Effect of prior lenalidomide or daratumumab exposure on hematopoietic stem cell collection and reconstitution in multiple myeloma.

BACKGROUND: The roles of Lenalidomide (Len) and Daratumumab (Dara) in multiple myeloma treatment are well-established, yet their influences on hematopoietic stem cell harvesting and reconstitution remain disputed. METHODS: We conducted a systematic database review to identify cohort studies or RCTs evaluating the effect of the use of Len or Dara on hematopoietic stem cell collection and peripheral blood count recovery in multiple myeloma patients. Effects on hematopoietic collection or reconstitution were estimated by comparing standardized mean differences (SMD) and mean differences (MD), or median differences. RESULTS: Eighteen relevant studies were identified, summarizing mobilization results. For Len, data from 13 studies were summarized, including total CD34+ cell yield, collection failure rate, and time to neutrophil and platelet engraftment. Results indicated that Len exposure led to decreased stem cell collection [SMD=-0.23, 95% CI (-0.34, -0.12)]. However, collection failure (<2×106) could be mitigated by plerixafor [OR=2.14, 95% CI (0.96, 4.77)]. For Dara, two RCTs and three cohort studies were included, showing that Dara exposure resulted in a reduction in total stem cells even with optimized plerixafor mobilization [SMD=-0.75, 95% CI (-1.26, -0.23)], and delayed platelet engraftment recovery [MD=1.20, 95% CI (0.73, 1.66)]. CONCLUSIONS: Our meta-analysis offers a comprehensive view of Len and Dara's impacts on hematopoietic stem cell collection and reconstitution in multiple myeloma. Len usage could lead to reduced stem cell collection, counteracted by plerixafor mobilization. Dara usage could result in diminished stem cell collection and delayed platelet engraftment.

The synergy of the XPO1 inhibitors combined with the BET inhibitor INCB057643 in high-grade B-cell lymphoma via downregulation of MYC expression.

High grade B-cell lymphoma with MYC and BCL2 rearrangements (HGBCL-DH) represents an uncommon B-cell lymphoma (BCL) with aggressive clinical courses and poor prognosis. Despite revolutionary therapeutic advances in BCL, there has been limited treatment progress in HGBCL-DH, thus necessitating additional therapeutic strategies for HGBCL-DH. This study demonstrated that the BET antagonist INCB057643 synergized with the XPO1 inhibitors (selinexor and eltanexor) to decrease cell viability and increase cell apoptosis in HGBCL-DH cells with or without TP53 mutations. As anticipated, the combined treatment of INCB057643 with selinexor slowed tumor growth and reduced the tumor burden in TP53-mutated HGBCL-DH xenografts. Mechanistically, MYC functional inhibition was a potential molecular mechanism underlying the synergy of the combined INCB057643 and selinexor treatment in HGBCL-DH cells independent of TP53 mutation status. In TP53 mutated HGBCL-DH cells, inducing DNA damage and impairing the DNA damage response (DDR) were involved in the therapeutic interaction of the combined regimen. In TP53 wild-type cells, the molecular mechanism was linked with upregulation of p53 levels and activation of its targeted pathways, rather than dysregulation of the DDR. Collectively, we might provide a potential promising combination therapy regimen for the management of HGBCL-DH. Clinical evaluations are warranted to confirm this conclusion.

Microfluidic chip with reversible interface for noninvasive remission status monitoring and prognosis prediction of acute myeloid leukemia.

Acute myeloid leukemia (AML) requires close monitoring of remission status for timely disease management. Liquid biopsy serves as a noninvasive approach for evaluating treatment response and guiding therapeutic modifications. Herein, we designed a non-invasive Leukemic stem cell Specific Capture Chip (LSC-Chip) with reversible recognition interface for AML remission status monitoring and prognosis prediction. A stem cell marker CD34 antibody coated herringbone chip with disulfide linkers was designed to capture and release leukemic stem cells (LSCs) in peripheral blood for efficient LSC enumeration and downstream single-cell analysis. Samples from 32 AML patients and 10 healthy donors were recruited for LSC enumeration and prognosis-associated subtyping with panels of official LSC markers (CD34+/CD123+/CD38-) and (Tie2+/CD34+/CD123+/CD38-), respectively. A cutoff value of 2.5 LSCs per milliliters of peripheral blood can be used to precisely distinguish non-remission AML patients from complete remission group. Moreover, single-cell RNA-seq of LSCs was performed to check different transcriptional profiles of LSC subtypes. Overall, the LSC-Chip with reversible recognition interface enabled reliable detection of LSCs from AML patient samples for noninvasive remission status monitoring and prognosis prediction in clinical AML management.

