Expanding the understanding of telomere biology disorder with reports from two families harboring variants in ZCCHC8 and TERC.

Telomere biology disorder (TBD) can present within a wide spectrum of symptoms ranging from severe congenital malformations to isolated organ dysfunction in adulthood. Diagnosing TBD can be challenging given the substantial variation in symptoms and age of onset across generations. In this report, we present two families, one with a pathogenic variant in ZCCHC8 and another with a novel variant in TERC. In the literature, only one family has previously been reported with a ZCCHC8 variant and TBD symptoms. This family had multiple occurrences of pulmonary fibrosis and one case of bone marrow failure. In this paper, we present a second family with the same ZCCHC8 variant (p.Pro186Leu) and symptoms of TBD including pulmonary fibrosis, hematological disease, and elevated liver enzymes. The suspicion of TBD was confirmed with the measurement of short telomeres in the proband. In another family, we report a novel likely pathogenic variant in TERC. Our comprehensive description encompasses hematological manifestations, as well as pulmonary and hepatic fibrosis. Notably, there are no other reports which associate this variant to disease. The families expand our understanding of the clinical implications and genetic causes of TBD.

ProGraME: A novel flow cytometry algorithm for the diagnosis of low-risk myelodysplastic syndromes in patients with cytopenia.

OBJECTIVES: Flow cytometry (FC) is, together with morphology, genetics, and cytogenetics, used in the diagnostic assessment of cytopenia, as its value in evaluating bone marrow dysplasia been highlighted by several studies. However, despite the development of algorithms and guidelines, there is still a lack of standardization of the FC assessment of bone marrow dysplasia. METHODS: By combining FC, together with morphological analysis and cytogenetic/molecular assessment in a training cohort of 209 patients, we created a novel score, ProGraME, which includes four parameters, each from a different cell lineage (Progenitor cells, Granulocytes, Monocytes, Erythroid precursors), solely based on relevant population gating. Points for ProGraME were attained for: lymphoid precursors ≤5% of all CD34+ cells (1.5 point); a granulocyte-to-lymphocyte side-scatter ratio ≤6 (1 point); a monocyte CD33-CV% ≥ 63 (2 points), and an erythroid precursor CD36-CV% ≥ 65 (2 points). RESULTS: Using a cutoff of ≥2 as suggestive of dysplasia, ProGraME showed a sensitivity of 91% and a specificity of 81% in the training cohort and 95% and 75%, respectively, in an independent validation cohort of 159 patients. In addition, ProGraME had a very high negative predictive value of 97.1% and 97.8% in the training and validation cohorts, respectively, offering a useful tool for excluding bone marrow dysplasia. Finally, among the 23 CCUS patients that scored positive for dysplasia with ProGraME in the training cohort, 16 of them (69%) carried high-risk mutations, suggesting that FC might help identify early changes of dysplasia. CONCLUSIONS: ProGraME can potentially optimize the FC diagnosis of low-risk myelodysplasia without minimal requirements of flow analysis other than accurate population gating.

Size matters in telomere biology disorders ‒ expanding phenotypic spectrum in patients with long or short telomeres.

The end of each chromosome consists of a DNA region termed the telomeres. The telomeres serve as a protective shield against degradation of the coding DNA sequence, as the DNA strand inevitably ‒ with each cell division ‒ is shortened. Inherited genetic variants cause telomere biology disorders when located in genes (e.g. DKC1, RTEL1, TERC, TERT) playing a role in the function and maintenance of the telomeres. Subsequently patients with telomere biology disorders associated with both too short or too long telomeres have been recognized. Patients with telomere biology disorders associated with short telomeres are at increased risk of dyskeratosis congenita (nail dystrophy, oral leukoplakia, and hyper- or hypo-pigmentation of the skin), pulmonary fibrosis, hematologic disease (ranging from cytopenia to leukemia) and in rare cases very severe multiorgan manifestations and early death. Patients with telomere biology disorders associated with too long telomeres have in recent years been found to confer an increased risk of melanoma and chronic lymphocytic leukemia. Despite this, many patients have an apparently isolated manifestation rendering telomere biology disorders most likely underdiagnosed. The complexity of telomere biology disorders and many causative genes makes it difficult to design a surveillance program which will ensure identification of early onset disease manifestation without overtreatment.

Epigenetic therapy in combination with a multi-epitope cancer vaccine targeting shared tumor antigens for high-risk myelodysplastic syndrome - a phase I clinical trial.

