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The interest in galectin-3 as a drug target in the cancer and fibrosis space has grown during the past few years with several new classes of compounds being developed. The first orally available galectin-3 inhibitor, GB1211 (h-galectin-3 K d = 0.025 μM), is currently in phase 2 clinical trials. Due to structural differences between human and mouse galectin-3 a significant reduction in mouse galectin-3 affinity is observed for most highly potent human galectin-3 inhibitors including GB1211 (m-galectin-3 K d = 0.77 μM). Pharmacokinetic experiments in mouse dosing GB1211 up to 100 mg/kg results in free plasma levels below m-galectin-3 K d , which is not comparable to the data observed in humans. To better support translation into clinical studies, a new improved mouse galectin-3 tool compound, GB2095 , was developed. Dosing this new compound in in vivo syngeneic mouse models of cancer resulted in reduction of the growth of breast and melanoma cancers.

Background and Purpose: Galectin-3 (Gal-3) is a pro-fibrotic β-galactoside binding lectin highly expressed in fibrotic liver and implicated in hepatic fibrosis. GB1107 is a novel orally active Gal-3 small molecule inhibitor that has high affinity for Gal-3 >1000-fold selectively over other galectins. The aim of this study was to characterise GB1107 and galectin-3 in vitro and in vivo in the context of fibrosis signalling and liver disease., Experimental Approach: Liver fibrosis was induced by administration of CCl 4 twice weekly by intraperitoneal injection in mice for 8 weeks. GB1107 was orally administered once daily (10 mg/kg) for the last 4 weeks of CCl 4 treatment. Fibrosis was assessed by picrosirius red staining of FFPE sections. Liver enzymes, Gal-3 and downstream biomarkers were assessed in liver and plasma. Paired-end sequencing was performed on the Nextseq 2000 platform. Pathway enrichment analysis was performed to determine enrichment of differentially expressed genes (DEGs) within Reactome pathways and Gene Ontology (GO) terms., Key Results: GB1107 significantly reduced plasma transaminases and liver Gal-3 and reduced liver fibrosis. RNAseq analysis of whole liver showed that 1659 DEGs were identified with CCl 4 treatment compared to control. Pathways enriched in up-regulated genes in the CCl 4 group included those related to the extracellular matrix, collagen biosynthesis and assembly, cell cycle and the immune system. Comparing GB1107 treatment with CCl 4 control 1147 DEGs were identified. GB1107 effectively reversed the majority of the CCl 4 induced gene changes., Conclusions and Implications: GB1107 attenuated liver fibrosis and highlights Gal-3 as a therapeutic target for hepatic fibrosis., Competing Interests: Declaration of competing interest Conflict of interest disclosure: DH, JR, IH, JM, RJS, ACM, AP, FZ, HS: employees, personal fees – Galecto Biotech AB, UJN, HL: shareholders, personal fees – Galecto Biotech AB., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background and Objectives: Selvigaltin (GB1211), an orally available small molecule galectin-3 inhibitor developed as a treatment for liver fibrosis and cirrhosis, was evaluated to assess the effect of hepatic impairment on its pharmacokinetics and safety to address regulatory requirements., Methods: GULLIVER-2 was a Phase Ib/IIa three-part study. Parts 1 and 3 had single-dose, open-label designs assessing pharmacokinetics (plasma [total and unbound] and urine), safety, and tolerability of 100 mg oral selvigaltin in participants with moderate (Child-Pugh B, Part 1) or severe (Child-Pugh C, Part 3) hepatic impairment, compared with healthy-matched participants (n = 6 each)., Results: All participants received selvigaltin and completed the study. No adverse events were reported. The median time to reach maximum total plasma concentration following drug administration was of 3.49 and 4.00 h post-dose for Child-Pugh B and C participants, respectively; comparable with controls. Total plasma exposure was higher for participants with hepatic impairment compared with controls. Whilst maximum plasma concentration (C max ) was unaffected in Child-Pugh B