Therapeutic inhibition of PPARα-HIF1α-PGK1 signaling targets leukemia stem and progenitor cells in acute myeloid leukemia.

Treatment of acute myeloid leukemia (AML) with chemotherapeutic agents fails to eliminate leukemia stem cells (LSC)，and thus patients remain at high risk for relapse. Therefore, the identification of agents that target LSC is an important consideration for the development of new therapies. Enhanced glycolysis in LSC contributes to the aggressiveness of AML, which is difficult to be targeted. In this study, we showed that targeting peroxisome-proliferator-activated receptor α (PPARα), a ligand-activated transcription factor by chiglitazar provided a promising therapeutic approach. We first identified that chiglitazar reduced cell viability and proliferation of the leukemia stem-like cells population in AML. Treatment with chiglitazar blocked the ubiquitination of PPARα and increased its expression, resulting in the inhibition of glucose metabolism and apoptosis of AML cells. Consistent with its anti-leukemia stem-like cells activity in vitro, chiglitazar treatment in vivo resulted in the significant killing of leukemia stem-like cells as demonstrated in AML patient-derived xenograft (PDX) models. Mechanistically, PPARα overexpression inhibited the expression and promoter activity of PGK1 through blocking HIF1-α interaction on the PGK1 promoter. Thus, we concluded that targeting PPARα may serve as a novel approach for enhancing stem and progenitor cells elimination in AML.

Anlotinib exerts potent antileukemic activities in Ph chromosome negative and positive B-cell acute lymphoblastic leukemia via perturbation of PI3K/AKT/mTOR pathway.

OBJECTIVES: Despite advances in the development of novel targeted therapies, the need for B-ALL alternative treatments has not been met. Anlotinib could blunt the proangiogenic activity of VEGFR, PDGFR, and FGFR, and has shown strong antitumor activities across multiple tumors. However, anlotinib cytotoxicity against B-ALL has not ever been evaluated, thus prompting us to initiate this study. METHODS: Expression2Kinases program was used to identify potential treatment targets. Cell viability and apoptosis were determined by CCK-8 and Annexin V/PI staining kit, respectively. qRT-PCR and Western blotting were utilized to investigate the molecular mechanisms. In vivo antileukemia activity of Anlotinib was evaluated in a Ph+ B-ALL patient-Derived Xenograft (PDX) model. RESULTS: Compared with treatment-naive B-ALL cases, RR B-ALL patients had higher activities in the VEGF/VEGFR signaling and the PI3K/AKT/mTOR pathway. Exposure of Ph- and Ph+ B-ALL cells to anlotinib resulted in significant cell viability reduction, apoptosis enhancement, and cell cycle arrest at G2/M phase. Importantly, anlotinib treatment led to remarkably decreased leukemia burdens and extended the survival period in a Ph+ B-ALL PDX model. Blockade of the role of the proangiogenic mediators, comprising VEGFR2, PDGFR-beta, and FGFR3, played a critical role in the cytotoxicity of anlotinib against Ph- and Ph+ B-ALL. Moreover, anlotinib dampened the activity of PI3K/AKT/mTOR pathway that resides in the convergence of the three mentioned proangiogenic signals. CONCLUSION: This work provides impressive preclinical evidence of anlotinib against Ph- and Ph+ B-ALL and raises a rationale for future clinical evaluation of this drug in the management of Ph- and Ph+ B-ALL.

Chidamide and apatinib are therapeutically synergistic in acute myeloid leukemia stem and progenitor cells.

