Antileukemic Activity Research Articles

Allogeneic DNT cell therapy synergizes with T cells to promote anti-leukemic activities while suppressing GvHD

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a second-line treatment with curative potential for leukemia patients. However, the prognosis of allo-HSCT patients with disease relapse or graft-versus-host disease (GvHD) is poor. CD4+ or CD8+ conventional T (Tconv) cells are critically involved in mediating anti-leukemic immune responses to prevent relapse and detrimental GvHD. Hence, treatment for one increases the risk of the other. Thus, therapeutic strategies that can address relapse and GvHD are considered the Holy Grail of allo-HSCT. CD3+CD4−CD8− double-negative T cells (DNTs) are unconventional mature T cells with potent anti-leukemia effects with “off-the-shelf” potential. A phase I clinical trial demonstrated the feasibility, safety, and potential efficacy of allogeneic DNT therapy for patients with relapsing acute myeloid leukemia (AML) post-allo-HSCT. Here, we studied the impact of DNTs on the anti-leukemic and GvHD-inducing activities of Tconv cells. DNTs synergized with Tconv cells to mediate superior anti-leukemic activity. Mechanistically, DNTs released soluble factors which activated and evoked potent anti-leukemic activities of Tconv cells. In contrast, DNTs suppressed GvHD-inducing activities of Tconv cells in a CD18-dependent manner by mediating cytotoxicity against proliferative Tconv cells. The seemingly opposite immunological activities of DNTs were dictated by the presence or absence of AML cells. Collectively, these results support the potential of DNTs as an adjuvant to allo-HSCT to address both disease relapse and GvHD.

Synthesis, biological activities, DFT calculations and molecular docking studies of O-methyl-inositols.

The concise synthesis of O-methyled-inositol derivative and conduritol derivatives was obtained starting from p-benzoquinone. Spectroscopic methods have been performed for characterization of new synthesized compounds. Cyclitols are useful molecules with anticancer, antibiotic, antinutrient and antileukemic activity. Inositol class molecules, known as the most important cyclitol derivatives, were examined in this study for their 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide radical scavenging and butyrylcholinesterase (BChE) and glycosidase inhibition activities. It was observed that compound 5, in particular, showed efficacy that competed with the standards in terms of both antioxidant activity and enzyme inhibitor potential. Additionally, compound 5 shows effective antimicrobial activity. The water-soluble characteristics and lipophilic properties of the compounds were also considered and discussed. Also, the quantum chemical analyses were performed in light of the DFT/B3LYP/6-311G** level computations to elucidate/compare the studied inositols' possible reactivity directions. Additionally, the interactions of the molecules were analyzed against Acetylcholinesterase (AChE), Peroxiredoxin 5, and DNA Gyrase by molecular docking methods. Cholinesterase inhibitors have an important status as the most important drug group used in the treatment of Alzheimer's disease today. Considering the effects of inhibition of the α-glucosidase enzyme by inhibitors, such molecules can also be used as therapeutic components in the treatment of diabetes.

Discovery of Novel RNA Demethylase FTO Inhibitors Featuring an Acylhydrazone Scaffold with Potent Antileukemia Activity.

Fat mass obesity-associated protein (FTO) has been emerging as a potential therapeutic target for drug discovery in RNA epigenetics. In this work, a series of novel FTO inhibitors featuring an acylhydrazone scaffold were identified, and the optimized compounds 8t-v showed potent FTO inhibitory activities with IC50 values ranging from 7.1 to 9.4 μM. FTO inhibitor 8t, as the lead compound, exhibited potent antiproliferative capacities against MOLM13, NB4, and THP-1 with IC50 values of 0.35, 0.59, and 0.70 μM, respectively, and remarkably induced NB4 cell apoptosis. Compound 8t also inhibited the FTO demethylation, enhanced the abundance of m6A, stabilized FTO protein folding, and regulated the oncogenic FTO signaling pathway. Importantly, compound 8t significantly caused a tumor volume reduction and tumor weight loss with a tumor growth inhibition (TGI) value of 51% in NB4 xenograft mice. Overall, our work provided valuable lead compounds for FTO inhibitors featuring an acylhydrazone scaffold with potent antileukemia activity both in vitro and in vivo.

