Permanent black spots on breasts treated with radiation therapy.

Breast cancer patients who receive radiation therapy are tattooed with a dark spot on their breasts. I am not sure whether that applies to just some patients, most patients, or all patients, and would like to hear from you if you know about these tattoos.
The purpose of these tattoos is to provide a permanent marking so that any radiologist can target the same exact spot repeatedly, as might be necessary.
But when the radiation therapy is complete, the black spot remains.
Though the rational for the tattoo makes good sense, I think it is unfortunate that the treatment results in a permanent black spot on the breast. Maybe it could pass as a beauty mark, but more likely it enters the imagination as a mark of treatment, a reminder of the disease, and of the treatment that was endured.
Thankfully, a British group of doctors has developed an alternative – an invisible tattoo that can be detected by fluorescence after illumination with an ultraviolet light.
With this method, the doctors can see where the radiation beam had been, and therefore where it should go the next time, with the same precision as the black mark tattoo. But the patient never gets to see it.
Does this matter to the patient? Apparently so because they found that “Fifty-six percent of the women with the invisible tattoos felt better about their bodies one month after treatment, compared with 14 percent of those with dark ink tattoos”.
The fluorescence approach has another advantage; the black mark tattoo is not always readily visualized in dark-skinned patients.
Let us hope that the fluorescence approach will be phased in quickly in the US.
You can read the story, which was presented online in MedlinePlus, http://www.nlm.nih.gov/medlineplus/healthnews.html,
just below:

Breast Cancer Patients Might Prefer ‘Invisible Tattoo’
Dark ink used to mark treatment area is a permanent reminder of the disease, researchers say

By Robert Preidt,
Tuesday, November 4, 2014
HealthDay News
Using “invisible” tattoos instead of permanent dark ink ones when breast cancer patients undergo radiation therapy could help improve how patients feel about themselves, a new study finds.
The skin markings are needed to ensure that radiation therapy is given in the exact same spot during each treatment session. However, previous research has found that the permanent tattoos remind breast cancer patients of their disease for years after treatment, lowering levels of body confidence and self-esteem.
Also, the dark ink tattoos can be difficult to spot on dark-skinned women, which could result in inconsistent radiation treatment in the targeted areas, the researchers said.
The new study included 42 breast cancer patients who were undergoing radiation therapy and were asked how they felt about their body before treatment and one month later. Half of the women had conventional dark ink tattoos and half had fluorescent tattoos only visible under ultraviolet light.
Fifty-six percent of the women with the invisible tattoos felt better about their bodies one month after treatment, compared with 14 percent of those with dark ink tattoos, the researchers found. Treatment accuracy was the same in both groups of patients.
The findings were presented this week at a National Cancer Research Institute meeting in the United Kingdom.
“These findings suggest that offering fluorescent radiotherapy tattoos as an alternative to dark ink ones could help ameliorate the negative feelings some women feel towards their bodies after treatment,” study author Steven Landeg, a senior radiographer at the Royal Marsden Hospital in London, said in a research institute news release.
“It’s important to remember that body image is subjective, and dark ink radiotherapy tattoos will affect patients differently, but we hope that these results will go some way towards making this a viable option for radiotherapy patients in the future,” he added.
The data and conclusions of research presented at meetings are usually considered preliminary until published in a peer-reviewed medical journal.
SOURCE: Cancer Research U.K., news release, Nov. 1, 2014
HealthDay
Copyright (c) 2014 HealthDay. All rights reserved.

A new type of personalized cancer therapy

When I think about “personalized cancer medicine”, what comes to mind is a genomic analysis, and therapy based on the specific mutation associated with, and perhaps causative of, the cancer. In the past I’ve written about some of the problems with this approach including what is now becoming quite apparent, that the mutational profile of a tumor can be quite heterogeneous, and it also changes with time.
It was a delight to read about a new type of personalized cancer treatment, reported in Science magazine on October 3, 2014. Basically, as the cover says, it is about “Building a better mouse”.
Well, better only in the sense that is growing the patients specific tumor taken from the patient’s body. It’s the patient’s personalized mouse.
It goes something like this. A piece of the tumor (or metastasized colony) is removed by a biopsy, and the cells from the biopsy are grown in culture. When the population expands sufficiently, some samples are frozen but others are injected into living mice, mice that were selected genetically for an absence of an immune system.
These mice have to be handled with care and kept in a germ-free environment. But the important thing is that because they lack an immune system they cannot reject the human cells, and the tumor cells can begin to grow and form tumors. And they do.
Now, with a dozen mice with the patient’s very own tumor growing in each, it becomes possible to screen the mice, asking which of several different possible treatment scenarios is most effective in drawing down that tumor. It is not too great a leap to make to suppose that whichever treatment works best among the mice is most likely going to be the best that will work with the patient. After all, it is the very same tumor.
The tumor could have changed with time, so there is no absolute guarantee that the patient’s tumor will respond in the same way. but it is a reasonable guess. So far, among a limited number of patients, the idea has held up and treatment scenarios have been effective. And at such a high level to warrant further testing in a larger set of patients, in a clinical trial, and one is now underway.
The biggest problem, apparently, is that this approach takes time. While the patient’s tumor is growing in the lab, and then growing in the mice, and then responding, if at all, to the treatments being tested, it is still growing and spreading in the patient. The patient is getting sicker while the key to a potential cure is growing in the mouse. As the article notes, some patients were unable to wait that long. They didn’t make it to the point where the treatment might have been useful.
I like the approach, but clearly it is best used on patients at an early stage of a cancer, and who can be treated with something to keep them alive long enough for the potential treatment to work.
You can read the Science article below:

