Marine Cytotoxin Santacruzamate A Derivatives as Potent HDAC1-3 Inhibitors and Their Synergistic Anti-Leukemia Effects with Venetoclax.

Acute myeloid leukemia (AML) is a hematologic malignancy characterized by infiltration of the blood and bone marrow, exhibiting a low remission rate and high recurrence rate. Current research has demonstrated that class I HDAC inhibitors can downregulate anti-apoptotic proteins, leading to apoptosis of AML cells. In the present investigation, we conducted structural modifications of marine cytotoxin Santacruzamate A (SCA), a compound known for its inhibitory activity towards HDACs, resulting in the development of a novel series of potent class I HDACs hydrazide inhibitors. Representative hydrazide-based compound 25c exhibited concentration-dependent induction of apoptosis in AML cells as a single agent. Moreover, 25c exhibited a synergistic anti-AML effect when combined with Venetoclax, a clinical Bcl-2 inhibitor employed in AML therapy. This combination resulted in a more pronounced downregulation of anti-apoptotic proteins Mcl-1 and Bcl-xL, along with a significant upregulation of the pro-apoptotic protein cleaved-caspase3 and the DNA double-strand break biomarker γ-H2AX compared to monotherapy. These results highlighted the potential of 25c as a promising lead compound for AML treatment, particularly when used in combination with Venetoclax.

Discovery of Novel 2,3-Dihydro-1H-indene-5-sulfonamide NLRP3 Inflammasome Inhibitors Targeting Colon as a Potential Therapy for Colitis.

The NLRP3 inflammasome is a multiprotein complex that plays a crucial role in the pathophysiology of multiple inflammation-related diseases. In this study, we designed and synthesized a series of novel 2,3-dihydro-1H-indene-5-sulfonamide analogues as NLRP3 inflammasome inhibitors, and then identified compound 15z as a potent and specific inhibitor (IC50: 0.13 µM) with low toxicity. Mechanistic studies indicate that 15z binds directly to NLRP3 protein (KD: 102.7 nM), blocking the assembly and activation of the NLRP3 inflammasome and effectively inhibiting cell pyroptosis. Given the notable distribution of 15z in the colon, the DSS-induced colitis model was employed to evaluate its in vivo effectiveness. 15z significantly impacted NLRP3 inflammasome activation and relieved inflammatory bowel disease symptoms in this model. Acute and subacute toxicity studies suggested that 15z has a favorable safety profile. Our results indicate that 15z has great potential to be further developed as a candidate for the treatment of inflammatory bowel disease.

Discovery of a Novel Ubenimex Derivative as a First-in-Class Dual CD13/Proteasome Inhibitor for the Treatment of Cancer.

The CD13 inhibitor ubenimex is used as an adjuvant drug with chemotherapy for the treatment of cancer due to its function as an immunoenhancer, but it has limitations in its cytotoxic efficacy. The proteasome inhibitor ixazomib is a landmark drug in the treatment of multiple myeloma with a high anti-cancer activity. Herein, we conjugated the pharmacophore of ubenimex and the boric acid of ixazomib to obtain a dual CD13 and proteasome inhibitor 7 (BC-05). BC-05 exhibited potent inhibitory activity on both human CD13 (IC50 = 0.13 µM) and the 20S proteasome (IC50 = 1.39 µM). Although BC-05 displayed lower anti-proliferative activity than that of ixazomib in vitro, an advantage was established in the in vivo anti-cancer efficacy and prolongation of survival time, which may be due to its anti-metastatic and immune-stimulating activity. A pharmacokinetic study revealed that BC-05 is a potentially orally active agent with an F% value of 24.9%. Moreover, BC-05 showed more favorable safety profiles than those of ixazomib in preliminary toxicity studies. Overall, the results indicate that BC-05 is a promising drug candidate for the treatment of multiple myeloma.

Design, synthesis, and biological evaluation of novel HDAC/CD13 dual inhibitors for the treatment of cancer.

Aminopeptidase N (APN/CD13) plays a role in tumors progression, but its inhibitor lacks cytotoxicity and is used as an adjuvant drug in cancer treatment. Histone deacetylases (HDACs) are a type of epigenetic targets, and HDAC inhibitors are cytotoxic and exhibit synergistic effects with other anticancer agents. Herein, a novel series of HDAC/CD13 dual inhibitors were rationally designed and synthesized to combine the anti-metastasis and anti-invasion of CD13 inhibitor with the cytotoxic of HDAC inhibitor. The representative compound 12 exhibited more potent inhibitory activity against human CD13, HDAC1-3, and antiproliferative activity than positive controls bestatin and SAHA. Compound 12 effectively induced apoptosis in MV4-11 cells, while arresting A549 cells in G2/M phase. Moreover, 12 exhibited significantly better anti-metastasis and anti-invasion effects than mono-inhibitors 32 and 38, indicating that it is a promising anti-cancer agent for further investigation.

Potent Hydrazide-Based HDAC Inhibitors with a Superior Pharmacokinetic Profile for Efficient Treatment of Acute Myeloid Leukemia In Vivo.

As "Michael acceptors" may induce promiscuous responses in mammalian cells by reacting with various proteins, we modified the cinnamamide of our previous hydrazide-based HDAC inhibitors (HDACIs) to deactivate the Michael reaction. Representative compound 11h is 2-5 times more potent than lead compound 17 in both HDAC inhibitory activity (IC50 = 0.43-3.01 nM) and cell-based antitumor assay (IC50 = 19.23-61.04 nM). The breakthrough in the pharmacokinetic profile of 11h (oral bioavailability: 112%) makes it a lead-in-class oral active agent, validated in the in vivo anti-AML study (4 mg/kg p.o., TGI = 78.9%). Accumulated AcHH3 and AcHH4 levels in tumor tissue directly correlate with the in vivo efficacy, as panobinostat with lower AcHH3 and AcHH4 levels than 11h displays limited activity. To the best of our knowledge, this work contributes the first report of in vivo antitumor activity of hydrazide-based HDACIs. The outstanding pharmacokinetic/pharmacodynamic and antitumor activity of 11h could potentially extend the clinical application of current HDACIs.

Design of Hydrazide-Bearing HDACIs Based on Panobinostat and Their p53 and FLT3-ITD Dependency in Antileukemia Activity.

Here, we present a new series of hydrazide-bearing class I selective HDAC inhibitors designed based on panobinostat. The cap, linker, and zinc-binding group were derivatized to improve HDAC affinity and antileukemia efficacy. Lead inhibitor 13a shows picomolar or low nanomolar IC50 values against HDAC1 and HDAC3 and exhibits differential toxicity profiles toward multiple cancer cells with different FLT3 and p53 statuses. 13a indirectly inhibits the FLT3 signaling pathway and down-regulates master antiapoptotic proteins, resulting in the activation of pro-caspase3 in wt-p53 FLT3-ITD MV4-11 cells. While in the wt-FLT3 and p53-null cells, 13a is incapable of causing apoptosis at a therapeutic concentration. The MDM2 antagonist and the proteasome inhibitor promote 13a-triggered apoptosis by preventing p53 degradation. Furthermore, we demonstrate that apoptosis rather than autophagy is the key contributing factor for 13a-triggered cell death. When compared to panobinostat, 13a is not mutagenic and displays superior in vivo bioavailability and a higher AUC0-inf value.