CRISPR/Cas12a Collateral Cleavage-Driven Transcription Amplification for Direct Nucleic Acid Detection.

The clustered regularly interspaced short palindromic repeat/Cas (CRISPR/Cas) system is a powerful tool for nucleic acid detection owing to specific recognition as well as cis- and trans-cleavage capabilities. However, the sensitivity of CRISPR/Cas-based diagnostic approaches is determined by nucleic acid preamplification, which has several limitations. Here, we present a method for direct nucleic acid detection without preamplification, by combining the CRISPR/Cas12a system with signal enhancement based on light-up RNA aptamer transcription. We first designed two DNA templates to transcribe the light-up RNA aptamer and kleptamer (Kb) RNA: the first DNA template encodes a Broccoli RNA aptamer for fluorescence signal generation, and the Kb DNA template comprises a dsDNA T7 promoter sequence and an ssDNA sequence that encodes an antisense strand for the Broccoli RNA aptamer. Hepatitis B virus (HBV) target recognition activates a CRISPR/Cas12a complex, leading to the catalytic cleavage of the ssDNA sequence. Transcription of the added Broccoli DNA template can then produce several Broccoli RNA aptamer transcripts for fluorescence enhancement. The proposed strategy exhibited excellent sensitivity and specificity with 22.4 fM detection limit, good accuracy, and stability for determining the target HBV dsDNA in human serum samples. Overall, this newly designed signal enhancement strategy can be employed as a universal sensing platform for ultrasensitive nucleic acid detection.

Energy status regulates levels of the RAR/RXR ligand 9-cis-retinoic acid in mammalian tissues: Glucose reduces its synthesis in ß-cells.

9-cis-retinoic acid (9cRA) binds retinoic acid receptors (RAR) and retinoid X receptors (RXR) with nanomolar affinities, in contrast to all-trans-retinoic acid (atRA), which binds only RAR with nanomolar affinities. RXR heterodimerize with type II nuclear receptors, including RAR, to regulate a vast gene array. Despite much effort, 9cRA has not been identified as an endogenous retinoid, other than in pancreas. By revising tissue analysis methods, 9cRA quantification by liquid chromatography-tandem mass spectrometry becomes possible in all mouse tissues analyzed. 9cRA occurs in concentrations similar to or greater than atRA. Fasting increases 9cRA in white and brown adipose, brain and pancreas, while increasing atRA in white adipose, liver and pancreas. 9cRA supports FoxO1 actions in pancreas ß-cells and counteracts glucose actions that lead to glucotoxicity; in part by inducing Atg7 mRNA, which encodes the key enzyme essential for autophagy. Glucose suppresses 9cRA biosynthesis in the ß-cell lines 832/13 and MIN6. Glucose reduces 9cRA biosynthesis in 832/13 cells by inhibiting Rdh5 transcription, unconnected to insulin, through cAMP and Akt, and inhibiting FoxO1. Through adapting tissue specifically to fasting, 9cRA would act independent of atRA. Widespread occurrence of 9cRA in vivo, and its self-sufficient adaptation to energy status, provides new perspectives into regulation of energy balance, attenuation of insulin and glucose actions, regulation of type II nuclear receptors, and retinoid biology.

Guadecitabine vs treatment choice in newly diagnosed acute myeloid leukemia: a global phase 3 randomized study.

This phase 3 study evaluated the efficacy and safety of the new hypomethylating agent guadecitabine (n = 408) vs a preselected treatment choice (TC; n = 407) of azacitidine, decitabine, or low-dose cytarabine in patients with acute myeloid leukemia unfit to receive intensive induction chemotherapy. Half of the patients (50%) had poor Eastern Cooperative Oncology Group Performance Status (2-3). The coprimary end points were complete remission (19% and 17% of patients for guadecitabine and TC, respectively [stratified P = .48]) and overall survival (median survival 7.1 and 8.5 months for guadecitabine and TC, respectively [hazard ratio, 0.97; 95% confidence interval, 0.83-1.14; stratified log-rank P = .73]). One- and 2-year survival estimates were 37% and 18% for guadecitabine and 36% and 14% for TC, respectively. A large proportion of patients (42%) received <4 cycles of treatment in both the arms. In a post hoc analysis of patients who received ≥4 treatment cycles, guadecitabine was associated with longer median survival vs TC (15.6 vs 13.0 months [hazard ratio, 0.78; 95% confidence interval, 0.64-0.96; log-rank P = .02]). There was no significant difference in the proportion of patients with grade ≥3 adverse events (AEs) between guadecitabine (92%) and TC (88%); however, grade ≥3 AEs of febrile neutropenia, neutropenia, and pneumonia were higher with guadecitabine. In conclusion, no significant difference was observed in the efficacy of guadecitabine and TC in the overall population. This trial was registered at www.clinicaltrials.gov as #NCT02348489.