BACKGROUND: Leukemia stem cells (LSCs) are responsible for the initiation and perpetuation of acute myeloid leukemia (AML), and also represent leukemia relapse reservoirs with limited therapeutic approaches. Thus, additional treatment strategies are medical unmet needs to eliminate LSCs. METHODS: Cell counting kit-8 and Annexin-V-FITC/PI assays were used to examine the interaction of chidamide and apatinib on LSC-like cell lines (CD34+CD38- KG1α and Kasumi-1 cells) and primary CD34+ AML cells. AML patient-derived xenografts were established to investigate the in vivo efficacy of the combined regimen. RNA sequencing, Glutamine uptake assay, oxygen consumption assay, and western blotting were employed to explore the molecule mechanism for the cytotoxicity of chidamide with or without apatinib against LSC-like cell lines and/or primary CD34+ AML cells. RESULTS: In this study, chidamide and apatinib were synergisitc to diminish cell viability and induce apoptosis in CD34+CD38- KG1α and Kasumi-1 cells and in CD34+ primary AML cells. Importantly, chidamide combined with apatinib had more powerful in reducing leukemia burden and improving prognosis than single drug alone in an AML PDX model without significant adverse effects. Chidamide cytotoxicity was associated with decreasing glutamine uptake. The therapeutic synergy of chidamide and apatinib correlated with reprogramming of energy metabolic pathways. In addition, inactivating the VEGFR function and reducing the anti-apoptotic ability of the Bcl2 family contributed to the synergism of chidamide and apatinib in CD34+CD38- KG1α cells and CD34+ primary AML cells. CONCLUSION: Chidamide in combination with apatinib might be a promising therapeutic strategy to get rid of the population of AML stem and progenitor cells, and thus provide a potentially curative option in the treatment of patients with AML, although further clinical evaluations are required to substantiate the conclusion.

Therapeutic synergy of Triptolide and MDM2 inhibitor against acute myeloid leukemia through modulation of p53-dependent and -independent pathways.

Dysregulation of MDM2, a p53 negative regulator, frequently occurs in acute myeloid leukemia (AML) and is associated with unfavorable prognoses, rendering the p53-MDM2 axis an attractive target for the development of small-molecule inhibitors. MDM2 antagonists have been intensely developed but only lead to limited clinical activity, suggesting combination with additional drugs is an unmet medical need. In this study, we reported that Triptolide synergized with MDM2 inhibitor Nutlin-3a to suppress cell proliferation and induce mitochondrial-mediated apoptosis in p53 wt AML in vitro and ex vivo. More importantly, Triptolide cooperated with Nutlin-3a to delay tumor growth and abrogate leukemia burden in an AML xenograft model. In addition, we observed that Triptolide and Nutlin-3a were also cooperative in part of p53 deficient cases. Mechanistically, Nutlin-3a upregulated the transcriptional expressions of the p53 downstream targets PUMA and p21, while Triptolide declined the mRNA levels of two anti-apoptotic factors, XIAP and Mcl-1, in p53 wt cells. These effects were more notable when Triptolide and Nutlin-3a were combined. Our results revealed that Triptolide monotherapy exerted its antileukemia effect via both p53-dependent and independent ways, with the latter through perturbation of the MYC-ATF4 axis-mediated ER stress. Collectively, these data suggested that the Triptolide-Nutlin-3a combination might be a novel potential therapeutic intervention for patients with AML and it warrants further clinical evaluations.

Preclinical Evaluation of the HDAC Inhibitor Chidamide in Transformed Follicular Lymphoma.

The key factors leading to transformed follicular lymphoma (t-FL) include the aberrations of epigenetic modifiers as early and driving events, especially mutations in the gene encoding for histone acetyltransferase. Therefore, reversal of this phenomenon by histone deacetylase (HDAC) inhibitors is essential for the development of new treatment strategies in t-FL. Several t-FL cell lines were treated with various doses of chidamide and subjected to cell proliferation, apoptosis and cell cycle analyses with CCK-8 assay, Annexin V/PI assay and flow cytometry, respectively. Chidamide dose-dependently inhibited cell proliferation, caused G0/G1 cycle arrest and triggered apoptosis in t-FL cells. In addition, the effects of chidamide on tumor growth were evaluated in vivo in xenograft models. RNA-seq analysis revealed gene expression alterations involving the PI3K-AKT signaling pathway might account for the mechanism underlying the antitumor activity of chidamide as a single agent in t-FL. These findings provide a basis for further clinical exploration of chidamide as a promising treatment for FL.

