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Bone marrow mesenchymal stromal cells (BMMSCs) are widely sourced and easily amplified in vitro; thus, they have a great potential in the treatment of hemopathies. Recent findings suggested that BMMSCs express the aryl hydrocarbon receptor (AHR). However, few studies have reported on the regulation of proliferative behaviors and metabolism by AHR in BMMSCs. In the present study, we found that activating AHR reduced the proliferation of BMMSCs and enhanced their mitochondrial function, whereas inhibiting AHR exerted the opposite effects. This study may provide the basis for further unveiling the molecular mechanisms and therapeutic potential of AHR in BMMSCs.

Background The underlying mechanism of myeloid malignancies like myelodysplastic syndrome (MDS) and acute myelocytic leukemia (AML) with bone marrow (BM) fibrosis (hereafter referred to as MDS-F and AML-F) is not fully understood. This study aimed to investigate the role of the E3 protein ubiquitin ligase Itch in the pathogenesis of these diseases preliminarily. Methods Through bioinformatic methods we found that the E3 protein ubiquitin ligase Itch might play a role in the pathogenesis of MDS-F and AML-F as well as the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. We first investigated whether the PI3K/Akt pathway could regulate the expression Itch and its substrate p73 by using the myeloid neoplasm cell line K562 as a model. Then we assayed the Itch mRNA level of clinical samples in different subgroups to have a knowledge of its role in the myeloid diseases. Results Through the cellular experiments we got that the PI3K/Akt pathway might not regulate the expression of Itch and its substrate p73. In patients with high risk MDS, AML, fibrosis or higher white blood cells (WBC) count, Itch mRNA level significantly increased when compared with the control groups. But the mRNA level didn’t show significant difference in the subgroups classified by karyotype. Through correlative analysis we found that the mRNA level had positive correlation with the WBC count of the patients. Conclusions The PI3K/Akt pathway may not get involved in the regulation of the expression of Itch in K562 cells or myeloid tumors and Itch may play a role both in the proliferation and the generation of fibrosis in myeloid malignancies.

We aim to explore and analyze the related influencing factors of liver and cardiac iron overload in MDS patients detected by magnetic resonance imaging (MRI).We have detected cardiac T2* and liver T2* by MRI in 105 MDS patients. Among them, 20 patients accepted MRI examination before and after iron chelation therapy (ICT).These results showed special attention should be paid to these related influencing factors of liver and cardiac T2* expression when we evaluated iron overload and detected the efficacy of ICT in MDS patients.

The prognostic significance of bone marrow fibrosis (MF) grade in patients with myelodysplastic syndrome (MDS) is still debated and the molecular changes remain unclear. In our large cohort, a normal reticulum was found in 211 (25.9%) patients, whereas MF1, MF2 and MF3 were detected in 478 (58.7%), 90 (11.1%) and 35 (4.3%) patients at initial diagnosis, respectively. Patients with MF often correlated with some poor prognostic characteristics, including older age, anemia, unfavorable karyotype, higher BM blast and a higher IPSS-R category. For the entire cohort, the median OS was not reached, 30, 16 and 15 months for patients with MF 0, 1, 2 and 3, respectively. After adjusting for IPSS-R, the hazard ratio for mortality was 1.56 (95% CI, 1.18–2.06) for patients with MF1, 2.29 (95% CI, 1.61–3.27) for patients with MF2 and 2.75 (95% CI, 1.69–4.49) for patients with MF3 compared with those with MF0. The mutational landscape of 370 patients showed that TP53, U2AF1 and KMT2D mutations were more frequent in patients with MF2-3. In addition, of the 408 patients with MF0-1, 62 patients (15.1%) progressed to MF2-3 during the follow-up interval. The clinical features, mutation landscape and prognosis of patients with progressed fibrosis were similar to those of patients with MF2-3 at diagnosis. We concluded that BM fibrosis (MF1, 2 and 3) was an adverse prognosis feature in primary MDS and correlated with TP53 mutations both at the time of initial diagnosis and during the course of the disease. Therefore, BM fibrosis should be included in the revised prognostic scoring system and carefully considered in treatment selection.

Type 1 insulin‑like growth factor receptor (IGF‑IR) signaling is considered to serve a key role in the development of cancer. However, the effects of IGF‑IR on the malignant characteristics of myelodysplastic syndrome (MDS) clonal cells remains to be determined. In the present study it was demonstrated that knockdown of IGF‑IR reduced the proliferation and increased the apoptosis of MDS/leukemia cells. Integrated analysis of gene expression profiles using bioinformatics identified the MAPK signaling pathway as a critical downstream factor of IGF‑IR, and this was confirmed in vitro using western blotting which revealed that IGF‑IR knockdown significantly increased the expression of activated MAPK. Furthermore, IGF‑IR signaling was inhibited to investigate the potential of IGF‑IR as a therapeutic target of MDS. The results revealed that the IGF‑IR inhibitor picropodophyllin (PPP) inhibited cell proliferation, promoted cell apoptosis and arrested the cell cycle at the G2/M phase in MDS/leukemia cells. Similar to the effects of IGF‑IR knockdown, PPP treatment also increased MAPK signaling in vitro. In conclusion, IGF‑IR may serve as a potential therapeutic target of MDS.

