Reducing Blasts in MPNs
The transformation of MPNs to blast-phase (BP) is generally associated with poorer long-term survival. A recently published study in Blood Advances looked at outcomes of intensive and non-intensive blast reduction strategies in both the blast phase and accelerated phase of MPNs.
Blasts are immature white blood cells found naturally in the bone marrow and circulating blood, typically representing less than 5% of total white blood cells (WBCs). In the blast phase, the number of WBCs exceeds 20%. When blasts are 10-19% it is considered an accelerated phase (AP).
There is currently no standard treatment approach for MPN patients diagnosed with either AP or BP to reduce blasts prior to transplant, according to the study authors. Historically, these MPN patients were treated similarly to those with acute myeloid leukemia (AML). Unlike de novo AML, however, patients with MPN-AP/BP frequently revert to a chronic state of MPN disease and symptoms after blast-reduction treatment. And this may interfere with subsequent therapy decisions, including criteria for hematopoietic cell transplantation (HCT).
“The current study confirms our previous findings that consolidation with HCT after blast reduction is required to achieve long-term survival benefit in MPN-AP/BP,” the authors write. “Moreover, we show that both intensive and non-intensive blast reduction strategies can be used as a bridge to HCT in carefully selected patients.”
Taken together, the results of this study highlight that both intensive and non-intensive blast-reduction modalities, “have limited disease-modifying and clonal clearance capability on their own, and consolidative HCT is required to impart long-term disease control and survival benefit.” This is important because sicker or frail patients may need less intensive treatment.
The authors conclude that MPN-AP/BP represents an ongoing area of unmet need for the development of effective disease-modifying therapies.
Davidson MB, Kennedy JA, Capo-Chichi JM, et al. Outcomes of intensive and nonintensive blast-reduction strategies in accelerated and blast-phase MPN. Blood Adv. 2024. doi:10.1182/bloodadvances.2023011735
Davidson MB, Kennedy JA, Capo-Chichi JM, Shi Y, Xu W, Cheung V, Arruda A, Bankar A, Richard-Carpentier G, Chan S, Maze D, Minden MD, Schimmer AD, Schuh AC, Sibai H, Yee K, Tierens A, Viswabandya A, Gupta V. Outcomes of intensive and nonintensive blast-reduction strategies in accelerated and blast-phase MPN. Blood Adv. 2024 Mar 12;8(5):1281-1294. doi: 10.1182/bloodadvances.2023011735. PMID: 38170760; PMCID: PMC10918486.