Engineering and characterization of Hu3A4: A novel humanized antibody with potential as a therapeutic agent against myeloid lineage leukemias.

Leukemia stem cells (LSCs) play a critical role in the initiation, recurrence, and resistance to treatment of leukemia. Eradicating LSCs is crucial for the complete elimination of the disease. CD45RA is identified as an important marker for LSC subsets in acute myeloid leukemia (AML), providing a strategic target for therapy. In this report, we introduce Hu3A4, an innovative humanized CD45RA antibody devised to target LSCs expressing this antigen. Hu3A4 retains the antigen-recognition ability of its parental antibody while removing sequences from the variable region that could elicit human anti-mouse immune reactions. The modified variable regions of the heavy and light chains were intricately fused with the constant regions of human IgG1 heavy and light chains, respectively, producing a humanized antibody that emulates the structure of natural IgG. Hu3A4 was produced through recombinant expression in Chinese Hamster Ovary (CHO) cells, which ensured stable gene integration. In vitro tests revealed that Hu3A4 could effectively target and lyse the cells. Further, in vivo studies highlighted Hu3A4's substantial anti-leukemic activity, significantly prolonging survival times in treated animal models compared to controls (P < 0.01). To summarize, Hu3A4 exhibits remarkable bioactivity and offers a promising therapeutic potential for the treatment of leukemia patients. Progressing Hu3A4 through additional preclinical and clinical studies is crucial to validate its efficacy as a therapeutic agent for leukemia.

Apigenin facilitates apoptosis of acute lymphoblastic leukemia cells via AMP-activated protein kinase-mediated ferroptosis.

The outcomes of pediatric patients with acute lymphoblastic leukemia (ALL) remain far less than favorable. While apigenin is an anti-cancer agent, studies on the mechanism by which it regulates ALL cell cycle progression are inadequate. Ferroptosis and AMP-activated protein kinase (AMPK) signaling are important processes for ALL patients. However, it remains unclear whether apigenin works by affecting AMPK and apoptosis. SUP-B15 and T-cell Jurkat ALL cells were treated with apigenin, and cell viability and apoptosis were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays, respectively. The thiobarbituric acid-reactive substances (TBARS) assay was used to evaluate lipid peroxidation. Intracellular Fe2+ levels were measured using a commercial kit. Corresponding proteins were detected by western blotting. Results showed that apigenin reduced cell viability and the levels of Ki67 and proliferating cell nuclear antigen (PCNA) expression in a concentration-dependent manner in both types of ALL cells. Apigenin also exerted anti-apoptotic effects on SUP-B15 and Jurkat cells. Apigenin activated AMP-activated protein kinase (AMPK) signaling and induced ferroptosis, and those effects were attenuated by inhibition of AMPK. Eventually, the reduced cell proliferation and increased cell apoptosis caused by apigenin in ALL cells were partly abolished by AMPK inhibition. In summary, apigenin exerted anti-leukemia activity in ALL cells, and that effect was partially achieved by activation of AMPK signaling. Our findings suggest apigenin as a potential drug for treatment of ALL.

Obinutuzumab in Combination with Alternative Chlorambucil Schedules in Front-Line Treatment of Chronic Lymphocytic Leukemia: A Study by KroHem, the Croatian Cooperative Group for Hematologic Diseases.

