Anti-fibrotic Drugs 2026: IPF, MASH & Renal Fibrosis Hub
2026 anti-fibrotic drugs hub: approvals (Pirfenidone, Nintedanib, Resmetirom, Wegovy/MASH, Filspari/FSGS) + Phase 2/3 IPF/MASH/renal pipeline.
Anti-fibrotic Drugs 2026 Hub: Approved Therapies and Next-Generation Pipeline
Introduction: The Dawn of Fibrosis Therapeutics
Fibrosis was once considered "irreversible," with almost no effective treatments. The 2014 approvals of Pirfenidone and Nintedanib for Idiopathic Pulmonary Fibrosis (IPF) changed that paradigm. The 2024 approval of Resmetirom for MASH (F2-F3 fibrosis), the August 2025 FDA approval of Wegovy (semaglutide) for MASH with moderate-to-advanced fibrosis, and the April 2026 full FDA approval of Filspari (sparsentan) for FSGS have extended the frontier into the liver and kidney. Anti-fibrotic drug discovery has entered a multi-organ era.
This article serves as a hub page summarizing approved drugs, Phase 3 candidates, and Phase 2 candidates — each linked to its dedicated detailed article.
For researchers tracking fibrosis & inflammation R&D
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Quick Reference: Anti-fibrotic Pipeline Table
| Indication | Approved | Phase 3 | Phase 2 |
|---|---|---|---|
| IPF | Pirfenidone / Nintedanib | Nerandomilast (PDE4B) | BMS-986278 (LPA1) / Integrin inhibitors / Rentosertib (TNIK) |
| MASH | Resmetirom (THR-β) / Semaglutide (Wegovy) | — | ENV-101 (Hedgehog) / Buloxibutid (AT2) / GLP-1 dual/triple agonists |
| CKD / Renal Fibrosis | Finerenone (MRA) / Sparsentan (FSGS) | Atrasentan (ERA) / Sibeprenlimab (IgAN) | Inaxaplin (APOL1) / Iptacopan (Factor B) / Atacicept (BAFF) |
| SSc-ILD | Nintedanib / Tocilizumab | — | — |
| Cross-organ | — | — | Senolytics |
Organ-level landscapes: IPF Treatment Landscape 2025 / MASH Comprehensive Analysis / CKD/Renal Fibrosis Landscape / Anti-fibrotic DMT Market 2026 / Liver Anti-fibrotic Drugs 2026
1. Approved Anti-fibrotic Drugs
Pirfenidone: The "Origin" with Pleiotropic Effects
Approved Indications
- Idiopathic Pulmonary Fibrosis (IPF) (Approved by FDA in 2014)
- Slows the rate of FVC (Forced Vital Capacity) decline in IPF patients by approximately 50%.
Mechanism of Action
Although the exact mechanism of Pirfenidone is not fully elucidated, the following pleiotropic effects have been reported (American Journal of Respiratory Cell and Molecular Biology):
-
Anti-fibrotic Action
- Suppression of TGF-β1: Reduces TGF-β1 mRNA expression and protein production, suppressing Smad3 signaling.
- Inhibition of Fibroblast Proliferation: Inhibits differentiation into myofibroblasts and reduces collagen synthesis.
- Inhibition of mTOR/p70S6K Pathway: Suppresses Collagen I production.
-
Anti-inflammatory Action
- Suppresses production of pro-inflammatory cytokines like TNF-α and IL-1β.
- Also targets the inflammasome pathway.
-
Antioxidant Action
- Neutralizes Reactive Oxygen Species (ROS) and reduces oxidative stress.
Clinical Results
- CAPACITY Trial, ASCEND Trial: Significantly suppressed FVC decline in IPF patients2.
- Side Effects: Gastrointestinal symptoms (nausea, anorexia), photosensitivity.
Nintedanib: Multi-Kinase Inhibitor
Approved Indications
- Idiopathic Pulmonary Fibrosis (IPF) (Approved by FDA in 2014)1
- Systemic Sclerosis-Associated Interstitial Lung Disease (SSc-ILD) (September 2019 FDA approval, SENSCIS trial)
- Progressive Fibrosing Interstitial Lung Diseases (PF-ILD) (March 9, 2020 FDA approval, based on INBUILD trial)5
Mechanism of Action
Nintedanib is a Triple Angiokinase Inhibitor that simultaneously inhibits multiple Receptor Tyrosine Kinases (RTKs):
- PDGFR (α/β): Suppresses fibroblast proliferation and migration.