Simvastatin potentiates the cell-killing activity of imatinib in imatinib-resistant chronic myeloid leukemia cells mainly through PI3K/AKT pathway attenuation and Myc downregulation.

Constitutively activated BCR-ABL kinase is considered the driver event responsible in the initiation and development of chronic myeloid leukemia (CML). The advent of the first BCR-ABL inhibitor imatinib has significantly improved the clinical outcome of CML cases. However, resistance to imatinib occurs in 25-30% of CML patients. Due to the lack of effective therapeutic strategies, novel treatment approaches are urgently required for imatinib-resistant CML. Simvastatin, a well-known HMG-CoA reductase inhibitor that confers tremendous clinical benefits in cardiovascular diseases, has attracted mounting attentions for its potent antitumor effects on multiple tumor types. In this study, we demonstrated that simvastatin monotherapy was effective in diminishing cell viability in both imatinib-sensitive and imatinib-resistant CML cells, including T351I mutated cells, with the latter being less vulnerable to the simvastatin than the former. Notably, we found that simvastatin acted as a robust cytotoxic sensitizer of imatinib to kill imatinib-resistant and T315I mutated CML cells in vitro and in vivo. Mechanistically, the cooperative interaction of simvastatin and imatinib was associated with the inactivation of the PI3K/Akt signaling pathway, which was a classical downstream pro-survival cascade of the BCR-ABL kinase. In addition, this drug combination obviously decreased Myc expression through attenuation of canonical Wnt/ß-catenin signaling and increased H3K27 trimethylation. Taken together, we provide attractive preclinical results for the combinatorial regimen of simvastatin and imatinib against imatinib-resistant and T315I mutated CML cells. This combined regimens warrants further clinical investigations in patients with imatinib-resistant CML.

Therapeutic Interaction of Apatinib and Chidamide in T-Cell Acute Lymphoblastic Leukemia through Interference with Mitochondria Associated Biogenesis and Intrinsic Apoptosis.

T-cell acute lymphoblastic leukemia (T-ALL) shows poor clinical outcome and has limited therapeutic options, indicating that new treatment approaches for this disease are urgently required. Our previous study demonstrated that apatinib, an orally selective VEGFR-2 antagonist, is highly effective in T-ALL. Additionally, chidamide, a histone deacetylase inhibitor, has proven to be cytotoxic against T-ALL in preclinical and clinical settings. However, whether the therapeutic interaction of apatinib and chidamide in T-ALL remains unknown. In this study, apatinib and chidamide acted additively to decrease cell viability and induce apoptosis in T-ALL in vitro. Notably, compared with apatinib or chidamide alone, the combinational regimen was more efficient in abrogating the leukemia burden in the spleen and bone marrow of T-ALL patient-derived xenograft (PDX) models. Mechanistically, the additive antileukemia effect of apatinib and chidamide was associated with suppression of mitochondrial respiration and downregulation of the abundance levels of several rate-limiting enzymes that are involved in the citric acid cycle and oxidative phosphorylation (OXPHOS). In addition, apatinib enhanced the antileukemia effect of chidamide on T-ALL via activation of the mitochondria-mediated apoptosis pathway and impediment of mitochondrial biogenesis. Taken together, the study provides a potential role for apatinib in combination with chidamide in the management of T-ALL and warrants further clinical evaluations of this combination in patients with T-ALL.

Clinical features and outcomes of 1845 patients with follicular lymphoma: a real-world multicenter experience in China.

