Busulfan treatment of myeloproliferative neoplasms (MPNs) demonstrated high response rates and infrequent adverse events (AEs), according to a study of real-world data from hospitals in the United Kingdom.
“Given the lack of prospective studies on the use of busulphan, our study contributes valuable real-world data on the safety and efficacy of busulphan which clinicians should find useful in managing this challenging cohort,” the researchers wrote in their report.
In the retrospective study, researchers analyzed data from 115 patients with MPNs from 13 hospitals. The median age of the cohort was 78 years and 44% of patients were male. The majority of patients had a diagnosis of essential thrombocythemia (ET) at 67%, followed by 24% with polycythemia vera (PV), 5% with MPN not otherwise specified, and 4% with myelofibrosis. JAK2 and CALR mutations were present among 62% and 13% of patients, respectively.
There were 16% of patients with a history of malignancy, including 8% of nonmelanoma skin cancers, and 8% with cancers that included those of the breast, prostate, lung, low-grade lymphoma, and melanoma.
One previous line of therapy (LOT) had been received by 13% of patients, 63% had 2 LOTs, 19% had 3 LOTs, and 5% had 4 LOTs. The most common previous cytoreductive therapy was hydroxycarbamide (78%), followed by anagrelide (16%), pegylated interferon (8%), P32 (3%), and ruxolitinib (2%).
The dosing regimens of busulfan included repeated single doses (31%) with a median dose of 38 mg, 1- to 4-week courses (30%) with a median dose 3.5 mg, and continuous therapy lasting more than 4 weeks (35%) with a median dose of 2 mg.
The median time from busulfan initiation to last follow-up or death was 23 months. There were 14% of patients who were alive with acceptable blood count control without any other cytoreductive therapy.