Hope in a mouse
Jennifer Couzin-Frankel

Robyn Stoller’s husband, Alan, died as drugs were being tested in mice carrying his sarcoma. None worked well, but she takes comfort in knowing that “we tried everything.”

In the end, it became a race against time. “Maybe 5 days before he actually died, 4 days, I remember saying to him, ‘Alan, you’ve got to hang on, you’ve got to hang on, the drugs are in the mice, they’re looking at them,’” says his wife, Robyn Stoller. The couple had three children in elementary school and lived in a suburb of Washington, D.C. Alan, a 47-year-old who worked in real estate finance, had a virulent form of sarcoma that had spread to his brain.

Forty miles away, scientists at a company in Baltimore, Maryland, were pushing the limits of biology. They had implanted samples of Alan’s tumor into mice without a functioning immune system. Nine cohorts of animals received one of nine different drug combinations, a test of what might work best on Alan’s tumor. But the process took months, time Alan didn’t have. He died at home on 12 July 2010.

The journey to what Robyn calls “bleeding-edge technology” had begun almost 8 months earlier, on the couple’s 13th wedding anniversary, when they drove to see oncologist David Sidransky at Johns Hopkins Hospital in Baltimore. Alan “was very sick,” Sidransky remembers. “There was a lot of pressure not to treat him anymore.”

The Stollers had sought out an alternative in Sidransky. He had recently formed a company called Champions Oncology, its main lab a 15-minute walk away. Champions aims to personalize cancer care with mice that, Sidransky argues, are unusually predictive of how individual patients will respond to particular drugs. That’s because each mouse is an individual patient—or rather, carries tumor harvested from one.

Champions is far from alone in building these mice, called patient-derived xenograft (PDX) models. The drug company Novartis has more than 1000 PDX models from as many patients, which it’s applying to drug testing. The National Cancer Institute in Bethesda, Maryland, is developing a bank of PDX mice for rare cancers and patients enrolled in trials. The Jackson Laboratory in Bar Harbor, Maine, a major mouse supplier for academic and corporate labs, has more than 350. “There’s a big push” for these mice, says Carol Bult, scientific director of the PDX program there, and many scientists are using them to examine tumor biology and drug resistance.

What most people aren’t doing is selling the models to patients. The Stollers paid many thousands of dollars to Champions, which markets the animals as a treatment guide. The mice are called avatars, analogous to a computer game in which an avatar is a graphical representation of the person playing it. “There may be hope for your specific cancer,” Champions assures patients on its website.

Many find this pledge troubling. The company is “selling a promise to patients before that promise has been judged to be true by really rigorous data,” asserts George Demetri, an oncologist who treats sarcomas at the Dana-Farber Cancer Institute in Boston. Even though he advises his own patients against paying for avatar mice, Demetri is part of Champions’ scientific advisory board. There, he says, he acts as a “gadfly” pushing for more and better studies to prove how predictive avatars are and whether any benefits are enough to justify the cost.

Right now, Champions charges $2000 to create an avatar mouse, and about $2500 for each drug test it runs—normally a recommended minimum of about three or four, with no upper limit. The company says it loses money on the personalized service; from April 2013 to April 2014, it brought in $2.3 million but spent $2.7 million, not including marketing and other indirect costs. Champions makes money off a separate business: testing therapies on PDX mice for drug companies.

Sidransky acknowledges that with avatars, patients are paying for a strategy that’s still experimental. But he sees no other way to offer it.

CHAMPIONS’ STORY began with a single patient. About 8 years ago, Sidransky and another Hopkins oncologist, Manuel Hidalgo, were studying PDX mice. The tissue for the models came from Hopkins patients, but the mice were intended solely for research. That is, until a man with metastatic pancreatic cancer asked Hidalgo, “Can’t we use the results” for treatment? The oncologists sought permission from their institutional review board to transfer therapy from mouse to man. “It was all intuition,” says Hidalgo, now an oncologist at the Spanish National Cancer Research Centre in Madrid. “Really, there were no data.”

The patient lived almost 5 more years, unusually long for someone with his disease. “That wowed us,” Sidransky says.