BACKGROUND: Standard care for patients with high-risk myelodysplastic syndrome (MDS) is hypomethylating agents such as azacitidine (AZA), which can induce expression of methylated tumor-associated antigens and therefore potentiate immunotherapeutic targeting. METHOD: In this phase 1 trial, we combined AZA with a therapeutic peptide vaccine targeting antigens encoded from NY-ESO-1, MAGE-A3, PRAME, and WT-1, which have previously been demonstrated to be upregulated by AZA treatment. RESULT: Five patients who had responded to AZA monotherapy were included in the study and treated with the vaccine. The combination therapy showed only few adverse events during the study period, whereof none classified as serious. However, no specific immune responses could be detected using intracellular cytokine staining or ELISpot assays. Minor changes in the phenotypic composition of immune cells and their expression of stimulatory and inhibitory markers were detected. All patients progressed to AML with a mean time to progression from inclusion (TTP) of 5.2 months (range 2.8 to 7.6). Mean survival was 18.1 months (range 10.9 to 30.6) from MDS diagnosis and 11.3 months (range 4.3 to 22.2) from inclusion. Sequencing of bone marrow showed clonal expansion of malignant cells, as well as appearance of novel mutations. CONCLUSION: The patients progressed to AML with an average time of only five months after initiating the combination therapy. This may be unrelated to the experimental treatment, but the trial was terminated early as there was no sign of clinical benefit or immunological response. Why the manuscript is especially interesting This study is the first to exploit the potential synergistic effects of combining a multi-peptide cancer vaccine with epigenetic therapy in MDS. Although our results are negative, they emphasize challenges to induce immune reactivity in patients with high-risk MDS.

Outcome of treatment with carfilzomib before and after treatment with daratumumab in relapsed or refractory multiple myeloma patients.

Real world evidence is important since most patients cannot be included in randomized clinical trials (RCTs). In a nationwide, cohort of relapsed/refractory multiple myeloma patients treated with daratumumab (N = 635), we retrospective studied patients treated with carfilzomib (N = 251). Data were collected by audit of medical records. We compared characteristics of patients treated with carfilzomib before daratumumab (Car-Da; N = 150) and after daratumumab (Da-Car; N = 101) with those not treated with carfilzomib (N = 384). Furthermore, we examined effectiveness and safety of carfilzomib. The group of patients treated with carfilzomib differed from patients not treated with carfilzomib in the following parameters: They were younger, more were treated up-front with high dose melphalan and autologous stem cell transplantation (HDM-ASCT)and had relapse within 18 months thereafter, and more had high-risk cytogenetic abnormalities (CA) and amplification 1q (amp1q). In patients treated with Car-Da, 30.3% had high-risk CA and 30.1% had amp1q and in Da-Car it was 43.3% and 41%, respectively. In the Car-Da cohort, 34.4% experienced early relapse after HDM-ASCT versus 47.4% in the Da-Car cohort. The percentage of patients with very good partial remission was higher in patients treated with Car-Da compared to Da-Car (31.7% vs. 17.4%). The median duration of treatment and time to next treatment (TNT) of Car-Da/Da-Car were 4.6/4.3 months and 7.1/4.3 months and only a trend toward superior TNT for Car-Da was found (p = 0.06). Toxicity of carfilzomib was the same as reported in RCT. A similar poor TNT of daratumumab was found when used before (5.6 months) or after carfilzomib (4.9 months). In this cohort of patients with sequential treatment with carfilzomib and daratumumab or vice versa, a high percentage of patients were high-risk by CA, amp1q, and early relapse after HDM-ASCT. Outcome of Car-DA and outcome of Da-Car were equally poor. These patients should be considered for new promising treatment strategies.

Mutations in idiopathic cytopenia of undetermined significance assist diagnostics and correlate to dysplastic changes.