Clinical features and outcomes of FL patients in Chinese population are limited, thus promoting us to perform this analysis on a large cohort of 1845 patients with FL enrolled from nine medical centers nationwide in China. In this cohort, the median age of patients at diagnosis was 53 years, which was comparable to that reported previously for Chinese FL patients (49-51 years) but younger than that for Western FL patients (60-65 years). In contrast with Western patients, Chinese FL patients more likely involved extranodal sites but less frequently infiltrated bone marrow. Other clinical characteristics were comparable between two populations. In this study, 91% of patients were managed with chemotherapy, yielding 72% and 46% of overall-response rate and complete remission. After median 55-month follow-up, 5-year progressive-free and overall survival were 61% and 89%, respectively. Both were analogous to those reported in prior Chinese and Western studies. Consistent with published data, addition of rituximab into both induction (Ri) and maintenance (Rm) treatment led to the most favorable outcomes. Interestingly, Ri only had better outcomes than Rm only. Notably, 7% of patients experienced histologic transformation (HT) and correlated with poor survival. Of the transformed FL cases, 3% and 4% of HT events occurred prior to or post-treatment, respectively. Importantly, the latter displayed worse outcomes than the former. Altogether, this study provides real-world information of the largest cohort of FL patients so far in China, which might lay a foundation for clinical investigation of Chinese FL in future.

Disulfiram/copper shows potent cytotoxic effects on myelodysplastic syndromes via inducing Bip-mediated apoptosis and suppressing autophagy.

Patients with myelodysplastic syndromes (MDS) who resist or fail to respond to hypomethylating agents (HMAs) show very poor outcomes and have no effective treatment strategies. Therefore, new therapeutic approaches are urgently needed for MDS patients harboring adverse prognostic factors. Repurposing disulfiram (DSF), an alcohol-abuse drug, with or without Copper (Cu) has attracted considerable attentions as a candidate anti-tumor therapy in diverse malignancies. However, the effect of DSF in the presence or absence of Cu on MDS has not been reported yet. In this study, we found that monotherapy with DSF showed mild cytotoxic effects on MDS preclinical models. However, the anti-tumor activity of DSF was significantly enhanced in the presence of Cu in MDS in vitro and in vivo with minimal safety profiles. DSF/Cu combination blocked MDS cell cycle progression at the G0/G1 phase, accompanied by reduction of the S phase. Accordingly, co-treatment with DSF and Cu downregulated the expression of Cyclin D1 and Cyclin A2, whereas this combination upregulated the level of P21 and P27. Mechanistically, the anti-MDS effectiveness of DSF/Cu was potentially associated with activation of the ER stress-related Bip pathway and inactivation of the Akt pathway. In addition, inhibition of autophagy process also contributed to the cytotoxicity of DSF/Cu in MDS cells. In conclusion, these findings provide impressive evidence that the DSF/Cu complex shows potent anti-tumor efficacies on MDS preclinical models, representing a potential alternative therapy for MDS patients and warranting further investigation in clinical contexts.

CS2164 and Venetoclax Show Synergistic Antitumoral Activities in High Grade B-Cell Lymphomas With MYC and BCL2 Rearrangements.

High-grade B-cell lymphoma with concurrent MYC and BCL2 rearrangements (HGBL-DHL) is a rare, aggressive mature B-cell malignancy with a high likelihood of treatment failure following front-line immunochemotherapies. Patients with HGBL-DHL who develop a relapsed or refractory disease have little effective therapeutic strategies and show very poor clinical outcomes, thus calling for development of novel therapies for this specific patient population. In this study, we investigated the preclinical anti-lymphoma efficacies and potential mechanism of action of a novel treatment approach, combining the BCL2 inhibitor venetoclax with CS2164, a new orally active multitarget inhibitor, in HGBL-DHL models. This combination therapy exhibited a robust synergistic cytotoxicity against HGBL-DHL cells, evidenced by cooperatively inducing loss of cell viability and promoting cell apoptosis. Moreover, coadministration of CS2164 and venetoclax resulted in significant superior suppression of HGBL-DHL cell growth and remarkably abrogated tumor burden in a HGBL-DHL-xenografted mouse model. The synergistic lethality of CS2164 and venetoclax in HGBL-DHL cells was associated with induction of DNA damage and impairment of DNA repair ability. Of importance, the combined treatment almost abolished the expression of both BCL2 and MYC, two hallmark proteins of HGBL-DHL, and substantially blunted the activity of PI3K/AKT/mTOR signaling cascade. In addition, MCL1 and BCL-XL, two well-characterized contributors for venetoclax resistance, were significantly lessened in the presence of CS2164 and venetoclax, thus leading to the accumulation of proapoptotic proteins BAX and PUMA and then initiating the intrinsic apoptosis pathway. Taken together, these findings suggest that the regimen of CS2164 and venetoclax is highly effective to eliminate HGBL-DHL cells in the preclinical setting, warranting further clinical investigations of this regimen for the treatment of unfavorable HGBL-DHL patients.