Background/Objectives: Obinutuzumab was approved for front-line treatment of chronic lymphocytic leukemia in combination with chlorambucil pulses administered every 2 wks. Alternative schedules of chlorambucil enable the administration of higher total chlorambucil doses, and have better antileukemia activity. So far, evidence on the feasibility of combining obinutuzumab with alternative chlorambucil schedules is lacking. We performed this retrospective analysis to analyze real life outcomes in chronic lymphocytic leukemia patients receiving a combination of obinutuzumab with different chlorambucil schedules. Methods: This was a retrospective survey performed in order to analyze the feasibility and efficacy of different obinutuzumab and chlorambucil combinations in a real-life setting. Patients receiving this combination as a front-line therapy for chronic lymphocytic leukemia in participating centers, outside of clinical trials, in 2017 and 2018 were included. Results: Seventy-three patients fulfilling entry criteria were identified. Their median age was 76 years, and ranged from 58 to 90 years. The median follow up time was 59 months. The response rate was 89%, with a median progression-free survival time of 27 months, and an overall survival time of 49 months. Chlorambucil was administered as planned in 15 of the 22 (79%) patients treated with chlorambucil pulses every 2 weeks; in 15 of the 42 (34%) patients treated with 7-day courses of chlorambucil administered every 4 weeks; and in 0 of the 10 patients treated with a continuous high dose of chlorambucil (p = 0.002). Changes in treatment schedules were made due to side effects. The progression-free and overall survival rates were similar between the three groups. Conclusions: The combinations of obinutuzumab with more intensive chlorambucil schedules are less feasible, preventing the administration of the intended higher total dose of chlorambucil, and do not improve outcomes in comparison to chlorambucil pulses administered every 2 weeks.

The Anticancer Activity of Cannabinol (CBN) and Cannabigerol (CBG) on Acute Myeloid Leukemia Cells.

Several cannabis plant-derived compounds, especially cannabinoids, exhibit therapeutic potential in numerous diseases and conditions. In particular, THC and CBD impart palliative, antiemetic, as well as anticancer effects. The antitumor effects include inhibition of cancerous cell growth and metastasis and induction of cell death, all mediated by cannabinoid interaction with the endocannabinoid system (ECS). However, the exact molecular mechanisms are still poorly understood. In addition, their effects on leukemia have scarcely been investigated. The current work aimed to assess the antileukemic effects of CBN and CBG on an acute monocytic leukemia cell line, the THP-1. THP-1 cell viability, morphology and cell cycle analyses were performed to determine potential cytotoxic, antiproliferative, and apoptotic effects of CBN and CBG. Western blotting was carried out to measure the expression of the proapoptotic p53. Both CBN and CBG inhibited cell growth and induced THP-1 cell apoptosis and cell cycle arrest in a dose- and time-dependent manner. CBN and CBG illustrated different dosage effects on THP-1 cells in the MTT assay (CBN > 40 μΜ, CBG > 1 μM) and flow cytometry (CBN > 5 μM, CBG > 40 μM), highlighting the cannabinoids' antileukemic activity. Our study hints at a direct correlation between p53 expression and CBG or CBN doses exceeding 50 μM, suggesting potential activation of p53-associated signaling pathways underlying these effects. Taken together, CBG and CBN exhibited suppressive, cell death-inducing effects on leukemia cells. However, further in-depth research will be needed to explore the molecular mechanisms driving the anticancer effects of CBN and CBG in the leukemia setting.

Dual-Targeted Drug Delivery to Myeloid Leukemia Cells via Complement- and Transferrin-Based Protein Corona.

Although traditionally regarded as an impediment, the protein corona can facilitate the advancement of targeted drug delivery systems. This study presents an innovative approach for targeting acute myeloid leukemia (AML) using nanoparticles with agglutinated protein (NAPs). Agglutinated transferrin and C3b in NAPs selectively bind to CD71 and CD11b, receptors that are overexpressed on myeloid leukemic cells compared to nonmalignant cells. In vitro, NAPs achieved a 73.9% doxorubicin (DOX) uptake in leukemic cells, compared to 6.19% for the free drug, while significantly reducing off-target accumulation in normal cells from 42.9% to 5.76%. In vivo, the distribution of NAPs correlated to the organ infiltration pattern of leukemic cells. NAPs demonstrated antileukemic activity in both in vitro and in vivo NSG mouse models, inducing cell death via apoptosis and ferroptosis. In conclusion, NAP-mediated targeted drug delivery represents a promising therapeutic strategy for AML, enhancing treatment efficacy and minimizing off-target effects.

