CD44 Expression Profile Varies According to Maturational Subtypes and Molecular Profiles of Pediatric T-Cell Lymphoblastic Leukemia.

CD44 is a glycoprotein expressed in leucocytes and a marker of leukemia-initiating cells, being shown to be important in the pathogenesis of T cell acute lymphoblastic leukemia (T-ALL). In this study, we have (i) identified the aberrant antigenic pattern of CD44 and its isoform CD44v6 in T-ALL; (ii) tested the association with different T-cell subtypes and genomic alterations; (iii) identified the impact of CD44 status in T-ALL outcome. Samples from 184 patients (123 T-ALL and 61 AML; <19 years) were analyzed throughout multiparametric flow cytometry. Mutations in N/KRAS, NOTCH1, FBXW7 as well as STIL-TAL1 and TLX3 rearrangements were detected using standard molecular techniques. CD44 expression was characterized in all T-ALL and AML cases. Compared with AML samples in which the median fluorescence intensity (MFI) was 79.1 (1-1272), T-ALL was relatively low, with MFI 43.2 (1.9-1239); CD44v6 expression was rarely found, MFI 1 (0.3-3.7). T-ALL immature subtypes (mCD3/CD1aneg) had a lower CD44 expression, MFI 57.5 (2.7-866.3), whereas mCD3/TCRγδpos cases had higher expressions, MFI 99.9 (16.4-866.3). NOTCH1 mut and STIL-TAL1 were associated with low CD44 expression, whereas N/KRAS mut and FBXW7 mut cases had intermediate expression. In relation to clinical features, CD44 expression was associated with tumor infiltrations (p = 0.065). However, no association was found with initial treatment responses and overall survival prediction. Our results indicate that CD44 is aberrantly expressed in T-ALL being influenced by different genomic alterations. Unraveling this intricate mechanism is required to place CD44 as a therapeutic target in T-ALL

CD44 expression profile varies according to maturational subtypes and molecular profiles of pediatric T-cell lymphoblastic leukemia

CD44 is a glycoprotein expressed in leucocytes and a marker of leukemia-initiating cells, being shown to be important in the pathogenesis of T cell acute lymphoblastic leukemia (T-ALL). In this study, we have (i) identified the aberrant antigenic pattern of CD44 and its isoform CD44v6 in T-ALL; (ii) tested the association with different T-cell subtypes and genomic alterations; (iii) identified the impact of CD44 status in T-ALL outcome. Samples from 184 patients (123 T-ALL and 61 AML; &lt;19 years) were analyzed throughout multiparametric flow cytometry. Mutations in&nbsp;N/KRAS, NOTCH1, FBXW7&nbsp;as well as&nbsp;STIL-TAL1&nbsp;and&nbsp;TLX3&nbsp;rearrangements were detected using standard molecular techniques. CD44 expression was characterized in all T-ALL and AML cases. Compared with AML samples in which the median fluorescence intensity (MFI) was 79.1 (1&ndash;1272), T-ALL was relatively low, with MFI 43.2 (1.9&ndash;1239); CD44v6 expression was rarely found, MFI 1 (0.3-3.7). T-ALL immature subtypes (mCD3/CD1aneg) had a lower CD44 expression, MFI 57.5 (2.7&ndash;866.3), whereas mCD3/TCR&gamma;&delta;pos&nbsp;cases had higher expressions, MFI 99.9 (16.4&ndash;866.3).&nbsp;NOTCH1mut&nbsp;and&nbsp;STIL-TAL1&nbsp;were associated with low CD44 expression, whereas&nbsp;N/KRASmut&nbsp;and&nbsp;FBXW7mut&nbsp;cases had intermediate expression. In relation to clinical features, CD44 expression was associated with tumor infiltrations (p&nbsp;= 0.065). However, no association was found with initial treatment responses and overall survival prediction. Our results indicate that CD44 is aberrantly expressed in T-ALL being influenced by different genomic alterations. Unraveling this intricate mechanism is required to place CD44 as a therapeutic target in T-ALL.</p

T-lymphoid/myeloid mixed phenotype acute leukemia and early T-cell precursor lymphoblastic leukemia similarities with NOTCH1 mutation as a good prognostic factor

Elda Pereira Noronha, Lu&iacute;sa Vieira Code&ccedil;o Marques, Francianne Gomes Andrade, Ingrid Sardou-Cezar, Filipe Vicente dos Santos-Bueno, Carolina Da Paz Zampier, Eug&ecirc;nia Terra-Granado, Maria S Pombo-de-OliveiraPaediatric Haematology-Oncology Program, Research Centre, Instituto Nacional de C&acirc;ncer, Rio de Janeiro, RJ, BrazilPurpose: T-lymphoid/Myeloid Mixed phenotype acute leukemia (T/M-MPAL) is ambiguous leukemia which overlaps with early T-cell precursor lymphoblastic leukemia (ETP-ALL). We have revisited the immunophenotyping profile of T/M-MPAL and ETP-ALL to identify differences and/or similarities, as these entities represent a therapeutic challenge in clinical practice.Patients and methods: A total of 26 ETP-ALL and 10 T/M-MPAL cases were identified among 857 cases of childhood leukemia (T-ALL, n=266 and AML, n=591) before any treatment decisions. The variables analyzed were age strata, sex, clinical features, immunophenotyping, and molecular aberrations. Immunophenotyping was performed in all samples using a panel of cytoplasm and membrane antibodies to identify the lineage and blast differentiation. The mutational status of STIL-TAL1, TLX3, RUNX1, NOTCH1, FBXW7, FLT3, IL7R, RAS, KTM2A, and CDKN2A/B was tested using RT-PCR, FISH, and PCR sequencing methods. The outcomes were assessed in terms of overall survival (OS).Results: The immunophenotypes were similar in ETP-ALL and T/M-MPAL, regarding the cellular expression of CD34, CD117, CD13/CD33, and CD11b, although CD2 and HLA-DR were more frequent in T/M-MPAL (p&lt;0.01). aMPO positivity and myelomonocyte differentiation were definitive in separating both entities. NOTCH1, FLT3-ITD, and N/KRAS mutations as well as TLX3 and KMT2A rearrangements were found in both ETP-ALL and T/M-MPAL. Thirty-one patients received ALL protocol whereas five had AML therapy. The overall 5-year survival rate (pOS) was 56.4% for patients treated using ALL protocols. No differences were observed between T/M-MPAL (pOS of 57%) and ETP-ALL (pOS of 56%) patients. The prognostic value of NOTCH1mut, was associated with significantly better OS (pOS 90%) than NOTCH1wt, (pOS 37%) (p=0.017).Conclusion: This research can potentially contribute to NOTCH1 as targeted therapy and prognostic assessment of T-cell mixed phenotype leukemia.Keywords: T-lymphoid/myeloid mixed phenotype acute leukemia, early T-cell precursor lymphoblastic leukemia, NOTCH1 mutation