Nilotinib with or without cytarabine for Philadelphia-positive acute lymphoblastic leukemia.

ABSTRACT: We previously demonstrated that a reduced-intensity chemotherapy schedule can safely replace hyper-CVAD (cyclophosphamide-vincristine-doxorubicin [Adriamycin]-dexamethasone) cycle 1 when combined with imatinib in adults with Philadelphia-positive acute lymphoblastic leukemia. In the present randomized GRAAPH-2014 trial, we used nilotinib and addressed the omission of cytarabine (Ara-C) in consolidation. The primary objective was the major molecular response (MMR) rate measured by BCR::ABL1 quantification after cycle 4 (end of consolidation). All patients were eligible for allogeneic stem cell transplant (SCT), whereas those in MMR could receive autologous SCT, followed by 2-year imatinib maintenance in both cases. After the enrollment of 156 of 265 planed patients, the data and safety monitoring board decided to hold the randomization because of an excess of relapse in the investigational arm. Among the 155 evaluable patients, 76 received Ara-C during consolidation (arm A) and 79 did not (arm B). Overall, 133 patients (85%) underwent SCT, 93 allogeneic and 40 autologous. The noninferiority end point regarding MMR was reached with 71.1% (arm A) and 77.2% (arm B) of patients reaching MMR. However, the 4-year cumulative incidence of relapse was higher in arm B compared with arm A (31.3% [95% confidence interval {CI}, 21.1%-41.9%] vs 13.2% [95% CI, 6.7%-21.9%]; P = .017), which translated to a lower relapse-free survival. With a median follow-up of 3.8 years, 4-year overall survival was 79.0% (95% CI, 70.6%-89.3%) in arm A vs 73.4% (95% CI, 63.9%-84.4%) in arm B (P = .35). Despite a noninferior rate of MMR, more relapses were observed when ARA-C was omitted without impact on survival. ClinicalTrials.gov ID, NCT02611492.

Clinical and biological features of B-cell neoplasms with CDK6 translocations: an association with a subgroup of splenic marginal zone lymphomas displaying frequent CD5 expression, prolymphocytic cells, and TP53 abnormalities.

A translocation involving the cyclin-dependent kinase 6 (CDK6) gene [t(CDK6)] is a rare but recurrent abnormality in B-cell neoplasms. To further characterise this aberration, we studied 57 cases; the largest series reported to date. Fluorescence in situ hybridisation analysis confirmed the involvement of CDK6 in all cases, including t(2;7)(p11;q21) immunoglobulin kappa locus (IGK)/CDK6 (n = 51), t(7;14)(q21;q32) CDK6/immunoglobulin heavy locus (IGH) (n = 2) and the previously undescribed t(7;14)(q21;q11) CDK6/T-cell receptor alpha locus (TRA)/T-cell receptor delta locus (TRD) (n = 4). In total, 10 patients were diagnosed with chronic lymphocytic leukaemia, monoclonal B-cell lymphocytosis or small lymphocytic lymphoma, and 47 had small B-cell lymphoma (SmBL) including 36 cases of marginal zone lymphoma (MZL; 34 splenic MZLs, one nodal MZL and one bronchus-associated lymphoid tissue lymphoma). In all, 18 of the 26 cytologically reviewed cases of MZL (69%) had an atypical aspect with prolymphocytic cells. Among the 47 patients with MZL/SmBL, CD5 expression was found in 26 (55%) and the tumour protein p53 (TP53) deletion in 22 (47%). The TP53 gene was mutated in 10/30 (33%); the 7q deletion was detected in only one case, and no Notch receptor 2 (NOTCH2) mutations were found. Immunoglobulin heavy-chain variable-region (IGHV) locus sequencing revealed that none harboured an IGHV1-02*04 gene. Overall survival was 82% at 10 years and not influenced by TP53 aberration. Our present findings suggest that most t(CDK6)+ neoplasms correspond to a particular subgroup of indolent marginal zone B-cell lymphomas with distinctive features.

Impact of cytogenetic abnormalities in adults with Ph-negative B-cell precursor acute lymphoblastic leukemia.