Novel Small Molecule Derived from Hydroxy Naphthaldhyde as Potential Anti-Leukemia Agents: Spectroscopic, DFT, Docking Molecular and ADME/T Investigations

New ligand derived from hydroxy naphthaldhyde (LCAT1) was synthetized and the structure of the formed Schiff base was confirmed by various analytical and spectroscopic methods. Elemental analysis, mass spectrometry and NMR studies confirmed the structure of the ligand. Theoretical calculations (DFT) were performed to study the molecular structure, chemical reactivity and electronic properties of this ligand. This study shows good agreement with the experimental results obtained using infrared spectrometry and UV-visible spectrophotometry. The optimized structure has been used to perform the molecular docking studies. The homology modeling and molecular docking were investigated in order to check their anti-leukemia activities toward several leukemia cells. In addition, in silico ADME/T modeling was employed to evaluate absorption, distribution, metabolism, and excretion pharmacological parameters of the ligand. The DFT study indicates that the evaluated parameters, such as Mulliken charges and molecular orbitals, as well as the MEP results, are consistent with the localization of electrophilic and nucleophilic attack sites. Furthermore, the data indicate significant chemical reactivity associated with low kinetic stability of the ligand. In accordance with the principle of a 90% critical assessment, the homological modeling model used is considered to be the most appropriate. The molecular docking results indicated that our molecule has a strong affinity for DNA by forming hydrogen bonds with the donor’s groups and exhibits a good leukemia activity against cell lines through the formation of strong interaction with their receptors. The results showed high binding energy and remarkable inhibition constants toward receptors 5VOM (−8.03 Kcal/mol, 1. 31 µM), 1NJS (−7.68 Kcal/mol, 2.35 µM), 7JXU. In silico ADME/T modeling showed that the properties of the synthesized ligand are similar to those of the drugs. The predicted toxicity of the ligand reveals that LCAT1 is nontoxic, with no hepatotoxicity, no mutagenicity and no carcinogenicity.

Novel conditioning and prophylaxis regimens for relapse prevention.

The last 20 years witnessed relevant clinical advancements in the field of hematopoietic cell transplantation (HCT) for leukemia patients. The introduction of novel conditioning regimens, a better prophylaxis and management of graft- versus-host disease, and an ameliorated posttransplant support system improved safety and, therefore, outcomes. On the other hand, leukemia relapse remains the major cause of allogeneic HCT failure. Efforts have been made to understand the mechanisms of leukemia relapse, and new insights that clarify how donor immunity exerts graft-versus- leukemia (GVL) activity are available. Such studies set the base to design novel transplant strategies that can improve disease control. In our review we begin by discussing the most relevant criteria to choose a donor that provides a strong GVL effect. We also report some of the novel conditioning regimens that aim to deliver and extend myeloablation in order to reduce the disease burden at time of graft infusion. Finally, we discuss how the graft can be manipulated to limit the use of immune suppression and ensure potent antileukemic activity.

Effects of Hypomethylating Agents on Gene Modulation in the Leukemic Microenvironment and Disease Trajectory in a Mouse Model of AML.

Hypomethylating agents (HMAs), such as decitabine and 5-azacytidine (AZA), are valuable treatment options for patients with acute myeloid leukemia that are ineligible for intensive chemotherapy. Despite providing significant extensions in survival when used alone or in combination, eventual relapse and resistance to HMAs are observed. The mechanisms leading to these outcomes are still not well defined and may, in part, be due to a focus on leukemic populations with limited information on the effects of HMAs on non-leukemic cells in the blood and other tissue compartments. In this study, we elucidated effects on immune-related gene expression in non-leukemic blood cells and the spleen during AZA treatment in leukemia-challenged mice. We observed significant changes in pathways regulating adhesion, thrombosis, and angiogenesis as well as a dichotomy in extramedullary disease sites that manifests during relapse. We also identify several genes that may contribute to the anti-leukemic activity of AZA in blood and spleen. Overall, this work has identified novel gene targets and pathways that could be further modulated to augment efficacy of HMA treatment.