Background BCOR (BCL6 corepressor) is an epigenetic regulator gene involved in the specification of cell differentiation and body structure development. Recurrent somatic BCOR mutations have been identified in myelodysplastic syndrome (MDS). However, the clinical impact of BCOR mutations on MDS prognosis is controversial and the response of hypomethylating agents in MDS with BCOR mutations (BCORMUT) remains unknown. Results Among 676 MDS patients, 43 patients (6.4%) harbored BCOR mutations. A higher frequency of BCOR mutations (8.7%) was investigated in patients with normal chromosome, compared to 4.2% in patients with abnormal karyotype (p = 0.040). Compared to the BCORWT patients, the BCORMUT patients showed a higher ratio of refractory anemia with excess blasts subset (p = 0.008). The most common comutations with BCOR genes were ASXL1 (p = 0.002), DNMT3A (p = 0.114) and TET2 (p = 0.148). When the hierarchy of somatic mutations was analyzed, BCOR mutations were below the known initial mutations (ASXL1 or TET2) but were above U2AF1 mutations. Transformation-free survival was significantly shorter in BCORMUT patients than that in BCORWT patients (16 vs. 35 months; p = 0.035). RNA-sequencing was performed in bone marrow mononuclear cells from BCORMUT and BCORWT patients and revealed 2030 upregulated and 772 downregulated genes. Importantly, HOXA6, HOXB7, and HOXB9 were significantly over-expressed in BCORMUT patients, compared to BCORWT patients. Eight of 14 BCORMUT patients (57.1%) achieved complete remission (CR) with decitabine treatment, which was much higher than that in BCORWT patients (28.7%, p = 0.036). Paired sequencing results (before and after decitabine) showed three of 6 CR patients lost the mutated BCOR. The median survival of CR patients with a BCORMUT was 40 months, which was significantly longer than that in patients with BCORWT (20 months, p = 0.036). Notably, prolonged survival was observed in three BCORMUT CR patients even without any subsequent therapies. Conclusions BCOR mutations occur more frequently in CN MDS patients, predicting higher risk of leukemia transformation. BCORMUT patients showed a better response to decitabine and achieved longer post-CR survival.

Bone marrow stromal cells from patients with myelodysplastic syndrome (MDS) display a senescence phenotype, but the underlying mechanism has not been elucidated. Pro-inflammatory signaling within the malignant clone and the bone marrow microenvironment has been identified as a key pathogenetic driver of MDS. Our study revealed that S100A9 is highly-expressed in lower-risk MDS. Moreover, normal primary mesenchymal stromal cells (MSCs) and the human stromal cell line HS-27a co-cultured with lower-risk MDS bone marrow mononuclear cells acquired a senescence phenotype. Exogenous supplemented S100A9 also induced cellular senescence in MSCs and HS-27a cells. Importantly, Toll-like receptor 4 (TLR4) inhibition or knockdown attenuated the cellular senescence induced by S100A9. Furthermore, we showed that S100A9 induces NLRP3 inflammasome formation, and IL-1β secretion; findings in samples from MDS patients further confirmed these thoughts. Moreover, ROS and IL-1β inhibition suppressed the cellular senescence induced by S100A9, whereas NLRP3 overexpression and exogenous IL-1β supplementation induces cellular senescence. Our study demonstrated that S100A9 promotes cellular senescence of bone marrow stromal cells via TLR4, NLRP3 inflammasome formation, and IL-1β secretion for its effects. Our findings deepen the understanding of the molecular mechanisms involved in MDS reprogramming of MSCs and indicated the essential role of S100A9 in tumor-environment interactions in bone marrow.

Myelodysplastic syndromes (MDSs) refractory or relapsed after hypomethylating agents (HMAs) remain a therapeutic challenge. The CHG regimen has been demonstrated to be effective in initially treating higher risk MDS. The current study evaluated the efficacy and toxicity of the CHG regimen in patients who were resistant to decitabine. Patients with higher risk MDS relapsed or refractory to decitabine were enrolled in this study. Each patient received the CHG regimen (cytarabine (25 mg/day, days 1–14) and homoharringtonine (1 mg/day, days 1–14) intravenously with G-CSF (300 μg/day) subcutaneously from day 0 until neutrophil count recovery to 2.0 × 109 cells/L). Next gene sequencing with a 31-gene panel was carried out in patients. Thirty-three patients were enrolled, including 12 relapsed and 21 refractory cases. The overall response rate (ORR) was 39.4% (13 of 33), with 9 (27.3%) achieving complete remission (CR), 2 having marrow CR (mCR), and 2 achieving partial remission (PR). The CR rate was higher in patients harboring fewer gene mutations (0–1) (55.6%) than in those with more gene mutations (> 1) (12.5%) (p = 0.021). The median overall survival (OS) of the 33 patients was 7.0 months. Patients who achieved a response had significantly longer survival times than were found in those without a response (21.0 M vs. 4.0 M, p