Multiple cytogenetic subgroups have been described in adult Philadelphia chromosome (Ph)-negative B-cell precursor (BCP) acute lymphoblastic leukemia (ALL), often comprising small numbers of patients. In this study, we aimed to reassess the prognostic value of cytogenetic abnormalities in a large series of 617 adult patients with Ph-negative BCP-ALL (median age, 38 years), treated in the intensified Group for Research on Adult Acute Lymphoblastic Leukemia (GRAALL)-2003/2005 trials. Combined data from karyotype, DNA index, fluorescence in situ hybridization, and polymerase chain reaction screening for relevant abnormalities were centrally reviewed and were informative in 542 cases (88%), allowing classification in 10 exclusive primary cytogenetic subgroups and in secondary subgroups, including complex and monosomal karyotypes. Prognostic analyses focused on cumulative incidence of failure (including primary refractoriness and relapse), event-free survival, and overall survival. Only 2 subgroups, namely t(4;11)/KMT2A-AFF1 and 14q32/IGH translocations, displayed a significantly worse outcome in this context, still observed after adjustment for age and after censoring patients who received allogeneic stem cell transplantation (SCT) in first remission at SCT time. A worse outcome was also observed in patients with low hypodiploidy/near triploidy, but this was likely related to their higher age and worse tolerance to therapy. The other cytogenetic abnormalities, including complex and monosomal karyotypes, had no prognostic value in these intensive protocols designed for adult patients up to the age of 60 years.

Dasatinib and low-intensity chemotherapy in elderly patients with Philadelphia chromosome-positive ALL.

Prognosis of Philadelphia-positive (Ph(+)) acute lymphoblastic leukemia (ALL) in the elderly has improved during the imatinib era. We investigated dasatinib, another potent tyrosine kinase inhibitor, in combination with low-intensity chemotherapy. Patients older than age 55 years were included in the European Working Group on Adult ALL (EWALL) study number 01 for Ph(+) ALL (EWALL-PH-01 international study) and were treated with dasatinib 140 mg/day (100 mg/day over 70 years) with intrathecal chemotherapy, vincristine, and dexamethasone during induction. Patients in complete remission continued consolidation with dasatinib, sequentially with cytarabine, asparaginase, and methotrexate for 6 months. Maintenance therapy was dasatinib and vincristine/dexamethasone reinductions for 18 months followed by dasatinib until relapse or death. Seventy-one patients with a median age of 69 years were enrolled; 77% had a high comorbidity score. Complete remission rate was 96% and 65% of patients achieved a 3-log reduction in BCR-ABL1 transcript levels during consolidation. Only 7 patients underwent allogeneic hematopoietic stem cell transplantation. At 5 years, overall survival was 36% and up to 45% taking into account deaths unrelated to disease or treatment as competitors. Thirty-six patients relapsed, 24 were tested for mutation by Sanger sequencing, and 75% were T315I-positive. BCR-ABL1(T315I) was tested by allele-specific oligonucleotide reverse transcription-quantitative polymerase chain reaction in 43 patients and detection was associated with short-term relapses. Ten patients (23%) were positive before any therapy and 8 relapsed, all with this mutation. In conclusion, dasatinib combined with low-intensity chemotherapy was well-tolerated and gave long-term survival in 36% of elderly patients with Ph(+) ALL. Monitoring of BCR-ABL1(T315I) from diagnosis identified patients with at high risk of early relapse and may help to personalize therapy.

Interphase FISH for BCR-ABL1 rearrangement on neutrophils: A decisive tool to discriminate a lymphoid blast crisis of chronic myeloid leukemia from a de novo BCR-ABL1 positive acute lymphoblastic leukemia.

Discrimination between lymphoid blast crisis of chronic myeloid leukemia (CML) and de novo BCR-ABL1 positive acute lymphoblastic leukemia (ALL) represents a diagnostic challenge because this distinction has a major incidence on the management of patients. Here, we report an uncommon pediatric case of ALL with cryptic ins(22;9)(q11;q34q34) and p190-type BCR-ABL1 transcript. We performed interphase fluorescence in situ hybridization (FISH) for BCR-ABL1 rearrangement on blood neutrophils, which was positive consistent with the diagnosis of lymphoid blast crisis of CML. This case illustrates the major interest of interphase FISH for BCR-ABL1 rearrangement on blood neutrophils as a decisive method to discriminate a lymphoid blast crisis of CML from a de novo BCR-ABL1 positive ALL.