Calaspargase-Pegol-Mknl Combined with BCL-2 and MCL-1 Inhibition for Acute Myeloid Leukemia.

Our previous studies have demonstrated that pegcrisantaspase (PegC), a long-acting Erwinia asparaginase, synergizes with the BCL-2 inhibitor Venetoclax (Ven) in vitro and in vivo; however, the anti-leukemic activity of E. coli-derived asparaginases in combination with BCL-2 inhibition, and potential synergy with inhibitors of MCL-1, a key resistance factor of BCL-2 inhibition, has yet to be determined. Using a combination of human AML cells lines, primary samples, and in vivo xenograft mouse models, we established the anti-leukemic activity of the BCL-2 inhibitor S55746 and the MCL-1 inhibitor S63845, alone and in combination with the long-acting E. coli asparaginase calaspargase pegol-mknl (CalPegA). We report that CalPegA enhances the anti-leukemic effect of S55746 but does not impact the activity of S63845. The S55746-CalPegA combination inhibited protein synthesis and increased eIF4E/4EBP1 interaction, suggesting an inhibition of translational complex formation. These results support the clinical evaluation of CalPegA in combination with BCL-2 inhibition for AML.

New metal complexes of 1H-benzimidazole-2-yl hydrazones: Cytostatic, proapoptotic and modulatory activity on kinase signaling pathways

The copper complexes of two 1H-benzimidazole-2-yl hydrazones were obtained by complexation with copper chloride. The molecular structure of the complexes was studied by microchemical analysis, SEM-EDX, IR and micro-Raman spectroscopy and DFT calculations. It was found that both ligands form 1:1 complexes with the copper, where the Cu ions are coordinated by N-atom from the benzimidazole ring, N-atom of the azomethine bond, O-atom from the ortho-OH group of the aromatic ring and one chlorine atom. The coordination process significantly affected their cytotoxicity profile. The conversion of 2-(2-hydroxybenzylidene)-1-(1H-benzimidazol-2-yl)hydrazine 1.1. into a Cu complex 2.1. led to a 2.4-fold increase in its antileukemic activity against AR-230 cells and an 8-fold increase in the cytostatic activity against MCF-7 breast cancer cell line. The growth-inhibitory effect of the Cu complex of 2-(2-hydroxy-4-methoxybenzylidene)-1-(1H-benzimidazol-2-yl)hydrazine 2.2. on the MCF-7 cells was comparable to that of the respective ligand, however lacked towards the leukemic AR-230 cell population. Regarding their cytotoxic potential towards CCL-1 cells, both Cu complexes exhibited a weaker selectivity pattern as compared to their ligands. The proapoptotic and modulatory activity of 1.1 and 2.1. on key kinase signaling pathways was further studied in the ER + breast cancer (MCF-7) and bcr-abl + leukemic (AR-230) in vitro tumor models in a comparative manner to the reference drugs tamoxifen and imatinib, respectively. Inhibition of the JAK/STAT signaling pathway was outlined as a prominent mechanism in the antileukemic activity against the Ph + AR-230 in vitro model, whereas recruitment and activation of the extrinsic apoptotic pathway was established in the MCF-7 cells.

Deciphering the Therapeutic Potential of Novel Pentyloxyamide-Based Class I, IIb HDAC Inhibitors against Therapy-Resistant Leukemia.

Histone deacetylase inhibitors (HDACi) are established anticancer drugs, especially in hematological cancers. This study aimed to design, synthesize, and evaluate a set of HDACi featuring a pentyloxyamide connecting unit linker region and substituted phenylthiazole cap groups. A structural optimization program yielded HDACi with nanomolar inhibitory activity against histone deacetylase class I/IIb enzymes. The novel inhibitors (4d and 4m) showed superior antileukemic activity compared to several approved HDACi. Furthermore, 4d and 4m displayed synergistic activity when combined with chemotherapeutics, decitabine, and clofarabine. In vitro pharmacokinetic studies showed the most promising profile for 4d with intermediate microsomal stability, excellent plasma stability, and concentration-independent plasma protein binding. Additionally, 4d demonstrated comparable in vivo pharmacokinetics to vorinostat. When administered in vivo, 4d effectively inhibited the proliferation of leukemia cells without causing toxicity. Furthermore, the binding modes of 4d and 4m to the catalytic domain 2 of HDAC6 from Danio rerio were determined by X-ray crystallography.

