Perceptions of Patient Disease Burden and Management Approaches of Systemic Mastocytosis (SM) By Healthcare Providers: Results from the TouchStone SM Survey
Authors: Mesa Ruben A. , Sullivan Erin M. , Dubinsky David , Carroll Brittany , Slee Valerie M. , Jennings Susan , Finnerty Celeste , Bohannon Linda , Mathias Susan , Castells Mariana 
Published: February 2021

Introduction: SM is a rare, mast cell neoplasm characterized by uncontrolled proliferation, accumulation, and activation of abnormal mast cells (MCs). Approximately 95% of patients with SM harbor the D816V mutation, which results in constitutive activation of the KIT receptor, causing debilitating symptoms across all SM subtypes such as pruritus, headaches, bone pain, nausea, vomiting, diarrhea, brain fog, and anaphylaxis.
Patients with SM are managed across specialties depending on symptom severity and organ involvement. Hematologists/oncologists and allergists/immunologists both play key roles in the management of disease. With few multidisciplinary SM practices in the US, more information is needed across specialties to enable optimal SM care. Here we report findings from the TouchStone SM survey of healthcare providers (HCPs) in the US to inform perceptions of disease and disease management strategies.
Methods: HCPs completed an online survey containing 47 items covering a range of concepts related to diagnosis (how made, how long it takes), symptoms (how assessed, what symptoms patients experience, how HCPs discuss symptoms with patients, treatment and management), perceived impact on daily life, treatment received (prescription and over-the-counter, treatment goals, unmet needs) and satisfaction (symptom management, overall treatment and disease management). The focus of these analyses are HCP perceptions of disease severity, treatment goals, and disease management. Practicing hematologists/oncologists and allergists/immunologists were eligible if caring for ≥4 SM patients and in practice ≥3 years post fellowship. HCPs were recruited through double-blinded market research survey panels, with individual responses kept confidential. Descriptive analyses were performed on survey responses.
Results: Of 304 HCPs contacted, 60 allergists/immunologists and 59 hematologists/oncologists were enrolled with an average of 14 years of practice experience. On average, participating HCPs had 25 SM patients (range: 4-100) under their care. HCPs reported perceived prevalence of the KIT D816V mutation at 46% of patients (range 0-100), substantially lower than published prevalence rates of up to 95%.1 Among HCPs, the average perceived time from patient symptom onset to diagnosis was 8 months, in contrast to 7 years as reported by patients.2
Allergist/immunologists reported primarily seeing patients with non-advanced disease (80%), while hematologists/oncologists reported managing both non-advanced (50%) and advanced patients (50%). Participating HCPs reported that 58% of their patients have moderate-severe SM. HCP treatment goals for SM patients were consistent across specialties. The 2 most important treatment goals for non-advanced patients were improved quality of life (QoL) (40%; 48/120) and improvement of symptoms (24%; 29/119), while the 2 most important treatment goals for advanced patients were improved progression-free survival /improved overall survival (34%, 35/104) and improved QoL (25%, 26/104).
Conclusions: Allergists/immunologists co-manage SM care with hematologists/oncologists, particularly in non-advanced SM, and have similar treatment goals for this patient population, including improvement in QoL and symptom control. In this sample of HCPs, the perceived prevalence of the KIT D816V mutation as well as the perceived time from symptom onset to diagnosis were substantially lower than published estimates. These gaps identified suggest a need to improve HCP awareness of SM symptoms and diagnostic tools to help facilitate earlier patient diagnosis.
1. Garcia-Montero et al. Blood. 2006;108(7):2366-2372.
2. Jennings SV et al. Immuno Allergy Clin North Am. 2018;38(3):505-525.

Disclosures
Mesa: Promedior: Research Funding; Incyte: Research Funding; Genetech: Research Funding; CTI: Research Funding; Celgene: Research Funding; Abbvie: Research Funding; Sierra Onc: Consultancy; Novartis: Consultancy; LaJolla Pharma: Consultancy; Samus: Research Funding. Sullivan:Blueprint Medicines Corporation: Current Employment, Current equity holder in publicly-traded company. Dubinsky:Blueprint Medicines Corporation: Current Employment, Current equity holder in publicly-traded company. Carroll:Blueprint Medicines Corporation: Consultancy, Current equity holder in publicly-traded company. Mathias:Blueprint Medicines Corporation: Other: employed by Health Outcomes Solutions, which received funding Blueprint for providing assistance in developing the Touchstone survey. Castells:Blueprint Medicines Corporation: Consultancy, Other: Clinical trials: Principle Investigator; UpToDate: Other: Author fee; Annals of Allergy, Asthma & Immunology: Other: Editorial Board.