Cyp26a1 supports postnatal retinoic acid homeostasis and glucoregulatory control.

Considerable evidence confirms the importance of Cyp26a1 to all-trans-retinoic acid (RA) homeostasis during embryogenesis. In contrast, despite its presence in postnatal liver as a potential major RA catabolizing enzyme and its acute sensitivity to induction by RA, some data suggested that Cyp26a1 contributes only marginally to endogenous RA homeostasis postnatally. We report reevaluation of a conditional Cyp26a1 knockdown in the postnatal mouse. The current results show that Cyp26a1 mRNA in WT mouse liver increases 16-fold upon refeeding after a fast, accompanied by an increased rate of RA elimination and a 41% decrease in the RA concentration. In contrast, Cyp26a1 mRNA in the refed homozygotic knockdown reached only 2% of its extent in WT during refeeding, accompanied by a slower rate of RA catabolism and no decrease in liver RA, relative to fasting. Refed homozygous knockdown mice also had decreased Akt1 and 2 phosphorylation and pyruvate dehydrogenase kinase 4 (Pdk4) mRNA and increased glucokinase (Gck) mRNA, glycogen phosphorylase (Pygl) phosphorylation, and serum glucose, relative to WT. Fasted homozygous knockdown mice had increased glucagon/insulin relative to WT. These data indicate that Cyp26a1 participates prominently in moderating the postnatal liver concentration of endogenous RA and contributes essentially to glucoregulatory control.

Development of a Next-generation Sequencing-based Gene Panel Test to Detect Measurable Residual Disease in Acute Myeloid Leukemia.

Background: AML is a heterogeneous disease, and despite intensive therapy, recurrence is still high in AML patients who achieve the criterion for cytomorphologic remission (residual tumor burden [measurable residual disease, MRD]<5%). This study aimed to develop a targeted next-generation sequencing (NGS) panel to detect MRD in AML patients and validate its performance. Methods: We designed an error-corrected, targeted MRD-NGS panel without using physical molecular barcodes, including 24 genes. Fifty-four bone marrow and peripheral blood samples from 23 AML patients were sequenced using the panel. The panel design was validated using reference material, and accuracy was assessed using droplet digital PCR. Results: Dilution tests showed excellent linearity and a strong correlation between expected and observed clonal frequencies (R>0.99). The test reproducibly detected MRD in three dilution series samples, with a sensitivity of 0.25% for single-nucleotide variants. More than half of samples from patients with morphologic remission after one month of chemotherapy had detectable mutations. NGS-MRD positivity for samples collected after one month of chemotherapy tended to be associated with poor overall survival and progression-free survival. Conclusions: Our highly sensitive and accurate NGS-MRD panel can be readily used to monitor most AML patients in clinical practice, including patients without gene rearrangement. In addition, this NGS-MRD panel may allow the detection of newly emerging clones during clinical relapse, leading to more reliable prognoses of AML.

DRP1 Inhibition Enhances Venetoclax-Induced Mitochondrial Apoptosis in TP53-Mutated Acute Myeloid Leukemia Cells through BAX/BAK Activation.