The pair began offering this boutique option to the small number of patients who had time to wait. Initially, it cost about $50,000 per patient—funded by a clinical trial—and took about a year for mouse results to come in. “After 2 years of doing this, we decided to start a company,” Sidransky says. In 2011, he and Hidalgo published outcomes on the 11 Hopkins patients they had treated. Fifteen of 17 treatments given (some people got more than one) “resulted in durable partial remissions,” they wrote in the journal Molecular Cancer Therapeutics. “Overall, there was a remarkable correlation between drug activity in the model and clinical outcome.”

Champions says it has replicated that study many times over. About 175 people have gone through the full process—avatars created, drugs tested on the mice, and information on those drugs offered to the oncologist. At the European Society for Medical Oncology meeting in Madrid this week, the company presented data on 102 drug regimens in 70 patients; 89% benefited from a given therapy if a mouse did, too, says Ronnie Morris, the company’s president. The few correlations recorded by other researchers are roughly comparable to those claimed by Champions.

There are lingering questions, though, about what exactly “benefit” means—for instance, is it assessed by objective rules? “It is all about how one phrases the questions,” Demetri notes, and the definition of “benefit” is “not a trivial concern.” He is in discussions with Champions about designing clinical trials to address these issues. The first of several Champions trials, focused on sarcoma, will launch this fall. All the studies will offer avatar mice at no cost and will track more systematically whether a mouse response matches a patient’s. The company has no plans to perform a randomized trial, in which some patients receive the therapy their doctors recommend and others follow the mice.

“We can’t be responsible for good and bad drugs,” Morris explains. “We want to be an empiric test” of which drug a patient should take.

Avatar studies outside Champions are also picking up. Hidalgo is beginning a randomized trial comparing therapy directed by avatars against standard therapy in pancreatic cancer. At the Mayo Clinic in Rochester, Minnesota, oncologist Paul Haluska has created mice from about 400 ovarian cancer patients, with an eye toward successfully treating the relapses so many women suffer. All four approved therapies for ovarian cancer are tested on the avatars, and Haluska offers the most successful to a patient if her cancer resurges. “I need to prove that this is the way to go,” he says, “that doing the avatars is better than standard” therapy.

One scientific shortcoming of PDX mice is that the animals lack a functioning immune system. This precludes trying immunologic therapies; it may also give misleading information about how drugs will behave in a person. Today’s PDX mice, Hidalgo says, are “version 1.0.” Several labs are developing and testing mice with a “humanized” immune system, but widespread use may be a year or more off.

Champions has run into other problems, too. Like anyone working with PDX mice, the company is unable to build avatars for everyone, and fails 30% of the time. For example, some tumor types, such as certain breast cancers and prostate cancer, don’t readily engraft.

Of the patients who get a mouse, “about half choose to go further” into the drug testing phase, Morris says. Most who don’t are bedeviled by time. In fact relatively few patients with advanced cancer survive long enough to use avatars as a road map, as critics of Champions are quick to point out.

“If you are selling … to patients the idea of an avatar that could benefit their cancer, you are misleading them because often, there is no time to play the game,” says Pier Paolo Pandolfi, who is studying genetically engineered mouse models at Harvard University.

Although Champions has sped up the avatar-making process, it still takes about 4 months. Sidransky doubts it can get much faster. Many people die in that interim or become too sick to consider additional toxic therapy. This drop-off helps explain why more than 500 people have signed on with Champions, but only about 175 have been offered the option of mouse-inspired therapy.

Alan was in the two-thirds who don’t reach the finish line. When he signed on with Champions, he was in such bad shape that he couldn’t undergo surgery to gather fresh tumor tissue. Instead, the company convened an “expert panel” of sarcoma physicians and researchers who studied his initial biopsy, its sequence and molecular profile, and recommended a course of action as a stopgap until, they hoped, mice could be created. (The company no longer offers expert panels.) Alan began that chemotherapy, which appeared somewhat successful. Doctors were then able to remove some of his tumor and implant it in avatar mice.

Ultimately, Robyn says, two regimens had a very modest effect in the mice, but none was aggressively killing off the cancer. One of those two was what the expert panel had already recommended. By the time the mouse results began streaming in, he was hours from death. Even a perfect avatar is only as good as the drugs available, and in Alan’s case, none was good enough, at least not for the mice. “You want an answer,” Sidransky says. “If the answer is no”—nothing works—“it’s sobering, but it’s still an answer.”

Robyn feels the same way. She believes the initial analysis and treatment recommendations coordinated by the company helped extend her husband’s life by perhaps 6 months. The mice ravaged by his cancer despite a barrage of drugs confirmed, for her, that there was nothing else they could have done. “We left no stones unturned,” she says. “My kids and I can sleep at night. I don’t ever wonder, ‘If only.’” She has spoken out in support of Champions and now runs a website called CancerHAWK to connect families fighting cancer with resources that can help them.

To those who question whether Champions should be selling its promise, Robyn has a ready response. “It would really frustrate me as a patient advocate if there was a technology that might help” and yet was inaccessible, she says. “No matter what it costs—let me get my hands on it.”

