• Dr. Lawrence Afrin, Dr. Tania Dempsey

Mast Cell Activation Syndrome (MCAS) Questions Answered: Ask the NY MCAS Expert

Updated: Jul 13


I am currently on methotrexate, ketotifen, fexofenadine, and sodium crom but STILL reacting to food - what else is left to do?

Fortunately, there is a great assortment of interventions which have been found helpful in various MCAS patients, but unfortunately, we cannot yet predict which interventions are most likely to benefit which MCAS patients. Therefore, patient, persistent, methodical “trial and error” is the only presently viable approach toward ultimately identifying the specific regimen which best controls the patient’s symptoms. It would take virtually an entire textbook written at this point to list and explain the great many other treatments which might be reasonable for you to try (presuming you have MCAS), and it obviously is not practical to write such a textbook here, nor would it be prudent for me to speculate which other treatments would be more appropriate (or even inappropriate!) in you specifically. The only approach I can responsibly recommend for you is to first be as sure as you can, via appropriate consultation and evaluation, that you have as accurate a diagnosis as possible as to the cause of your food reactions – perhaps your issues are due to mast cell disease, or perhaps not – and then consult with a healthcare professional who is experienced with the specific diagnosis determined as to other treatments which are appropriate to try for that disease and which would be felt safe to be tried specifically in you.

Do cancer drugs "treat" or put MCAD into remission? If so, what treatments work better? 


These are simple questions which require complicated answers. In general, no, the sorts of drugs which most people think of as “cancer drugs” do not effectively treat MCAD or put it into remission. In fact, it is virtually impossible (at least at present, and likely to continue for a long time to come) to “cure” MCAD (i.e., get rid of it permanently) or even achieve a truly complete “remission” (i.e., complete *control* over it, so that it is producing *no* symptoms), and instead it virtually always is the case that improvements seen from treatment of MCAD are “partial” remissions, with the patient still having *some* symptoms *some* of the time even once an “optimal” treatment regimen has been identified.

I think it is important in a discussion of these questions to distinguish mastocytosis from mast cell activation syndrome (MCAS). There are few “cancer drugs” which have been found helpful in mastocytosis (which is a cancer of mast cells); there are even fewer such drugs which have been found helpful in MCAS. Most people think of the terms “cancer drugs” or “chemotherapy” as drugs which kill the excessively proliferating/reproducing cells at the heart of a cancer. In most patients with mastocytosis (specifically patients with “cutaneous mastocytosis” and “indolent systemic mastocytosis”), such excessive proliferation typically progresses at a very slow *rate*, and most or all of the symptoms suffered by those patients are due *not* to their excessive *numbers* of mast cells but rather to the inappropriate *activation* (i.e., mediator production and release) also seen in those excessive numbers of mast cells. As such, applying “cancer drugs” to kill those excessive cells usually is not worth the side effects of such drugs (not to mention that it also turns out to be the case that mast cells are hardy souls which tend to be resistant to cell-killing cancer drugs), and instead it’s usually better to focus on controlling the inappropriate mast cell activation. And in MCAS, even though many such patients can be found to have at least a little bit of excessive mast cell proliferation (though nowhere close to the degree seen in mastocytosis), such proliferation just is not a significant issue and instead the symptoms are resulting entirely from the improper mast cell *activation* present in the patient, in which case it again doesn’t make much sense (given all the potential side effects) to apply cancer drugs with a goal of killing a mildly (if at all) increased number of mast cells.

There is an important semantic consideration in this discussion, though, in that some drugs which can help reduce the *number* of mast cells also can help reduce the *activation* of mast cells. And the situation gets further complicated by the fact that there are some “cancer drugs” – i.e., drugs which clearly can help reduce the number of cancer cells – which actually work *not* by *killing* cancer cells but rather lead to a reduction in cancer cells by other mechanisms, such as inhibiting cancer cells from reproducing, thereby bringing about a natural reduction over time in total cancer cells from *natural* death of cancer cells. (Cancer generally only becomes a problem when the rate of natural growth/reproduction of the abnormal cells comprising that cancer chronically exceeds the rate of natural death of those abnormal cells.)

As a result, there are some drugs which commonly are thought of as “cancer-killing drugs” but which, in truth, do not *kill* cancer cells and instead just inhibit their reproduction/growth. Many of the tyrosine kinase inhibitors (TKIs), for example, function in this way – and some of the TKIs, too, can inhibit mast cell activation (often at doses far less than needed in fighting cancer). Therefore, it unfortunately is a confusing situation that, at least on the surface, it sometimes seems like “cancer drugs” are being applied (sometimes quite successfully) to the non-cancerous situation that is MCAS, when in truth one has no intention or expectation of getting any killing of mast cells out of use of those drugs. Again, the devil in all of this lies in understanding the details about how the disease is actually operating and what the drug is actually doing. Painting broad brushstrokes (i.e., making generalizations) such as “MCAS is not a cancer, so one should never use any ‘cancer drugs’ to treat it” is not accurate, and if one were to apply such generalizations to all patients bearing the inherently extremely variable disease that is MCAS, one would probably wind up disserving many patients by restricting them from accessing certain drugs which, given in manners appropriate for MCAS (rather than for cancer), might be able to provide them great benefit with relatively little risk for side effects.

Does Mast Cell Activation Syndrome (MCAS) damage organs?