Cytopenia is common in the elderly population and etiology may be difficult to assess. Here, we investigated the occurrence of mutations in patients with idiopathic cytopenia of undetermined significance and the usefulness in improving diagnostics. We included 60 patients with persistent cytopenia > 6 months without definite diagnosis of hematological neoplasm after routine assessment. Bone marrow material underwent a blinded morphology review and DNA was sequenced with a targeted 20 gene panel representing the most commonly mutated genes in myelodysplastic syndrome. Thirty seven (62%) patients carried at least one mutation at inclusion, and of these 95% carried a mutation in TET2, ASXL1, SRSF2, or DNMT3A. The most commonly mutated gene was TET2 observed in 43% of all patients. During one to eight years follow-up seven patients progressed to a myeloid neoplasm and six of these had a detectable mutation at study entry. Median time to progression was 53 months (range 10-78), and at time of progression each patient had at least two mutations detected. Mutations in TP53 and NRAS were not present in patients at inclusion, but identified as secondary hits triggering progression. The morphology review was concordant in 68% of all cases, and 93% of the cases reclassified into the group "highly suspicious for MDS" had a mutation. All patients who had a concordant review "highly suspicious for MDS" had at least two mutations detected. Overall, we show that morphology examination is challenging in this heterogeneous group and targeted sequencing helps identify patients at risk of progression. Am. J. Hematol. 91:1234-1238, 2016. © 2016 Wiley Periodicals, Inc.

Allelic methylation levels of the noncoding VTRNA2-1 located on chromosome 5q31.1 predict outcome in AML.

Deletions of chromosome 5q are associated with poor outcomes in acute myeloid leukemia (AML) suggesting the presence of tumor suppressor(s) at the locus. However, definitive identification of putative tumor suppressor genes remains controversial. Here we show that a 106-nucleotide noncoding RNA vault RNA2-1 (vtRNA2-1), previously misannotated as miR886, could potentially play a role in the biology and prognosis of AML. vtRNA2-1 is transcribed by polymerase III and is monoallelically methylated in 75% of healthy individuals whereas the remaining 25% of the population have biallelic hypomethylation. AML patients without methylation of VTRNA2-1 have a considerably better outcome than those with monoallelic or biallelic methylation (n = 101, P = .001). We show that methylation is inversely correlated with vtRNA2-1 expression, and that 5-azanucleosides induce vtRNA2-1 and down-regulate the phosphorylated RNA-dependent protein kinase (pPKR), whose activity has been shown to be modulated by vtRNA2-1. Because pPKR promotes cell survival in AML, the data are consistent with vtRNA2-1 being a tumor suppressor in AML. This is the first study to show that vtRNA2-1 might play a significant role in AML, that it is either mono- or biallelically expressed in the blood cells of healthy individuals, and that its methylation state predicts outcome in AML.

False positivity of ETV6/RUNX1 detected by FISH in healthy newborns and adults.

The leukemia-associated ETV6-RUNX1-translocation frequently emerges prenatally. Reverse-transcriptase PCR screening may indicate presence of ETV6-RUNX1 transcripts in random cord blood samples. Subsequent cell enrichment validation finds significantly lower levels than validation applying fluorescence in situ hybridization (FISH) (<10(-5) vs. 10(-3) to 10(-4)). Using three FISH probe sets, we screened 179,000 cells from ETV6-RUNX1-positive dilution series, healthy adults and random cord blood samples. The t(12;21) single fusion extra signal translocation probe and the ETV6 break apart probe gave false positive results mimicking ETV6-RUNX1-positive cell levels of 10(-3). This questions the paradigm that 1% of newborns have ETV6-RUNX1-positive cells at levels of 10(-3) to 10(-4).

Risk of cancer in relatives of patients with myelodysplastic neoplasia and acute leukemias.

BACKGROUND: The risk of cancer among relatives of patients with either myelodysplastic neoplasia (MDS), acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) has not been thoroughly examined. METHODS: We linked the Danish Civil Registration System with the Danish Cancer Registry, the Danish National Acute Leukemia Registry, and the Danish Myelodysplastic Syndrome Database to estimate the relative risk of cancer among relatives of patients with MDS/AML/ALL. We used standardized incidence ratios (SIRs), i.e., the ratio of observed to expected number of cancers among the relatives as a measure of relative risk. RESULTS: We identified 13010 first-degree (FDR) and 22051 second-degree (SDR) relatives of 8386 patients with MDS/ALL/AML. Disregarding basal cell carcinoma (BCC), the relative risk for cancer overall was increased in both FDR (SIR=1.3; 95% confidence interval (CI) 1.1-1.4) and SDR (SIR=1.5; 95% CI 1.2-1.8). SIRs among FDRs were statistically significantly increased for malignant melanoma, BCC and for the combined groups of cancers of the male genital organs, urinary tract, and MDS/AML/ALL. Among SDRs, SIRs were statistically significantly increased for malignant melanoma, BCC, and cancers in the digestive organs and peritoneum. CONCLUSIONS: We observed an increased risk of cancer among FDR and SDR of patients with MDS/AML/ALL.