Lighting up cancers to destroy them

An important article appeared in June that I believe may be a game-changer for cancer therapeutics. You would never know it from its title (1).
The paper discusses a fairly small organic compound that is taken up by cells into their membranes, including the outer cell membrane. It is referred to as an alkylphosphocholine, or APC.
In this study the authors examined a variety of closely related structures and identified one that has particularly interesting properties. Called CLR1404, it is preferentially taken up by cancer cells — and cancer stem cells — and remains stable in those cells for several days. In normal cells the APC is degraded.
The compound can be made radioactive, and by that means it can be detected by CAT, and PET scans and MRI imaging. Using mice, they could see tumors readily and clearly and distinguish between tumors and normal tissue. They were even able to rule out some possible false positives. Clearly this compound has remarkable diagnostic value.
Importantly, the compound identified a variety of different kinds of tumors, meaning it has universal value. With just a few exceptions, it can identify a tumor no matter what tissue it is found in or originated from.
Using a fluorescent analog of the compound individual tumor cells could be identified by fluorescence microscopy. Working with cancer stem cells that could be identified by their surface markers, it was shown that cancer stem cells could also be picked out with this compound.
Finally, because radioactive Iodine is used not only for diagnostic purposes but has also also been used to kill certain types of cancer cells, like thyroid cells and prostate cells, with a high degree of specificity, it follows that adding radioactive iodine to CLR1404 and allowing the compound to be absorbed into virtually any type of cancer, then virtually any type of cancer can be treated, at least partially, with this compound. This was tested with mice and verified.
But the potential is even greater. If Iodine can be added to the compound, and a fluorescent molecule added to the compound, then it should be possible to add other moieties as well, for example small artificial peptides to which monoclonal antibodies can be made with great specificity. Then, inside a body, after normal cells have had a chance to metabolize the compound leaving only cancer cells and their cancer stem cells labeled, introducing a monoclonal antibody should be able to wipe out ALL of the cancer cells without damage to other systems of the body.
If this can be done, and if it works with almost all types of cancers, then there will be no need for gene-related, genome sequenced classification of tumors and personalized cancer drugs. One drug should work with almost all cancers.
This is something to look forward to.
Still unanswered by this paper is whether non-solid cancers, such as lymphomas and leukemias can also be identified by this compound. Presumably the answer is yes, but that remains to be tested.
I hope this lab group gets all the support it needs to further its research and develop collaborations with cancer centers throughout the world.

1. Weichert JP, Clark PA, Kandela IK, Vaccaro AM, Clarke W, Longino MA, Pinchuk AN, Farhoud M, Swanson KI, Floberg JM, Grudzinski J, Titz B, Traynor AM, Chen HE, Hall LT, Pazoles CJ, Pickhardt PJ, Kuo JS. 2014. Alkylphosphocholine analogs for broad-spectrum cancer imaging and therapy. Science translational medicine 6:1-10

Immune cells in breast tumors that support cancer — and can be eliminated

It always amazes, impresses and delights me when something basic and simple is discovered, even now, after so many years of intensive research.

That was my reaction on reading about the type of immune cells that are found in a breast cancer lump in mice.

It was known that throughout mammary gland tissue one could find macrophages, large phagocytic white blood cells. That’s true for any tissue of the body; macrophages are there. Macrophages act as scavenger cells mopping up bacteria, viruses, and debris from tissues all over the body. They remind me of the brush-whirling trucks that clean the streets of our cities, removing trash that builds up near the sidewalk curbs, when most residents are asleep.

Macrophages also play an important role in the immune response because they are able to transfer some of the proteins they engulf to their cell surface, rather than digesting them to their component amino acids, and “present” them to lymphocytes. Lymphocytes that recognize the protein (the protein now serves as an antigen) are stimulated to divide, expand their population, and then target residual antigen in the body.

Researchers in NY (1) asked if macrophages found in mammary tumors are the same type of macrophages found in the rest of the mammary tissue. Or are they different? What a simple question! And if they are different, how are they different, and how does that difference matter? But to begin with, how can you tell one macrophage from another?

That was the hard part. The investigators had to examine macrophages from normal mammary gland tissue and from tumors within that mammary tissue, and then compare them with respect to a variety of different properties.

But once that process was done, their data led to the simple conclusion that the two populations of macrophages were indeed different. There were regular Mammary Tissue Macrophages (MTM’s), and there were altogether different Tumor Associated Macrophages (TAM’s). The two types of cells have different cell surface markers, differentiate from different precursor cells, and express different sets of genes.

This is shown for mice, and only for breast cancer, but presumably this is a general phenomenon. Tumors have their own type of macrophages. We didn’t know that before this study.

Why does this matter? For one thing it means that the micro-environment of the tumor must be different from that of normal mammary tissue. That follows from the fact that the macrophages are able to detect that difference. It could be useful to know what difference is detected, at the molecular level, by the macrophages, because that might be exploitable for development of new therapies. Secondly, the tumor associated macrophages may play a functional role in the support of tumor growth.

The latter possibility was tested by inhibiting the differentiation of the TAM’s in mice. This was possible once it was known that they differentiated from a different set of precursor cells than MTM’s, and the molecular regulator of that differentiation was determined.