participants, area under the plasma concentration-time curve from time zero to infinity (AUC ∞ ) increased by ~ 1.7-fold compared with controls, and half-life was prolonged (geometric mean 28.15 vs 16.38 h). In Child-Pugh C participants, C max increased by ~ 1.3-fold, AUC ∞ increased by ~ 1.5-fold, and half-life was prolonged (21.05 vs 16.14 h). No trend was observed in plasma unbound fractions or urinary excretion of unchanged selvigaltin in either group., Conclusion: Hepatic impairment increased selvigaltin exposure without safety concerns. These data can inform dose recommendations for future clinical programmes., Trial Registration: Clinicaltrials.gov NCT05009680., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Integrin-mediated activation of the profibrotic mediator transforming growth factor-β1 (TGF-β1), plays a critical role in idiopathic pulmonary fibrosis (IPF) pathogenesis. Galectin-3 is believed to contribute to the pathological wound healing seen in IPF, although its mechanism of action is not precisely defined. We hypothesized that galectin-3 potentiates TGF-β1 activation and/or signaling in the lung to promote fibrogenesis. We show that galectin-3 induces TGF-β1 activation in human lung fibroblasts (HLFs) and specifically that extracellular galectin-3 promotes oleoyl-L-α-lysophosphatidic acid sodium salt-induced integrin-mediated TGF-β1 activation. Surface plasmon resonance analysis confirmed that galectin-3 binds to αv integrins, αvβ1, αvβ5, and αvβ6, and to the TGFβRII subunit in a glycosylation-dependent manner. This binding is heterogeneous and not a 1:1 binding stoichiometry. Binding interactions were blocked by small molecule inhibitors of galectin-3, which target the carbohydrate recognition domain. Galectin-3 binding to β1 integrin was validated in vitro by coimmunoprecipitation in HLFs. Proximity ligation assays indicated that galectin-3 and β1 integrin colocalize closely (≤40 nm) on the cell surface and that colocalization is increased by TGF-β1 treatment and blocked by galectin-3 inhibitors. In the absence of TGF-β1 stimulation, colocalization was detectable only in HLFs from IPF patients, suggesting the proteins are inherently more closely associated in the disease state. Galectin-3 inhibitor treatment of precision cut lung slices from IPF patients' reduced Col1a1, TIMP1, and hyaluronan secretion to a similar degree as TGF-β type I receptor inhibitor. These data suggest that galectin-3 promotes TGF-β1 signaling and may induce fibrogenesis by interacting directly with components of the TGF-β1 signaling cascade., Competing Interests: Conflict of interests R. G. J. is a trustee for Action for Pulmonary Fibrosis. A. E. J. is a founder and shareholder of Alevin Therapeutics. J. F. C., F. R. Z., A. C. M., and R. J. S. are Galecto employees with shares/options in the company. N. R. P. is a Roche employee. L. A. B. is a director and shareholder of FibroFind. G. H., R. M. L., P. S., S. B. C., D. J. S., and I. D. S. declare that they have no conflict of interests with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

A new series of orally available α-d-galactopyranosides with high affinity and specificity toward galectin-1 have been discovered. High affinity and specificity were achieved by changing six-membered aryl-triazolyl substituents in a series of recently published galectin-3-selective α-d-thiogalactosides (e.g., GB1107 K d galectin-1/3 3.7/0.037 μM) for five-membered heterocycles such as thiazoles. The in vitro pharmacokinetic properties were optimized, resulting in several galectin-1 inhibitors with favorable properties. One compound, GB1490 ( K d galectin-1/3 0.4/2.7 μM), was selected for further characterization toward a panel of galectins showing a selectivity of 6- to 320-fold dependent on galectin. The X-ray structure of GB1490 bound to galectin-1 reveals the compound bound in a single conformation in the carbohydrate binding site. GB1490 was shown to reverse galectin-1-induced apoptosis of Jurkat cells at low μM concentrations. No cell cytotoxicity was observed for GB1490 up to 90 μM in the A549 cells. In pharmacokinetic studies in mice, GB1490 showed high oral bioavailability ( F % > 99%).