Although TP53 mutations in acute myeloid leukemia (AML) are associated with poor response to venetoclax, the underlying resistance mechanism remains unclear. Herein, we investigated the functional role of dynamin-related protein 1 (DRP1) in venetoclax sensitivity in AML cells with respect to TP53 mutation status. Effects of DRP1 inhibition on venetoclax-induced cell death were compared in TP53-mutated (THP-1 and Kasumi-1) and TP53 wild-type leukemia cell lines (MOLM-13 and MV4-11), as well as in primary AML cells obtained from patients. Venetoclax induced apoptosis in TP53 wild-type AML cells but had limited effects in TP53-mutated AML cells. DRP1 expression was downregulated in MOLM-13 cells after venetoclax treatment but was unaffected in THP-1 cells. Cotreatment of THP-1 cells with venetoclax and a TP53 activator NSC59984 downregulated DRP1 expression and increased apoptosis. Combination treatment with the DRP1 inhibitor Mdivi-1 and venetoclax significantly increased mitochondria-mediated apoptosis in TP53-mutated AML cells. The combination of Mdivi-1 and venetoclax resulted in noticeable downregulation of MCL-1 and BCL-xL, accompanied by the upregulation of NOXA, PUMA, BAK, and BAX. These findings suggest that DRP1 is functionally associated with venetoclax sensitivity in TP53-mutated AML cells. Targeting DRP1 may represent an effective therapeutic strategy for overcoming venetoclax resistance in TP53-mutated AML.

Changing the strategic paradigm for the treatment of adult acute myeloid leukemia

Acute myeloid leukemia (AML) is a representative blood cancer, accounting for most adult leukemia cases in Korea. Until recently, intensive chemotherapy and hematopoietic stem cell transplantation were the only curative treatment options for AML. However, the recent introduction of new drugs is bringing about changes in the strategic paradigm for the treatment of AML.Current Concepts: Along with the clinical eligibility for receiving intensive treatment and hematopoietic stem cell transplantation, the most critical determinants in treating AML are precise classification and risk stratification based on cytogenetic and molecular information. The recently revised World Health Organization classification, newly proposed International Consensus Classification, and the latest version of the European LeukemiaNet risk stratification reflect the importance of cytogenetic and molecular information. Although there have been no significant changes for a long time in the landscape of AML, especially in the field of treatment, the treatment paradigm has started to evolve with the introduction of new drugs. This evolution is led by FLT3 inhibitors, Bcl-2 inhibitors, isocitrate dehydrogenase inhibitors, target agents against CD33 antigens, and liposomal formulations of chemotherapeutics.Discussion and Conclusion: Successful initial treatment to induce complete remission followed by post-remission treatment to remove residual disease can lead to the achievement of long-term survival and cure goals in AML. We hope that new drugs will markedly improve the treatment outcomes for patients with AML.

Therapy-related Acute Lymphoblastic Leukaemia has a Unique Genetic Profile Compared to De Novo Acute Lymphoblastic Leukaemia.

Background: Unlike therapy-related myeloid neoplasms, therapy-related acute lymphoblastic leukaemia (tr-ALL) is poorly defined due to its rarity. However, increasing reports have demonstrated that tr-ALL is a distinct entity with adverse genetic features and clinical outcomes. Methods: We compared the clinicopathological characteristics and outcomes of patients diagnosed with tr-ALL (n = 9) or de novo ALL (dn-ALL; n = 162) at a single institution from January 2012 to March 2021. The mutational landscapes of eight tr-ALL and 63 dn-ALL patients were compared from a comprehensive next-generation sequencing panel. Results: All tr-ALL patients had the B-cell phenotype. The most frequently mutated genes were IKZF1 (37%), CDKN2A (14%), SETD2 (13%), and CDKN2B (11%) in dn-ALL, whereas TP53 (38%) and RB1 (25%) mutations were most common in tr-ALL. tr-ALL patients did not show a statistically significant difference in overall survival (p = 0.70) or progression-free survival (p = 0.94) compared to dn-ALL patients. Conclusions: In this study, we determined the clinical and genetic profiles of Korean patients with tr-ALL. We found alterations in genes constituting the TP53/RB1 pathway are more frequent in tr-ALL. Due to the rarity of the disease, multi-institutional studies involving a larger number of patients are required in future study.

Exploring medical students' perception of non-face-to-face theory and face-to-face laboratory classes during COVID-19 pandemic: focusing on anatomy course.