Molecular and genetic biomarkers implemented from next-generation sequencing provide treatment insights in clinical practice for Waldenström macroglobulinemia.

Waldenström macroglobulinemia (WM) is a distinct type of indolent lymphoplasmacytic lymphoma (LPL) with a high frequency of MYD88L265P mutation. Treatment for WM/LPL is highly variable in clinic and ibrutinib (a Bruton tyrosine kinase inhibitor, BTKi) has become a new treatment option for WM. To investigate the clinical impact of genetic alterations in WM, we assembled a large cohort of 219 WMs and 12 LPLs dividing into two subcohorts: a training cohort, patients sequenced by a same targeted 29-gene next-generation sequencing (NGS) panel, and a validation cohort, patients sequenced by allele specific-PCR or other targeted NGS panels. In both training and validation subcohorts, MYD88L265P and TP53 mutations showed favorable and adverse prognostic effects, respectively. CXCR4 nonsense/missense mutations (CXCR4NS/MS), cytogenetic complex karyotypes, and a family history of lymphoma/leukemia in first-degree relatives were associated with significantly worse clinical outcomes only or more in the validation subcohort. We further investigated the efficacy of various treatments and interaction with genetic factors in the entire cohort. Upfront dexamethasone usage was associated with poorer clinical outcomes in patients who received non-proteasome-containing chemotherapy as first-line treatment independent of genetic factors. Maintenance rituximab was associated with better survival. Ibrutinib/BTKi showed potential benefit in relapsed/refractory patients and patients without CXCR4NS/MS including those with TP53 mutations. In conclusion, genetic testing for MYD88L265P, TP53, and CXCR4 mutations and cytogenetic analysis provide important information for prognosis prediction and therapy selection. The findings in these study are valuable for improving treatment decisions on therapies available for WM/LPL patients with integration of NGS in clinic.

Low-Dose Triptolide Enhanced Activity of Idarubicin Against Acute Myeloid Leukemia Stem-like Cells Via Inhibiting DNA Damage Repair Response.

Leukemia stem cells (LSCs) are considered to be the root of relapse for acute myeloid leukemia (AML). Conventional chemotherapeutic drugs fail to eliminate LSCs. Therefore, new therapeutic strategies eliminating LSCs are urgently needed. Our results showed that low-dose Triptolide (TPL) enhanced the anti-AML activity of Idarubicin (IDA) in vitro against LSC-like cells (CD34 + CD38- KG1αand CD34 + CD38- kasumi-1 cells) and CD34+ primary AML cells, while sparing normal cells. Inspiringly, the combination treatment with low-dose TPL and IDA was also effective against CD34 + blasts from AML patients with FLT3-ITD mutation, which is an unfavorable risk factor for AML patients. Moreover, the combination of TPL and IDA induced a remarkable suppression of human leukemia growth in a xenograft mouse model. Mechanistically, the enhanced effect of low dose TPL on IDA against LSCs was attributed to inhibiting DNA damage repair response. Thus, our study may provide a theoretical basis to facilitate the development of a novel LSCs-targeting strategy for AML.Graphical abstract.

Aggressive B-cell Lymphoma with MYC/TP53 Dual Alterations Displays Distinct Clinicopathobiological Features and Response to Novel Targeted Agents.

