Blast-phase MPN and leukemic transformation

Current understanding

Blast-phase MPN (MPN that has progressed to AML) carries a markedly worse prognosis than de novo AML, with response rates as low as ~13% to standard AML therapies in observational cohorts. Although JAK2/CALR/MPL driver mutations can also appear in de novo AML (combined with broader cytokine-receptor/JAK-STAT pathway mutations totaling ~10% of AML), the dismal outcomes in blast-phase MPN appear to reflect the accumulated mutational and clonal context (high-risk co-mutations, prior clonal evolution) rather than the JAK-STAT driver mutation itself.

Evidence log

• 2026-10-07 — Outcome heterogeneity in CALR-mutated myeloproliferative neoplasms.: CALR-mutated MPN cohort reinforces that leukemic/transformation risk is driven by acquired HMR co-mutations (TP53, KRAS, RUNX1) rather than the CALR driver, consistent with the accumulated-co-mutation model and supporting early transplant consideration for CALR-mutant HMR patients. (novelty: 3)
• 2026-09-19 — Clinicopathologic Characteristics of SomaticMutations in Philadelphia Chromosome-Negative Myeloproliferative Neoplasms: A Systematic Review.: Systematic review confirms TP53 mutations are enriched in AP/BP MPN (~10% vs ~3% chronic phase) with high clonal burden and frequent unfavorable karyotype, reinforcing TP53 disruption as a hallmark of the transformed compartment. (novelty: 3)
• 2026-09-01 — Genomic Evolution of Myeloproliferative Neoplasms and Therapy-Associated Mutagenesis.: Longitudinal WGS shows leukemic transformation is genomically encoded years before clinical progression via one of three distinct trajectories (TP53 biallelic loss, stepwise driver accumulation, or an independent leukemic clone unrelated to the chronic-phase MPN clone), refining the mechanistic model of blast-phase evolution beyond generic co-mutation accumulation. (novelty: 4)
• 2026-08-01 — Dual BCL-xL and BCL-2 Inhibition for Advanced Myeloid Neoplasms: A Phase I Dose-Escalation Study of Navitoclax, Venetoclax, and Decitabine.: cross-connection with bcl2-bclxl-dual-inhibition-apoptosis-mpn: Dual BCL-2/BCL-xL inhibition with decitabine shows early efficacy in accelerated/blast-phase MPN, implicating apoptotic resistance as a targetable axis in leukemic transformation. (novelty: 3)
• 2026-07-18 — Acute Myeloid Leukemia Subtype-Specific Prognostic Value of NGS in the Setting of Intensive Chemotherapy.: Mayo NGS series in intensively-treated AML found post-MPN AML had particularly dismal outcomes (27% CR/CRi; 0% 5-year transplant-censored survival) with NGS-based mutation risk stratification largely uninformative in this subgroup, supporting that post-MPN AML biology is distinct from post-MDS AML and not captured by standard AML mutation risk schemes. (novelty: 3)
• 2026-08-12 — Additional myelodysplasia-related gene mutations alter clinical presentation and worsen prognosis in patients with/co-mutated myeloid neoplasms.: Retrospective analysis links accumulation of myelodysplasia-related gene mutations (ASXL1 predominantly) on a TET2-mutant background to increased AML transformation from CMML, supporting the accumulated-co-mutation model of leukemic progression in TET2-driven myeloid neoplasms. (novelty: 3)
• 2026-07-13 — Mutational profile and cardiovascular risk factors impact prognosis in triple-negative essential thrombocythemia.: In triple-negative ET, non-driver mutations in ASXL1, CBL, EZH2, and ZRSR2 predicted leukemic progression, reinforcing that transformation risk in MPN tracks with accumulated high-risk co-mutations independent of canonical JAK2/CALR/MPL driver status. (novelty: 3)
• 2026-08-04 — Survival outcomes and treatment patterns in myelofibrosis in the JAK inhibitor era.: Spanish national registry of 1649 MF patients diagnosed from 2010 onward found acute leukemic transformation was the leading cause of death despite JAK inhibitor use in ~half of patients, and only 25% of transplant-eligible int-2/high-risk patients underwent transplant—underscoring that current JAK inhibition does not prevent progression to blast phase and that curative transplant remains underutilized. (novelty: 3)
• 2026-08-18 — Immune and cytokine landscape differs between cytopenic and proliferative phenotypes in primary myelofibrosis.: Cytopenic PMF’s enrichment for high-molecular-risk mutations and NF-κB inflammatory activation may partly explain its more aggressive clinical course and elevated transformation risk relative to proliferative PMF. (novelty: 3)
• 2026-07-01 — Phase I Trial of Pacritinib in Combination With Venetoclax and Azacitidine for the Treatment of Accelerated and Blast Phase Myeloproliferative Neoplasms: Phase I pacritinib + venetoclax + azacitidine trial tests a triple-mechanism regimen (JAK-STAT + BCL-2 + hypomethylation) specifically in AP/BP MPN, targeting the high-unmet-need transformation setting where standard AML therapies yield ~13% response. (novelty: 4)
• 2026-07-01 — DDX5: a versatile RNA helicase in cancer and cell fate determination-linking c-Myc and JAK2 V617F signalling to emerging therapeutics.: Review implicates a DDX5–c-Myc positive feedback loop as a mediator of JAK2 V617F-driven transformation, suggesting DDX5-directed degraders (FL118) as a candidate strategy to disrupt MYC-driven proliferative programs implicated in MPN leukemic progression. (novelty: 4) (novelty: 4)
• 2026-06-05 — The impact of novel bet inhibitors on the treatment armamentarium of Myelofibrosis.: Review notes BET inhibitor activity against MYC-driven proliferative programs and raises the open question of whether pelabresib-type agents can delay or modify leukemic transformation in high-risk MF, though long-term survival data remain immature. (novelty: 3)
• 2026-06-01 — Cytokine receptor and JAK/STAT pathway mutations in acute myeloid leukemia: Prevalence and clinical impact.: cross-connection with jak-stat-signaling: Blast-phase MPN retains JAK-STAT driver mutations but its dismal prognosis is not explained by JAK-STAT activation alone, indicating leukemic transformation is driven by co-mutational accumulation layered on the JAK-STAT-activated clone. (novelty: 3)

Open questions

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