Background: Galectin-3 (Gal-3) is a β-galactoside-binding lectin that is highly expressed within the tumor microenvironment of aggressive cancers and has been suggested to predict a poor response to immune checkpoint therapy with the anti-PD-1 monoclonal antibody pembrolizumab. We aimed to assess if the effect of Gal-3 was a result of direct interaction with the immune checkpoint receptor., Methods: The ability of Gal-3 to interact with the PD-1/PD-L1 complex in the absence and presence of blocking antibodies was assessed in in vitro biochemical and cellular assays as well as in an in vivo syngeneic mouse cancer model., Results: Gal-3 reduced the binding of the checkpoint inhibitors pembrolizumab (anti-PD-1) and atezolizumab (anti-PD-L1), by potentiating the interaction between the PD-1/PD-L1 complex. In the presence of a highly selective Gal-3 small molecule inhibitor (GB1211) the binding of the anti-PD-1/anti-PD-L1 therapeutics was restored to control levels. This was observed in both a surface plasmon resonance assay measuring protein-protein interactions and via flow cytometry. Combination therapy with GB1211 and an anti-PD-L1 blocking antibody reduced tumor growth in an in vivo syngeneic model and increased the percentage of tumor infiltrating T lymphocytes., Conclusion: Our study suggests that Gal-3 can potentiate the PD-1/PD-L1 immune axis and potentially contribute to the immunosuppressive signalling mechanisms within the tumor microenvironment. In addition, Gal-3 prevents atezolizumab and pembrolizumab target engagement with their respective immune checkpoint receptors. Reversal of this effect with the clinical candidate GB1211 offers a potential enhancing combination therapeutic with anti-PD-1 and -PD-L1 blocking antibodies., Competing Interests: UN, FZ, RS, JR, IH, and AM have ownership interest including stock, patents, etc. in Galecto Biotech AB. AP is the COO at Galecto Biotech and has ownership interest including stock, patents, etc. in Galecto Biotech. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Mabbitt, Holyer, Roper, Nilsson, Zetterberg, Vuong, Mackinnon, Pedersen and Slack.)

Galectin-3 is a beta-galactoside-binding mammalian lectin that is one of a 15-member galectin family that can bind several cell surface glycoproteins via its carbohydrate recognition domain (CRD). As a result, it can influence a range of cellular processes including cell activation, adhesion and apoptosis. Galectin-3 has been implicated in various diseases, including fibrotic disorders and cancer, and is now being therapeutically targeted by both small and large molecules. Historically, the screening and triaging of small molecule glycomimetics that bind to the galectin-3 CRD has been completed in fluorescence polarisation (FP) assays to determine K D values. Surface plasmon resonance (SPR) has not been widely used for compound screening and in this study it was used to compare human and mouse galectin-3 affinity measures between FP and SPR, as well as investigate compound kinetics. The K D estimates for a set of compounds selected from mono- and di-saccharides with affinities across a 550-fold range, correlated well between FP and SPR assay formats for both human and mouse galectin-3. Increases in affinity for compounds binding to human galectin-3 were driven by changes in both k on and k off whilst for mouse galectin-3 this was primarily due to k on . The reduction in affinity observed between human to mouse galectin-3 was also comparable between assay formats. SPR has been shown to be a viable alternative to FP for early drug discovery screening and determining K D values. In addition, it can also provide early kinetic characterisation of small molecule galectin-3 glycomimetics with robust k on and k off values generated in a high throughput manner., Competing Interests: Declaration of Competing Interest The authors have been, or are currently, employees of Galecto Biotech AB or NovAliX., (Copyright © 2023 Galecto Biotech. Published by Elsevier Inc. All rights reserved.)