Randomized study of reduced-intensity chemotherapy combined with imatinib in adults with Ph-positive acute lymphoblastic leukemia.

In this study, we randomly compared high doses of the tyrosine kinase inhibitor imatinib combined with reduced-intensity chemotherapy (arm A) to standard imatinib/hyperCVAD (cyclophosphamide/vincristine/doxorubicin/dexamethasone) therapy (arm B) in 268 adults (median age, 47 years) with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). The primary objective was the major molecular response (MMolR) rate after cycle 2, patients being then eligible for allogeneic stem cell transplantation (SCT) if they had a donor, or autologous SCT if in MMolR and no donor. With fewer induction deaths, the complete remission (CR) rate was higher in arm A than in arm B (98% vs 91%; P = .006), whereas the MMolR rate was similar in both arms (66% vs 64%). With a median follow-up of 4.8 years, 5-year event-free survival and overall survival (OS) rates were estimated at 37.1% and 45.6%, respectively, without difference between the arms. Allogeneic transplantation was associated with a significant benefit in relapse-free survival (hazard ratio [HR], 0.69; P = .036) and OS (HR, 0.64; P = .02), with initial white blood cell count being the only factor significantly interacting with this SCT effect. In patients achieving MMolR, outcome was similar after autologous and allogeneic transplantation. This study validates an induction regimen combining reduced-intensity chemotherapy and imatinib in Ph+ ALL adult patients and suggests that SCT in first CR is still a good option for Ph+ ALL adult patients. This trial was registered at www.clinicaltrials.gov as #NCT00327678.

First case of B ALL with KMT2A-MAML2 rearrangement: a case report.

BACKGROUND: A large number of chromosomal translocations of the human KMT2A gene, better known as the MLL gene, have so far been characterized. Genetic rearrangements involving KMT2A gene are frequently involved in lymphoid, myeloid and mixed lineage leukemia. One of its rare fusion partners, the mastermind like 2 (MAML2) gene has been reported in four cases of myeloid neoplasms after chemotherapy so far: two acute myeloid leukemias (AML) and two myelodysplasic syndrome (MDS), and two cases of secondary T-cell acute lymphoblastic leukemia (T-ALL). CASE PRESENTATION: Here we report the case of a KMT2A - MAML2 fusion discovered by Next-Generation Sequencing (NGS) analysis in front of an inv11 (q21q23) present in a 47-year-old female previously treated for a sarcoma in 2014, who had a B acute lymphoid leukemia (B ALL). CONCLUSION: It is, to our knowledge, the first case of B acute lymphoblastic leukemia with this fusion gene. At the molecular level, two rearrangements were detected using RNA sequencing juxtaposing exon 7 to exon 2 and exon 9 to intron 1-2 of the KMT2A and MAML2 genes respectively, and one rearrangement using Sanger sequencing juxtaposing exon 8 and exon 2.

Characterization of the novel Sezary lymphoma cell line BKP1.

Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of lymphomas primarily involving the skin. The most common types are mycosis fungoides (MF) and Sezary Syndrome (SS). We report a novel long-term fast-growing SS line termed BKP1 that was characterized by flow cytometry (FC), conventional and molecular cytogenetic [FISH/multi-FISH together with array comparative genomic hybridization (aCGH)]. FC immunophenotype of the BKP1 is CD2+CD5+CD3+CD4+CD8-CD7-CD25-CD26-CD30-CD158k+. The TCRγ characterization of BKP1 by PCR identified a clonal rearrangement. The conventional cytogenetic and Multi-FISH analysis showed complex chromosomal rearrangements. aCGH analysis highlighted the loss of genes involved in cell cycle control, in immune response (HLA, complement complex) and DNA damage repair mechanisms. The BKP1 is another lymphoma cell line thoroughly characterized that can be a valuable tool for both basic and applied research such as identification of deregulated genes and/or pathways and screening for new antilymphoma drugs.

A Phase 2 study of L-asparaginase encapsulated in erythrocytes in elderly patients with Philadelphia chromosome negative acute lymphoblastic leukemia: The GRASPALL/GRAALL-SA2-2008 study.

