Acyldepsipeptides (ADEPs) are potent ClpP dysregulators that are active against a range of Gram-positive bacteria, but have limited potency against Mycobacterium tuberculosis (Mtb). To address potency, we employed a strategy of macrocycle rigidification and side-chain optimization enabled by a novel solid-phase peptide synthesis route. Among 35 compounds synthesized, ADEP 19 was as much as 12-fold more potent against Mtb and other bacteria than ADEP 4, the prototypical ADEP having efficacy in animal infection models. Biophysical, enzymatic, crystallographic, and microbiological studies showed that conformational restriction of both the macrocycle and side chain enhanced ClpP1P2 binding affinity and antibacterial potency. Our observation that ADEP 19 caused a reduction in intracellular ATP in Mtb suggested potential synergy of ADEPs with bedaquiline (BDQ), a tuberculosis drug that inhibits ATP synthesis. Checkerboard assays and experiments in a zebrafish TB model affirmed synergy between ADEP 19 and BDQ that could be leveraged to address BDQ-associated cardiotoxicity.

Targeted radionuclide therapy (TRT) is a promising strategy for precision oncology but is limited by the lack of high-performance targeting ligands. Here, we report a lutetium-177 (177Lu)-labeled PTK7-targeted cyclized bivalent aptamer (CBSgc8) for treating an orthotopic hepatoblastoma. The cyclized multivalent design enhances biostability and binding affinity, while 177Lu labeling preserves its functional properties. The resulting 177Lu-CBSgc8 exhibited high serum stability, strong specificity for PTK7-positive cells, efficient internalization, and dose-dependent cytotoxicity in vitro. In vivo, 177Lu-CBSgc8 inhibited tumor growth in an OVCAR3 ovarian cancer model, although tumor accumulation remained limited. Given its PTK7-targeting capability and preferential hepatic distribution, we further evaluated its therapeutic potential in an orthotopic HepG2 hepatoblastoma model. In this setting, 177Lu-CBSgc8 achieved 76.6% tumor growth inhibition with a favorable safety. These findings demonstrate the potential of exploiting tissue distribution characteristics together with molecular targeting to expand the applicability of aptamer-based TRTs.

Dual inhibition of the histamine H1 and H4 receptors (H1R and H4R) has been shown to provide superior anti-inflammatory efficacy in preclinical models of allergic disease compared to selective inhibition of either receptor alone. Building on this concept, we initiated a fragment-based discovery program and previously identified a quinazoline-containing fragment hit. Here, we describe the lead optimization toward compounds with unique dual H1R/H4R activity. Structure-activity relationship studies yielded potent and balanced ligands with nanomolar affinities for both receptors, as well as pharmacokinetic properties suitable for ocular administration. Among these, quinazoline 35.HCl (GD136) and tetrahydroquinazoline 72.HCl (GD134) demonstrate robust in vivo efficacy in a ragweed-induced mouse model of allergic conjunctivitis, significantly reducing hyperemia and outperforming selective H1R or H4R antagonists. Based on its pharmacological profile, ADME properties, ease of formulation, and in vivo efficacy, GD134 was selected as the clinical development candidate for a first-in-class dual-targeted therapy of allergic conjunctivitis.

We report a family of tethered rhodium(III) complexes of formula [Rh(η5:κ1-C5Me4(CH2)npyN)(C,N)]+ (n = 1 or 2; C,N = 2-phenylpyridine or benzoquinoline), their nontethered analogues, and their iridium(III) counterparts. The tethered pyridine, κ1-coordinated to the metal, does not dissociate in water, yet the metal-Npy(tether) bond can be cleaved by strong nucleophiles, enabling metal activation. We corroborated that metal-Z bond reactivity correlated with cytotoxicity in breast cancer cells; complexes lacking reactive metal-Z bonds exhibited low anticancer potency, while excessive reactivity impaired efficacy likely through off-target reactions. For the highly potent tethered complexes, we determined the kinetics of pyridine cleavage using DMSO and confirmed that N-acetylcysteine can also promote pyridine dissociation. In tethered complexes, metal-mediated reactivity is crucial to potency, as metal-pyridine bonds with higher activation energy produce complexes less damaging to cells. We confirmed mitochondrial involvement in cell death, demonstrating that the most cytotoxic complexes inhibit OXPHOS more efficiently.