Purpose: Galectin-3, a β-galactoside-binding lectin, plays a key role in several cellular pathways involved in chronic inflammation, heart disease and cancer. GB1211 is an orally bioavailable galectin-3 inhibitor, developed to be systemically active. We report safety and pharmacokinetics (PK) of GB1211 in healthy participants., Methods: This phase 1, double-blind, placebo-controlled, first-in-human study (NCT03809052) included a single ascending-dose phase (with a food-effect cohort) where participants across seven sequential cohorts were randomized 3:1 to receive oral GB1211 (5, 20, 50, 100, 200 or 400 mg) or placebo. In the multiple ascending-dose phase, participants received 50 or 100 mg GB1211 or placebo twice daily for 10 days. All doses were administered in the fasted state except in the food-effect cohort where doses were given 30 min after a high-fat meal., Results: All 78 participants received at least one GB1211 dose (n = 58) or placebo (n = 20) and completed the study. No safety concerns were identified. Following single and multiple oral doses under fasted conditions, maximum GB1211 plasma concentrations were reached at 1.75-4 h (median) post-dose; mean half-life was 11-16 h. There was a ~ twofold GB1211 accumulation in plasma with multiple dosing, with steady-state reached within 3 days; 30% of the administered dose was excreted in urine as unchanged drug. Absorption in the fed state was delayed by 2 h but systemic exposure was unaffected., Conclusion: GB1211 was well tolerated, rapidly absorbed, and displayed favorable PK, indicating a potential to treat multiple disease types. These findings support further clinical development of GB1211., Clinical Trial Registration: The study was registered with ClinicalTrials.gov (identifier: NCT03809052)., (© 2023. The Author(s).)

Galectin-3 is a carbohydrate-binding protein central to regulating mechanisms of diseases such as fibrosis, cancer, metabolic, inflammatory, and heart disease. We recently found a high affinity (nM) thiodigalactoside GB0139 which currently is in clinical development (PhIIb) as an inhaled treatment of idiopathic pulmonary fibrosis. To enable treatment of systemically galectin-3 driven disease, we here present the first series of selective galectin-3 inhibitors combining high affinity (nM) with oral bioavailability. This was achieved by optimizing galectin-3 specificity and physical chemical parameters for a series of disubstituted monogalactosides. Further characterization showed that this class of compounds reduced profibrotic gene expression in liver myofibroblasts and displayed antifibrotic activity in CCl 4 -induced liver fibrosis and bleomycin-induced lung fibrosis mouse models. On the basis of the overall pharmacokinetic, pharmacodynamic, and safety profile, GB1211 was selected as the clinical candidate and is currently in phase IIa clinical trials as a potential therapy for liver cirrhosis and cancer.

Galectin (Gal)-3 is a profibrotic β-galactoside-binding lectin that plays a key role in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and IPF exacerbations. TD139 is a novel and potent small-molecule inhibitor of Gal-3.A randomised, double-blind, multicentre, placebo-controlled, phase 1/2a study was conducted to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of inhaled TD139 in 36 healthy subjects and 24 patients with IPF. Six dose cohorts of six healthy subjects were evaluated (4:2 TD139:placebo ratio) with single doses of TD139 (0.15-50 mg) and three dose cohorts of eight patients with IPF (5:3 TD139:placebo ratio) with once-daily doses of TD139 (0.3-10 mg) for 14 days.Inhaled TD139 was well tolerated with no significant treatment-related side-effects. TD139 was rapidly absorbed, with mean time taken to reach maximum plasma concentration ( C max ) values ranging from 0.6 to 3 h and a plasma half-life ( T 1/2 ) of 8 h. The concentration of TD139 in the lung was >567-fold higher than in the blood, with systemic exposure predicting exposure in the target compartment. Gal-3 expression on alveolar macrophages was reduced in the 3 and 10 mg dose groups