PURPOSE: The GRASPALL/GRAALL-SA2-2008 Phase II trial evaluated the safety and efficacy of L-asparaginase encapsulated within erythrocytes (GRASPA®) in patients ≥ 55 years with Philadelphia chromosome-negative acute lymphoblastic leukemia. FINDINGS: Thirty patients received escalating doses of GRASPA® on Day 3 and 6 of induction Phases 1 and 2. The primary efficacy endpoint was asparagine depletion < 2 µmol/L for at least 7 days. This was reached in 85 and 71% of patients with 100 and 150 IU/kg respectively but not with 50 IU/kg. Grade 3/4 infection, hypertransaminasemia, hyperbilirubinemia and deep vein thrombosis occurred in 77, 20, 7, and 7% of patients, respectively. No allergic reaction or clinical pancreatitis was observed despite 17% of Grade 3/4 lipase elevation. Anti-asparaginase antibodies were detected in 50% of patients and related to a reduction in the duration of asparagine depletion during induction Phase 2 without decrease of encapsulated L-asparaginase activity. Complete remission rate was 70%. With a median follow-up of 42 months, median overall survival was 15.8 and 9.7 months, in the 100 and 150 IU/kg cohorts respectively. CONCLUSIONS: The addition of GRASPA®, especially at the 100 IU/kg dose level, is feasible in elderly patients without excessive toxicity and associated with durable asparagine depletion. (clinicaltrials.gov identifier NCT01523782).

Cytogenetics in the management of myelodysplastic neoplasms (myelodysplastic syndromes, MDS): Guidelines from the groupe francophone de cytogénétique hématologique (GFCH).

Myelodysplastic neoplasms (MDS) are clonal hematopoietic neoplasms. Chromosomal abnormalities (CAs) are detected in 40-45% of de novo MDS and up to 80% of post-cytotoxic therapy MDS (MDS-pCT). Lately, several changes appeared in World Health Organization (WHO) classification and International Consensus Classification (ICC). The novel 'biallelic TP53 inactivation' (also called 'multi-hit TP53') MDS entity requires systematic investigation of TP53 locus (17p13.1). The ICC maintains CA allowing the diagnosis of MDS without dysplasia (del(5q), del(7q), -7 and complex karyotype). Deletion 5q is the only CA, still representing a low blast class of its own, if isolated or associated with one additional CA other than -7 or del(7q) and without multi-hit TP53. It represents one of the most frequent aberrations in adults' MDS, with chromosome 7 aberrations, and trisomy 8. Conversely, translocations are rarer in MDS. In children, del(5q) is very rare while -7 and del(7q) are predominant. Identification of a germline predisposition is key in childhood MDS. Aberrations of chromosomes 5, 7 and 17 are the most frequent in MDS-pCT, grouped in complex karyotypes. Despite the ever-increasing importance of molecular features, cytogenetics remains a major part of diagnosis and prognosis. In 2022, a molecular international prognostic score (IPSS-M) was proposed, combining the prognostic value of mutated genes to the previous scoring parameters (IPSS-R) including cytogenetics, still essential. A karyotype on bone marrow remains mandatory at diagnosis of MDS with complementary molecular analyses now required. Analyses with FISH or other technologies providing similar information can be necessary to complete and help in case of karyotype failure, for doubtful CA, for clonality assessment, and for detection of TP53 deletion to assess TP53 biallelic alterations.

Cytogenetics in the management of bone marrow failure syndromes: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH).

Bone marrow failure syndromes are rare disorders characterized by bone marrow hypocellularity and resultant peripheral cytopenias. The most frequent form is acquired, so-called aplastic anemia or idiopathic aplastic anemia, an auto-immune disorder frequently associated with paroxysmal nocturnal hemoglobinuria, whereas inherited bone marrow failure syndromes are related to pathogenic germline variants. Among newly identified germline variants, GATA2 deficiency and SAMD9/9L syndromes have a special significance. Other germline variants impacting biological processes, such as DNA repair, telomere biology, and ribosome biogenesis, may cause major syndromes including Fanconi anemia, dyskeratosis congenita, Diamond-Blackfan anemia, and Shwachman-Diamond syndrome. Bone marrow failure syndromes are at risk of secondary progression towards myeloid neoplasms in the form of myelodysplastic neoplasms or acute myeloid leukemia. Acquired clonal cytogenetic abnormalities may be present before or at the onset of progression; some have prognostic value and/or represent somatic rescue mechanisms in inherited syndromes. On the other hand, the differential diagnosis between aplastic anemia and hypoplastic myelodysplastic neoplasm remains challenging. Here we discuss the value of cytogenetic abnormalities in bone marrow failure syndromes and propose recommendations for cytogenetic diagnosis and follow-up.

