killed, it happens in humans as well. The mechanism is very similar.
Whether this activity is stable within the summer months, here each color represents an individual. This low point, we later found out, was after a day of extreme emotional stress. It took three days to recover. The other anecdotal evidence we discovered relates to another low point for this individual. This is another one of my graduate students. I sent him to an international meeting to make an oral presentation for the first time in his life. He got really worked up for a few weeks.
On his way back, there is a point that we missed, because there were just not enough granulocytes to do the assay. The white cell count was wiped out, and he was in a lot of trouble. This is our treatment proposal:
You can see that we select a donor according to their activity and then use an apheresis machine to collect their granulocytes. The FDA approved this within thirty days. It was a very fast approval. This is published data. There is a similar strategy using manipulated white cells from cancer resistant mice, which can cure a large tumor. We published this in ’06. It got a lot of media attention.
We also realized that there was something even more important. It turned out to be her.
Our institute was challenged with the assertion that this was not real cancer. They said you can induce prostate cancer by knocking out the p10 tumor suppressor gene. “If you can cure this, we will believe you.” We treated these mice with one injection of white cells from the resistant mice, and they all lived longer.
If you are a cell biologist and you look at these pictures of the prostate, you will recognize that this is scar tissue. This is very effective. What is the link between spontaneous regression and infection? There is a long history of suspicion that these two may be linked. William Coley is the first one to be credited with this.
Based on our knowledge, we have granulocytes, monocytes and lymphocytes. The only connection is this: with bacterial infection, the increase is in granulocytes, by ten or twenty times—sometimes even as much as one hundred times.
People have started to talk to me about possible collaborations. This is senator Tom Harkin, this is my lab, and the biggest credit should go to the mouse. Thank you.