Targeting the NLRP3 inflammasome is critical for treating fibrotic diseases; however, current NACHT domain inhibitors face mutational escape and limited isoform specificity. The autoinhibitory leucine-rich repeat (LRR) domain represents an underexplored pharmacological target. Here, we report QX-31, a novel covalent probe selectively engaging the LRR domain. QX-31 covalently binds to Cysteine 838, stabilizing NLRP3 in an inactive conformation and preventing inflammasome assembly with high selectivity over AIM2 and NLRC4. Furthermore, QX-31 reverses maladaptive immunometabolic reprogramming within the renal microenvironment by blunting the PI3K/AKT/HIF-1α axis, suppressing aberrant glycolysis and glutaminolysis. Evaluated in human kidney organoids and murine models of renal injury (UUO and IRI), QX-31 demonstrated potent antifibrotic efficacy comparable to reference drugs, alongside a favorable safety profile. Collectively, QX-31 serves as a valuable chemical tool, demonstrating that covalent targeting of this conformational regulatory domain is a viable therapeutic strategy for fibrotic diseases.

Starting from our internally discovered, potent panKRAS inhibitor BRSD-143 (1), we executed a targeted bioisosteric optimization of the naphthol and fluoropyrrolizidine motifs to preserve (or increase) KRAS pan-inhibitory potency while improving DMPK/ADME liabilities. These studies delivered 12 (BRSD-212), a highly potent and efficacious lead in which (2-azabicyclo[4.2.0]octan-6-yl)methanol (ABO) serves as a bioisostere for the widely deployed 2-fluoropyrrolizidine substituent. In parallel, replacement of the naphthol moiety with an indazole afforded 21, which demonstrated improved pharmacokinetic performance and ADME characteristics by mitigating glucuronidation-mediated clearance as the dominant metabolic pathway.

Xinyne, a diaryl-N-methylamine analogue of isoCombretastatin A-4 was synthesized via a late-stage Cl-exchange using KCN. Xinyne exhibited potent antiproliferative activity at nanomolar concentrations against various human cancer cell lines, inhibited tubulin polymerization, induced apoptosis, and induced G2/M phase cell cycle arrest in 4T1 cells. To investigate its in vivo behavior, radiolabeled [14C]-Xinyne was prepared using [14C]-KCN. Pharmacokinetic analysis revealed significant sex-based differences: males showed faster absorption and more efficient elimination, whereas females exhibited broader tissue distribution and slower clearance. A biodistribution study demonstrated preferential accumulation of [14C]-Xinyne in the liver and the small intestine, with larger elimination through feces. Finally, the antitumor efficacy of Xinyne was confirmed in a murine breast cancer model.

Adenosine is an essential signaling molecule with a well-recognized role in the central nervous, cardiovascular, and immune systems. Its immunosuppressive effects have gained significant attention in oncology, as adenosine accumulation within the tumor microenvironment can profoundly inhibit antitumor immunity. Therapeutic strategies to counteract this pathway include inhibiting adenosine-generating enzymes CD39 and CD73 or blocking adenosine A2A and A2B receptors. In this study, we report the development of compound 45, a novel imidazopyrazine derivative acting as a long-lasting, dual A2A/A2B receptor antagonist with nanomolar in vitro potency. This compound exhibits extended receptor residence time and maintains dual antagonistic activity even at high micromolar adenosine levels. Compound 45 demonstrates favorable ADME characteristics as well as pharmacokinetic properties, providing high oral bioavailability and systemic exposure across multiple preclinical species. In efficacy studies, this agent robustly reduced metastatic burden in a murine MCA205 pulmonary metastasis model.