PURPOSE: This study investigated students' perceptions of non-face-to-face theory classes and face-to-face laboratory classes conducted in anatomy courses at medical schools during the coronavirus disease 2019 pandemic. METHODS: This study utilized a questionnaire to assess self-reported academic achievement level, satisfaction with non-face-to-face theory classes, satisfaction with face-to-face laboratory classes, and self-directed learning level, and conducted difference verification and regression analysis for 51 students who took anatomy courses from the fall semester of 2020 to the spring semester of 2021. RESULTS: The group with a high self-reported academic achievement level was more satisfied with the non-face-to-face theory classes than the group with a low self-reported academic achievement level. The group with a high self-reported academic achievement level had a higher self-directed learning level than the group with a low self-reported academic achievement level. In addition, it was found that the higher the self-directed learning level, the higher the satisfaction with non-face-to-face theory classes. CONCLUSION: These results suggest that to enhance satisfaction with non-face-to-face theory classes in an anatomy course, a favorable class environment that can increase the self-directed learning level is needed. In particular, careful concern is required when designing non-face-to-face classes for students with a low self-reported academic achievement.

A new brain-cutting device and ultraviolet resin-mounted human brain slices as a teaching adjunct for neuroanatomy education.

Although the level of neuroscience research is rapidly developing with the introduction of new technologies, the method of neuroanatomy education remains at the traditional level and requires improvement to meet the needs of educators and trainees. We developed a new three-dimensional (3D) printed device (human brain-cutting mold, HBCM) for creating human brain slices; moreover, we demonstrated a simple method for creating semi-permanent ultraviolet (UV) resin-mounted brain slice specimens for neuroanatomy education. We obtained brain slices of uniform thickness (3 mm) through the HBCM; the resultant brain slices were optimal for assessing morphological details of the human brain. Furthermore, we used an agar-embedding method for brain-slicing with the HBCM, which minimized geometrical distortions of the brain slices. Also, we prepared semi-permanent brain serial specimens using an acrylic brain slice frame and UV-curable resin, which was highly compatible with moist bio-specimens. During UV resin curing, neither air bubble formation nor color change occurred. The resultant UV resin-mounted brain slices produced definite coronal sections with high transparency and morphological accuracy. We also performed 3D modeling by stacking brain slice images that differentiated the cortical area and nine subcortical regions via manual segmentation. This method could be a reliable alternative for displaying high-quality human brain slices and would be helpful for students and trainee to understand anatomical orientation from 2D images to 3D structures. Also, this may present an innovative approach for preparing and preserving coronal sections of the normal or pathological human brain.

The glucocorticoid receptor represses, whereas C/EBPß can enhance or repress CYP26A1 transcription.

Retinoic acid (RA) counters insulin's metabolic actions. Insulin reduces liver RA biosynthesis by exporting FoxO1 from nuclei. RA induces its catabolism, catalyzed by CYP26A1. A CYP26A1 contribution to RA homeostasis with changes in energy status had not been investigated. We found that glucagon, cortisol, and dexamethasone decrease RA-induced CYP26A1 transcription, thereby reducing RA oxidation during fasting. Interaction between the glucocorticoid receptor and the RAR/RXR coactivation complex suppresses CYP26A1 expression, increasing RA's elimination half-life. Interaction between CCAAT-enhancer-binding protein beta (C/EBPß) and the major allele of SNP rs2068888 enhances CYP26A1 expression; the minor allele restricts the C/EBPß effect on CYP26A1. The major and minor alleles associate with impaired human health or reduction in blood triglycerides, respectively. Thus, regulating CYP26A1 transcription contributes to adapting RA to coordinate energy availability with metabolism. These results enhance insight into CYP26A1 effects on RA during changes in energy status and glucocorticoid receptor modification of RAR-regulated gene expression.

Trifluoperazine and Its Analog Suppressed the Tumorigenicity of Non-Small Cell Lung Cancer Cell; Applicability of Antipsychotic Drugs to Lung Cancer Treatment.