The researchers found – hold onto your seats – that if TAM’s were blocked from differentiating, if these special macrophages did not therefore take up residence in the tumor, then the tumors did not continue to grow. Further investigation showed that TAMs block the body’s own cytotoxic T cells from attacking cancer cells. By eliminating TAMs, the body’s immune system can succeed against cancer cells.

This is not only a very satisfying piece of research, it opens up entirely new avenues for cancer therapy. Instead of (or in addition to) killing cancer cells (as with radiation and chemotherapy) it may be possible to limit cancer by blocking TAM cells in tumors and letting the body do the work of killing cancer cells.

The big question now is whether tumors of other tissues also have special Tumor Associated Macrophages, and whether each tumor has its own type of TAM or whether there is a universal property to TAM’s. If the latter, then it could be possible for one type of drug to help suppress any type of cancer.

This may take a number of years to work out, but it is wonderfully promising.

1. Franklin RA, Liao W, Sarkar A, Kim MV, Bivona MR, Liu K, Pamer EG, Li MO. 2014. The cellular and molecular origin of tumor-associated macrophages. Science 344:921-925.

Cancer cells that drink themselves to death!

I really like this paper, partly because of the fabulous results presented — this could lead to a real “cure” for brain tumors (glioblastomas), one of the most deadly cancers — and partly because its approach flies in the face of the new dogma of personalized medicine through genomics (1).

 It starts with the premise that mutations in the many different genes that cause cancer may be having affects on cells in more ways than just in the control of cell division and migration, ways that we perhaps don’t much about right now. If so, they reasoned, then perhaps by interfering with one of those “side effects” of cancer genes, we might be able to halt the cancer itself.

They started with a grab bag of over a thousand different chemicals, treated samples different strains of glioblastoma cells and normal cells with each one, and assayed for something different in the appearance of the tumor cells that did not occur in the normal cells.  That’s all. Using a microscope they looked to see (with the help of a computer program) if there were size changes, shape changes or some other kind of change such as cell death.

And, wouldn’t you know it, they found that several compounds, with one particular one standing out, caused such changes. The compound killed glioblastoma cells in culture (and, they soon found, also in living mice), but had no affect on normal cells. 

What is particularly interesting is that before the cells die, they filled up with clear vacuoles. And before that the cell surface became turbulent. Filling in the gaps, they showed quite definitively that the active compound (which they call Vacquinol) was causing cells to form channels that brought fluid into the cells, a drinking process called macropinocytois. The fluid entered the vacuoles and the vacuoles increased in number and size until the cells literally burst – and died.

No one has ever seen this before. In fact, this represents a new form of cell death, a new way that cells can die that has not been reported before. Something about the physiology of the glioblastoma cells (we still don’t know what that is) makes them sensitive to very low concentrations of Vacquinol which causes them to drink themselves to death!

Extraordinarily, the few other cancer cell types tested were, like normal cells, unresponsive to Vacquinol. In this study only glioblastomas responded.

The researchers were lucky. They did a marvelous job of analyzing what was happening to the cells in response to Vacquinol, and showed that because of its effectiveness in living mice (6 of 8 vacquinol treated tumor-induced mice were still alive at 80 days, while all untreated mice with tumors were dead by 60 days), it is ready for clinical trials, but they were lucky that some compound in their random bag of chemicals actually works, especially since it works only on the cancer type they used, and not others.

One reason glioblastoma tumors have been so intractable is that even after treatment, even after many cells are killed by the chemotherapy drug used, disease recurs as the tumor continues to grow. There seems to be a reservoir of cells that are not affected by the cytotoxic drug. They may represent a stem cell-like population that is generally quiescent, which means that that they do not divide for long periods of time and therefore would be unaffected by any drug that targets the proliferative process.  But Vacquinol is different. It doesn’t target proliferation; because it affects a fundamental property, it can impact on quiescent cells as well. The kill rate is therefore substantially higher than for a traditional chemotherapeutic drug.

Let’s hope that we will see other cancers tested with whatever grab bags of small molecule chemicals that are available.

1.         Kitambi SS, Toledo EM, Usoskin D, Wee S, Harisankar A, Svensson R, Sigmundsson K, Kalderen C, Niklasson M, Kundu S, Aranda S, Westermark B, Uhrbom L, Andang M, Damberg P, Nelander S, Arenas E, Artursson P, Walfridsson J, Forsberg Nilsson K, Hammarstrom LG, Ernfors P. 2014. Vulnerability of glioblastoma cells to catastrophic vacuolization and death induced by a small molecule. Cell 157:313-328.

 

 

Coumadin at very low dose may slow metastasis

   Natural Killer cells are part of the immune system, and unlike their T-lymphocyte cousins, they seem to have an innate ability to kill virally infected cells and cancer cells. This is not something they learn from experience, as do other T cells. They act as if by instinct.

