High genomic complexity (HGC) is linked to poor prognosis in CLL, but its independent prognostic value remains uncertain amid emerging biomarkers. We analysed copy number alterations (CNA) in 495 untreated patients from (immuno)chemotherapy trials (CLL4, ADMIRE, ARCTIC), incorporating IGHV status, telomere length (TL), targeted sequencing and DNA-methylation subtypes. Patients harboured low (LGC, ≤2 CNAs; n = 334), intermediate (IGC, 3-4 CNAs; n = 97), or high (HGC, ≥5 CNAs; n = 64) genomic complexity. HGC associated with U-CLL (81%, p < 0.001), TP53-aberration (36%, p < 0.001), short TL (TL-S; 61%, p < 0.05), del13q (50%, p < 0.001) and del11q (22%, p < 0.05). IGC was enriched forbiallelic ATM disruption and BIRC3 deletions (p < 0.001). Trisomy 12 and NOTCH1 mutations were enriched in LGC (p < 0.001). HGC associated with shorter progression-free and overall survival in univariate models but only remained independent for OS in CLL4 (HR = 1.61, p = 0.02). Independent prognostic factors included TP53 aberration, U-CLL, TL-S and n-CLL. Of 64 HGC patients, 23 had TP53-aberration; 92% of TP53 wild-type cases had other high-risk features (TL-S, U-CLL, or n-CLL). HGC may reflect a convergence of high-risk features rather than represent an independent biomarker. The interplay of telomere attrition, IGHV status and DNA methylation subtype necessitates further validation in targeted therapy cohorts to enhance risk assessment in prognostic models.

Menin inhibition leads to an antileukemic effect through hematopoietic differentiation. Treatment with the menin inhibitor revumenib results in clinical remissions in relapsed or refractory (R/R) acute myeloid leukemia (AML) with either rearrangement of lysine methyltransferase2A (KMT2A) or mutation in nucleophosmin 1 (NPM1), leading to regulatory approval of this drug. However, determinants of response to revumenib have not been fully elucidated. We examined the immunophenotype of leukemia cells by flow cytometry, in sequential bone marrow specimens from 48 patients with R/R AML treated with revumenib. We observed dynamic changes in the immunophenotype after treatment in 16 of 31 (52%) patients, characterized by a switch from a myeloid/stem-like to a monocytic or myelomonocytic immunophenotype, or vice versa, or by substantial changes in the intensity of antigen expression or in patterns of leukemia-associated immunophenotypes. Morphologic remission with undetectable measurable residual disease (MRD) by flow cytometry following revumenib was associated with improved overall survival, with a median of 23.6 months compared with 20.8 months in patients with morphologic response and detectable MRD, and 3.2 months in non-responders. In summary, treatment monitoring of AML by flow cytometry, following menin inhibition, requires recognition of phenotypic changes associated with differentiation.

Whether mitigation of myeloproliferation improves prognosis of CMML independently of bone marrow response is unknown. Flow-defined classical monocytes (cMo) and immature granulocytes (iGRAN) have not yet been studied as biomarkers of response. We inspected the prognostic value of WBC, circulating monocytes, cMo and iGRANs in the 120 DACOTA (NCT02214407) patients randomized to decitabine (n = 63) or hydroxyurea (n = 57) evaluated after 3 cycles with BM aspiration and complete blood count. Across arms, 59% and 56% patients had monocytes > 1 × 109/L or WBC > 10 × 109/L at the 3- and 6-cycle evaluation respectively. After 6 cycles, persistence of monocytes > 1 × 109/L or WBC > 10 × 109/L increased the hazard of death (HR = 5.38, p = 0.0003) irrespective of treatment, baseline CPSS and persistence of BM blast excess. After 3 cycles, both higher absolute cMo and iGRAN counts independently predicted poorer OS, without significant interaction with treatment arm. Median OS from landmark was 35.1 months in the 28% patients with cMo ≤ 0.94 ×109/L AND iGRAN ≤ 0.40 ×109/L versus 15.3 months in others (p = 0.013). Biomarkers integrating blood counts and flow cytometry may predict CMML prognosis irrespective of treatment.

Disease progression, graft-versus-host disease (GVHD), and non-relapse mortality (NRM) are the main causes of failure after allogeneic hematopoietic cell transplantation (SCT) for myeloid neoplasms. T-cell epitope-based models classify HLA-DPB1 mismatches by permissiveness and have been associated with differential risks of GVHD, relapse, and NRM. However, most studies were conducted before the routine use of post-transplant cyclophosphamide (PTCy) as GVHD prophylaxis for unrelated donor (UD) SCT. We retrospectively analyzed 541 adults undergoing 8/8 UD SCT with PTCy prophylaxis, categorized as DP-matched (DP-M, n = 176), permissive mismatch (DP-P, n = 219), non-permissive graft-versus-host (DP-NP-GVH, n = 82), or host-versus-graft (DP-NP-HVG, n = 64). Outcomes were compared across groups with stratification by disease risk and remission/MRD status. Two-year relapse incidence was lower with DP-P versus DP-M (18% vs 28%; HR 0.6, 95% CI 0.4-0.9, p = 0.03), most pronounced in high-risk AML/MDS, where relapse rates approached those of lower-risk disease. This effect persisted after adjustment for remission and MRD status. GVHD incidence was unaffected by DPB1 status. OS and PFS did not differ significantly; age and comorbidity were dominant predictors of NRM. In UD SCT with PTCy, DPB1-permissive mismatching reduces relapse in high-risk AML/MDS without increasing GVHD or NRM, supporting DP-P mismatching as an actionable donor-selection criterion.