Despite significant advances in diagnostic and therapeutic technologies, lung cancer remains the leading cause of cancer-related mortality worldwide. Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer cases. Recently, some antipsychotics have been shown to possess anticancer activity. However, the effects of antipsychotics on NSCLC need to be further explored. We examined the effects of trifluoperazine (TFP), a commonly used antipsychotic drug, and its synthetic analogs on A549 human lung cancer cells. In addition, cell proliferation analysis, colony formation assay, flow cytometry, western blot analysis, and in vivo xenograft experiments were performed. Key genes and mechanisms possibly affected by TFP are significantly related to better survival outcomes in lung cancer patients. Treatment with TFP and a selected TFP analog 3dc significantly inhibited the proliferation, anchorage-dependent/independent colony formation, and migration of A549 cells. Treatment with 3dc affected the expression of genes related to the apoptosis and survival of A549 cells. Treatment with 3dc promoted apoptosis and DNA fragmentation. In all experiments, including in vivo studies of metastatic lung cancer development, 3dc had more substantial anticancer effects than TFP. According to our analysis of publicly available clinical data and in vitro and in vivo experiments, we suggest that some kinds of antipsychotics prevent the progression of NSCLC. Furthermore, this study indicates a synthetic TFP analog that could be a potential therapeutic for lung cancer.

Real-world data on prognostic value of measurable residual disease assessment by fragment analysis or next-generation sequencing in multiple myeloma.

Measurable residual disease (MRD) negativity is a strong prognostic indicator in multiple myeloma (MM). However, the optimal use of MRD in daily clinical practice has been hampered by the limited feasibility of MRD testing. Therefore, we examined the clinical relevance of commercially available MRD modalities based on clonality assays by fragment analysis with IdentiClone® (n = 73 patients) and next-generation sequencing (NGS) with LymphoTrack® (n = 116 patients) in newly diagnosed patients with MM who received autologous stem cell transplantation (ASCT). MRD was assessed at the end of induction (pre-ASCT) and/or at 100 days after ASCT (post-ASCT). MRD could not predict survival when assessed by fragment analysis. However, NGS-based MRD negativity at pre- or post-ASCT was beneficial in terms of progression-free and overall survival. Moreover, NGS-based MRD negativity was independently associated with improved progression-free and overall survival, and MRD-positive patients both pre- and post-ASCT had worst outcome. Indeed, initial adverse prognostic features by high-risk cytogenetics could be mitigated upon achieving MRD negativity by NGS. We demonstrate the feasibility and clinical benefit of achieving MRD negativity by commercially available clonality-based MRD assays in MM and support incorporating NGS, but not fragment analysis, to tailor therapeutic strategies in real-world practice.

Predictive Factors of Event-Free Survival at 24 Months in Patients with Peripheral T-Cell Lymphoma: A Retrospective Study.

PURPOSE: Event-free survival at 24 months (EFS24) is known to be a surrogate marker for overall survival (OS) for patients with peripheral T-cell lymphoma (PTCL). We examined the role of EFS24 in PTCL compared to diffuse large B-cell lymphoma (DLBCL), and then assessed the clinical predictive factors of achieving EFS24. MATERIALS AND METHODS: Patients with newly diagnosed PTCL treated with anthracycline-based chemotherapy were included. Subsequent OS was defined as the time elapsed from 24 months after diagnosis until death from any cause in those who achieved EFS24. RESULTS: Overall, 153 patients were evaluated, and 51 patients (33.3%) achieved EFS24. Patients who achieved EFS24 showed superior OS compared to patients who did not (p < 0.001). EFS24 could stratify the subsequent OS although it did not reach to that of the general population. After matching the PTCL group to the DLBCL group based on the international prognostic index, the subsequent OS in patients who achieved EFS24 was similar between the two groups (p=0.094). Advanced stage was a significant factor to predict the failing EFS24 by multivariable analysis (p < 0.001). CONCLUSION: Patients with PTCL who achieve EFS24 could have a favorable subsequent OS. Since advanced disease stage is a predictor of EFS24 failure, future efforts should focus on developing novel therapeutic strategies for PTCL patients presenting with advanced disease.