Mutations in the U2 small nuclear RNA auxiliary factor 1 (U2AF1) gene are the common feature of a major subset in myelodysplastic syndromes (MDS). However, the genetic landscape and molecular pathogenesis of oncogenic U2AF1S34F mutation in MDS are not totally understood. We performed comprehensive analysis for prognostic significance of U2AF1 mutations in acute myeloid leukemia (AML) cohort based on The Cancer Genome Atlas (TCGA) database. Functional analysis of U2AF1S34F mutation was performed in vitro. Differentially expressed genes (DEGs) and significantly enriched pathways were identified by RNA sequencing. The forkhead box protein O3a (FOXO3a) was investigated to mediate the function of U2AF1S34F mutation in cell models using lentivirus. Chromatin immunoprecipitation, immunoblotting analyses, and immunofluorescence assays were also conducted. U2AF1 mutations were associated with poor prognosis in MDS and AML samples, which significantly inhibited cell proliferation and induced cellular apoptosis in cell models. Our data identified that U2AF1-mutant cell lines undergo FOXO3a-dependent apoptosis and NLRP3 inflammasome activation, which induces pyroptotic cell death. Particularly, an increase in the level of FOXO3a promoted the progression of MDS in association with restored autophagy program leading to NLRP3 inflammasome activation in response to U2AF1S34F mutation. Based on the result that U2AF1S34F mutation promoted the transcriptional activity of Bim through upregulating FOXO3a with transactivation of cell cycle regulators p21Cip1 and p27Kip1, FOXO3a, a potentially cancer-associated transcription factor, was identified as the key molecule on which these pathways converge. Overall, our studies provide new insights that U2AF1S34F mutation functions the crucial roles in mediating MDS disease progression via FOXO3a activation, and demonstrate novel targets of U2AF1 mutations to the pathogenesis of MDS.

The transformation biology of sAML from MDS is still not fully understood. Here, we performed a big cohort of paired sequences including target, whole-exome and single cell sequencing to search AML transformation-related last events. The results showed that fifty-five out of the 64 (85.9%) patients presented presumptive last mutation events involving activated signaling, transcription factors, or tumor suppressors. Most last mutation events (63.6%, 35 cases) emerged at the leukemia transformation point. All five of the remaining nine patients analyzed by paired whole exome sequencing showed transformation-related mutations which are not included in the reference targets. Single-cell sequencing indicated that the activated cell signaling route was related to last gene mutation events which take place prior to phenotypic development. Of note, last gene mutation events defined using target sequencing was limited to a small set of genes (less than ten, in the order: NRAS/KRAS, CEBPA, TP53, FLT3, RUNX1, CBL, PTPN11 and WT1, accounted for 91.0% of the mutations). In conclusion, somatic mutations involving in activated signaling, transcription factors, or tumor suppressors appeared to be a precondition for AML transformation from myelodysplastic syndromes. The transformation-related gene mutations may be considered as new therapy targets.