Off-Target Inhibition of Human Dihydroorotate Dehydrogenase (hDHODH) Highlights Challenges in the Development of Fat Mass and Obesity-Associated Protein (FTO) Inhibitors.

FTO, an N 6-methyladenosine (m6A) and N 6,2'-O-dimethyladenosine (m6Am) RNA demethylase, is a promising target for treating acute myeloid leukemia (AML) due to the significant anticancer activity of its inhibitors in preclinical models. Here, we demonstrate that the FTO inhibitor FB23-2 suppresses proliferation across both AML and CML cell lines, irrespective of FTO dependency, indicating an alternative mechanism of action. Metabolomic analysis revealed that FB23-2 induces the accumulation of dihydroorotate (DHO), a key intermediate in pyrimidine nucleotide synthesis catalyzed by human dihydroorotate dehydrogenase (hDHODH). Notably, structural similarities between the catalytic pockets of FTO and hDHODH enabled FB23-2 to inhibit both enzymes. In contrast, the hDHODH-inactive FB23-2 analog, ZLD115, required FTO for its antiproliferative activity. Similarly, the FTO inhibitor CS2 (brequinar), known as one of the most potent hDHODH inhibitors, exhibited FTO-independent antileukemic effects. Uridine supplementation fully rescued leukemia cells from FB23-2 and CS2-induced growth inhibition, but not ZLD115, confirming the inhibition of pyrimidine synthesis as the primary mechanism of action underlying their antileukemic activity. These findings underscore the importance of considering off-target effects on hDHODH in the development of FTO inhibitors to optimize their therapeutic potential and minimize unintended consequences.

Olverembatinib After Failure of Tyrosine Kinase Inhibitors, Including Ponatinib or Asciminib

Patients with chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) resistant or intolerant to BCR-ABL1 tyrosine kinase inhibitors (TKIs) have limited treatment options. Olverembatinib, which is approved in China, has only been tested in Chinese patients. To assess the pharmacokinetics, safety, efficacy, and recommended dose of olverembatinib in patients with CML or Philadelphia chromosome-positive ALL resistant or intolerant to at least 2 TKIs. This multicenter phase 1b randomized clinical trial was conducted from January 28, 2020, to January 2, 2024, with a median (range) follow-up of 48 (0-166) weeks. Patients with CML or Philadelphia chromosome-positive ALL were enrolled. This bridging study was performed in part to confirm that there are no racial differences in the pharmacokinetic profile of olverembatinib. Patients were randomly assigned to 30, 40, or 50 mg of olverembatinib orally every other day in 28-day cycles. Pharmacokinetic profile of olverembatinib. Of 80 included patients, 46 (58%) were male, and the median (range) age was 54.0 (21-80) years. The pharmacokinetic profile of olverembatinib was compatible with alternate-day dosing and similar to that in Chinese patients. Based on investigators' assessments, 60 patients (75%) experienced at least 1 treatment-related adverse event; 32 (40%) experienced grade 3 or higher treatment-related adverse events; and 12 (15%) experienced treatment-related serious adverse events, none of which were fatal. Frequently reported (10% or more) treatment-emergent adverse events included elevated blood creatine phosphokinase (all grades, 31 [39%]; grade 3 or higher, 10 [13%]) and thrombocytopenia (all grades, 23 [29%]; grade 3 or higher, 14 [18%]). Among evaluable patients with chronic-phase CML, complete cytogenetic response (CCyR) occurred in 31 of 51 patients (61%; 95% CI, 46.1-74.2), and major molecular response (MMR) occurred in 25 of 59 patients (42%; 95% CI, 29.6-55.9). Cytogenetic and molecular responses were similar in patients with or without T315I variants. A total of 15 of 26 patients with prior ponatinib treatment (58%; 95% CI, 36.9-76.6) achieved CCyR, and 11 of 30 (37%; 95% CI, 19.9-56.1) achieved MMR. A total of 4 of 8 patients with asciminib resistance (50%; 95% CI, 15.7-84.3) had CCyR, and 4 of 12 (33%; 95% CI, 9.9-65.1) had MMR. The recommended phase 3 dose of olverembatinib is 30 mg every other day in patients without T315I variants. In this trial, olverembatinib had a favorable pharmacokinetic profile, was generally well tolerated, and showed strong antileukemic activity in patients with heavily pretreated chronic-phase CML with or without T315I variants, including prior ponatinib and/or asciminib failure. Olverembatinib may provide a viable new treatment option for patients after failure of 2 or more TKIs. ClinicalTrials.gov Identifier: NCT04260022.