Yes, MCAS can damage organs. At its core, MCAS is a disease of chronic multisystem illness with general themes of inflammation +/- allergic-type phenomena +/- abnormalities in growth/development in potentially any tissue. Chronic inflammation can damage organs, allergic reactions (especially when severe) can damage organs, and abnormal growth and development can damage organs, so, yes, MCAS can damage organs.

Can you have Mastocytosis and Mast Cell Activation Syndrome? I was diagnosed as an infant with UP masto which faded during adolescence. Now in my 30’s severely affected with systemic but don’t fit the diagnostic criteria for SM.

Mastocytosis is a disease featuring *both* grossly inappropriate (i.e., to a cancerous degree) proliferation/reproduction/growth of mast cells *and* inappropriate activation (i.e., production and release of assorted mediators) of mast cells (though note it’s usually the mast cell activation, not the proliferation, that causes most or all of the symptoms in most patients who have mastocytosis, namely, those with cutaneous (skin-confined) mastocytosis and “indolent” systemic mastocytosis), whereas MCAS (as its name implies) is a disease featuring inappropriate activation of mast cells (thus, again, causing a wide array of symptoms) but with relatively little (or even no) inappropriate proliferation/reproduction/growth of mast cells. As such, if one has mastocytosis, then virtually by definition one is going to be having a “mast cell activation syndrome,” but it’s simpler to just carry a diagnosis of mastocytosis, which is understood (or at least *should* be understood) to also incur inappropriate mast cell activation as “part and parcel” of the disease. As such, I do not additionally log a diagnosis of MCAS in the charts of my patients who have mastocytosis.

It has long been recognized that urticaria pigmentosa (UP, the dominant form of cutaneous mastocytosis and which dominantly arises in childhood rather than adulthood) frequently spontaneously resolves by some point in adolescence, and it once was thought that that was the end of that disease in that patient. However – and I’ll take care to note this phenomenon has not yet been the subject of any peer-reviewed, published studies that I’m aware of – it has been my consistent experience in the mere decade I’ve been working in the mast cell arena that virtually all patients who enjoyed spontaneous remission of UP then saw emergence of MCAS within the next decade. Therefore, based solely on this anecdotal experience, it would appear more likely that in these patients there was an underlying mast cell disorder to begin with which featured both abnormal mast cell proliferation and the abnormal mast cell activation which almost inevitably accompanies abnormal mast cell proliferation, and then the disease transformed (for quite unclear reasons) such that the abnormal proliferation remitted, but nevertheless the abnormal activation persists (usually for the rest of the patient’s life). As such, patients who have seen their childhood UP remit (and the physicians of those patients) should remain alert to the possibility that symptoms and medical problems which emerge after that remission might be due to persistence of mast cell activation, thus leading to a new diagnosis of MCAS following “cure” of the diagnosis of UP.

What treatment options have you recently had success with that we may not know about? Have there been any treatments that have offered significant improvements that were unexpected?

Given that I don’t know which treatment options you “may not know about,” it’s difficult for me to answer this question. As I’ve noted in previous answers, there fortunately is a very wide array of treatments which have been shown helpful in a vast array of MCAS patients, and it simply is not practical to review here such a wide array of treatments. I’ve also noted many times that there are no methods yet identified for reliably predicting which MCAS-directed treatments are most likely to help which MCAS patients, and thus there is no “shortcut” to both the MCAS patient and the treating physician practicing an awful lot of patience, persistence, and a methodical approach in stepping through trials of the great many treatments which are reasonable to try in MCAS. I am not aware of any recently discovered treatment options which are providing significantly more success than older, long available options. Nevertheless, it’s always good, of course, to see new options become available because it’s always possible that a patient who hasn’t responded satisfactorily to older options might then respond better to a more recently discovered option. Physicians who are interested in learning about the wide array of treatments in MCAS are encouraged to review the peer-reviewed, published literature in this area (for example, https://www.ncbi.nlm.nih.gov/pubmed/27132234), and patients who are interested in learning about these treatments but for whom the medical literature is either inaccessible or gobbledygook are encouraged to consult physicians who either are experienced in this area or at least have read some of this literature and can “translate” it for the patient.

What are your favorite prostaglandin inhibitors that are gentle on the stomach?

Those prostaglandin inhibitors (often also referred to as non-steroidal anti-inflammatory drugs, nor NSAIDs) which only inhibit the cyclooxygenase-2 (COX-2) enzyme and not both the COX-1 and COX-2 enzymes have been demonstrated to be “gentler on the stomach” as compared to the “traditional” NSAIDs, which block both COX-1 and COX-2. The only COX2-selective inhibitor currently available on the U.S. market is celecoxib. Other COX2-selective inhibitors are available in other markets around the world. Some traditional NSAIDs, like meloxicam, are “more selective” in inhibiting COX-2 than COX-1 (and thus may be “gentler on the stomach” than other traditional NSAIDs) but nevertheless still inhibit COX-1 to some degree.

If you have additional questions on Mast Cell Activation Syndrome (MCAS), be sure to leave them on our MCAS Facebook page here. We will be putting out a new blog post every Friday answering a batch of randomly selected questions posted on our Facebook page.

If you would like to see a NY Mast Cell Activation Disorder specialist, Dr. Lawrence Afrin is now seeing patients in a private practice setting at our office in Armonk, NY. To make an appointment with Dr. Afrin, please call the office or contact us here

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