   Strangely, even though we have this natural defense system in our bloodstream, we still develop cancers that spread, via the bloodstream, to other parts of the body. And it is this spread of a cancer, metastasis, which makes cancer such a lethal disease.

   This has been a troubling puzzle for some time now: if we have Natural Killer cells, why don’t they kill cancer cells? Or at least, why not those that leave the primary tumor and enter the blood stream, where NK cells are found?

    So it is big news when a study comes along that identifies a way that Natural Killer (NK) cells can be influenced to do a better job killing cancer cells. Such a study has recently been published (1).

    It had been known that the deletion of a particular gene from mice provided them with greater resistance to the spread of cancer, and an increased lifetime of mice with cancer, compared to their normal counterparts. That gene encodes a protein with a tongue-twister name called “E3 cbl-b ubiquitin ligase”.  Let’s just call it “E3” here.

    The question that was addressed is what is the function of that protein, and what cells are affected by the elimination of that protein (via its gene deletion or inhibition of gene expression)?

    Along the way they made an unexpected discovery, that low doses of Coumadin (also known as warfarin), the inexpensive and widely used drug that retards the coagulation of blood, is effective at unleashing the cancer-killing ability of NK cells.  It reduced colonization of several difference cancer types, and increases the lifespan of mice with cancer. Its impact was just about as good as a specially designed drug that “awakens” NK cells. Coumadin was effective even at concentration so low that blood-clotting is not at all affected, which means that negative side effects are virtually non-existent. It should be emphasized that Coumadin had no effect on the growth of the primary tumor, and it did not totally prevent metastasis, but it slowed the process of metastasis significantly, and reduced the spread of the cancer.

    To repeat, the study was limited to mice, to two different strains of mice, so it may be possible that there will be no positive benefits of low dose Coumadin in human beings. But, since Coumadin is so inexpensive, and has been used for so long with so many people, and at the low concentrations used has no negative side effects, and it ie possible, perhaps likely, that it will work in humans as well as in mice, why not prescribe it as soon as a person is diagnosed with any type of solid tumor. It just may slow the spread of cancer enough to buy time, and to allow drugs that prevent the growth of tumors to have their maximal effect.

     If I had a solid tumor I would ask this of my doctor. It is not a cure, but together with a drug that limits growth of a tumor, it could offer increased hope.

    If you are a doctor reading this (to the end), and who has read the paper referenced below, can you think of a reason for NOT prescribing low dose Coumadin?

     Now let’s get back to the study, for those who would like to follow the investigative process.

     The researchers started their study by reproducing the published observation that deletion of the E3 gene in mice slows metastasis and extends life. They also observed increased infiltration of NK cells into the tumor mass, indicating that NK cells were somehow influenced by the E3 deletion. That influence could have been indirect, for example, tumor cells with missing E3 might secrete something that attracts NK cells. Or E3 deletion could have directly altered the properties of the NK cells themselves.

    They next isolated NK cells from E3–deleted mice and tested them in normal mice that still had the E3 gene. Once again metastasis was slowed. It follows that E3 deletion affects the NK cells directly. Please note that this does not rule out the possibility that other cells are also affected in some way by the  elimination of E3. 

    What does the E3 enzyme do? It adds a chemical group called ubiquitin to existing proteins thereby changing their functional properties. This is referred to a post-translational modification, because it alters a protein after it has already been synthesized (translated from the DNA code).

    The researchers then asked, which proteins in the NK cells are modified? They tested 9000 different proteins for ubiquitination by E3, and found that one protein stood out. That protein was one of a three-member of family of proteins (each of which could be ubiquitinated) collectively known as TAM.

     There are things known about TAM. It appears in cells other than NK cells, it is part of a trans-membrane protein found at the surface of cells. Its exterior part serves as a signal receptor (known signaling molecules, or ligands, include Gas6 and Protein S) and its interior, cytoplasmic, side has tyrosine kinase activity. When a TAM molecule binds to its ligand, it is ubiquitinated by E3, and this induces endocytosis, or the formation of a phagocytic vesicle.

    Incidentally, TAM also function in the phagocytosis of apoptotic cells, and mutations in TAM are associated with some types of autoimmune diseases.

    It seems that TAM negatively regulates the NK cells; Gas6, which activates TAM and induces endocytosis, prevents killing activity, while E3 deletion which blocks endocytosis awakens NK ability to kill cancer cells.

    The investigators reasoned that by inhibiting the tyrosine kinase activity of the receptor they could suppress the negative regulation of NK cells. So they set out to design a small molecule inhibitor of TAM based on the known structure of the active site of the tyrosine kinase portion of the molecule. In this they succeeded, and they called their inhibitor LDC1267.

    By the way, this approach stands in contrast to the development of most other drugs, which are discovered by screening thousands of known compounds, many extracted from living plants, fungi and other organisms.

    LDC1267 worked. It worked just as effectively as if the E3 gene had been deleted. So it, or a similar drug that may work even better in humans, will likely soon be tested in clinical trials.