The synthesis and antileukemic activity of 5-substituted thiazolyl urea derivatives

A series of novel 5-substituted thiazolyl urea derivatives were synthesized and evaluated for their efficacy as antileukemic agents against two human leukemic cell lines (THP-1 and MV-4-11). Results showed that the activities of the investigated compounds were quite sensitive to the positions and properties of the aromatic substituents. Among these compounds, compound 12k showed the highest activity with IC50 values of 29 ± 0.3 nM for THP-1 cells and 98 ± 10 nM for MV-4-11 cells.

Identification and characterization of vasoactive intestinal peptide receptor antagonists with high-affinity and potent anti-leukemia activity.

Vasoactive intestinal peptide (VIP) is a neuropeptide involved in tumor growth and immune modulating functions. Previous research indicated that a VIP antagonist (VIPhyb) enhances T-cell activation and induces T-cell-dependent anti-leukemic activity in mice. We created a combinatorial library of VIPhyb C-terminal sequence variations to develop a more potent VIP-receptor (VIP-R) antagonist, hypothesizing that specific amino acid substitutions would improve receptor binding and plasma stability. In silico screening analyses identified sequences with improved docking scores predicting increased binding affinity to human VIP receptors VPAC1 and VPAC2. Fifteen peptides were synthesized and tested for their ability to potentiate activation of purified mouse and human T cells and enhance T cell-dependent anti-leukemia responses in murine models of acute myeloid leukemia. Treating C57Bl/6 mice engrafted with a C1498 myeloid leukemia cell line with daily subcutaneous injections of VIP-R antagonist peptides induced T cell activation resulting in specific anti-leukemia responses. Strikingly, the predicted binding affinity of the VIP-R antagonists to VIP receptors correlated positively with their ability to augment mouse T-cell proliferation and anti-leukemia activity. ANT308 and ANT195 emerged as top candidates due to their high predicted VIP-R binding, low EC 50 for in vitro T cell activation, and potent anti-leukemia activities. ANT308 decreased CREB phosphorylation, a downstream signaling pathway of the VIP receptor, and stimulated granzyme B and perforin expression in CD8+ T cells from AML patients. Combining in silico modeling, in vitro T cell activation properties, and in vivo anti-leukemia activity has identified promising VIP-R antagonist candidates for further development as novel immunotherapies for AML, especially for patients with relapsed disease.

Dnmt3a Mutant Hematopoietic Stem Cells Produce Hyperactive T Cells with Increased Alloimmune and Anti-Leukemic Activity

<i>Dnmt3a</i> Mutant Hematopoietic Stem Cells Produce Hyperactive T Cells with Increased Alloimmune and Anti-Leukemic Activity

Targeting Poly(U) Binding Splicing Factor 60 (PUF60): A Small-Molecule Inhibitor Shows Anti-Leukemic Activity and Impacts Cell Cycle in Leukemia Models