Cytogenetics in the management of hematologic neoplasms with germline predisposition: guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH).

The number of predisposing genes is continuously growing with the widespread availability of DNA sequencing, increasing the prevalence of hematologic malignancies with germline predisposition. Cytogenetic analyses provide an effective approach for the recognition of these malignancies with germline predisposition, which is critical for proper diagnosis, optimal treatment and genetic counseling. Based on the World Health Organization and the international consensus classifications as well as the European LeukemiaNet recommendations, this review first presents an advanced classification of neoplasms with germline predisposition focused on the acquired cytogenetic alterations during leukemogenesis. The various genetic rescue mechanisms and the progression to transformation are then explained. The review also outlines the specific constitutional and somatic cytogenetic aberrations indicative of germline predisposition disorders in B-acute lymphoblastic leukemia (ALL), T-ALL, bone marrow failure syndrome and myeloid neoplasms. An emphasis is made on monosomy 7 in the predisposition field, its frequency and diagnosis impact as well as its various circumstances of occurrence. Lastly, we propose cytogenetic technical recommendations and guidelines for clinical reporting of these specific aberrations.

Cytogenetics in the management of B-cell acute lymphoblastic leukemia: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH).

Cytogenetic analysis is mandatory at initial assessment of B-cell acute lymphoblastic leukemia (B-ALL) due to its diagnostic and prognostic value. Results from chromosome banding analysis and complementary FISH are taken into account in therapeutic protocols and further completed by other techniques (RT-PCR, SNP-array, MLPA, NGS, OGM). Indeed, new genomic entities have been identified by NGS, mostly RNA sequencing, such as Ph-like ALL that can benefit from targeted therapy. Here, we have attempted to establish cytogenetic guidelines by reviewing the most recent published data including the novel 5th World Health Organization and International Consensus Classifications. We also focused on newly described cytogenomic entities and indicate alternative diagnostic tools such as NGS technology, as its importance is vastly increasing in the diagnostic setting.

Cytogenetics in the management of T-cell acute lymphoblastic leukemia (T-ALL): Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH).

Molecular analysis is the hallmark of T-cell acute lymphoblastic leukemia (T-ALL) categorization. Several T-ALL sub-groups are well recognized based on the aberrant expression of specific transcription factors. This recently resulted in the implementation of eight provisional T-ALL entities into the novel 2022 International Consensus Classification, albeit not into the updated World Health Organization classification system. Despite this extensive molecular characterization, cytogenetic analysis remains the backbone of T-ALL diagnosis in many countries as chromosome banding analysis and fluorescence in situ hybridization are relatively inexpensive techniques to obtain results of diagnostic, prognostic and therapeutic interest. Here, we provide an overview of recurrent chromosomal abnormalities detectable in T-ALL patients and propose guidelines regarding their detection. By referring in parallel to the more general molecular classification approach, we hope to offer a diagnostic framework useful in a broad clinical genetic setting.

Cytogenetics in the management of acute myeloid leukemia and histiocytic/dendritic cell neoplasms: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH).

Genetic data are becoming increasingly essential in the management of hematological neoplasms as shown by two classifications published in 2022: the 5th edition of the World Health Organization Classification of Hematolymphoid Tumours and the International Consensus Classification of Myeloid Neoplasms and Acute Leukemias. Genetic data are particularly important for acute myeloid leukemias (AMLs) because their boundaries with myelodysplastic neoplasms seem to be gradually blurring. The first objective of this review is to present the latest updates on the most common cytogenetic abnormalities in AMLs while highlighting the pitfalls and difficulties that can be encountered in the event of cryptic or difficult-to-detect karyotype abnormalities. The second objective is to enhance the role of cytogenetics among all the new technologies available in 2023 for the diagnosis and management of AML.

Adult Low-Hypodiploid Acute Lymphoblastic Leukemia Emerges from Preleukemic TP53-Mutant Clonal Hematopoiesis.