Background ATG-010 (selinexor), a novel, oral selective inhibitor of nuclear export, inhibits exportin1. In preclinical and clinical studies, ATG-010 has demonstrated activity against multiple myeloma (MM). ATG-010 (80 mg biweekly) plus dexamethasone (20 mg biweekly) (Sd) has been approved by US FDA for treatment of patients (pts) with penta-refractory MM based on the STORM study. MARCH is a single arm, Phase 2 study to assess efficacy and safety of Sd in Chinese pts with RRMM. Methods Enrolled Chinese pts were previously treated with and refractory to PI, IMiD, and the last line of therapy. Sd was administered in 4-week cycles. The primary endpoint was overall response rate (ORR) per independent review committee. The total planned 82 pts provide -80% power to test against H0 of 15% ORR at one-sided α of 0.025. This abstract includes data from the first 60 treated pts. Results As of 13 Oct 2020, 18 (30%) of the 60 pts were on treatment. Median follow-up was 9.5 months (mo) (range: 1.9-12.8). Median age was 61 years (range 43-82; 42% > 65). Pts had received a median of 5 (range 1-16) prior MM regimens, with the following baseline risk factors: 72% R-ISS II/III, 70% cytogenetic abnormalities, 22% del (17p13),20% renal impairment, 15% prior CAR-T therapy, and 25% pre-treated with daratumumab (considered ‘triple-class exposed’). ORR was 26.7% (95% CI: 16.1, 39.7). Median duration of response (DOR) was 4.6 mo (95% CI: 1.42, NE). Median progression free survival was 3.7 mo (95% CI: 1.92, 4.66). Median overall survival (OS) was not reached; 9-mo OS rate was 68.5%. ORR was 33.3% in triple-class-exposed pts. Nine pts had prior CAR-T therapy with a median of 9 prior regimens (range 5-12). Among them, ORR was 44.4%, and median DOR was 3 mo (95% CI; 0.96, 4.63). Common treatment emergent adverse events (TEAEs) of any grade included: thrombocytopenia (87%), nausea (87%), leukopenia (85%), anemia (85%), lymphopenia (78%), neutropenia (73%), weight loss (72%), hyponatremia (65%), decreased appetite (63%), asthenia (62%)/fatigue (17%), hyperglycemia (53%), vomiting (52%), hypocalcemia (38%), hypokalemia (30%), diarrhea (30%), and pneumonia (27%). Common TEAEs of Grade ≥ 3 included: anemia (60%), thrombocytopenia (55%), leukopenia (42%), lymphopenia (42%), neutropenia (38%), hyponatremia (28%), and pneumonia (23%). Thirty pts (50%) had TESAEs, including (>3%): thrombocytopenia (15%), pneumonia (15%), anemia (6.7%), and hyponatremia (3.3%). Eight pts (13.3%) had TEAEs leading to treatment discontinuation, including (>2%): thrombocytopenia (5%) and pneumonia (3%). There were three fatal TEAEs: pneumonia, intracranial hemorrhage, and sudden death (1 each). Conclusions MM pts refractory to both IMiD and PI remain a high unmet medical need. The MARCH study confirms the efficacy of Sd in Chinese patients with a manageable safety profile. These data are consistent with the STORM trial and offer a new, oral therapeutic option for MM patients.

Objective: The purpose of this study was to identify the difference between dual energy spectral computed tomography (DECT) and magnetic resonance imaging (MRI) used to detect liver/cardiac iron content in Myelodysplastic syndrome (MDS) patients with differently adjusted serum ferritin (ASF) levels.Method: Liver and cardiac iron content were detected by DECT and MRI. Patients were divided into different subgroups according to the level of ASF. The receiver operating characteristic curve (ROC) analysis was applied in each subgroup. The correlation between iron content detected by DECT/MRI and ASF was analyzed in each subgroup.Result: ROC curves showed that liver virtual iron content (LVIC) Az was significantly less than liver iron concentration (LIC) Az in the subgroup with ASF < 1,000 ng/ml. There was no significant difference between LVIC Az and LIC Az in the subgroup with 1,000 ≤ ASF < 2,500 ng/ml and 2,500 ≤ ASF < 5,000 ng/ml. LVIC Az was significantly higher than LIC Az in the subgroup with ASF 5,000 mg/L in LIC, LIC became correlated with ASF. There was no significant difference between the subgroup with 2,500 ≤ ASF < 5,000 ng/ml and 5,000 ng/ml ≤ ASF in LIC expression. Furthermore, both LIC and liver VIC had significant correlations with ASF in patients with ASF < 2,500 ng/ml, while LVIC was still correlated with ASF, LIC was not correlated with ASF in patients with 2,500 ng/ml ≤ ASF. Moreover, neither cardiac VIC nor myocardial iron content (MIC) were correlated with ASF in these subgroups.Conclusion: MRI and DECT were complementary to each other in liver iron detection. In MDS patients with high iron content, such as ASF ≥ 5,000 ng/ml, DECT was more reliable than the MRI in the assessment of iron content. But in patients with low iron content, such as ASF < 1,000 ng/ml, MRI is more reliable than DECT. Therefore, for the sake of more accurately evaluating the iron content, the appropriate detection method can be selected according to ASF.

Despite the improvements in prognostication of the revised International Prognostic Scoring System (IPSS-R) in myelodysplastic syndrome (MDS), there remain a portion of patients with lower risk (low/intermediate risk, LR) but poor prognostics. This study aimed to evaluate the relative contribution of mutational status when added to the IPSS-R, for estimating overall survival (OS) and progression-free survival (PFS) in patients with LR-MDS. We retrospectively analyzed clinical and laboratory variables of 328 patients diagnosed with MDS according to the FAB criteria. Twenty-nine-gene NGS assay was applied to bone marrow samples obtained at diagnosis. 233 (71.04%) patients were classified as LR-MDS. Univariate analysis showed association between inferior outcome (OS and PFS) and presence of JAK2 (p = 0.0177, p = 0.0002), RUNX1 (p = 0.0250, p = 0.0387), and U2AF1 (p = 0.0227, p = 0.7995) mutations. Multivariable survival analysis revealed JAK2 (p < 0.0001) and RUNX1 (p = 0.0215) mutations were independently prognostic for PFS in LR-MDS. Interestingly, bone marrow blast >1.5% could further predict disease progression of patients with LR-MDS (HR 8.06, 95%CI 2.95–22.04, p < 0.0001). Incorporation of JAK2, RUNX1 mutation and bone marrow blast in the IPSS-R can improve risk stratification in patients with LR-MDS. In summary, our result provided new risk factors for LR-MDS prognostics to identify candidates for early therapeutic intervention.

