Ziretaxestat, an oral autotaxin (ATX) inhibitor originated by Galapagos, once garnered excitement as the first molecule to complete a Ph. III clinical program in idiopathic pulmonary fibrosis since the approvals of nintedanib and pirfenidone. Following the disappointing clinical data and discontinuation of the molecule, this annotation revisits ziritaxestat in the context of other inhibitors, recaps the therapeutic hypothesis and how it was discovered, summarizes notable molecular properties for drug discovery scientists, and discusses what happened and what’s next.

Camlipixant is an orally administered antagonist of the ATP-sensing P2X3 homotrimeric receptor ion channel, originated by AstraZeneca AB and assigned to the Canadian NEOMED Institute (now adMare), and developed by BELLUS Health (Canada), for the treatment of chronic cough. Chronic cough remains difficult to treat – the last FDA-approved anti-tussive, dextromethorphan, was first approved in 1958 and has demonstrated limited clinical efficacy.

PDE4 inhibitors have shown promise in a range of pulmonary, dermatological and neurological diseases, but have been hampered by side effects including emesis and diarrhea . Difamilast , originated by Otsuka , recently approved for the treatment of atopic dermatitis [...]

Gamma-secretase is most well-known as a target for Alzheimer’s disease, though such programs have not been successful to date. Nirogacestat is a gamma-secretase inhibitor that Pfizer originally intended to treat AD, but found life at Springworks Therapeutics as a treatment as a first-in-class drug for rare and aggressive desmoid tumors (DTs). Nirogacestat received the first FDA approval for a treatment for desmoid tumors in Nov. 2023, and this article reviews how it was discovered, how the therapeutic hypothesis emerged after confusing assay disconnects, and lessons learned from the program.

Pfizer has announced the FDA-approval of zavegepant ( ZAVZPRET TM , BHV-3500) for the treatment of acute migraine in adults based on positive Ph. II/III results. As the first and only calcitonin gene-related peptide (CGRP) receptor antagonist nasal spray [...]

Resmetirom is an oral, liver-targeting, once-daily THRβ-selective agonist, which in December 2022 became the first drug to meet its primary endpoints in Ph. III for NASH, demonstrating both NASH resolution and no worsening of fibrosis by biopsy over placebo in 316 test patients. Madrigal will file an NDA for resmetirom in 2023, allowing it to [...]

Bexotegrast is a dual-selective αvβ6-αvβ1 integrin inhibitor with surprising efficacy and safety data from a Ph. II trial in idiopathic pulmonary fibrosis (IPF). The αv integrins have been studied for decades in indications such as cancer and IPF. Both small molecule and antibody-based integrin inhibitors have demonstrated preclinical toxicities in non-human primates. This article highlights the unmet need for effective therapies for IPF and related conditions, a comparison of bexotegrast with other integrin binders, and possible reasons why bexotegrast is different in terms of safety.

What is it? GB0139 is a selective, inhaled inhibitor of galectin-3 and galectin-1 in Ph. II for IPF and COVID-19 pneumonitis, and is Galecto’s ($GLTO) lead asset. Galecto was founded in 2011 with Lund University academic galectin research leaders Ulf Nilsson and Hakon Leffler, and has had a research focus on galectin-3 modulators to treat [...]

On Mar. 14th, 2024, resmetirom (REZDIFFRA™) became the first and only medicine approved by the FDA for the treatment of NASH (non-alcoholic steatohepatitis, aka MASH). Resmetirom, an oral, liver-targeting, once-daily THR-β-selective agonist originally discovered at Roche Nutley, was first highlighted as a Molecule of the Month in Dec. 2022. Now, with the FDA’s accelerated approval, this 2023 Molecule of the Year nominee reflects a historic milestone for liver drug discovery. This article reviews how the molecule works, how it was discovered, and why it’s a big deal.

Omidenepag isopropyl (Omlonti) is a prodrug of a prostaglandin E2 (EP2) receptor agonist that reduces pressure in the eye. Upon topical administration to the eye, the molecule penetrates the lipophilic and negatively charged corneal epithelium and is converted to the pharmacologically active form by the enzyme carboxylesterase-1. The [...]

Context. CHF-6366 (Chiesi Farmaceutici S.p.A) is a muscarinic antagonist and β2 agonist (MABA) being developed as an inhaled treatment for respiratory diseases. Muscarinic antagonists and β2 agonists both act to inhibit bronchoconstriction, but through different mechanisms, making the combination of both agents a desirable strategy for [...]