Predictive Factors of Event-Free Survival at 24 Months in Patients with Peripheral T-Cell Lymphoma: A Retrospective Study / Journal of the Korean Cancer Association, 대한암학회지

Purpose@#Event-free survival at 24 months (EFS24) is known to be a surrogate marker for overall survival (OS) for patients with peripheral T-cell lymphoma (PTCL). We examined the role of EFS24 in PTCL compared to diffuse large B-cell lymphoma (DLBCL), and then assessed the clinical predictive factors of achieving EFS24. @*Materials and Methods@#Patients with newly diagnosed PTCL treated with anthracycline-based chemotherapy were included. Subsequent OS was defined as the time elapsed from 24 months after diagnosis until death from any cause in those who achieved EFS24. @*Results@#Overall, 153 patients were evaluated, and 51 patients (33.3%) achieved EFS24. Patients who achieved EFS24 showed superior OS compared to patients who did not (p < 0.001). EFS24 could stratify the subsequent OS although it did not reach to that of the general population. After matching the PTCL group to the DLBCL group based on the international prognostic index, the subsequent OS in patients who achieved EFS24 was similar between the two groups (p=0.094). Advanced stage was a significant factor to predict the failing EFS24 by multivariable analysis (p < 0.001). @*Conclusion@#Patients with PTCL who achieve EFS24 could have a favorable subsequent OS. Since advanced disease stage is a predictor of EFS24 failure, future efforts should focus on developing novel therapeutic strategies for PTCL patients presenting with advanced disease.

Retinoic acid exerts sexually dimorphic effects on muscle energy metabolism and function.

The retinol dehydrogenase Rdh10 catalyzes the rate-limiting reaction that converts retinol into retinoic acid (RA), an autacoid that regulates energy balance and reduces adiposity. Skeletal muscle contributes to preventing adiposity, by consuming nearly half the energy of a typical human. We report sexually dimorphic differences in energy metabolism and muscle function in Rdh10+/- mice. Relative to wild-type (WT) controls, Rdh10+/- males fed a high-fat diet decrease reliance on fatty-acid oxidation and experience glucose intolerance and insulin resistance. Running endurance decreases 40%. Rdh10+/- females fed this diet increase fatty acid oxidation and experience neither glucose intolerance nor insulin resistance. Running endurance increases 220%. We therefore assessed RA function in the mixed-fiber type gastrocnemius muscles (GM), which contribute to running, rather than standing, and are similar to human GM. RA levels in Rdh10+/- male GM decrease 38% relative to WT. Rdh10+/- male GM increase expression of Myog and reduce Eif6 mRNAs, which reduce and enhance running endurance, respectively. Cox5A, complex IV activity, and ATP decrease. Increased centralized nuclei reveal existence of muscle malady and/or repair in GM fibers. Comparatively, RA in Rdh10+/- female GM decreases by less than half the male decrease, from a more modest decrease in Rdh10 and an increase in the estrogen-induced retinol dehydrogenase Dhrs9. Myog mRNA decreases. Cox5A, complex IV activity, and ATP increase. Centralized GM nuclei do not increase. We conclude that Rdh10/RA affects whole body energy use and insulin resistance partially through sexual dimorphic effects on skeletal muscle gene expression, structure, and mitochondria activity.

Age and remission induction therapy for acute myeloid leukemia: An analysis of data from the Korean acute myeloid leukemia registry.

OBJECTIVE: The clinical characteristics and therapeutic strategy in acute myeloid leukemia (AML) are influenced by patients' age. We evaluated the impact of age on remission induction therapy for AML. METHODS: We retrospectively analyzed 3,011 adult AML patients identified from a nationwide database between January 2007 and December 2011. RESULTS: Three hundred twenty-nine (10.9%) acute promyelocytic leukemia (APL) and 2,682 (89.1%) non-APL patients were analyzed. The median age was 51 years and 55% of patients were male. Six hundred twenty-three patients (21%) were at favorable risk, 1522 (51%) were at intermediate risk, and 743 (25%) were at poor risk. As the age increased, the proportion of those at favorable risk and who received induction chemotherapy decreased. After induction therapy, complete response (CR) was achieved in 81.5% (243/298) of APL and 62.4% (1,409/2,258) of non-APL patients; these rates decreased as the age increased, with an obvious decrement in those older than 60 years. The median overall survival of non-APL patients was 18.7 months, while that of APL patients was not reached, with a 75% five-year survival rate. CONCLUSIONS: Age impacts both the biology and clinical outcomes of AML patients. Further studies should confirm the role of induction remission chemotherapy by age group.