Background: Little is known about the function of tumor suppressor gene Forkhead box 1 (FOXO1) in myelodysplastic syndromes (MDS). The aim of this study was to elucidate the role of FOXO1 through decitabine (DAC) treatment. Methods: Microarray analysis was used to identify differentially expressed genes (DEGs) from 2 MDS cell lines by DAC treatment. WebGestalt was used to perform gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) for constructing protein–protein interaction (PPI) network analysis. Cell apoptosis, cycle arrest, differentiation, and immunoregulation were performed to validate the function of FOXO1 by silencing its expression prior to DAC treatment in MDS. Results: The results showed that the FOXO signaling pathway was one of the most promising. FOXO1 exists in a hyperphosphorylated, inactive form in MDS-L cells. DAC treatment both induces FOXO1 expression and reactivates the protein through reducing its phosphorylation level. Furthermore, we showed that this FOXO1 activation is responsible for the DAC-induced apoptosis, cell cycle arrest, antigen differentiation, and immunoregulation in MDS-L cells. The results also demonstrated that DAC-induced FOXO1 activation upregulated anti-tumor immune response in higher risk MDS specimens.Conclusions: These results suggest that DAC induces FOXO1 activation, which plays an important role in anti-MDS tumors.

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MDS development is a dynamic process during which the accumulation of somatic mutations leads to specific malignant evolution. To elucidate the differential roles of gene mutations in typical MDS, we used targeted sequencing to investigate clonal patterns from 563 patients and focused on cases (199/563 cases) with initial mutations (ASXL1, DNMT3A and TET2) at MDS diagnosis. The consistency of frequency and distribution in patients with or without aberrant chromosomes suggested early events of these initial mutations. Some additional driver mutations (SF3B1, U2AF1 or RUNX1) played roles to keep the basic disease features, or give rise to different phenotypes (BCOR, EZH2 or TP53) in individual patients. Notably, analysis in paired samples before and after MDS progression showed that the mutations identified as last events (involving active signaling, myeloid transcription or tumor suppressor) seemed necessary for MDS development to be AML. Last mutations can exist at MDS diagnosis, or emerge at AML transformation, and involve a small group of genes. Single-allele CEBPA mutations and diverse TP53 mutations were checked as the most common last event mutations. Considering the necessity of last event mutations and limited gene involvement in AML transformations, it is possible to validate a small group of last events involved mutations to develop some new strategies to block MDS progression.

Background Vancomycin is a first-line antibiotic used for the treatment of severe gram-positive bacterial infections. Clinical guidelines recommend that the vancomycin trough concentration be 10-15 mg/L for regular infections and 15-20 mg/L for severe infections. We investigated whether increasing the vancomycin concentration would result in better clinical outcomes with sustainable adverse effects (AEs) in the Chinese population. Methods A prospective, open, multicenter clinical observational study was performed in patients with gram-positive bacterial infections from 13 teaching hospitals. Patients received vancomycin therapeutic drug monitoring. Clinical, microbiological, and laboratory data were collected. Results In total, 510 patients were enrolled, and 470 were evaluable, of whom 370 were adults and 100 were children; 35.53% had methicillin-resistant Staphylococcus aureus infections (vancomycin 50% minimum inhibitory concentration [MIC50] = 1, 90% minimum inhibitory concentration [MIC90] = 1), and 23.19% had Enterococcus species infections (vancomycin MIC50 = 1, MIC90 = 2). The average trough concentration was 10.54 ± 8.08 mg/L in adults and 6.74 ± 8.93 mg/L in children. The infection was eradicated in 86.22% of adults and 96% of children. Thirty-six vancomycin-related nephrotoxicity cases were reported in the enrolled population. No severe AEs or deaths were related to vancomycin therapy. Logistic regression analysis showed that trough concentration had no relationship with clinical outcomes (adults P = .75, children P = .68) but was correlated with adult nephrotoxicity (P < .0001). Vancomycin trough concentration had an applicable cut point at 13 mg/L. Conclusions Our study shows that vancomycin trough concentration has no statistical correlation with clinical outcomes, and is an indicator of nephrotoxicity in the observed population. We found no evidence that increasing vancomycin trough concentration to 15-20 mg/L can benefit Chinese patients with complicated infections. Clinical Trials Registration ChiCTR-OPC-16007920.