Context. S udapyridine (WuXi AppTec) is an oral mycobacterial ATP synthase inhibitor being developed for tuberculosis (TB) . Despite the significant success achieved with the discovery of antibiotic drugs in the last several decades, drug resistance, particularly related to agents targeting organisms such as M. tuberculosis , remains a [...]

Context. “compound 4e” (Chiesi Farmaceutici) is an inhaled p38α/β mitogen-activated protein kinase (MAPK) inhibitor being developed for lung inflammatory diseases . As a regulator of key proinflammatory mediators, p38 MAPK has been extensively explored as a therapeutic target for inflammatory diseases, including those of the lung. However [...]

Context. MAGLi 432 (Roche) is a novel, reversible monoacylglycerol lipase (MAGL) inhibitor . There has been increasing interest in the role of inflammation and blood-brain barrier dysfunction in neurology. The appeal of MAGL as an anti-neuroinflammatory therapeutic target comes from its hallmark role as the enzyme that links the [...]

Context. Tenapanor (Ardelyx) is an oral, first-in-class Na + /H + exchanger isoform 3 (NHE3) inhibitor approved by the FDA for irritable bowel syndrome with constipation (IBS-C) in adults. NHE3 is expressed predominantly in the gut and kidney and its role as a key mediator of sodium and water homeostasis makes the protein an ideal target for [...]

MK-1454 (Merck) is an intratumoral stimulator of interferon (IFN) genes (STING) agonist that is being developed for treatment of advanced solid tumors and lymphomas. The molecule follows Aduro’s ADU-S100 , which was terminated after Ph. II due to a lack of substantial activity. Another chemotype of STING agonist, Eisai’s E7766 , has [...]

DS-3801b is a non-macrolide GPR38 agonist and a Ph. I clinical candidate for treatment of chronic constipation (SAD 1-100 mg PO). GPR38 is the receptor for the GI hormone motilin, which as the name suggests, regulates GI motility. Agonism of GPR38 is expected to reduce constipation by activating GI tract smooth muscle cells to move things [...]

LEO 134310 is a non-steroidal, selective glucocorticoid receptor (GR) agonist in Ph. I for plaque psoriasis. Glucocorticoid receptor modulators are widely used in tissue-restricted forms (think Flonase) for their acute effects, but prolonged engagement of GR is undesirable. Previously LEO Pharma described the identification of this topical [...]

bradanicline (ATA-101 or TC-5619) is a molecule first disclosed a decade ago by Targacept. It is a selective agonist of the alpha-7 neuronal nicotinic acetylcholine receptor, and was intended as a drug candidate for treatment of cognitive impairment in neurological disorders. It is highly selective for the CNS over peripheral receptor [...]

Velsecorat (AZD7594) is an inhaled, non-steroidal glucocorticoid receptor modulator and antedrug (soft drug) for treatment of asthma and other respiratory conditions that has completed several Ph. II studies . While the paper states that the results support progression into Ph. III studies, a Ph. III study does not appear to have started and [...]

JAK kinases are now well-established targets in immunology, but the class has always had safety concerns hanging over it. The safety issues were exacerbated by a recent FDA decision to expand the black box warnings for the class for major cardiovascular events. Inhaled, lung-restricted JAK inhibitors have been of interest because they could [...]

The Altos Therapeutics /Takeda D2/D3 receptor antagonist, TAK-906 , is a peripherally-restricted, non-BBB penetrant molecule, targeting the stomach and vomiting center in the area postrema to treat gastroparesis. Gastroparesis is a chronic condition characterized by delayed gastric emptying, resulting in nausea, vomiting, pain, and anorexia [...]

The Janssen gut-restricted COX-2 inhibitor, compound 10 , is a tool compound used to test the hypothesis that gut-restricted COX-2 inhibition would be beneficial for cancer without the cardiovascular risk of systemic COX-2 inhibition. Unfortunately, IVIVC of several compounds demonstrated that in vivo efficacy was not driven by gut COX-2 [...]

The Mirum Pharmaceuticals IBAT bile acid transporter inhibitor, maralixibat , has a long history, having been first patented by scientists at Searle in 1994 and published by the time Searle became part of Pharmacia in 2005 . It was finally approved in Sep. 2021 for treatment of cholestatic pruritis in patients with Alagille Syndrome, and is [...]

PF-05221304 is a liver targeted inhibitor of acetyl-CoA carboxylase (ACC). ACC is a key regulator of lipid metabolism, and there has been significant interest in ACC inhibitors for the treatment of multiple indications including NASH and diabetes. Pfizer previously took a systemic ACC inhibitor into the clinic (PF-05175157), which was found [...]