Dr Sudipto Mukherjee Discusses Survival Outcomes Data in US Patients With ISM

Data on disease progression among patients with indolent systemic mastocytosis (ISM) are limited and have clinical implications. Therefore, having a better understanding of survival outcomes among these patients can lead to timely treatment interventions and potentially improved outcomes.

The data found in this population-level analysis suggest that perhaps not all patients with ISM are truly indolent, says Sudipto Mukherjee, MD, PhD, MPH, hematology and medical oncology at Cleveland Clinic.

Transcript

What motivated the need for this large-scale population level analysis in the US on overall survival in patients with indolent systemic mastocytosis (ISM)?

Systemic mastocytosis or mast cell disease are a very heterogeneous group of diseases. As per the WHO [World Health Organization] classification, indolent systemic mastocytosis is one of the entities under the umbrella of systemic mastocytosis. As the name "indolent" suggests, it gives us a perception that these diseases are indolent, which means they may remain quiet for a long time without causing any kind of difficulties or symptomatic problems to the patients. The reason why we conducted this large population-based study from the US is there has been a spade of studies recently that have shown that compared to the previously held notion that patients with indolent systemic mastocytosis have an indolent course, recent studies suggest that may not be the case.

For example, in 2019, a paper published in Lancet Haematology looked at 1006 indolent systemic mastocytosis patients. This was from the European Cutaneous Mastocytosis Network registry that showed when these 1000 patients with ISM were compared to patients with cutaneous mastocytosis, their survival was diminished. More recently, a population-level study from the Danish National Health Registry included close to about 400 ISM patients, and this was compared to a non-ISM–matched cohort, which showed that the mortality was increased in patients with ISM, with a hazard ratio that fluctuated between 1.53 and 2.59, with a median follow-up of 9 years.

These data are provocative and troubling, and it does challenge our perception and notion that maybe not all ISM patients need to be considered indolent. There might be some among these who are progressing at a faster rate and therefore need to be clinically monitored and started on appropriate therapies.

This led us to look at the outcome or the survival of the ISM patients, particularly in the US, because there have not been any significant, large scale population-level studies on systemic mastocytosis from the US. Most of the data that we have come from the European registries.