MicroRNA-130a-mediated down-regulation of Smad4 contributes to reduced sensitivity to TGF-ß1 stimulation in granulocytic precursors.

Smad4 is important in the TGF-ß pathway and required for transcriptional activation and inhibition of cell growth after TGF-ß1 stimulation. We demonstrate that miR-130a is differentially expressed during granulopoiesis and targets Smad4 mRNA. The transcript for Smad4 is present throughout neutrophil maturation, but Smad4 protein is undetectable in the most immature cells, where miR-130a is highly expressed. Two miR-130a binding sites were identified in the 3'-untranslated region of the Smad4 mRNA. Overexpression of miR-130a in HEK293, A549, and 32Dcl3 cells repressed synthesis of Smad4 protein without affecting Smad4 mRNA level. Repression of Smad4 synthesis in a granulocytic cell line by miR-130a reduced its sensitivity to TGF-ß1-induced growth inhibition. This effect was reversed by inhibiting the activity of miR-130a with an antisense probe or by expressing a Smad4 mRNA lacking miR-130a binding sites. High endogenous miR-130a and Smad4 mRNA levels and low expression of Smad4 protein were found in the t(8;21)(q22;q22) acute myelogenous leukemia-derived cell line Kasumi-1. When miR-130a was inhibited by an antisense RNA, the amount of Smad4 protein increased in Kasumi-1 cells and rendered it susceptible for TGF-ß1-mediated cell growth inhibition. Our data indicate that miR-130a is involved in cell cycle regulation of granulocytic cells through engagement of Smad4 in the TGF-ß pathway.

High frequency of BTG1 deletions in acute lymphoblastic leukemia in children with down syndrome.

Previous cytogenetic studies of myeloid and acute lymphoblastic leukemias in children with Down syndrome (ML-DS and DS-ALL) have revealed significant differences in abnormality patterns between such cases and acute leukemias in general. Also, certain molecular genetic aberrations characterize DS-related leukemias, such as GATA1 mutations in ML-DS and deregulation of the CRLF2 gene in DS-ALL. Whether microdeletions/microduplications also vary between DS and non-DS cases is presently unclear. To address this issue, we performed single nucleotide polymorphism array analyses of eight pediatric ML-DS and 17 B-cell precursor DS-ALL. In the ML-DS cases, a total of 29 imbalances (20 gains and nine losses) and two partial uniparental isodisomies (pUPDs) were detected. None of the 11 small (defined as <10 Mb) imbalances were recurrent, nor were the pUPDs, whereas of the 18 large aberrations, three were recurrent-dup(1q), +8 and +21. In contrast, several frequent changes were identified in the DS-ALL cases, which harbored 82 imbalances (30 gains and 52 losses) and four pUPDs. Of the 40 large changes, 28 were gains and 12 losses, with +X, dup(Xq), dup(1q), del(7p), dup(8q), del(9p), dup(9p), del(12p), dup(17q), and +21 being recurrent. Of the 40 microdeletions identified, several targeted specific genes, with the following being repeatedly deleted: BTG1 and CDKN2A/B (29% of cases), ETV6, IKZF1, PAX5 and SERP2 (18%), and BTLA, INPP4B, P2RY8, and RB1 (12%). Loss of the SERP2 and INPP4B genes, encoding the stress-associated endoplasmic reticulum protein family member 2 and the inositol polyphosphate 4-phosphatase-II, respectively, has previously never been implicated in leukemia. Although deletions of the other genes have been associated with ALL, the high frequency of BTG1 loss is a novel finding. Such deletions may characterize a clinical subgroup of DS-ALL, comprising mainly boys with a high median age. In conclusion, ML-DS and DS-ALL are genetically distinct, with mainly gains in ML-DS and deletions in DS-ALL. Furthermore, DS-ALL is characterized by several recurrent gene deletions, with BTG1 loss being particularly frequent.

National clinical Genetic Networks - GENets - Establishment of expert collaborations in Denmark.