- FGFR (1/2/3): Suppresses fibroblast activation and angiogenesis.
- VEGFR (1/2/3): Suppresses angiogenesis and vascular permeability.
- Also inhibits non-receptor tyrosine kinases like Src and Lck.
By blocking these pathways, it comprehensively suppresses fibroblast activation, ECM deposition, and angiogenesis.
Clinical Results
- INPULSIS-1/2 Trials: Suppressed the annual rate of FVC decline in IPF patients by approximately 50% (compared to placebo)1.
- SENSCIS Trial: Delayed lung function decline in SSc-ILD patients.
- INBUILD Trial: Slowed FVC decline by approximately 57% across non-IPF progressive fibrosing ILDs5.
- Side Effects: Diarrhea is the most frequent adverse event.
Resmetirom: First MASH Treatment for F2-F3 Fibrosis (Approved 2024)
Approved Indications
- MASH (Metabolic Dysfunction-Associated Steatohepatitis) with F2-F3 fibrosis (FDA accelerated approval, March 14, 2024)4
Mechanism of Action
- Thyroid Hormone Receptor β (THR-β) Selective Agonist
- Improves lipid metabolism in the liver and reduces inflammation and fibrosis.
Significance
The first approved drug for MASH with moderate-to-advanced liver fibrosis (F2-F3) — see the dedicated Resmetirom article for clinical details.
Semaglutide (Wegovy): Second MASH Approval (2025)
Approved Indications
- Adults with MASH and moderate-to-advanced liver fibrosis (F2-F3) (FDA accelerated approval, August 15, 2025, based on Phase 3 ESSENCE trial)6
- Health Canada also granted Notice of Compliance with Conditions (NOC/c) for the same indication on December 15, 2025.
Mechanism of Action
- GLP-1 receptor agonist
- In ESSENCE, at week 72: MASH resolution without worsening of fibrosis 63% vs placebo 34%; fibrosis improvement without worsening of MASH 37% vs 22%.
- See Semaglutide MASH indication for full clinical details.
Finerenone, Sparsentan & Tocilizumab: Renal and SSc-ILD Approvals
- Finerenone: Non-steroidal mineralocorticoid receptor antagonist (MRA). Approved for diabetic kidney disease (DKD).
- Sparsentan (Filspari): Dual ET-A/AT1 antagonist. After IgA nephropathy (accelerated approval 2023), it received full FDA approval for FSGS (adults and pediatric patients aged 8+ without nephrotic syndrome) on April 13, 20267.
- Tocilizumab (Actemra): IL-6 receptor antibody. FDA-approved for SSc-ILD on March 4, 2021 (based on focuSSced trial NCT02453256, with FVC improvement as a secondary endpoint)8.
2. Promising Candidates in Phase 2/3 Clinical Trials
Idiopathic Pulmonary Fibrosis (IPF)
PDE4B Inhibitor
- Nerandomilast (Boehringer Ingelheim)
- Achieved endpoints in Phase 3 FIBRONEER-IPF trial (2024). Suppresses cAMP degradation, exerting anti-inflammatory and anti-fibrotic effects.
LPA1 Antagonist
- BMS-986278 (LPA1 receptor antagonist)
- LPA is a lipid mediator promoting fibroblast migration and proliferation. Phase 2 trials suggested suppression of FVC decline.
Integrin Inhibitors
- Integrin αvβ6/αvβ1 dual inhibitors
- Fundamentally suppresses latent TGF-β activation. Promising Phase 2 results.
TNIK Inhibitor
- Rentosertib (INS018_055)
- First-in-class TNIK inhibitor discovered via AI. Phase 2 ongoing.
Comprehensive reviews: IPF Next-Generation Antifibrotics / IPF Clinical Trials
MASH / Liver Fibrosis
- Beyond GLP-1: MASH pipeline: Tirzepatide, Survodutide and other dual/triple agonists.
- ENV-101 (Hedgehog inhibitor): Developed for both IPF and MASH.
- Buloxibutid (AT2 receptor agonist): Cross-organ (liver/lung) Phase 2.
