TEAD Inhibitors for Mesothelioma

TEAD Inhibitors for Mesothelioma
At a Glance
Drug class	YAP/TEAD (Hippo-pathway) inhibitors
FDA status	Investigational — none approved
Lead agent	VT3989 (Vivace Therapeutics)
Best phase 1/2 signal	32% response rate (n=22, optimized dose)
Molecular target	NF2 / Hippo-pathway–altered tumors
Phase 3	Planned to begin H1 2026
Discontinued programs	IK-930 (2024), IAG933 (2025)

Executive Summary

TEAD inhibitors are a new class of investigational targeted drugs that block the final step of the Hippo signaling pathway, a growth-control circuit that is abnormally active in most mesotheliomas. They are among the most distinctive drug targets in mesothelioma because the disease so frequently carries loss of the NF2 gene and related Hippo-pathway defects, which switch this pathway on. As of mid-2026, no TEAD inhibitor is approved by the U.S. Food and Drug Administration (FDA) for mesothelioma or any other cancer — every agent in this class remains experimental and available only through clinical trials.

The most advanced agent is VT3989, developed by Vivace Therapeutics. In a phase 1/2 trial published in Nature Medicine in 2025, VT3989 produced an objective response rate of 32% and a disease control rate of 86% in a group of 22 heavily pretreated mesothelioma patients treated at the optimized dose, with a median progression-free survival of about 40 weeks. The FDA granted VT3989 Orphan Drug and Fast Track designations in 2025, and Vivace has announced plans to begin a registrational phase 3 trial in the first half of 2026. These are early-phase results in a small cohort; they signal activity but do not yet prove a survival benefit, which the phase 3 trial is designed to test.

VT3989 is currently the sole surviving TEAD inhibitor program in mesothelioma. Two other agents that reached the clinic were discontinued: IK-930 (Ikena Oncology) was halted in 2024 after showing no confirmed responses, and IAG933 (Novartis) was discontinued in 2025 for insufficient activity and tolerability. That history is part of why TEAD is regarded as a difficult but important target — and why VT3989's durable responses have drawn attention. Patients interested in TEAD-directed therapy should discuss molecular testing and clinical-trial eligibility with their oncology care team.

At-a-Glance

TEAD inhibitors in mesothelioma at a glance:

• Investigational class — TEAD inhibitors block YAP/TAZ–TEAD, the endpoint of the Hippo pathway; none is FDA-approved for any cancer as of mid-2026.
• Why mesothelioma — roughly 40–50% of pleural mesotheliomas carry loss of the NF2 (merlin) tumor-suppressor gene, and broader Hippo-pathway defects occur in up to 60% of cases, driving tumor growth through TEAD.
• VT3989 response rate — 32% objective response and 86% disease control at the optimized dose (n=22) in a phase 1/2 trial.
• Durability — median progression-free survival of about 40 weeks (~10 months) at the optimized dose, with some responses lasting beyond a year.
• Not NF2-restricted — responses were seen in patients both with and without NF2 mutations, and no companion diagnostic has been announced.
• Safety — most side effects were mild to moderate; the main class effect is proteinuria (protein in the urine), managed with an intermittent two-weeks-on / two-weeks-off schedule.
• FDA designations — VT3989 holds Orphan Drug (2025) and Fast Track (2025) designations, which can expedite review but are not approvals.
• Phase 3 — Vivace has announced a registrational phase 3 mesothelioma trial planned to begin in the first half of 2026.
• Discontinued programs — Ikena's IK-930 (halted 2024) and Novartis's IAG933 (discontinued 2025) show the target's difficulty.
• How to access — TEAD inhibitors are available only in clinical trials; eligibility is checked at trial centers and on ClinicalTrials.gov.

