Human Phospholipase A2 Group V (hPLA2-G5) is elevated in inflammatory conditions and promotes neutrophil and macrophage recruitment. Its enzymatic activity activates lipid receptors and cytosolic phospholipase A2 (cPLA2), leading to arachidonic acid release and PGE2 production─key mediators of chronic inflammation. Thus, hPLA2-G5 represents a promising therapeutic target for diseases with inflammatory pain, such as in endometriosis─a highly debilitating disease characterized by the ectopic growth of endometriotic cells in the abdominal cavity. High-throughput and fragment-based screening identified structurally related small molecule hits. Optimization of the physicochemical and pharmacokinetic properties of the HTS hit led to the identification of BAY-439, a potent and selective hPLA2-G5 inhibitor with single-digit nanomolar activity. Accepted as a donated chemical probe by the Structural Genomics Consortium, both BAY-439 and the inactive negative probe BAY-163 are freely available as valuable pharmacological tools to investigate the role of hPLA2-G5 both under physiological and pathological conditions.

DCAF1 is a donut shaped WD40 repeat protein and a substrate receptor of two distinct E3 ligases. In HIV-1 infection, the viral protein Vpr binds to the top surface of DCAF1, changes its substrate specificity to degrade human proteins involved in antiviral activities, enabling HIV-1 to replicate. We hypothesized that artificial top-to-top self-dimerization of DCAF1 could result in DCAF1 loss-of-function and blocking of the Vpr-DCAF1 interaction. We designed and synthesized seven compounds we call SDIPTACs (Self-dimerization Induced Proximity Targeting Chimeras) which artificially induce DCAF1 self-dimerization through the Vpr interaction surface. Interestingly, SDIPTACs C8 and C9, inhibited Vpr-dependent HIV replication in CD4+ T cells. Biophysical data and crystal structures of four DCAF1-SDIPTAC-DCAF1 ternary complexes revealed more details on DCAF1-DCAF1 complex stability, conformation, and their contribution to compound efficacy. Using SDIPTACs with unique mechanism may therefore be an efficient strategy in the development of future therapeutics for HIV infection and other diseases.

Antibody-drug conjugates have transformed the treatment of cancer, yet their clinical utility can be limited by suboptimal tumor penetration, complex manufacturing, and safety concerns. Replacing antibodies with low-molecular-weight ligands enables the generation of small molecule-drug conjugates with enhanced tumor-targeting performance. Here, we report the results of a proof-of-concept study in canine cancer patients with OncoFAP glidotin, a small molecule-based targeted cytotoxic directed against Fibroblast Activation Protein. OncoFAP glidotin was evaluated in a dose-escalation trial in eight client-owned pet dogs bearing spontaneous FAP-positive tumors. The agent displayed an excellent safety profile, with no severe treatment-related adverse events. Six (75%) patients responded to the therapy. A tumor volume reduction of up to ∼88% in target lesions was observed on whole-body computed tomography, after only 4 weeks of treatment. These findings support further translational development activities of OncoFAP glidotin for both human and veterinary cancer patients.

Functionalizing anticancer drugs with activatable peptides offers a versatile strategy to achieve tumor-selective delivery while minimizing systemic toxicity. Here, we report a γ-glutamyltransferase (GGT)-responsive cell-penetrating peptide (P-EE) generated by γ-glutamyl masking of penetratin for tumor-selective activation in hepatocellular carcinoma. Upon GGT-mediated cleavage, P-EE restores its cationic charge and helical conformation, enabling efficient membrane translocation and selective accumulation in GGT-overexpressing tumor cells. P-EE showed enhanced internalization and approximately 5-fold higher cytotoxic potency in HepG2 cells compared with NHDF normal cells. Covalent conjugation of camptothecin (CPT) to P-EE yielded a peptide-drug conjugate (CPT-P-EE) with greatly improved aqueous solubility, potent antitumor activity, and over 50-fold reduced toxicity to normal cells. In vivo, CPT-P-EE significantly suppressed tumor growth and prolonged survival without inducing systemic toxicity. This study establishes a generalizable enzyme-activatable peptide-drug conjugate platform that integrates conformational switching with targeted delivery, offering a promising direction for precision chemotherapy against GGT-positive malignancies.

