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Terminal deoxynucleotidyl transferase as a biological marker for human leukemia.

High levels of terminal deoxynucleotidyl transferase have been observed in leukocytes of 7 out of 20 patients with chronic myelogenous leukemia in acute blast phase of the disease. These levels are comparable to the levels observed in human and calf thymus gland and cell lines with some T cell characteristics (Molt 4 and 8402). Negligible levels of this activity were observed in chronic myelogenous leukemia not in an acute blast phase of the disease, chronic lymphocytic leukemia, human B cells, mature T cells, and the mixed population of lymphocytes present in normal human blood. The detection of this enzyme in some patients with chronic myelogenous leukemia in acute blast phase of the disease suggests that the blast proliferation may involve primitive stem cells which have more lymphoid than myelogenous characteristics. This enzyme assay may be of use as a biological marker for following patients during treatment and in remission.

Cations, Divalent

Genetic Profile, Treatment Response, and Outcomes of BCR::ABL1-Positive Mixed-Phenotype Acute Leukemia: A Study From the BCR::ABL1 Pathology Group.

Mixed-phenotype acute leukemia (MPAL) with BCR::ABL1 fusion is rare, and its clinicopathological features, genetic landscape, therapeutic response, and patient outcomes remain incompletely defined, as does its relationship to blast-phase chronic myeloid leukemia. In this multicenter study of 44 patients, 86.4% had B/myeloid MPAL, 72.7% showed lymphoid predominance, 40.9% had complex karyotypes, and 68.3% harbored somatic mutations, most commonly RUNX1 mutations (46.3%). RUNX1 mutations frequently co-occurred with acute myeloid leukemia (AML)-associated alterations, whereas DNMT3A, TET2, and BCORL1 mutations were restricted to RUNX1-mutated cases. In contrast, acute lymphoblastic leukemia (ALL)-associated alterations (IKZF1 mutation/deletion and ETV6 mutations) were confined to RUNX1-wild-type patients. TP53 and signaling pathway mutations (NRAS, KRAS, PTPN11, and FLT3) were not detected. Forty-two patients received induction chemotherapy and/or immunotherapy combined with tyrosine kinase inhibitors: 74.2% of lymphoid-predominant patients and 63.6% of myeloid-predominant patients received ALL- and AML-type therapies, respectively. Ten patients relapsed, and 2 had primary refractory disease; some exhibited a dynamic shift in predominant lineage immunophenotype, chromosomal alterations, and somatic mutations at the relapse or refractory stage. The overall remission rate was 86.8%, with no significant differences across ALL-, AML-, or hybrid-type regimens. After a median follow-up of 24.2 months, the median overall survival was 52.5 months. Complex karyotype was associated with inferior overall survival compared with cases lacking additional chromosomal alterations (P = .02), whereas RUNX1 mutations were not. No significant differences in genetic profiles, treatment response, or outcomes were observed between patients with and without chronic myeloid leukemia-like features. This study provides a comprehensive genomic and clinical characterization of BCR::ABL1-positive MPAL, supporting improved risk stratification and future therapeutic strategies.

Adolescent

Heterogeneity of morphological, cytochemical, and cytogenetic features in the blastic phase of chronic granulocytic leukemia.

Possible predictive criteria of the refractoriness to therapy of the blastic phase of Ph-1-positive chronic granulocytic leukemia (CGL) have been sought. Eight cases in the blastic phase were studied. The blasts were noted to be of two types: some displayed a high nuclear:cytoplasmic ratio with deep blue cytoplasm, while others had a comparatively low nuclear:cytoplasmic ratio and bluish gray cytoplasm containing a few small granules. Electron microscopic studies showed a variety of features, including defective organelles and giant mitochondria. Cytochemical staining revealed the majority of blast cells to be peroxidase- and Sudan black-negative; granular PAS positivity was the rule. Serial cytogenetic studies demonstrated increasing aneuploidy. Bone marrow biopsy showed myelofibrotic changes in two cases. Two patients entered complete remission with prednisone and vincristine and with Ara-C and thioguanine, respectively. It is concluded that the blastic phase of CGL may manifest heterogeneity.

Acute Disease

Collection, cryopreservation and subsequent viability of haemopoietic stem cells intended for treatment of chronic granulocytic leukaemia in blast-cell transformation.

We have stored at -196 degrees C peripheral blood buffy coat (BC) and bone marrow (BM) cells collected from 47 patients with chronic granulocytic leukaemia in the chronic phase. Dimethyl sulphoxide (DMSO) 10% was used as cryoprotective agent. As these cells include CFUc and probably pluripotential stem cells they may be transfused as part of the management of patients who enter blast cell transformation. The mean numbers of nucleated cells collected and stored per procedure was about 9 times greater for BC collections than for BM harvests (106 +/- 49 (SD) X 10(9) versus 11.9 +/- 6.6 X 10(9) respectively). Agar CFUc assay showed that stored cells may remain viable for up to 5 years. Since in vitro studies showed that CFUc proliferation is not inhibited by low concentrations of DMSO the removal of all DMSO during cell reconstitution before transfusion may not be necessary. If autologous BC cells are capable of repopulating the BM of patients treated for CGL in blast cell transformation the routine collection and storage of BC rather than BM cells may be desirable for all newly diagnosed patients.