- Market overview: MASH Future Landscape
CKD / Renal Fibrosis
- Atrasentan (ERA): Completed Phase 3 ALIGN for IgA nephropathy.
- Sibeprenlimab (anti-APRIL): Phase 3 VISIONARY in IgA nephropathy.
- Inaxaplin (APOL1 inhibitor): For genetic-risk FSGS/CKD.
- Iptacopan (Factor B inhibitor): Alternative complement pathway inhibition for C3 glomerulopathy and IgA nephropathy.
- Atacicept (anti-BAFF/APRIL): Phase 3 in IgA nephropathy.
Cross-organ Mechanisms
- Senolytics: Selective elimination of senescent cells as a pan-fibrotic approach.
3. Challenges and Prospects in Anti-fibrotic Drug Development
Difficulty of Phase 3 Translation
- In IPF, several Phase 2 promising candidates (zinpentraxin alfa, ziritaxestat, pamrevlumab) failed in Phase 3, and Nerandomilast FIBRONEER-IPF (2024) was the first IPF Phase 3 to meet its primary endpoint in roughly a decade.
- Fibrosis is a complex pathology spanning multiple organs, so single targets have limited efficacy.
- Common pitfalls include reliance on surrogate endpoints (e.g., FVC) and insufficient Phase 2 sample sizes.
Lack of Biomarkers
- Lack of biomarkers capable of evaluating early intervention effects other than FVC and tissue biopsy.
- Serum markers (KL-6, SP-D, Hyaluronic Acid, etc.) are supportive but limited for determining therapeutic efficacy.
Pan-fibrotic Approach
- Strategy targeting fibrosis mechanisms common across organs (TGF-β, Wnt, YAP/TAZ, NF-κB, etc.).
- Simultaneous inhibition of multiple pathways and combination therapies are gaining attention.
Tissue-Specific Delivery
- Organ-specific delivery using nanoparticles or antibody drugs is being developed to avoid side effects from systemic administration.
Conclusion
The success of Pirfenidone and Nintedanib proved that fibrosis is a "treatable disease." The 2024 approval of Resmetirom, the 2025 FDA approval of Wegovy for MASH, and the 2026 full FDA approval of Filspari for FSGS extended the frontier into the liver and kidney; cardiac and dermal indications are expected to follow.
Next-generation anti-fibrotic drugs target upstream mechanisms (TGF-β activation, mechanotransduction, cellular senescence) and employ combination therapies and organ-specific delivery to aim for "regression" of fibrosis. This hub page is updated periodically to reflect phase transitions and approvals (see the frontmatter updatedDate for the most recent revision).
Related Clusters
Organ-specific Landscapes
- IPF Treatment Landscape 2025
- MASH Comprehensive Analysis / MASH Future
- CKD & Renal Fibrosis Landscape 2026
Market & Business Analysis
Mechanisms & Pathways
References
- Richeldi L, et al. Efficacy and safety of nintedanib in idiopathic pulmonary fibrosis. N Engl J Med. 2014;370(22):2071-2082. PMID: 24836310
- King TE Jr, et al. A phase 3 trial of pirfenidone in patients with idiopathic pulmonary fibrosis. N Engl J Med. 2014;370(22):2083-2092. PMID: 24836312
- Henderson NC, Rieder F, Wynn TA. Fibrosis: from mechanisms to medicines. Nature. 2020;587(7835):555-566. PMID: 33239795
- Harrison SA, et al. A Phase 3, Randomized, Controlled Trial of Resmetirom in NASH with Liver Fibrosis. N Engl J Med. 2024;390(6):497-509. PMID: 38324483
- Boehringer Ingelheim: FDA approves Ofev® as first treatment for chronic fibrosing ILDs with a progressive phenotype (March 9, 2020 approval, based on INBUILD trial). Boehringer Ingelheim press release
- FDA: FDA Approves Treatment for Serious Liver Disease Known as 'MASH' (Wegovy, accelerated approval August 15, 2025). FDA Drug Update
- Travere Therapeutics: Announces Full FDA Approval of FILSPARI® (sparsentan), the First and Only Approved Medicine for FSGS (April 13, 2026 full approval). Travere IR press release
- FDA Drug Label: ACTEMRA (tocilizumab) injection (March 4, 2021 SSc-ILD indication added, based on focuSSced NCT02453256). FDA accessdata label PDF