compared with placebo, with a concentration-dependent inhibition demonstrated. Inhibition of Gal-3 expression in the lung was associated with reductions in plasma biomarkers centrally relevant to IPF pathobiology (platelet-derived growth factor-BB, plasminogen activator inhibitor-1, Gal-3, CCL18 and YKL-40).TD139 is safe and well tolerated in healthy subjects and IPF patients. It was shown to suppress Gal-3 expression on bronchoalveolar lavage macrophages and, in a concerted fashion, decrease plasma biomarkers associated with IPF progression., Competing Interests: Conflict of interest: N. Hirani reports grants from Galecto Biotech, during the conduct of the study. Conflict of interest: A.C. MacKinnon reports personal fees from Galecto Biotech, outside the submitted work; and has a patent CA2,794,066 issued, a patent US13/832,672 issued and a patent WO/2014/067986 pending (all patents are fully owned by Galecto Biotech). Conflict of interest: L. Nicol reports grants from Galecto Biotech, during the conduct of the study; personal fees for lectures from Boehringer Ingelheim, outside the submitted work. Conflict of interest: P. Ford reports personal fees and nonfinancial support from Galecto, during the conduct of the study; and has a patent TD139 issued. Conflict of interest: H. Schambye reports personal fees from Galecto Inc, outside the submitted work; and has a patent WO/2016/180483 pending (fully owned by Galecto Biotech). Conflict of interest: A. Pedersen reports personal fees from Galecto Biotech, outside the submitted work. Conflict of interest: U.J. Nilsson has a patent CA2,794,066 issued, a patent US13/832,672 issued, a patent WO/2014/067986 pending, a patent WO/2005/113569 pending and a patent WO/2009/139719 pending (all patents are fully owned by Galecto Biotech). Conflict of interest: H. Leffler has a patent CA2,794,066 issued, a patent US13/832,672 issued, a patent WO/2014/067986 pending and a patent WO/2005/113569 pending (all patents are fully owned by Galecto Biotech). Conflict of interest: T. Sethi reports personal fees from Galecto Biotech, outside the submitted work; and has a patent CA2,794,066 issued, a patent US13/832,672 issued and a patent WO/2014/067986 pending (patents are fully owned by Galecto Biotech). Conflict of interest: S. Tantawi reports personal fees from Galecto Biotech, outside the submitted work. Conflict of interest: L. Gravelle reports personal fees from Galecto Biotech, outside the submitted work; and has a patent WO/2017/103109 pending (fully owned by Galecto Biotech). Conflict of interest: R.J. Slack reports personal fees from Galecto Biotech, outside the submitted work. Conflict of interest: R. Mills has nothing to disclose. Conflict of interest: U. Karmakar has nothing to disclose. Conflict of interest: D. Humphries has nothing to disclose. Conflict of interest: F. Zetterberg reports personal fees from Galecto Biotech, outside the submitted work. Conflict of interest: L. Keeling has nothing to disclose. Conflict of interest: L. Paul has nothing to disclose. Conflict of interest: P.L. Molyneaux has, via his institution, received industry-academic funding from AstraZeneca and has received speaker and consultancy fees from Boehringer Ingelheim and Hoffman-La Roche, outside the submitted work. Conflict of interest: F. Li has nothing to disclose. Conflict of interest: W. Funston has nothing to disclose. Conflict of interest: I.A. Forrest reports personal fees for consultancy and meeting attendance from Boehringer Ingelheim, personal fees for lectures and meeting attendance from Roche Ltd, outside the submitted work. Conflict of interest: A.J. Simpson has nothing to disclose. Conflict of interest: M.A. Gibbons has nothing to disclose. Conflict of interest: T.M. Maher has, via his institution, received industry-academic funding from AstraZeneca and GlaxoSmithKline R&D, and has received consultancy or speaker fees from AstraZeneca, Bayer, Blade Therapeutics, Boehringer Ingelheim, Bristol-Myers Squibb, Galapagos, GlaxoSmithKline R&D, Indalo, Novartis, Pliant, Respivant, Roche and Samumed., (Copyright ©ERS 2021.)