Iron overload (IO) has been reported to contribute to mesenchymal stromal cell (MSC) damage, but the precise mechanism has yet to be clearly elucidated. In this study, we found that IO increased cell apoptosis and lowered cell viability in MSCs, accompanied by extensive mitochondrial fragmentation and autophagy enhancement. All these effects were reactive oxygen species (ROS) dependent. In MSCs with IO, the ATP concentrations were significantly reduced due to high ROS levels and low electron respiratory chain complex (ETC) II/III activity. Reduced ATP phosphorylated AMP-activated protein kinase (AMPK). Activation of AMPK kinase complexes triggered mitochondrial fission. Moreover, gene knockout of AMPK via CRISPR/Cas9 reduced cell apoptosis, enhanced cell viability and attenuated mitochondrial fragmentation and autophagy caused by IO in MSCs. Further, AMPK-induced mitochondrial fragmentation of MSCs with IO was mediated via phosphorylation of mitochondrial fission factor (MFF), a mitochondrial outer-membrane receptor for the GTPase dynamin-related protein 1 (Drp1). Gene knockdown of MFF reversed AMPK-induced mitochondrial fragmentation in MSCs with IO. In addition, MSCs from IO patients with myelodysplastic syndrome (MDS) showed increased cell apoptosis, decreased cell viability, higher ROS levels, lower ATP concentrations and increased mitochondrial fragmentation compared with MSCs from non-IO patients. In addition, iron chelation or antioxidant weakened the activity of the AMPK/MFF/Drp1 pathway in MDS-MSCs with IO from several patients, accompanied by attenuation of mitochondrial fragmentation and autophagy. Taken together, the AMPK/MFF/Drp1 pathway has an important role in the damage to MDS-MSCs caused by IO.

Background: ATG-010 (selinexor) is a novel, oral selective inhibitor of nuclear export, which blocks exportin 1. US FDA has approved selinexor plus low dose dexamethasone (Sd) to treat patients (pts) with penta-refractory MM based on the STORM study. MARCH is a single arm, Phase 2, registrational study to assess efficacy and safety of Sd in Chinese pts with RRMM. Methods: Enrolled Chinese pts were previously refractory to PI, IMiD, and last line of therapy. ATG-010 (80mg) plus dexamethasone (20mg) was administered twice weekly. The primary endpoint was overall response rate (ORR) per independent review committee. The planned 82 pts would provide ~80% power to test against null hypothesis (H 0) of 15% ORR at one-sided α of 0.025 at the primary analysis, which is presented here. Results: As of 6 th May 2021, 9 (11%) of the 82 pts were still on treatment. Median follow-up was 10.6 months (mo) (range: 2.3-19.6). Median age was 60 years (39% ≥ 65yrs). Median duration from MM initial diagnosis was 3.2 years. A total of 61 pts (74.4%) had cytogenetic abnormalities (del(17p): 22.0%), 18 (22.0%) with baseline plasmacytoma, and 18 (22.0%) with creatinine clearance < 60ml/min. Median number of prior regimens were 5 (range 1-16); 23 pts (28.0%) had received daratumumab (triple-class exposure), 20 pts were triple-class refractory (TCR), and10 pts (12.2%) had undergone CAR-T therapy. ORR was 29.3% (95% CI: 19.7, 40.4), rejecting H 0, including 4 VGPR (very good partial response). Median duration of response (DOR) was 4.7 mo, median progression free survival (PFS) was 3.7 mo, and median overall survival (OS) was 13.2 mo. Among 20 TCR pts, ORR was 25.0% (95% CI:8.7, 49.1), mDOR 10.2 mo, mPFS 2.9 mo, and mOS 11.9 mo. Efficacy was evident in elderly pts (≥ 65yrs), with ORR 25% (95% CI: 11.5, 43.4) and mPFS 2.8 mo. Median OS and DOR were not reached. Sd also demonstrated a similar response rate in pts with high-risk cytogenetic abnormalities, with an ORR of 24.6% (95% CI: 14.5, 37.3). Efficacy of Sd was generally consistent across cytogenetic risk subgroups, including del (17p) pts with ORR 22.2% (95% CI: 6.4, 47.6), mDOR 3.8mo, and mPFS 2.9 mo. The most common non-hematologic treatment-emergent adverse events (TEAEs) of any grade included nausea (78%), hyponatremia (67.1%), weight loss (65.9%), decreased appetite (62.2%), asthenia (59.8%)/fatigue (15.9%), and vomiting (50.0%). The most common grade≥3 non-hematologic TEAE were hyponatremia (29.3%), pneumonia (26.8%), hypokalemia (12.2%) and asthenia (9.8%)/fatigue (2.4%). The most common grade≥3 hematologic TEAEs were anemia (57.3%), lymphopenia (76.8%), thrombocytopenia (51.2%), and neutropenia (40.2%). TESAE occurred in 54.9% of pts, with the most common being thrombocytopenia and pneumonia (14.6% each). TEAE led to death in 7 pts (8.5%). Elderly pts had no significantly increased risk of adverse events, however, given their limited physical state, drug exposure was shorter in the elderly subgroup (12.6 vs 16.1 weeks), suggesting more active supportive care is required. Conclusions: MM refractory to both IMiD and PI remains a high unmet medical need, especially in China. The MARCH study demonstrates statistically significant and clinically meaningful ORR with Sd in Chinese RRMM pts, and efficacy was consistent across subgroups, including the elderly and pts with high-risk cytogenetics. Adverse events were as expected and manageable with appropriate supportive care and dose modification. These data are compatible with the STORM study and offers a new, oral therapeutic option for MM patients. Disclosures Yu: Antengene Therapeutics Ltd.: Current Employment. Wang: Antengene Therapeutics Ltd.: Current Employment. Yang: Antengene Therapeutics Ltd.: Current Employment. Yu: Antengene Therapeutics Ltd.: Current Employment. Lynch: Antengene Therapeutics Ltd.: Current Employment.

