Acute myeloid leukemia (AML) is an aggressive hematological malignancy with poor survival rates in adults, posing a significant economic burden. FMS-like tyrosine kinase 3 (FLT3) mutations are linked to poor prognosis in AML and resistance to clinically approved FLT3 inhibitors. Previously, we reported a novel benzimidazole-based FLT3 inhibitor, 4ACP, with nanomolar activities against FLT3-ITD and FLT3-TKD mutants, showing selective cytotoxicity against FLT3-ITD+ AML cell lines. In this study, we synthesized 31 derivatives by modifying the 4-acetamidophenyl group and varying substituents at N1-phenyl and C2 positions. We identified compound 21l (3-acetamidophenyl) as the most potent derivative (FLT3-TKD(D835Y) IC50 = 1.47 nM). Linking 21l to a solvent-accessible group yielded compound 22b, which exhibited a sub-nanomolar activity against FLT-TKD(D835Y) mutant with an IC50 value of 0.48 nM. Compound 22b showed preferential antiproliferative activities against MOLM-14, MV4-11, MOLM-14-D835Y, and MOLM-14-F691L AML cell lines with IC50 values of 16.1, 10.5, 26.5, and 160.3 nM, respectively. 22b induced dose-dependent inhibition of FLT3, ERK, STAT5, and S6 phosphorylation, G0/G1 cell-cycle arrest, and apoptotic cell death at low nanomolar concentrations in MOLM-14 and MOLM-14-D835Y cells. It was more selective for FLT3-dependent cell lines, showing about 80-fold selectivity toward FLT3-TKD(D835Y) over KIT, indicating relative safety and lower myelosuppression potential. The molecular dynamics study of 4ACP and 22b was conducted to explain the significant changes in activity resulting from subtle structural alterations. Altogether, these findings establish 22b as a potent mutant FLT3 inhibitor, warranting further investigation and optimization to target resistant AML.
© 2025 Deutsche Pharmazeutische Gesellschaft.

Transforming growth factor beta (TGFβ) and activin A suppress natural killer (NK) cell function and proliferation, limiting the efficacy of adoptive NK cell therapies. Inspired by the partial resistance to TGFβ of NK cells with SMAD4 haploinsufficiency, we used CRISPR-Cas9 for knockout of SMAD4 in human NK cells. Here we show that SMAD4KO NK cells were resistant to TGFβ and activin A inhibition, retaining their cytotoxicity, cytokine secretion and interleukin-2/interleukin-15-driven proliferation. They showed enhanced tumor penetration and tumor growth control, both as monotherapy and in combination with tumor-targeted therapeutic antibodies. Notably, SMAD4KO NK cells outperformed control NK cells treated with a TGFβ inhibitor, underscoring the benefit of maintaining SMAD4-independent TGFβ signaling. SMAD4KO conferred TGFβ resistance across diverse NK cell platforms, including CD19-CAR NK cells, stem cell-derived NK cells and ADAPT-NK cells. These findings position SMAD4 knockout as a versatile and compelling strategy to enhance NK cell antitumor activity, providing a new avenue for improving NK cell-based cancer immunotherapies.
© 2025. The Author(s).

Pancreatic β cells that produce insulin play a significant role in maintaining glucose homeostasis. However, high glucose (HG) causes oxidative stress, which leads to pancreatic β cell dysfunction. The synthesis of lipoic acid (LA) and plumbagin (PLU) conjugate (LA-PLU) was done and characterized using (1H) NMR, (13C) NMR, LC-ESI-MS/MS, and UV-visible spectroscopy techniques. ADME analysis confirmed the drug-like properties of LA-PLU. The present study revealed the protective effect of LA-PLU conjugate against HG (25 mM)-induced oxidative stress on pancreatic β cells. Cell viability was performed on RIN-5F cells and found that LA-PLU exhibits non-toxic up to 91.23 ± 2.61% of cell viability at 12.5 µM concentration. At 12.5 µM, LA-PLU protected pancreatic β cells up to 73.45 ± 3.72% under HG conditions. LA-PLU showed a protective effect on RIN-5F cells against HG-induced DNA damage, followed by preserving mitochondrial membrane potential and decreasing reactive oxygen species formation. Further, LA-PLU showed an anti-apoptotic effect by increasing the Bcl-2 (B cell lymphoma-2) level and decreasing the apoptotic proteins [Bcl-2 associated x (Bax), and cleaved caspase-3). Hence, the overall study concludes that LA-PLU could act as a potent antioxidant that protects the RIN-5F cells under HG conditions, resulting in the maintenance of glucose homeostasis.
© 2025. The Author(s).

Macroautophagy (often-named autophagy), a catabolic process involving autophagy-related (Atg) genes, prevents the accumulation of harmful cytoplasmic components and mobilizes energy reserves in long-lived and self-renewing cells. Autophagy deficiency affects antigen presentation in conventional dendritic cells (DCs) without impacting their survival. However, previous studies did not address epidermal Langerhans cells (LCs). Here, we demonstrate that deletion of either Atg5 or Atg7 in LCs leads to their gradual depletion. ATG5-deficient LCs showed metabolic dysregulation and accumulated neutral lipids. Despite increased mitochondrial respiratory capacity, they were unable to process lipids, eventually leading them to ferroptosis. Finally, metabolically impaired LCs upregulated proinflammatory transcripts and showed decreased expression of neuronal interaction receptors. Altogether, autophagy represents a critical regulator of lipid storage and metabolism in LCs, allowing their maintenance in the epidermis.
© 2024 Arbogast et al.

Stimulator of interferon genes (STING) is a promising antitumor target via bridging innate and adaptive immunity, yet the transient nature of immune signal transduction renders small-molecule agonists susceptible to short time effectiveness. Here, we report a dual-STING-activating micelle system (D-SAM) to dynamically program STING kinetics. Mechanistically, the natural ligand cGAMP encapsulated in D-SAM initiates STING signaling, while the pH-sensitive polymeric agonist PC7A disassembled from micelle shell buffers lysosomal protons and retards STING degradation. This prolonged STING activity facilitates dendritic cell (DC) antigen presentation and extends cytotoxic T lymphocyte priming. D-SAM improves efficacy over single soluble or delivered agonists against established, metastatic, and recurring murine tumors. Specific depletion of STING in DCs or blockade of CD8+ T cell infiltration abrogates therapeutic effects. The feasibility of immune modulation is further validated in resected human patient tissues. This work underscores the temporal rhythm of STING as crucial for mounting a potent and enduring antitumor immune response.
Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.