Blood Preservation

Acute lymphocytic leukemia with atypical cytochemical features.

In a series of 78 cases of acute lymphocytic leukemia, seven were found to demonstrate blast cells staining strongly for both the periodic acid-Schiff reaction and alpha-naphthyl acetate esterase. It is suggested that these features may represent a subclassification of acute lymphocytic leukemia or may be a marker for the leukemic phase of lymphoma.

Adolescent

The Novel Hypomethylating Agent NTX-301 Reprograms Epigenetic and Hippo Signaling Pathways and Exhibits Preclinical Activity in Venetoclax-Resistant and TP53-Mutant AML.

PURPOSE: Hypomethylating agent (HMA) and the BCL-2 inhibitor venetoclax (VEN) combinations have evolved into first-line therapies for patients with acute myeloid leukemia (AML), yielding high response rates. However, most patients ultimately relapse, particularly those with TP53 mutations. We investigated mechanisms of action and therapeutic efficacy of NTX-301, a next-generation HMA. EXPERIMENTAL DESIGN: Methods used include flow cytometry-based cell viability assays, Western blotting, reverse-phase protein arrays, RNA sequencing, Cytometry by Time-Of-Flight single-cell mass cytometry, and methylation profiling in various therapy-resistant AML models. RESULTS: We demonstrate that NTX-301 exhibits superior efficacy compared with 5-azacytidine (5-AZA) in 5-AZA- or VEN-resistant AML. It synergizes with VEN in VEN- or VEN/HMA-resistant and TP53-mutant AML blasts and stem/progenitor cells (combination index <1). NTX-301 inhibits DNA methyltransferase 1 (DNMT1) and increases p73 and caspase 8 (CASP8)/activated CASP8 levels in TP53 wild-type and TP53-mutant AML and activates p53 signaling. It extends survival (&#x2265;45%) in both xenograft and patient-derived xenograft models. Methylation profiling revealed that NTX-301 is a more targeted HMA compared with 5-AZA, enabling suppression of functionally enriched genes/pathways. Pathway analysis of 954 commonly hypomethylated genes showed profoundly greater enrichment of Hippo signaling in NTX-301-treated compared with 5-AZA-treated cells and enrichment of insulin signaling, VEGF pathway, and cell cycle selectively in NTX-301- but not in 5-AZA-treated cells. NTX-301-mediated Hippo signaling was validated at protein levels. CONCLUSIONS: Data suggest that NTX-301 exerts potent antileukemic activities superior to 5-AZA and synergizes with VEN in VEN-resistant and TP53-mutant AML, in part by suppressing DNMT1, inducing DNA damage responses and apoptosis through p53 signaling, and demethylating LATS1/2, thereby activating Hippo signaling.

Humans

Impact of Somatic Mutations on Treatment Response and Resistance in Chronic Myeloid Leukemia.

INTRODUCTION: Tyrosine kinase inhibitors (TKIs) have transformed the treatment of chronic myeloid leukemia (CML); yet, diverse molecular responses and resistance persist. BCR::ABL1 kinase-domain (TKD) mutations constitute just a fraction of this resistance, and the impact of additional somatic mutations on disease progression and early molecular response remains incompletely defined. METHODS: This single-centre cohort study analyzed 109 NGS-tested patients with CML, comprising 44 with TKI-resistant disease and 65 newly diagnosed patients. Targeted next-generation sequencing using a 135-gene myeloid panel was performed on 109 patients. An additional pilot subgroup of 30 TKI-resistant patients underwent BCR::ABL1 kinase-domain analysis by PCR/Sanger sequencing and was analyzed separately. Molecular response was assessed using BCR::ABL1 transcript levels on the International Scale and interpreted according to ELN 2020 recommendations. RESULTS: Somatic mutations were identified in 52.3% of TKI-resistant and 29.2% of newly diagnosed patients. All Cohort 1 blast-crisis patients were mutation-positive, and several concurrent abnormalities were more common in Cohort 1 than in Cohort 2, indicating clonal complexity. In Cohort 2, MMR was achieved in 28/39 (71.8%) mutation-negative and 6/13 (46.2%) mutation-positive patients. Mutation-positivity at baseline was associated with reduced MMR chances but not statistically significant (odds ratio 0.34; 95% confidence interval 0.09-1.23; p&#x2009;=&#x2009;0.099). ASXL1 emerged as the most common non-ABL1 mutation but was not statistically significant. CONCLUSIONS: In this Indian CML cohort, somatic mutations were prevalent in TKI-resistant disease, linked to advanced phase and clonal complexity, and demonstrated a non-significant trend toward lower early MMR at diagnosis, highlighting the importance of genomic testing in this context.

Humans