Genetic conditions are often familial, but not all relatives receive counseling from the same institution. It is therefore necessary to ensure consistency in variant interpretation, counseling practices, and clinical follow up across health care providers. Furthermore, as new possibilities for gene-specific treatments emerge and whole genome sequencing becomes more widely available, efficient data handling and knowledge sharing between clinical laboratory geneticists and medical specialists in clinical genetics are increasingly important. In Denmark, these needs have been addressed through the establishment of collaborative national networks called Genetic Expert Networks or "GENets". These networks have enhanced patient and family care significantly by bringing together groups of experts in national collaborations. This promotes coordinated clinical care, the dissemination of best clinical practices, and facilitates the exchange of new knowledge.

The idic(X)(q13) in myeloid malignancies: breakpoint clustering in segmental duplications and association with TET2 mutations.

Myelodysplastic syndromes and acute myeloid leukemia with an isodicentric X chromosome [idic(X)(q13)] occur in elderly women and frequently display ringed sideroblasts. Because of the rarity of idic(X)(q13), little is known about its formation, whether a fusion gene is generated, and patterns of additional aberrations. We here present an SNP array study of 14 idic(X)-positive myeloid malignancies, collected through an international collaborative effort. The breakpoints clustered in two regions of segmental duplications and were not in a gene, making dosage effects from the concurrent gain of Xpter-q13 and loss of Xq13-qter, rather than a fusion gene, the most likely pathogenetic outcome. Methylation analysis revealed involvement of the inactive X chromosomes in five cases and of the active in two. The ABCB7 gene, mutated in X-linked sideroblastic anemia and spinocerebellar ataxia, is in the deleted region, suggesting that loss of this gene underlies the frequent presence of ringed sideroblasts. Additional genetic abnormalities were present in 12/14 (86%), including partial uniparental disomies for 9p (one case) and 4q (two cases) associated with homozygous mutations of JAK2 and TET2, respectively. In total, TET2 mutations were seen in 4/11 (36%) analyzed cases, thus constituting a common secondary event in idic(X)-positive malignancies.

A predictive model for bone marrow disease in cytopenia based on noninvasive procedures.

Bone marrow specimens are the core of the diagnostic workup of patients with cytopenia. To explore whether next-generation sequencing (NGS) could be used to rule out malignancy without bone marrow specimens, we incorporated NGS in a model to predict presence of disease in the bone marrow of patients with unexplained cytopenia. We analyzed the occurrence of mutations in 508 patients with cytopenia, referred for primary workup of a suspected hematologic malignancy from 2015 to 2020. We divided patients into a discovery (n = 340) and validation (n = 168) cohort. Targeted sequencing, bone marrow biopsy, and complete blood count were performed in all patients. Mutations were identified in 267 (53%) and abnormal bone marrow morphology in 188 (37%) patients. Patients with isolated neutropenia had the lowest frequency of both mutations (21%) and abnormal bone marrow morphology (5%). The median number of mutations per patient was 2 in patients with abnormal bone marrow morphology compared with 0 in patients with a nondiagnostic bone marrow morphology (P < .001). In a multivariable logistic regression, mutations in TET2, SF3B1, U2AF1, TP53, and RUNX1 were significantly associated with abnormal bone marrow morphology. In the validation cohort, a model combining mutational status and clinical data identified 34 patients (20%) without abnormal bone marrow morphology with a sensitivity of 100% (95% confidence interval: 93%-100%). Overall, we show that NGS combined with clinical data can predict the presence of abnormal bone marrow morphology in patients with unexplained cytopenia and thus can be used to assess the need of a bone marrow biopsy.

Improved survival after allogeneic transplantation for acute lymphoblastic leukemia in adults: a Danish population-based study.

We investigated trends of survival in a population-based cohort study of all 181 adults who received HCT for ALL in Denmark between 2000-2019. Patients had a median (min-max) age of 36 (18-74) years at HCT and were followed for a median of eight years. Overall survival (OS) improved over time with an estimated 2-year OS of 49% (CI 27-66%) in year 2000 versus 77% (CI 59-88%) in year 2019. More patients achieved cure over time (OR for cure per year 1.07, CI 1.00-1.15), while the rate of death in non-cured patients remained stable (HR of excess mortality per year 0.99, CI 0.93-1.06). Relapse decreased over time (HR 0.92 per year, CI 0.87-0.98), whereas non-relapse mortality did not change notably (HR 0.98 per year, CI 0.93-1.04). In conclusion, survival after HCT in adults with ALL has improved over the past two decades, primarily due to more patients achieving cure.

Methotrexate/6-mercaptopurine maintenance therapy influences the risk of a second malignant neoplasm after childhood acute lymphoblastic leukemia: results from the NOPHO ALL-92 study.