Low hypodiploidy defines a rare subtype of B-cell acute lymphoblastic leukemia (B-ALL) with a dismal outcome. To investigate the genomic basis of low-hypodiploid ALL (LH-ALL) in adults, we analyzed copy-number aberrations, loss of heterozygosity, mutations, and cytogenetics data in a prospective cohort of Philadelphia (Ph)-negative B-ALL patients (n = 591, ages 18-84 years), allowing us to identify 80 LH-ALL cases (14%). Genomic analysis was critical for evidencing low hypodiploidy in many cases missed by cytogenetics. The proportion of LH-ALL within Ph-negative B-ALL dramatically increased with age, from 3% in the youngest patients (under 40 years old) to 32% in the oldest (over 55 years old). Somatic TP53 biallelic inactivation was the hallmark of adult LH-ALL, present in virtually all cases (98%). Strikingly, we detected TP53 mutations in posttreatment remission samples in 34% of patients. Single-cell proteogenomics of diagnosis and remission bone marrow samples evidenced a preleukemic, multilineage, TP53-mutant clone, reminiscent of age-related clonal hematopoiesis. SIGNIFICANCE: We show that low-hypodiploid ALL is a frequent entity within B-ALL in older adults, relying on somatic TP53 biallelic alteration. Our study unveils a link between aging and low-hypodiploid ALL, with TP53-mutant clonal hematopoiesis representing a preleukemic reservoir that can give rise to aneuploidy and B-ALL. See related commentary by Saiki and Ogawa, p. 102. This article is highlighted in the In This Issue feature, p. 101.

Wide diversity of PAX5 alterations in B-ALL: a Groupe Francophone de Cytogenetique Hematologique study.

PAX5 is the main target of somatic mutations in acute B lymphoblastic leukemia (B-ALL). We analyzed 153 adult and child B-ALL harboring karyotypic abnormalities at chromosome 9p, to determine the frequency and the nature of PAX5 alterations. We found PAX5 internal rearrangements in 21% of the cases. To isolate fusion partners, we used classic and innovative techniques (rolling circle amplification-rapid amplification of cDNA ends) and single nucleotide polymorphism-comparative genomic hybridization arrays. Recurrent and novel fusion partners were identified, including NCoR1, DACH2, GOLGA6, and TAOK1 genes showing the high variability of the partners. We noted that half the fusion genes can give rise to truncated PAX5 proteins. Furthermore, malignant cells carrying PAX5 fusion genes displayed a simple karyotype. These data strongly suggest that PAX5 fusion genes are early players in leukemogenesis. In addition, PAX5 deletion was observed in 60% of B-ALL with 9p alterations. Contrary to cases with PAX5 fusions, deletions were associated with complex karyotypes and common recurrent translocations. This supports the hypothesis of the secondary nature of the deletion. Our data shed more light on the high variability of PAX5 alterations in B-ALL. Therefore, it is probable that gene fusions occur early, whereas deletions should be regarded as a late/secondary event.

The CADM1 tumor suppressor gene is a major candidate gene in MDS with deletion of the long arm of chromosome 11.

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis leading to peripheral cytopenias and in a substantial proportion of cases to acute myeloid leukemia. The deletion of the long arm of chromosome 11, del(11q), is a rare but recurrent clonal event in MDS. Here, we detail the largest series of 113 cases of MDS and myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) harboring a del(11q) analyzed at clinical, cytological, cytogenetic, and molecular levels. Female predominance, a survival prognosis similar to other MDS, a low monocyte count, and dysmegakaryopoiesis were the specific clinical and cytological features of del(11q) MDS. In most cases, del(11q) was isolated, primary and interstitial encompassing the 11q22-23 region containing ATM, KMT2A, and CBL genes. The common deleted region at 11q23.2 is centered on an intergenic region between CADM1 (also known as Tumor Suppressor in Lung Cancer 1) and NXPE2. CADM1 was expressed in all myeloid cells analyzed in contrast to NXPE2. At the functional level, the deletion of Cadm1 in murine Lineage-Sca1+Kit+ cells modifies the lymphoid-to-myeloid ratio in bone marrow, although not altering their multilineage hematopoietic reconstitution potential after syngenic transplantation. Together with the frequent simultaneous deletions of KMT2A, ATM, and CBL and mutations of ASXL1, SF3B1, and CBL, we show that CADM1 may be important in the physiopathology of the del(11q) MDS, extending its role as tumor-suppressor gene from solid tumors to hematopoietic malignancies.