Diffuse large B-cell lymphoma (DLBCL) is the major type of aggressive B-cell lymphoma. High-grade B-cell lymphoma (HGBCL) with MYC/BCL2 double-hit (DH) represents a distinct entity with dismal prognosis after standard immunochemotherapy in the current WHO lymphoma classification. However, whether TP53 mutation synergizes with MYC abnormalities (MYC rearrangement and/or Myc protein overexpression) contributing to HGBCL-like biology and prognosis is not well investigated. In this study, patients with DLBCL with MYC/TP53 abnormalities demonstrated poor clinical outcome, high-grade morphology, and distinct gene expression signatures. To identify more effective therapies for this distinctive DLBCL subset, novel MYC/TP53/BCL-2-targeted agents were investigated in DLBCL cells with MYC/TP53 dual alterations or HGBCL-MYC/BCL2-DH. A BET inhibitor INCB057643 effectively inhibited cell viability and induced apoptosis in DLBCL/HGBCL cells regardless of MYC/BCL2/TP53 status. Combining INCB057643 with a MDM2-p53 inhibitor DS3032b significantly enhanced the cytotoxic effects in HGBCL-DH without TP53 mutation, while combining with the BCL-2 inhibitor venetoclax displayed potent therapeutic synergy in DLBCL/HGBCL cells with and without concurrent TP53 mutation. Reverse-phase protein arrays revealed the synergistic molecular actions by INCB057643, DS3032b and venetoclax to induce cell-cycle arrest and apoptosis and to inhibit AKT/MEK/ERK/mTOR pathways, as well as potential drug resistance mechanisms mediated by upregulation of Mcl-1 and RAS/RAF/MEK/ERK pathways. In summary, these findings support subclassification of DLBCL/HGBCL with dual MYC/TP53 alterations, which demonstrates distinct pathobiologic features and dismal survival with standard therapy, therefore requiring additional targeted therapies. IMPLICATIONS: The clinical and pharmacologic studies suggest recognizing DLBCL with concomitant TP53 mutation and MYC abnormalities as a distinctive entity necessary for precision oncology practice. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/2/249/F1.large.jpg.

XPO1 expression worsens the prognosis of unfavorable DLBCL that can be effectively targeted by selinexor in the absence of mutant p53.

The XPO1 inhibitor selinexor was recently approved in relapsed/refractory DLBCL patients but only demonstrated modest anti-DLBCL efficacy, prompting us to investigate the prognostic effect of XPO1 in DLBCL patients and the rational combination therapies in high-risk DLBCL. High XPO1 expression (XPO1high) showed significant adverse prognostic impact in 544 studied DLBCL patients, especially in those with BCL2 overexpression. Therapeutic study in 30 DLBCL cell lines with various molecular and genetic background found robust cytotoxicity of selinexor, especially in cells with BCL2-rearranged (BCL2-R+) DLBCL or high-grade B-cell lymphoma with MYC/BCL2 double-hit (HGBCL-DH). However, expression of mutant (Mut) p53 significantly reduced the cytotoxicity of selinexor in overall cell lines and the BCL2-R and HGBCL-DH subsets, consistent with the favorable impact of XPO1high observed in Mut-p53-expressing patients. The therapeutic effect of selinexor in HGBCL-DH cells was significantly enhanced when combined with a BET inhibitor INCB057643, overcoming the drug resistance in Mut-p53-expressing cells. Collectively, these data suggest that XPO1 worsens the survival of DLBCL patients with unfavorable prognostic factors such as BCL2 overexpression and double-hit, in line with the higher efficacy of selinexor demonstrated in BCL2-R+ DLBCL and HGBCL-DH cell lines. Expression of Mut-p53 confers resistance to selinexor treatment, which can be overcome by combined INCB057643 treatment in HGBCL-DH cells. This study provides insight into the XPO1 significance and selinexor efficacy in DLBCL, important for developing combination therapy for relapsed/refractory DLBCL and HGBCL-DH.

Disruption of CTCF Boundary at HOXA Locus Promote BET Inhibitors' Therapeutic Sensitivity in Acute Myeloid Leukemia.