Among 1614 children with acute lymphoblastic leukemia (ALL) treated with the Nordic Society for Paediatric Haematology and Oncology (NOPHO) ALL-92 protocol, 20 patients developed a second malignant neoplasm (SMN) with a cumulative risk of 1.6% at 12 years from the diagnosis of ALL. Nine of the 16 acute myeloid leukemias or myelodysplastic syndromes had monosomy 7 (n = 7) or 7q deletions (n = 2). In Cox multivariate analysis, longer duration of oral 6-mercaptopurine (6MP)/methotrexate (MTX) maintenance therapy (P = .02; longest for standard-risk patients) and presence of high hyperdiploidy (P = .07) were related to increased risk of SMN. Thiopurine methyltransferase (TPMT) methylates 6MP and its metabolites, and thus reduces cellular levels of cytotoxic 6-thioguanine nucleotides. Of 524 patients who had erythrocyte TPMT activity measured, the median TPMT activity in 9 patients developing an SMN was significantly lower than in the 515 that did not develop an SMN (median, 12.1 vs 18.1 IU/mL; P = .02). Among 427 TPMT wild-type patients for whom the 6MP dose was registered, those who developed SMN received higher average 6MP doses than the remaining patients (69.7 vs 60.4 mg/m2; P = .03). This study indicates that the duration and intensity of 6MP/MTX maintenance therapy of childhood ALL may influence the risk of SMNs in childhood ALL.

[Germ line predisposition for myeloid neoplasia in adults].

Myeloid neoplasms with germ line predisposition (hMN) are likely underdiagnosed and are estimated to constitute a substantial fraction of patients with myelodysplastic syndrome and acute myeloid leukaemia. Correct diagnosis of hMN is vital, as it can influence treatment decisions, facilitate genetic counselling and help identify family members at risk. In this review, we describe the symptoms associated with hMN and present an example of the underlying molecular mechanism. Furthermore, we summarise the current knowledge and recommendations for diagnosis, surveillance and treatment of hMN.

Allogeneic Hematopoietic Stem Cell Transplantation for Chronic Myelomonocytic Leukemia: Clinical and Molecular Genetic Prognostic Factors in a Nordic Population.

Chronic myelomonocytic leukemia (CMML) is an aggressive disease in which survival after allogeneic hematopoietic stem cell transplantation (HCT) remains relatively poor. An assessment of prognostic factors is an important part of treatment decision making and has the potential to be greatly improved by the inclusion of molecular genetics. However, there is a significant knowledge gap in the interpretation of mutational patterns. This study aimed to describe outcomes of allogeneic HCT in patients with CMML in relation to clinical and molecular genetic risk factors. This retrospective study included 64 patients with CMML who underwent allogeneic HCT between 2008 and 2018, with a median follow-up of 5.4 years. Next-generation sequencing using targeted myeloid panels was carried out on saved material from 51 patients from the time of transplantation. Kaplan-Meier and Cox regression were used for analysis of overall survival (OS), and cumulative incidence with competing risks and Fine and Gray models were used for analysis of relapse and nonrelapse mortality (NRM). Mutations were detected in 48 patients (94%), indicating high levels of minimal residual disease (MRD) positivity at transplantation, even among those in complete remission (CR) (n = 14), 86% of whom had detectable mutations. The most frequently mutated genes were ASXL1 (37%), TET2 (37%), RUNX1 (33%), SRSF2 (26%), and NRAS (20%). Risk stratification using the CMML-specific Prognostic Scoring System molecular score (CPSS-Mol) resulted in 45% of patients moving to a higher risk-group compared with risk stratification using the CPSS. High leucocyte count (≥13 × 109/L), transfusion requirement, and previous intensive chemotherapy were associated with higher incidence of relapse. Being in CR was not linked to better outcomes. Neither ASXL1 nor RUNX1 mutation was associated with a difference in OS, relapse, or NRM, despite being high risk in the nontransplantation setting. TET2 mutations were associated with a significantly higher 3-year OS (73% versus 40%; P = .039). Achieving MRD-negative CR was rare in this CMML cohort, which may explain why we did not observe better outcomes for those in CR. This merits further investigation. Our analyses suggest that the negative impact of ASXL1 and RUNX1 mutations can be overcome by allogeneic HCT; however, risk stratification is complex in CMML and requires larger cohorts and multivariate models, presenting an ongoing challenge in this rare disease.