    Indeed, Foretinib, a drug presently being tested in clinical trials, that inhibits some tyrosine kinase receptors, was recently tested with glioblastoma, a highly invasive and high morbidity tumor (2). The authors write: “Foretinib treatment in vivo abolished MerTK [the M in TAM] phosphorylation and reduced tumor growth 3-4 fold in a subcutaneous mouse model”. When M was completely inhibited, it completely stopped the growth of the tumor. (In this case, interestingly, Foretinib had a direct affect on the tumor cells themselves, in vitro, slowing growth and reducing migration.  So TAM activity may regulate both cancer cell behavior as well as NK cell behavior).

    It turns out that Gas6 and Protein S, the proteins that activate TAM, are Vitamin K dependent proteins. They need Vitamin K in order to be able to bind to TAM.  Vitamin K is a molecule of known importance in bone construction, and in blood coagulation.

    Blood coagulation? That brings us back to Coumadin, because Coumadin is an antagonist to Vitamin K. That is why Coumadin is useful as a so-called “blood thinner”. (It doesn’t really thin the blood, but by antagonizing Vitamin K it does decrease the probability of blood clot formation).

     Now we have a molecular explanation of just why Coumadin (warfarin) is such a good activator of NK cells. Because Coumadin antagonizes Vitamin K it reduces the functionality of Gas6 and Protein S. In turn that means that their ability to bind to TAM is reduced. Since Gas6 activates TAM and negatively regulates NK activity, Coumadin prevents activation of TAM and positively regulates NK cells In effect, TAM is inhibited, similar to its inhibition with LDC1267.

    In their Figure 4, a section of which I copied for this blog, one can readily see the splotches of melanoma cancer that had metastasized to the lung tissue in control (vehicle) mice. By contrast the number of metastatic colonies is significantly reduced when mice are treated with their inhibitor LDC1267. It is striking that common Warfarin (Coumadin) is just about as effective.

 Image

   It seems like before too long we will see some powerful anti-metastasis drugs made available to cancer patients.

   But meanwhile, I hope that doctors will start prescribing very low dose Coumadin to their cancer patients.

 REFERENCES

 1.         Paolino M, Choidas A, Wallner S, Pranjic B, Uribesalgo I, Loeser S, Jamieson AM, Langdon WY, Ikeda F, Fededa JP, Cronin SJ, Nitsch R, Schultz-Fademrecht C, Eickhoff J, Menninger S, Unger A, Torka R, Gruber T, Hinterleitner R, Baier G, Wolf D, Ullrich A, Klebl BM, Penninger JM. 2014. The E3 ligase Cbl-b and TAM receptors regulate cancer metastasis via natural killer cells. Nature 507:508-512.

2.         Knubel KH, Pernu BM, Sufit A, Nelson S, Pierce AM, Keating AK. 2014. MerTK inhibition is a novel therapeutic approach for glioblastoma multiforme. Oncotarget 5:1338-1351.

 

 

New insight into the most deadly form of breast cancervv

This could be important, or at least it could become important. In the journal Science, in an issue whose cover story is breast cancer, a short note appeared describing a gene that could be involved in causing breast cancer (1).

As the editorial in Science points out, a great deal has been learned about breast cancer in the last 20 years, and new treatment options have been developed Still, it is the leading cause of cancer death among women.

Some 5-10 % of breast cancers are caused by hereditary mutations in BRCA 1 or 2, which normally aid in the repair of damaged DNA (2)and for which there is no cure.

Most cases of breast cancer however, are associated with changes in the genes for hormone receptors, like estrogen receptors, progesterone receptors and epidermal growth factor receptors. Treatments exist for these kinds of cancers. For example, Herceptin is used for treatment of breast cancers with epidermal growth factor receptor mutations, and in the case of estrogen receptor mutations, tamoxifen is used. In both cases the drugs alter the behavior of the receptors without eliminating some of their important positive functions. Interestingly, tamoxifen seems to work best on women whose mammary tissue also expresses high levels of progesterone receptor as well as estrogen receptor (3). (To the best of my knowledge, there are no drugs working to modulate progesterone receptor protein in breast cancer treatment).

But – and here is the point relevant to this discussion — about 15-20% of cancers are classified as “triple negative”, meaning they show no signs of elevation of any of the three hormone receptors (and presumably are BRCA negative). These cancers are generally more life threatening, because they are more metastatic, and there is no treatment for them.

Now, a group of investigators from Cold Spring Harbor and the University of Toronto, report that triple negative cancers display high levels of a possible receptor for G protein activation (4). G proteins are important mediators of cell signaling. They are located in the cytoplasm and can be coupled to a receptor in the membrane when that receptor is bound by a signaling molecule, or ligand. When coupled, the G proteins are activated and can transmit the signal to other molecules in the cell that then migrate into the nucleus and activate a varied set of genes, including genes in growth control.

There are hundreds of different, but related, G proteins, and there are hundred of different, but related coupled receptors. For many of those receptors, the ligand is not known. Such is the case with the receptor reported in this study. It is likely a signal receptor at the cell surface of mammary cells, but its signal at this time is not known. It is a receptor without a known signal, an “orphan” receptor. Each orphan receptor discovered is given a number, in sequence. In this case it is G-Protein coupled Receptor 161, or GPR161.