Somatic mutations in RNA splicing regulators, including the serine/arginine-rich protein SRSF2, are frequently observed in myeloid malignancies. Using mouse models and primary human samples, we investigated the impact of SRSF2 mutations on erythropoiesis. We found reduced erythropoiesis in Srsf2P95H versus wild-type mice upon stress-induced erythropoiesis and identified that SRSF2 mutations correlate with reduced hemoglobin in JAK2-mutant patients with myeloproliferative neoplasms (MPN). Consistent with this, Jak2V617F-Srsf2P95H versus Jak2V617F mice displayed reduced red blood cell counts and erythroid precursor frequencies. RNA-sequencing on erythroid precursors showed reduced expression of heme metabolism and mitotic spindle-related genes, and increased expression of mTORC1 signaling in Srsf2P95H versus wild-type cells. RNA splicing analyses on the same cells and on human patient samples identified aberrant FYN splicing in SRSF2mut cells, with increased aberrant FYNB over normal FYNT transcripts. FYNB, but not FYNT, expression resulted in reduced erythroid differentiation and increased phosphorylation of mTORC1 downstream target S6. Additionally, increased S6 phosphorylation was confirmed in primary Srsf2P95H erythroid cells. mTORC1 pathway inhibition using rapamycin normalized FYNB- and Srsf2P95H-induced impaired erythropoiesis and significantly increased erythroid colony formation of SRSF2-mutant myelodysplastic neoplasm (MDS) bone marrow cells. Our data reveal targetable molecular mechanisms of impaired erythropoiesis in SRSF2-mutant cells.

While TP53 mutations in myeloproliferative neoplasms (MPN) are associated with an increased risk of leukemic transformation, not all patients carrying a TP53 mutation progress. To better risk-stratify MPN patients with TP53 mutations, we analyzed data from 1540 patients treated at four specialized cancer centers. Among them, 1429 had wildtype TP53 and 111 had mutations in the TP53 gene. At first MPN diagnosis, 32% had polycythemia vera, 39% had essential thrombocythemia, and 25% had primary myelofibrosis. Among all MPN patients with TP53 mutations, presence of fibrosis in the bone marrow (hazard ratio (HR): 3.84, 95% CI: 1.98-7.43), multi-hit TP53 mutation status (HR: 2.74, 95% confidence interval (CI): 1.52-4.97), and higher PHANTM score (HR: 1.87, 95% CI: 1.02-3.42) were associated with worse OS in a multivariable analysis. Based on these variables, we developed a risk model to identify TP53-mutated MPN patients who are at high risk for inferior OS. Median OS from time of TP53 detection was 0.5 years in high-risk patients, compared to 2.3 years for patients with intermediate risk and 6.3 years for patients with low risk. This scoring system may help refine risk stratification for chronic phase MPN patients harboring TP53 aberrations.

Tisagenlecleucel (tisa-cel), an autologous anti-CD19 CAR T-cell therapy, has significantly improved outcomes in pediatric, adolescents and young adults with relapsed/refractory B-cell precursor acute lymphoblastic leukemia (R/R BCP-ALL). However, 30-50% experience early failure or relapse. We retrospectively analyzed 52 cases of early failures (n = 13) or relapses (n = 39), evaluating post-tisa-cel outcomes and prognostic factors. CD19 antigen loss was the only factor associated with a lower complete remission rate after salvage therapy (OR = 0.16, 95%CI [0.03-0.90], p = 0.04). Median overall survival (OS) was 14.5 months, with a 2-year OS of 37.4% (95%CI [24.4-50.4]), similar between early failure (38.5%) and relapse (37.0%) groups (p = 0.78). Patients with measurable residual disease only at salvage initiation had significantly improved 2-year OS (61.9%, (95%CI [38.1-78.8])) compared to those with overt disease (20.7%, (95%CI [8.4-36.7], p = 0.008)). Factors associated with inferior OS included high pre-infusion tumor burden (HR = 3.57, p < 0.01), and prior inotuzumab ozogamicin exposure (HR = 3.81, p < 0.01). Although salvage therapies and hematopoietic stem cell transplantation benefit some patients, 5 of 18 transplanted patients died from treatment-related toxicity, underscoring the significant associated risks. These findings highlight the poor prognosis of tisa-cel failures and the urgent need for novel strategies.