Arsenic trioxide synergistically promotes the antileukaemic activity of venetoclax by downregulating Mcl-1 in acute myeloid leukaemia cells.

BACKGROUND: The evasion of apoptosis through dysregulated Bcl-2 family members is a hallmark of leukaemia stem cells (LSCs) in acute myeloid leukaemia (AML). Therefore, targeting Bcl-2 with venetoclax has been suggested as an attractive strategy for inducing apoptosis in AML LSCs. However, the selective inhibition of Bcl-2 in AML often leads to upregulation of Mcl-1, another dominant anti-apoptotic Bcl-2 family protein conferring venetoclax resistance. METHODS: We assessed the combined effect of venetoclax and arsenic trioxide (ATO) on leukaemic cell viability, apoptosis, combination index, and cell cycle in the human LSC-like KG1 and KG1a cells. The synergistic effect of venetoclax and ATO on apoptosis was also examined in primary CD34+ and CD34+CD38- LSCs from the bone marrow (BM) of AML patients, and compared with those from healthy donors. RESULTS: Venetoclax efficiently impaired cell viability and dose-dependently promoted apoptosis when combined with ATO; their synergism was aptly represented by the combination index. The combination of venetoclax and ATO impaired cell cycle progression by restricting cells within the sub-G1 phase and facilitating caspase-dependent apoptotic cell death associated with the loss of mitochondrial membrane potential, while sparing healthy BM haematopoietic stem cells. Mechanistically, ATO mitigated venetoclax-induced upregulation of Mcl-1 by the inhibition of AKT and ERK, along with activation of GSK-3ß. This led to the Mcl-1 destabilisation, triggering Noxa and Bim to facilitate apoptosis and the consequent activation of the apoptosis executioner protein Bak. Moreover, the combination promoted phosphorylation of ATM, Chk2, p38, and H2AX, indicating an active DNA damage response. CONCLUSIONS: Our findings demonstrate the synergistic, preferential antileukaemic effects of venetoclax and ATO on LSCs, providing a rationale for preclinical and clinical trials by combining these agents already being used in clinical practice to treat acute leukaemia.

Adaptive Natural Killer Cells Facilitate Effector Functions of Daratumumab in Multiple Myeloma.

PURPOSE: To investigate the different roles of heterogeneous natural killer (NK)-cell subpopulations in multiple myeloma and to identify NK-cell subsets that support the robust anti-myeloma activity of daratumumab via antibody-dependent cellular cytotoxicity (ADCC). EXPERIMENTAL DESIGN: We performed single-cell RNA sequencing of NK cells from patients with newly diagnosed multiple myeloma (NDMM) and delineated adaptive NK cells in their bone marrow (BM). We further characterized the distinct immunophenotypic features and functions of adaptive NK cells by multicolor flow cytometry in 157 patients with NDMM. RESULTS: Adaptive NK cells exhibit a significantly lower level of CD38 expression compared with conventional NK cells, suggesting that they may evade daratumumab-induced fratricide. Moreover, adaptive NK cells exert robust daratumumab-mediated effector functions ex vivo, including cytokine production and degranulation, compared with conventional NK cells. The composition of adaptive NK cells in BM determines the daratumumab-mediated ex vivo functional activity of BM NK cells in patients with NDMM. Unlike conventional NK cells, sorted adaptive NK cells from the BM of patients with NDMM exert substantial cytotoxic activity against myeloma cells in the presence of daratumumab. CONCLUSIONS: Our findings indicate that adaptive NK cells are an important mediator of ADCC in multiple myeloma and support direct future efforts to better predict and improve the treatment outcome of daratumumab by selectively employing adaptive NK cells.