Background: SCT400 is a recombinant, human-mouse chimeric anti-CD20 IgG1 monoclonal antibody and has the same variable regions and antigen-binding site as rituximab. SCT400 has the heavy and κ light chain constant regions of human IgG1 allotype G1m (1,17), which is common in Asians. There is only one amino acid difference between SCT400 and rituximab (V219A in the CH1 domain of the heavy chain). The phase Ⅱ study showed that pharmacokinetics, pharmacodynamics and safety of SCT400 are equivalent to rituximab in patients with CD20-positive non-Hodgkin lymphoma. Objectives: This phase III study aimed to evaluate the safety and efficacy of SCT400 plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) compared with rituximab plus CHOP in patients with treatment-naïve diffuse large B-cell lymphoma (DLBCL) (ClinicalTrials.gov, identifier: NCT02772822). Methods: In this multicenter, randomized, single-blind, parallel active-controlled, non-inferiority, phase III study, patients were enrolled from 37 centers in China. Eligible patients were aged 18～75 years with histologically confirmed CD20-positive, treatment-naïve DLBCL; international prognostic index (IPI) 0～2; an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0～2. Patients were randomly assigned in a 2:1 ratio to receive either SCT400 plus CHOP (S-CHOP) or rituximab plus CHOP (R-CHOP) every 21 days cycle treatment for six cycles. The primary endpoint was objective response rate (ORR) after six cycles of therapy, assessed by an independent review committee, with a non-inferiority margin of -12%. The secondary endpoints were complete response rate (CRR), progression-free survival (PFS), overall survival (OS), and safety. Results: Between October 19, 2016 and July 13, 2018, 534 patients were screened and 364 eligible patients were randomized to either the S-CHOP group (n=243) or R-CHOP group (n=121). Patient demographics and disease characteristics at baseline were well balanced between the two treatment groups. In the per protocol set (PPS), the best ORRs within six cycles of treatment were 94.5% (95% confidence interval [CI], 90.8% to 97.0%) and 94.1% (95%CI, 88.2% to 97.6%) in the S-CHOP and R-CHOP groups respectively, with an intergroup difference of 0.4% (95%CI, -4.7% to 5.6%, P=0.6569) (Figure 1A). The 95%CI lay on the positive side of the prespecified non-inferiority margin of -12%, meeting the criterion for non-inferiority. The results of using the full analysis set (FAS) were consistent with the primary efficacy analysis in the PPS. No significant differences were observed in the secondary efficacy endpoints, in either the PPS or the FAS (Figure 1B and Figure 2). There were no significant differences were observed in ≥1 adverse event (AE, 97.9% vs. 99.2%), grade≥3 AE (85.2% vs. 86.0%), serious AE (35.4% vs. 38.8%), treatment discontinuation due to AE (7.8% vs.12.4%) between S-CHOP and R-CHOP groups, respectively (Table 1). AEs of special interest occurred in 63.8% of patients in the S-CHOP group and in 59.5% of patients in R-CHOP group, including infection (46.5% vs. 46.3%), infusion-related reaction (20.2% vs. 17.4%), cardiotoxicity (17.7% vs. 11.6%), hepatitis B virus reactivation (1.2% vs. 3.3%), ileus and enterobrosis (1.2% vs. 0.8%), tumor lysis syndrome (0.0% vs. 0.8%) (Table 1). A total of 51 deaths were reported in the S-CHOP group (n=35, 14.4%) and R-CHOP group (n=16, 13.2%), and 10 deaths were due to AE (S-CHOP group: n=7, 2.9%; R-CHOP group: n=3, 2.5%) (Table 1). After treatment, study-drug related anti-drug antibodies (ADAs) were detected in 11(10.9%) patients in S-CHOP group and in 8(16.0%) patients in R-CHOP group (Table 1). Conclusion: SCT400 plus CHOP showed non-inferiority of efficacy to rituximab plus CHOP in patients with treatment-naïve DLBCL. The safety and immunogenicity profiles of SCT400 were comparable with rituximab, with no new treatment-related AE occurred. SCT400 could be a therapeutic option for DLBCL. Funding source: This study was supported by the sponsor, Sinocelltech Ltd., and by grants from the China National Major Project for New Drug Innovation (No. 2018ZX09736002 and No. 2017ZX09304015). Conflicts of interest: Liangzhi Xie is an employee of Sinocelltech Ltd. and has ownership interests in the company. All other authors declare no conflicts of interest. Figure 1 Figure 1. Disclosures Hu: Astellas Pharma, Inc.: Research Funding. Xie: Sinocelltech Ltd.: Current Employment, Current equity holder in publicly-traded company.

