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People living with systemic mastocytosis may experience a complex and lengthy path to diagnosis, a high burden of disease and poor quality of life, explains Kenneth Sake, head of international medical affairs at Blueprint Medicines. He describes insights from a new study that reveals the perceptions and realities of this rare mast cell disorder.

A medical doctor by training, Kenneth John-Sake has worked in the pharmaceutical industry for more than 30 years, building experience across several therapeutic areas, especially in allergy. He now works for Blueprint Medicines, a global biopharmaceutical company with International headquarters in Switzerland, which is focused on helping to meet the unmet needs of people living with mast cell disorders.

Systemic mastocytosis (SM) is caused by “an abnormal buildup of mast cells”, Kenneth explains. Mast cells are a type of white blood cell and they are “key drivers” in allergic and inflammatory responses. About one in 10,000 people will live with SM, he says, but the disease has “incredibly varied” manifestations, despite being driven by a single gene mutation in most cases. This variety makes raising awareness of the condition—and Blueprint Medicines’ goal of speeding up diagnosis—challenging. 

He explains one of the “dominant features” of SM is its effect on the skin, with symptoms such as hives or pruritus (itch). But, he adds, these symptoms are only seen in certain patients, with other patients having different symptoms that may not be easily recognised as allergy driven. Other symptoms include diarrhoea, bone or bone marrow problems, cognitive problems and fatigue. Better education is needed to achieve quicker diagnoses and better outcomes for patients, he says.

“There’s such a need to raise awareness, not just with patients but also with a lot of physicians and specialists. There’s so much still to be done to speed up diagnosis for those in need.”

-Kenneth

Indolent and advanced systemic mastocytosis

More than 90% of people with SM have indolent systemic mastocytosis (ISM). “ISM clinical manifestations can be very diverse and potentially debilitating, but under normal conditions and with an effective treatment plan, ISM patients have the same life expectancy as anybody else.” 

He emphasises the impact of ISM must not be underestimated, and people need to have proper care “as early as possible”. People with ISM may need to be managed by allergists, dermatologists as well as haematologists.

Advanced systemic mastocytosis (AdvSM) occurs when mast cells build up and cause damage in different organ systems, including the liver, spleen, bone marrow, gastrointestinal tract and/or skin, and the median life expectancy of people is “seriously impacted”, Kenneth explains. There are three main subtypes of AdvSM, including aggressive systemic mastocytosis (ASM), SM with an associated haematological neoplasm (SM-AHN)—in which people develop  SM alongside another condition that affects the blood cells – and the most extreme form, in rare cases, is mast cell leukaemia (MCL).

People with AdvSM need to be managed by haematologists (specialists in blood and bone marrow disorders) or, in the case of MCL, haemato-oncologists (specialists in blood cancer), Kenneth emphasises. 

The burden of systemic mastocytosis

The assumption may be, Kenneth explains, that the symptoms of ISM reflect what is familiar to many of us—some degree of allergic response, for example to certain foods or a wasp sting—but that is far from the lived experience of many patients. 

Data from the PRISM study reported in 2024—the largest European study to evaluate patient experiences and healthcare practitioners’ perceptions of SM—highlight that half of patients with ISM experience moderate-to-severe symptoms.

Overall, 51% of patients affected by the different forms of SM reported anaphylactic episodes in the previous year (anaphylaxis is a severe, life-threatening allergic reaction). 27% of patients reported experiencing five or more of such episodes.

“If you have one out of two patients reporting moderate to severe symptoms, you start looking at SM from a different perspective.”

-Kenneth

Another striking finding from the PRISM study was that people with SM take an average of seven treatments to manage their symptoms. But managing just the symptoms of this systemic disease is “not the solution for everyone”, Kenneth says, adding that “about 40% of the physicians in the study were basically not happy with their symptom-targeted treatment options”.

The study also gave insights into how SM “heavily impacts” people’s overall quality of life. “It has a substantial work impact, as reported by 59% of patients in the study,” Kenneth explains. “Many people living with ISM have either stopped working, changed job or reduced their working hours. And there is also a high impact on their social life.”

With triggers for the condition including certain foods or even sunlight, people living with SM need to make changes to their daily routines that protect them from these triggers. This may have a considerable physical and psychological toll.

Education, education, education

Raising awareness of SM in its varied forms is vital, Kenneth believes. 

The PRISM study shows that, sadly, for about 20% of patients with AdvSM, a diagnosis can take longer than one year. Kenneth says, “You want your diagnosis and your treatment as soon as possible.” 

The data also show that in ISM, “most patients saw around four different physicians before they got to a diagnosis”, which took, on average, “more than five years”.

“Due to the varied symptoms, you can imagine that it will take a few physicians before there’s one that starts thinking it might be SM, but that diagnosis is a critical one. That’s why we have these efforts to drive disease awareness and education, to help shorten the diagnostic journey.”

-Kenneth

For Kenneth, there is a strong need to raise awareness among healthcare professionals. “Not all dermatologists are familiar with SM. For them, it’s cutaneous so they manage the skin, whereas we know it affects much more than the skin.” He wants to see people living with SM being supported through a high-quality multi-disciplinary approach, so that treatment and overall management can be optimised. 

Kenneth also believes that patient advocacy groups play a key role in raising awareness, but they need support with this. Groups in the UK and Germany are paving the way, he says, but this work “often turns on just one or two individuals”.

“At Blueprint Medicines, we’re working to support patient associations so that patients can ask the right questions. As with everything, you don’t know what you don’t know. And with SM, it’s hard to find that information.”

-Kenneth

The PRISM study is the largest European study that evaluates how SM is perceived by patients and physicians. The acronym stands for “Perceptions, Realities and Insights on Systemic Mastocytosis”. PRISM brought together the perspectives of 540 patients and almost 620 doctors. As such, it expanded on an earlier study in the United States (called TOUCHSTONE), shedding new light on symptoms, people’s diagnostic journeys and their quality of life. PRISM was developed by a mixed panel of SM experts and patient advocates. It involved an extensive questionnaire of more than 100 questions for the patients and doctors taking part.

INTBP-PRAVAASM-24.012.1 9/2024

References:

1. Radia DH et al. The Burden of Systemic Mastocytosis in Europe: Results From the PRISM Patient Survey. Abstract P1676 presented at European Hematology Association (EHA) 2024, Madrid, Spain, June 13 – 16.
2. Radia DH et al. Patient Diagnostic Journey of Systemic Mastocytosis in Europe: Results From the PRISM Survey. Abstract P2292 presented at European Hematology Association (EHA) 2024, Madrid, Spain, June 13 – 16.
3. Triggianni M et al. The Burden of Indolent Systemic Mastocytosis in Europe: Results From the PRISM Patient Survey. Abstract presented at European Academy of Allergy and Clinical Immunology (EAACI) 2024, Valencia, Spain, May 31 – June 3.
4. Triggianni M et al. Healthcare Provider Perspectives on Management of European Patients With Systemic Mastocytosis. Abstract D3.422 presented at European Academy of Allergy and Clinical Immunology (EAACI) 2024, Valencia, Spain, May 31 – June 3.

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