Al-Mashdali, Abdulrahman F

e18597 Background: TP53 mutations ( TP53 m) are uncommon in chronic-phase (CP) Philadelphia (Ph) chromosome–negative myeloproliferative neoplasms (MPN) but are increasingly reported in myelofibrosis (MF) and accelerated/blast phase (AP/BP). Their distribution, allelic configuration, and associated clinical outcomes have not been systematically synthesized. Methods: A PRISMA-guided search of EMBASE and PubMed (1974-July 1, 2025) identified cohort studies reporting adult Ph–negative MPNs with molecularly confirmed TP53 m. Case reports were excluded; Conference abstracts were included if cohort-level data were available. Extracted variables included demographics, MPN subtype, disease phase, TP53 allelic status (per International Consensus Classification), variant allele frequency (VAF), allogeneic hematopoietic cell transplantation (allo-HCT), median overall survival (mOS), and leukemic transformation. Given heterogeneity and lack of comparators, pooled proportions with (95% CI) were generated for descriptive variables; outcomes were summarized descriptively. Results: 10 retrospective studies met inclusion criteria. Pooled mean age was 61 years (95% CI 57.18–65.17) with male predominance (58%, 95 CI 53–63). TP53 m were uncommon in patients with Ph-negative MPN (3%, 95% CI 0–15%) but were higher in MF/AP/BP (10%, 95% CI 4–24%). Among patients with TP53 m, disease distribution included MF (35%, 95% CI 13–65%), AP/BP (33%, 95% CI 26–41%), essential thrombocythemia (ET) (10%, 95% CI 3–28%), and polycythemia vera (PV) (8%, 95% CI 4–14%). Multi-hit TP53 m accounted for 52% (95% CI 40–64%), while single-hit comprised 47% (95% CI 34–60%). The pooled mean TP53 VAF was 37.48% (95% CI 30.73–44.24%). Allo-HCT was used in 16% (95% CI 13–20%). One cohort reported leukemic transformation in 47% with a median follow-up of 9.6 months (m). Reported mOS in TP53 m CP-MF ranged from 11.6–18 m and was not reached in PV/ET, whereas AP/BP mOS ranged from 4.5–6 months. Conclusions: TP53 m Ph–negative MPNs are enriched in MF and AP/BP and frequently demonstrate multi-hit TP53 m with high VAF and associated with high leukemic transformation. Standardized molecular reporting and prospective studies are needed to refine prognostication and treatment strategies in TP53m MPN. Characteristics of patients with TP53 m MPN. Variable Pooled variables (95% CI) Age 61.18 years (57.18–65.17) Male/Female 58% (53–63)/42% (53–63) TP53 mutation in the cohort 3% (0–15) TP53 in MF/AP/BP 10% (CI 4–24) Primary myelofibrosis 35% (13–65) MPN in AP/BP 33% (26–41) Essential thrombocythemia 10% (CI 3–28) Polycythemia vera 8% (CI 4–14) Multi-hit/single-hit TP53 52% (CI 40–64) 47% (CI 34–60) TP53 VAF 37.48% (30.73–44.24) Abbreviations: MF: Myelofibrosis, AP: accelerated phase, BP: Blast phase, MPN: myeloproliferative neoplasm, VAF: Variant Allele Frequency.

Abstract Background: Plasmacytoid dendritic cell-associated acute myeloid leukemia (pDC-AML) is an emerging, rare subtype of AML characterized by the clonal proliferation of plasmacytoid dendritic cells (pDCs) at various stages of maturation. Although infrequent, this leukemia subtype is clinically aggressive and poses significant diagnostic and therapeutic challenges. Objective: This review synthesizes current knowledge on the immunophenotypic, genetic, and clinical features of pDC-AML, explores its prognostic implications, and compares it with the related entity blastic plasmacytoid dendritic cell neoplasm (BPDCN). Methods: A comprehensive literature search was conducted using databases including PubMed, Scopus, and Web of Science. Studies describing the morphology, immunophenotype, cytogenetics, molecular alterations, clinical presentation, and treatment outcomes of pDC-AML were included. Data were extracted and compiled from 16 studies encompassing 231 patients. Results: pDC-AML predominantly affects older adults (median age ~69 years) and exhibits a male predominance (~68%). It presents with diverse AML subtypes, including AML with monocytic differentiation, minimal differentiation, and secondary AML. Bone marrow pDCs range from 2.2% to 30% and exhibit variable maturation, often expressing CD123, CD303, CD304, and variably CD34 and CD117. In contrast to BPDCN, CD56 is rarely expressed, and skin or lymph node involvement is uncommon. Genetically, pDC-AML exhibits a complex landscape. RUNX1 mutations are the most common (14–78%), possibly driving pDC lineage commitment. Additional mutations include ASXL1, DNMT3A, SRSF2, FLT3, and BCOR. Chromosomal abnormalities such as chromosome 7 deletions, trisomy 13, and MLL or CBFA rearrangements are frequently observed. Compared to BPDCN—which shows high CD56 and TCL1 expression and more frequent TET2 mutations—pDC-AML is more genetically and phenotypically heterogeneous. Therapeutic responses are inconsistent. Treatments include induction chemotherapy, hypomethylating agents (e.g., azacytidine plus venetoclax), and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Median overall survival ranges from 9.6 to 20 months, with frequent relapse even post-HSCT. Emerging therapies targeting CD123 (e.g., tagraxofusp) and immune-modulating agents are under investigation. Conclusion: pDC-AML is a clinically aggressive and biologically distinct AML subtype defined by clonal pDC expansion, frequent RUNX1 mutations, and suboptimal responses to current therapies. Accurate diagnosis relies on integrated immunophenotypic and genetic profiling. Despite progress, patient outcomes remain poor, underscoring the need for improved classification, prognostic markers, and targeted therapeutic strategies.