Erythroid apoptosis increases significantly in myelodysplastic syndrome (MDS) patients with iron overload, but the underlying mechanism is not fully clear. In this study, we aim to explore the effect of HIF-1a/ROS on erythroid apoptosis in MDS patients with iron overload. We found that iron overload injured cellular functions through up-regulating ROS levels in MDS/AML cells, including inhibited cell viability, increased cell apoptosis and blocked cell cycle at G0/G1 phase. Interestingly, overexpression of hypoxia inducible factor-1a (HIF-1a), which was under-expressed in iron overload models, reduced ROS levels and attenuated cell damage caused by iron overload in MDS/AML cells. And gene knockdown of HIF-1a got the similar results as iron overload in MDS/AML cells. Furthermore, iron overload caused high erythroid apoptosis was closely related with ROS in MDS patients. Importantly, the HIF-1a protein levels of erythrocytes elevated obviously after incubation with desferrioxamine (DFO) from MDS patients with iron overload, accompanied by ROS levels inhibited and erythroid apoptosis reduced. Taken together, our findings determine that the HIF-1a/ROS signaling pathway plays a key role in promoting erythroid apoptosis in MDS patients with iron overload.

e20002 Background: ATG-010 is a novel, oral selective inhibitor of nuclear export inhibiting exportin 1. In preclinical and clinical studies, ATG-010 has demonstrated activity against multiple myeloma (MM). ATG-010 (80 mg biweekly) plus dexamethasone (20 mg biweekly) (Sd) was approved by US FDA for treatment of patients (pts) with penta-refractory MM in 2019 based on the STORM study. MARCH is a single arm, Phase 2 study to assess efficacy and safety of Sd in Chinese pts with RRMM. Methods: Enrolled pts have been previously treated with and refractory to PI, IMiD, and the last line of therapy. Sd is administered in 4-week cycles. Primary endpoint is overall response rate (ORR) per independent review committee. The total planned enrollment of 82 pts provides ̃80% power to test against H0 of 15% ORR at one-sided α of 0.025. This abstract provides data from a planned analysis of the first 60 treated pts. Results: As of 13 Oct 2020, 18 (30%) of the 60 pts were on treatment. Median follow-up was 9.5 months (mo) (range: 1.9-12.8). Median age was 61 years (range 43-82; 42% > 65). Pts had received a median of 5 (range 1-16) prior MM regimens, with following baseline risk factors: 72% R-ISS II/III, 70% cytogenetic abnormalities, 22% del (17p13),20% renal impairment, 15% prior CAR-T therapy, and 25% pre-treated with daratumumab (considered ‘triple-class exposed’). ORR was 26.7% (95% CI: 16.1, 39.7). Median DOR was 4.6 mo (95% CI: 1.42, NE). Median PFS was 3.7 mo (95% CI: 1.92, 4.66). Median OS was not reached; 9-mo OS rate was 68.5%. ORR was 33.3% in triple-class-exposed pts, and 44.4% in pts with prior CAR-T. ORR was generally consistent across subgroups. Common TEAEs of any grade included: thrombocytopenia (87%), nausea (87%), leukopenia (85%), anemia (85%), lymphopenia (78%), neutropenia (73%), weight loss (72%), hyponatremia (65%), decreased appetite (63%), asthenia (62%)/fatigue (17%), hyperglycemia (53%), vomiting (52%), hypocalcemia (38%), hypokalemia (30%), diarrhea (30%), pneumonia (27%). Common TEAEs of Grade ≥ 3 included: anemia (60%), thrombocytopenia (55%), leukopenia (42%), lymphopenia (42%), neutropenia (38%), hyponatremia (28%), and pneumonia (23%). Thirty pts (50%) had TESAEs, including (> 3%): thrombocytopenia (15%), pneumonia (15%), anemia (6.7%), hyponatremia (3.3%). Eight pts (13.3%) had TEAEs leading to treatment discontinuation, including (> 2%): thrombocytopenia (5%) and pneumonia (3%). Three fatal TEAEs were pneumonia, intracranial hemorrhage and sudden death (1 each). Conclusions: In Chinese RRMM pts refractory to both IMiD and PI, with a highly unmet medical need, MARCH confirms the efficacy of Sd as a promising new oral therapeutic option with a manageable safety profile, which is consistent with STORM. Clinical trial information: NCT03944057.