A mid-stage trial assessing Novartis' experimental rare blood cancer (midostaurin) has shown high response rates in patients with systemic mastocytosis.
The Phase II trial CPKC412D2201, published in the New England Journal of Medicine, demonstrated an overall response rate, defined as a major or partial response, of 60 percent, while the median duration of response was 24.1 months.
Advanced SM is a rare disease in which abnormal mast cells accumulate in the bone marrow, liver, spleen and other organs, causing organ damage, low blood counts and weight loss, as well as debilitating systemic symptoms such as pruritus (chronic itching of skin).
The condition is also characterised by frequent activating mutations of the KIT gene, which triggers the abnormal proliferation and survival of mast cells.
Patients with advanced forms of the condition face a poor prognosis, with overall survival varying between less than six months to 3.5 years, depending on subtype, and no approved treatment for the majority of cases.
Midostaurin (PKC412) is an investigational, oral, multi-targeted kinase inhibitor that recently won Breakthrough status in the US for adults with newly-diagnosed FLT3-mutated acute myeloid leukemia (AML), and has orphan drug status on both sides of the Pond for both AML and mastocytosis.
As well as the high response rate, data from the trial also showed improvements in both bone marrow mast cell burden and serum tryptase levels - a marker for mast cell burden - in 78 percent of patients taking midostaurin, which were associated with disease regression, Novartis noted.
The data are also backed by findings from a compassionate use programme for midostaurin in advanced SM, also published by the journal, showing an overall response rate to treatment of 71 percent after median follow-up time of 18 months, and overall survival of 42.7 percent compared with 14.9 percent in a matched historic control group.
"If approved, midostaurin will offer patients a much needed treatment option," said Professor Andreas Reiter, Department of Haematology and Oncology, University Hospital Mannheim of the University of Heidelberg, Germany and senior author of the study.