The emerging role of altered RNA splicing in the development of myeloid neoplasms including MDS and AML has received wide attention. Facilitating genes, including the frequently mutated splicing factors, SF3B1, U2AF1, and SRSF2, have been reported to play a key role in leukemogenesis. Pharmacological intervention targeting cells harboring these mutations has been pursued, but limited agents have been reported. Rare events of more than one hit in splicing factors were found in MDS and AML patients' samples. This suggests that inhibiting another target in the splicing process may overcome the threshold of survival in these vulnerable cells carrying splicing factor mutations and induce toxicity. The concept has been demonstrated in the case of leukemia cells carrying U2AF1 mutations being vulnerable to inhibitors modulating wild-type SF3B1 function. The primary function of U2AF1 is to form a complex with U2AF2 for 3‘ splice site (SS) definition in RNA splicing and lower frequency U2AF2 mutations are also detected in MDS patients, underlying the significance of dysfunctional 3‘ SS definition as a potential facilitator of leukemogenesis. Here, we hypothesize that compounds inhibiting proteins participating in 3' SS selection may disrupt isoform patterns in leukemia cells. These agents may act alone or serve as a second hit in the RNA processing to invoke additional vulnerabilities to leukemia cells carrying the most frequent splicing factor mutations. Definition of 3' SS by U2AF2/U2AF1 is mediated by the recognition of the polypyridine tract (PPT) by U2AF2 and the binding of U2AF1 to the conserved AG dinucleotides at the 3' SS. Like U2AF2, PUF60 contains two zinc-finger domains, recognizing the polyuridine tract preceding 3' SS, and a U2 homology motif (UHM) domain that engages in protein-protein interaction with partner proteins including U2AF2, SF1, and SF3B1. Different from the U2AF1/U2AF2 complex, PUF60 does not have a protein domain to bind to the exon intron boundary junction at the 3' SS. PUF60 has been reported to enhance the splicing activity of U2AF1/U2AF2, but also directly regulates alternative splicing of a subset of genes. A recent finding indicated that knockout of PUF60 leads to alternative splicing switching of CDC25 from isoform A to isoform C to induce cell cycle arrest at G2/M in solid tumors. Leukemia patients carrying PUF60 overexpression have also been found to have less progression free survival (https://ualcan.path.uab.edu/cgi-bin/TCGA-survival1.pl?genenam=PUF60&amp;ctype=LAML) compared to patients with low expression of PUF60. To support our hypothesis, we undertook an inhibitor development campaign to discover small-molecule compounds selectively targeting PUF60. Based on a relatively less selective and weak inhibitor to the UHM domain, SF-153, we conducted chemical modifications and obtained a PUF60 inhibitor, SF2-69, with &amp;gt;15-fold selectivity against U2AF1, RBM39, SPF45, and U2AF2. We found SF2-69 had an IC50 value of ~3 mM in NKM-1 and K562 leukemia cell lines. In the cell cycle analysis, we found SF2-69 increased S and subG1 cell population in NKM-1 at 24h, but induced G1 arrest in K562 at 48h in a dose dependent manner. In comparison, E7820, an RBM39 degrader, increased G2/M phase in both NKM-1 and K562. RNA-seq analysis of NKM-1 treated with SF2-69 after 24h revealed that SF2-69 upregulated a set of genes participating in cholesterol biosynthesis, NME1-NME2 (a tumor suppressor kinase) and downregulated PLK1, a kinase that phosphorylates and activates CDC25C in G2/M transition. Because K562 is p53-null and NKM-1 has wild-type p53, SF2-69 likely induced p53-dependent and p53-independent responses in NKM-1 and K562 cells, respectively. In summary, SF2-69 is a new selective PUF60 inhibitor which disrupts cell cycle progression in leukemia cell lines by modulating p53-mediated responses. Upregulation of cholesterol biosynthesis may be a feedback loop to counteract the inhibition of PUF60 by SF2-69. Further optimization of SF2-69 will allow us to develop more effective and selective chemical probes for studying the role of PUF60 overexpression in leukemia and the potential use of PUF60 inhibitors in MDS and AML cells carrying splicing factor mutations.