Hypomethylating agents plus venetoclax compared with intensive induction chemotherapy regimens in molecularly defined secondary AML.

Molecularly defined secondary acute myeloid leukemia is associated with a prior myeloid neoplasm and confers a worse prognosis. We compared outcomes of molecularly defined secondary AML patients (n = 395) treated with daunorubicin and cytarabine (7 + 3, n = 167), liposomal daunorubicin and cytarabine (CPX-351, n = 66) or hypomethylating agents (HMA) + venetoclax (VEN) (n = 162). Median overall survival (OS) was comparable between treatment groups among patients aged >60 years. In a multivariable model HMA + VEN vs. 7 + 3 was associated with better OS (hazard ratio [HR] 0.64 [95% confidence interval (CI) 0.42-0.98, p = 0.041]), whereas CPX-351 vs. 7 + 3 was not (HR 0.79 [CI 95% 0.50-1.25, p = 0.31]). Allogeneic hematopoietic stem cell transplantation, BCOR and IDH mutations were associated with improved OS; older age, prior myeloid disease, NRAS/KRAS mutations, EZH2 mutation, and monosomal karyotype were associated with worse OS. When analyzed in each treatment separately, the IDH co-mutations benefit was seen with 7 + 3 and the detrimental effect of NRAS/KRAS co-mutations with HMA + VEN and CPX-351. In pairwise comparisons adjusted for age, HMA + VEN was associated with improved OS vs. 7 + 3 in patients with SF3B1 mutation and improved OS vs. CPX-351 in those with RNA splicing factor mutations. In molecularly defined secondary AML treatment with HMA + VEN might be preferred but could further be guided by co-mutations.

Effect of acute altitude exposure on physiological parameters and glucose metabolism in healthy lowland Peruvians.

BACKGROUND: High altitude exposure triggers a series of physiological changes to maintain homeostasis. Although longer-term (days to years) acclimatization processes are well studied, less is known about the physiological changes upon rapid ascent. We took advantage of Peru's geography to measure the first physiological changes following rapid transport from a low to a high-altitude environment among lowlanders. METHODS: Blood glucose, insulin, C-peptide, and salivary cortisol among healthy lowland Peruvians were measured before and after glucose ingestion at 40 m and upon arrival at 3470 m. Resting heart rate, blood oxygen saturation, and blood pressure were also monitored. RESULTS: At high altitude, we find a significant ( p<0.05) increase in heart rate and a decrease in blood oxygen saturation and salivary cortisol. Additionally, baseline levels of blood glucose, plasma C-peptide, and cortisol were reduced ( p<0.05). Blood glucose, plasma insulin, and plasma C-peptide returned to baseline or below faster at high altitude after glucose ingestion. CONCLUSIONS: Although many overlapping environmental and physiological factors are present in the high-altitude environment, the first steps of acclimatization in this population appear to be caused by increased energy expenditure and glucose metabolism to maintain oxygen homeostasis until the longer-term acclimatization mechanisms become more significant.

Outlier Expression of Isoforms by Targeted or Total RNA Sequencing Identifies Clinically Significant Genomic Variants in Hematolymphoid Tumors.

Recognition of aberrant gene isoforms due to DNA events can impact risk stratification and molecular classification of hematolymphoid tumors. In myelodysplastic syndromes, KMT2A partial tandem duplication (PTD) was one of the top adverse predictors in the International Prognostic Scoring System-Molecular study. In B-cell acute lymphoblastic leukemia (B-ALL), ERG isoforms have been proposed as markers of favorable-risk DUX4 rearrangements, whereas deletion-mediated IKZF1 isoforms are associated with adverse prognosis and have been extended to the high-risk IKZF1plus signature defined by codeletions, including PAX5. In this limited study, outlier expression of isoforms as markers of IKZF1 intragenic or 3' deletions, DUX4 rearrangements, or PAX5 intragenic deletions were 92.3% (48/52), 90% (9/10), or 100% (9/9) sensitive, respectively, and 98.7% (368/373), 100% (35/35), or 97.1% (102/105) specific, respectively, by targeted RNA sequencing, and 84.0% (21/25), 85.7% (6/7), or 81.8% (9/11) sensitive, respectively, and 98.2% (109/111), 98.4% (127/129), or 98.7% (78/79) specific, respectively, by total RNA sequencing. Comprehensive split-read analysis identified expressed DNA breakpoints, cryptic splice sites associated with IKZF1 3' deletions, PTD of IKZF1 exon 5 spanning N159Y in B-ALL with mutated IKZF1 N159Y, and truncated KMT2A-PTD isoforms. Outlier isoforms were also effective targeted RNA markers for PAX5 intragenic amplifications (B-ALL), KMT2A-PTD (myeloid malignant cancers), and rare NOTCH1 intragenic deletions (T-cell acute lymphoblastic leukemia). These findings support the use of outlier isoform analysis as a robust strategy for detecting clinically significant DNA events.

BCOR and BCORL1 Mutations Drive Epigenetic Reprogramming and Oncogenic Signaling by Unlinking PRC1.1 from Target Genes.

Polycomb repressive epigenetic complexes are recurrently dysregulated in cancer. Unlike polycomb repressive complex 2 (PRC2), the role of PRC1 in oncogenesis and therapy resistance is not well-defined. Here, we demonstrate that highly recurrent mutations of the PRC1 subunits BCOR and BCORL1 in leukemia disrupt assembly of a noncanonical PRC1.1 complex, thereby selectively unlinking the RING-PCGF enzymatic core from the chromatin-targeting auxiliary subcomplex. As a result, BCOR-mutated PRC1.1 is localized to chromatin but lacks repressive activity, leading to epigenetic reprogramming and transcriptional activation at target loci. We define a set of functional targets that drive aberrant oncogenic signaling programs in PRC1.1-mutated cells and primary patient samples. Activation of these PRC1.1 targets in BCOR-mutated cells confers acquired resistance to treatment while sensitizing to targeted kinase inhibition. Our study thus reveals a novel epigenetic mechanism that explains PRC1.1 tumor-suppressive activity and identifies a therapeutic strategy in PRC1.1-mutated cancer. SIGNIFICANCE: We demonstrate that BCOR and BCORL1 mutations in leukemia unlink PRC1.1 repressive function from target genes, resulting in epigenetic reprogramming and activation of aberrant cell signaling programs that mediate treatment resistance. Our study provides mechanistic insights into the pathogenesis of PRC1.1-mutated leukemia that inform novel therapeutic approaches. This article is highlighted in the In This Issue feature, p. 85.

Significance of Clonal Mutations in Bone Marrow Failure and Inherited Myelodysplastic Syndrome/Acute Myeloid Leukemia Predisposition Syndromes.

Clonal hematopoiesis as a hallmark of myelodysplastic syndrome (MDS) is mediated by the selective advantage of clonal hematopoietic stem cells in a context-specific manner. Although primary MDS emerges without known predisposing cause and is associated with advanced age, secondary MDS may develop in younger patients with bone marrow failure syndromes or after exposure to chemotherapy, respectively. This article discusses recent advances in the understanding of context-dependent clonal hematopoiesis in MDS with focus on clonal evolution in inherited and acquired bone marrow failure syndromes.