Both HOX gene expression and CTCF regulation have been well demonstrated to play a critical role in regulating maintenance of leukemic stem cells (LSCs) that are known to be resistant to BET inhibitor (BETi). To investigate the regulatory role of CTCF boundary in aberrant HOX gene expression and the therapeutic sensitivity of BETi in AML, we employed CRISPR-Cas9 genome editing technology to delete 47 base pairs of the CTCF binding motif which is located between HOXA7 and HOXA9 genes (CBS7/9) in different subtypes of AML with either MLL-rearrangement or NPM1 mutation. Our results revealed that HOXA9 is significantly downregulated in response to the CBS7/9 deletion. Moreover, CBS7/9 boundary deletion sensitized the BETi treatment reaction in both MOLM-13 and OCI-AML3 cells. To further examine whether BETi therapeutic sensitivity in AML is depended on the expression level of the HOXA9 gene, we overexpressed the HOXA9 in the CBS7/9 deleted AML cell lines, which can rescue and restore the resistance to BETi treatment of the CBS7/9 KO cells by activating MAPK signaling pathway. Deletion of CBS7/9 specifically decreased the recruitment of BRD4 and RNA pol II to the posterior HOXA genes, in which, a transcription elongation factor ELL3 is the key factor in regulating HOXA gene transcription monitored by CBS7/9 chromatin boundary. Thus, disruption of CBS7/9 boundary perturbs HOXA9 transcription and regulates BETi sensitivity in AML treatment. Moreover, alteration of CTCF boundaries in the oncogene loci may provide a novel strategy to overcome the drug resistance of LSCs. Graphical abstract.

Preclinical evaluation of a regimen combining chidamide and ABT-199 in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous myeloid neoplasm with poor clinical outcome, despite the great progress in treatment in recent years. The selective Bcl-2 inhibitor venetoclax (ABT-199) in combination therapy has been approved for the treatment of newly diagnosed AML patients who are ineligible for intensive chemotherapy, but resistance can be acquired through the upregulation of alternative antiapoptotic proteins. Here, we reported that a newly emerged histone deacetylase inhibitor, chidamide (CS055), at low-cytotoxicity dose enhanced the anti-AML activity of ABT-199, while sparing normal hematopoietic progenitor cells. Moreover, we also found that chidamide showed a superior resensitization effect than romidepsin in potentiation of ABT-199 lethality. Inhibition of multiple HDACs rather than some single component might be required. The combination therapy was also effective in primary AML blasts and stem/progenitor cells regardless of disease status and genetic aberrance, as well as in a patient-derived xenograft model carrying FLT3-ITD mutation. Mechanistically, CS055 promoted leukemia suppression through DNA double-strand break and altered unbalance of anti- and pro-apoptotic proteins (e.g., Mcl-1 and Bcl-xL downregulation, and Bim upregulation). Taken together, these results show the high therapeutic potential of ABT-199/CS055 combination in AML treatment, representing a potent and alternative salvage therapy for the treatment of relapsed and refractory patients with AML.

Combining triptolide with ABT-199 is effective against acute myeloid leukemia through reciprocal regulation of Bcl-2 family proteins and activation of the intrinsic apoptotic pathway.

Bcl-2 inhibitors display an effective activity in acute myeloid leukemia (AML), but its clinical efficacy as a monotherapy was limited in part owing to failure to target other antiapoptotic Bcl-2 family proteins, such as Mcl-1. In this context, the combination strategy may be a promising approach to overcome this barrier. Here, we report the preclinical efficacy of a novel strategy combining ABT-199 with triptolide (TPL), a natural product extracted from a traditional Chinese medicine, in AML. Combination treatment exhibited markedly increased cytotoxicity in leukemic cells irrespective of p53 status while largely sparing normal cells of the hematopoietic lineage. Moreover, co-administration of ABT-199 with TPL dramatically suppressed leukemia progression as well as prolonged animal survival in a xenograft AML model. The potentiated effect of ABT-199 and TPL against AML was associated with activation of the mitochondrum-related intrinsic apoptotic pathway through a mechanism reciprocally modulating Bcl-2 family proteins. In this case, TPL not only downregulated Mcl-1 but also upregulated proapoptotic BH3-only proteins, thereby overcoming the resistance toward ABT-199. Conversely, ABT-199 abrogated Bcl-2-mediated cytoprotection against TPL. Together, these findings suggest that the regimen combining TPL and ABT-199 might be active against AML by inducing robust apoptosis through reciprocal regulation of anti- and proapoptotic Bcl-2 family proteins, therefore providing a strong rationale for the clinical investigation of this combination regimen for the treatment of AML.