Positive allosteric modulators (PAMs) of the delta-opioid receptor (DOR) enhance endogenous opioid signaling while avoiding the convulsant liability of orthosteric agonists. However, the prototypical DOR-PAM, BMS-986187, also potentiates mu-opioid receptor (MOR) signaling, raising concerns regarding respiratory depression and abuse liability. Here, we report a structure-activity study of the benzyloxy moiety of BMS-986187 to improve selectivity for DOR over MOR, while retaining DOR-PAM potency. Fifty-two new analogues and 12 previously reported ones featuring mono- and disubstitution of the benzyl ring and phenyl-heterocycle replacements were synthesized and evaluated in β-arrestin2 recruitment assays. Ortho-substituted derivatives consistently enhanced DOR-PAM potency, although often increased MOR-PAM activity. One pyridyl derivative (compound 35) retained high DOR-PAM potency and efficacy (EC50 = 0.1 μM, Emax = 91%) with no detectable MOR activity. In mice, compound 35 enhanced DOR-mediated reversal of nitroglycerin-induced hyperalgesia, an effect absent in DOR-knockout mice, without enhancing MOR-mediated antinociception, demonstrating in vivo selectivity.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a promising target for atopic dermatitis due to its role in skin barrier repair, yet effective modulators of Nrf2 are lacking. Here, we report an itaconate-iridium(III) complex conjugation strategy for the disruption of the Keap1-Nrf2 protein-protein interaction (PPI) for treating atopic dermatitis. The conjugate (1) specifically engages cytoplasmic Keap1 to restore Nrf2 activity, thus upregulating anti-inflammatory genes HO-1 and NQO1 while suppressing reactive oxygen species (ROS) in keratinocytes. It also reduces IL-13 production and boosts skin barrier proteins filaggrin and involucrin in a reconstructed human epidermis (RHE) model. In vivo studies revealed that compound 1 ameliorated DNFB-induced atopic dermatitis-like lesions and hypersensitivity. Its optical characteristics further enabled the flow cytometric discrimination of HaCaT cells based on Keap1 levels. This work provides a promising strategy for developing bioactive molecules to efficiently disrupt subcellular PPIs, laying the basis to progress theranostic candidates for atopic dermatitis.

Chikungunya virus (CHIKV), an arthropod-borne alphavirus, has emerged as a global health threat due to its rapid transmission and the lack of effective antiviral therapies. The cysteine protease activity of the virus-encoded nonstructural protein 2 (nsP2) is critical for CHIKV replication, as it processes viral polyproteins and counteracts host antiviral defenses, establishing it as a highly attractive target for therapeutic intervention. In this study, we present a rapid drug development platform that integrates covalent docking with direct-to-biology (D2B) synthesis and screening to identify nsP2 inhibitors. Candidates prioritized by in silico docking were synthesized and directly tested in FRET enzymatic assays without purification. This approach led to the identification of several nsP2 inhibitors with diverse chemical scaffolds, potent enzymatic inhibition, and antiviral activity. Together, these findings establish a streamlined strategy for covalent inhibitor development and provide promising leads for CHIKV antiviral development.

Programmed death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) represents a critical immune checkpoint in cancer immunotherapy; however, most small-molecule PD-1/PD-L1 inhibitors suffer from poor aqueous solubility. Here, we designed a series of quaternary ammonium-based PD-1/PD-L1 inhibitors. Among them, QA9 exhibited potent PD-1/PD-L1 inhibition (IC50 = 18.7 nM), outperforming the lead compound NP19, and demonstrated a 600-fold improvement in water solubility (0.642 vs 0.001 mg/mL). X-ray crystallography revealed that QA9 stabilizes the PD-L1 dimer through multiple interactions, providing a structural basis for its high affinity. In MC38/Jurkat and HCT116/Jurkat coculture models, QA9 enhanced immune-mediated tumor cell death. Additionally, QA9 suppressed VEGF-A-induced tube formation and migration in HUVECs, which was associated with reduced FAK phosphorylation. Furthermore, in an MC38 mouse colon cancer model, QA9 showed robust antitumor activity without overt toxicity. Collectively, the quaternary ammonium strategy represents an effective approach to developing water-soluble PD-1/PD-L1 inhibitors with dual immunomodulatory and antiangiogenic functions.