Patients with blood cancers linked to systemic mastocytosis (SM) may face very different outcomes depending on the type of KIT gene mutation they carry, with non-D816 variants associated with less aggressive disease, lower mast cell involvement and significantly better survival, according to a study published recently in Cancer Genetics.
The study analyzed 40 patients with myeloid neoplasms, including acute myeloid leukemia. Among them, 26 had the well-known D816 KIT mutation and 14 had non-D816 changes. While both groups had similar types of blood cancers and chromosome patterns, their disease behavior differed in important ways that could affect patients’ experiences and prognoses.
What is a KIT gene mutation?
SM is usually caused by a sporadic mutation in the KIT gene, which codes for a protein called CD117 transmembrane tyrosine kinase. The protein is involved in the growth, survival and migration of mast cells. The most common KIT mutation associated with SM is the D816V mutation, which results in the amino acid aspartic acid being replaced by the amino acid valine in the protein chain.
One of the most striking differences involved SM. SM developed in 31% of patients with D816 mutations, either at the same time or later in the disease course. In contrast, none of the patients with non-D816 mutations developed SM. Tissue testing also showed that patients with D816 mutations had a much higher mast cell burden, suggesting a stronger link between this mutation and mast cell–driven disease.
The timing of mutations also varied. Non-D816 KIT mutations were present at diagnosis in 92% of cases, compared with 60% of D816 cases. In many D816 cases, the mutation appeared later as a secondary event, which may signal disease progression. Patients with D816 mutations also tended to have more complex genetic profiles, including additional mutations in genes involved in chromatin regulation.
Read more about SM causes and risk factors
“Our limited study result demonstrated that the group with D816 change has more diverse genetic features, higher mortality and worse [overall survival] compared to the non-D816 group,” the study’s authors explained.
Despite some similarities in treatment response, survival outcomes differed sharply. The mortality rate was 88% in the D816 group compared with 31% in the non-D816 group. Overall survival was significantly longer in patients with non-D816 mutations. Among a small subgroup with a specific leukemia subtype, all patients with D816 mutations died, while all those with non-D816 mutations were alive at the time of analysis.
For patients, these findings highlight that not all KIT mutations carry the same risk, even within diseases connected to SM. Identifying the exact mutation type could help doctors better predict disease course, tailor monitoring and potentially guide treatment choices. As genetic testing becomes more widely used, this distinction may offer patients clearer expectations and more personalized care.
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