But the important thing is that GPR161 levels are elevated in triple-negative cancers. This is more cause than effect, because in cell cultures, experimentally elevated expression of the gene for GPR161 induced proliferation and increased the cells’ invasive properties.

The hunt must now be on for the signaling molecule for GPR61, because if the activity of the “receptor” could be modulated pharmacologically, as others are with tamoxifen and Herceptin, another category of breast cancer could be controlled.

REFERENCES:

  1. Kiberstis PA. 2014. Negative Reinforcement. Science 343:6178.
  2. Campeau PM, Foulkes WD, Tischkowitz MD. 2008. Hereditary breast cancer: new genetic developments, new therapeutic avenues. Human genetics 124:31-42.
  3. Stendahl M, Ryden L, Nordenskjold B, Jonsson PE, Landberg G, Jirstrom K. 2006. High progesterone receptor expression correlates to the effect of adjuvant tamoxifen in premenopausal breast cancer patients. Clinical cancer research : an official journal of the American Association for Cancer Research 12:4614-4618.
  4. Feigin ME, Xue B, Hammell MC, Muthuswamy SK. 2014. G-protein-coupled receptor GPR161 is overexpressed in breast cancer and is a promoter of cell proliferation and invasion. Proceedings of the National Academy of Sciences of the United States of America 111:4191-4196.

A promising new drug to treat Acute Myeloid Leukemia

    The financial news was abuzz today about a report by Agios, a biotech company, that in a small Phase 1 study, a drug they are developing was remarkably successful with a subset of Acute Myeloid Leukemia (AML) patients. The patients tested had been through at least one round of chemotherapy, and up to four rounds, without success. The Agios drug, AG-221, was tested for how well it would be tolerated by AML patients. The results were very good, in that adverse side effects were few and limited. The big news though was that 6 of the 7 evaluable patients showed complete remission of their leukemia.
    It is rare to see such impressive results in a preliminary study that deals with dose tolerance. In response to the news, the stock price of Agios rose significantly today.
    Some 10% of AML patients might benefit from AG-221, those with a mutation in a metabolic enzyme, isocitrate dehydrogenase-2. Cells with that mutation produce a higher than normal concentration of 2-hydroxyglutarate, which leads to brain cancers (gliomas and blastomas) as well as AML. How that oncometabolite causes cancer is still being examined. In any event, additional clinical trials with AG-221 are on their way.

Tumor, parasite, and ancient dog — all at once

 

This is a story about an extraordinary tumor.

You know that most cancers arise from mutations in a person’s gene complex, though in some cases a viral infection can cause cancer. An example of the latter is the human papillomavirus, or HPV, a virus is transmitted sexually and that can cause cervical cancer in women.

Now comes word that there is a tumor in dogs that is also sexually transmitted, but it is not caused by a virus. Instead infection occurs by the passage, during sex, of some of the cancer cells themselves. By this means they take up residence in a new dog. It is referred to as the Canine Transmissible Venereal Tumor, or CTVT.

After it is passaged it can cause the growth of a tumor in the recipient organism.  Tumor growth commonly occurs in the genital orifice, but can also appear in other places, including the skin. It generally does not metastasize, and quite inexplicably it regresses after a period of a few months. After that the affected dog is immune from further infection. But meanwhile it can have passed the tumor cells on to other dogs through sexual activity.

For all practical purposes, it acts like a parasitic organism, growing in a host and transmitted by a particular behavior; it is not generally harmful to the host organism, and death from the tumor is rare.

This cancer cell has been passed from dog to dog for many generations. In fact, according to genomic analysis, it may have originated some 11,000 years ago from a breed of dog that no longer exists.

It has survived in dogs as if it were a parasitic single celled organism. But it is not a protozoan. It is a cell that originated from a dog, but no longer belongs to a dog.

This is like a HeLa cell that uses host dogs instead of Petri dishes to provide its growth conditions.

I don’t know of anything comparable.

Meanwhile, according to the investigators from England and Australia who did the genomic analysis[1], it is extraordinary that the cell has survived all this time. Its genome has undergone 1.9 million base substitutions, undergone thousands of rearrangements, and has lost 646 genes. The cell has changed dramatically over millennia, while allowing it – or enabling it – to grow and reproduce and survive passage from one dog to another — and produce tumors that do not kill their host organism.

As they write, “Our results provide a genetic identikit of an ancient dog, and demonstrate the robustness of mammalian somatic cells to survive for millennia despite a massive mutation burden”.

These are two “firsts” for me; a tumor that is transmitted from one organism to another by tumor cells themselves, and a mammalian cell that has survived away from its original organism for over 10,000 years.  Extraordinary.

1.         Murchison EP, Wedge DC, Alexandrov LB, et al. Transmissible dog cancer genome reveals the origin and history of an ancient cell lineage. Science 2014;343:437-40.