The talin2-β-integrin interaction modulates focal adhesion dynamics, promoting tumor cell migration and invasion, and thus represents an attractive anticancer target. Here, we identified the first talin2-β-integrin peptide inhibitor using structure-based virtual screening. Peptide-2 exhibited nanomolar binding affinity for talin2 (Kd = 8.05 ± 0.17 nM) and favorable in vitro selective inhibition. Molecular dynamics (MD) simulations indicated that Peptide-2 binds stably to talin2. Further studies showed that Peptide-2 significantly suppressed the proliferation, migration, and invasion of MDA-MB-231 cells as well as tube formation in HUVECs, with no significant toxicity toward normal cells. It inhibited FAK phosphorylation at Y397 and Y576, and displayed good cellular uptake and cytoplasmic localization. Moreover, Peptide-2 showed strong in vivo antitumor activity without obvious toxicity. Peptide-2 exhibited favorable in vitro serum stability and in vivo pharmacokinetic characteristics. In conclusion, Peptide-2 is a novel inhibitor that offers a potential new strategy for breast cancer therapy.

Developing targeted antitumor agents with minimal systemic toxicity is highly desirable. Exatecan, a potent camptothecin derivative, is clinically restricted due to its toxicity and limited efficacy. Targeting the tumor-enriched enzyme AKR1C3 enables selective drug activation. We designed two novel AKR1C3-responsive Exatecan conjugates, EP-1 and EP-2, with a fluorescence-quenched module for real-time "turn-on" tracking of drug release. The conjugates exhibited potent cytotoxicity in AKR1C3-high cancer cells (IC50: 7.7 ± 0.2 nM for EP-1, 4.6 ± 0.4 nM for EP-2), similar to Exatecan, but markedly reduced toxicity in AKR1C3-low and normal cells, and overcame sorafenib resistance. Cellular and zebrafish imaging confirmed a targeted release. In a mouse model, EP-2 displayed potent efficacy with significantly reduced systemic toxicity (MTD > 60 mg/kg) compared to Exatecan. These results nominate EP-2 as an ideal candidate for selective and safe tumor therapy, providing a new paradigm for biomarker-driven antitumor drug design.

Inhibitors of the 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), an enzyme of the nonmevalonate pathway, represent a promising class of antiplasmodial compounds, as DXR is essential for human pathogens but absent in their host. The natural product fosmidomycin was the first clinical DXR inhibitor, however high rates of recrudescence attributed to the polar phosphonic acid group have prevented progression beyond phase II clinical trials. Herein, lipophilic N-benzamidoalkyl and N-phthalimidoalkyl substituents were introduced into reverse α-phenyl fosmidomycin derivatives to mimic the nicotinamide moiety of the NADPH cofactor and enhance antiplasmodial activity. Elongation of the alkyl linker markedly improved enzymatic inhibition (15e PfDXR IC50 = 4.3 nM) and antiplasmodial activity (16e PfDd2 IC50 = 0.28 μM). Mode of inhibition studies showed competitive inhibition with the DXR substrate and the cofactor NADPH (16e Ki = 0.068 μM). Co-crystallization with the PfDXR enzyme revealed that the introduced residues bind within the NADPH binding site.

Drug-resistant Neisseria gonorrheae is becoming an increasingly concerning threat as cases continue to rise, highlighting the need for novel therapeutics. We, therefore, have further developed our previously established structure-activity relationship for derivatives of acetazolamide, an FDA-approved carbonic anhydrase inhibitor. A large cohort of acetazolamide-based analogs was investigated for their activity against N. gonorrheae and their binding to NgCAs. Lead compounds were carried forward for in vitro ADME evaluation before prioritizing two molecules, 18 and 33, for in vivo PK analysis. These compounds were orally bioavailable and metabolically stable, and exhibited low cytotoxicity against mammalian cell lines. When investigated for in vivo efficacy in an infected mouse model, 18 was found to significantly decrease gonococcal bioburden compared with the vehicle control. Our studies culminated in the finding that acetazolamide-based compounds can be developed as effective drugs against N. gonorrheae and may be an answer in the search for new therapeutics.

Deubiquitinase-targeting chimera (DUBTAC) has recently emerged as a promising technology for inducing targeted protein stabilization (TPS). DUBTACs are heterobifunctional molecules that recruit deubiquitinases (DUBs) to induce deubiquitination and stabilization of target proteins. However, DUBTAC development has been hindered by the scarcity of DUB ligands. In this study, we report the discovery of novel covalent ligands of the OTUB1 DUB through structure-activity relationship (SAR) studies of the previously reported OTUB1 ligand EN523. Our lead compound 34 (MS8572), which features a new heterocyclic core, covalently modified OTUB1 faster and more effectively, while also displaying enhanced stability and aqueous solubility compared to EN523. Furthermore, 34 was selective for OTUB1 over several cysteine-containing proteins and did not inhibit the OTUB1 deubiquitinase activity. Lastly, by utilizing 34, we developed an effective CFTR DUBTAC. Overall, we developed new and improved OTUB1 covalent ligands, expanding the limited number of DUB ligands that can be harnessed for TPS.