Key Facts

Measure	Finding (Source)
Drug class	YAP/TEAD (Hippo-pathway) inhibitors — investigational
Lead agent	VT3989 — Vivace Therapeutics, phase 1/2 (NCT04665206)
Objective response rate	32% at optimized dose (7 of 22 patients), phase 1/2, 2025
Disease control rate	86% at optimized dose (n=22), phase 1/2
Median progression-free survival	~40 weeks (~10 months) at optimized dose
Grade 3–4 treatment-related events	8.7% of patients across the phase 1/2 trial (n=172)
Molecular target population	NF2 loss in ~40–50% of pleural mesothelioma; Hippo defects up to ~60%
FDA designations	Orphan Drug (2025) + Fast Track (2025) — not an approval
Phase 3 status	Registrational trial planned to begin H1 2026
Discontinued agents	IK-930 (Ikena, 2024); IAG933 (Novartis, 2025)

What Is a TEAD Inhibitor?

A TEAD inhibitor is a targeted cancer drug that shuts down TEAD (TEA-domain transcription factors), the proteins that carry out the final instructions of the Hippo signaling pathway. Under normal conditions, the Hippo pathway acts as a brake on cell growth. When that brake is removed — most commonly through loss of the NF2 gene — two partner proteins called YAP and TAZ move into the cell nucleus, bind to TEAD, and switch on genes that drive cell survival, invasion, and proliferation. TEAD inhibitors are designed to interrupt that switch, cutting off the growth signal at its source.

There are two main chemical strategies. VT3989 is an auto-palmitoylation inhibitor: it blocks a fatty-acid modification that TEAD needs in order to work, effectively disabling the protein. Other agents, such as the discontinued IAG933, instead tried to physically pry apart the YAP/TAZ–TEAD connection (a protein–protein-interaction, or PPI, inhibitor). Both approaches aim at the same endpoint but differ in how they get there, and those differences have mattered for how well each drug was tolerated.

It is important to be precise about what these drugs are and are not. TEAD inhibitors are investigational — none has been approved by the FDA for mesothelioma or any other cancer, and they are available only through clinical trials. They are also not a response to what causes mesothelioma. Asbestos exposure remains the established cause of the disease; the Hippo-pathway changes these drugs target are alterations that arise within the tumor after it has formed, and they represent a treatment opportunity rather than an explanation of how the cancer began. For more on the molecular changes found in mesothelioma tumors, see Mesothelioma Molecular and Genetic Testing.

How Does the Hippo Pathway Drive Mesothelioma?

The Hippo pathway is one of the most frequently disrupted growth-control circuits in mesothelioma, which is what makes it such an attractive drug target. Its central brake is a protein called merlin, encoded by the NF2 gene. When merlin is working, it helps keep the pathway "on," which in turn keeps YAP and TAZ out of the nucleus and cell growth in check. When NF2 is lost or mutated, the brake fails, YAP/TAZ flood into the nucleus, and they team up with TEAD to drive relentless tumor growth.

These defects are strikingly common in mesothelioma. Loss of the NF2 gene is found in roughly 40–50% of pleural mesotheliomas, and when related Hippo-pathway components — including LATS1/2 and other regulators — are counted, up to about 60% of cases show some form of pathway disruption. That prevalence is far higher than for most targetable alterations in solid tumors, and it means a large share of mesothelioma patients could, in principle, have tumors dependent on this pathway.

Crucially, these are somatic alterations — changes acquired by the tumor cells themselves, not inherited traits and not an alternative cause of the disease. They sit alongside other well-documented molecular features of mesothelioma such as BAP1 and CDKN2A loss. Readers can compare these targets on the BAP1 gene mutation page and in the overview of histological subtypes of mesothelioma. Because Hippo-pathway disruption is so widespread in the disease, a drug that can safely block TEAD has long been viewed as a potentially high-impact addition to mesothelioma treatment — if the target could be drugged without unacceptable side effects.

What Did the VT3989 Trial Show?

VT3989 is the first TEAD inhibitor to produce peer-reviewed clinical evidence of activity in mesothelioma. The pivotal dataset comes from an open-label phase 1/2 dose-escalation and expansion study (NCT04665206) that enrolled 172 patients across U.S. and Australian sites, including MD Anderson Cancer Center and the University of California, San Francisco. Of those patients, 135 (about 79%) had mesothelioma. The results were published in Nature Medicine in 2025 and presented at the 2025 European Society for Medical Oncology (ESMO) Congress.

The most informative data come from the 22 mesothelioma patients treated at the clinically optimized dose and schedule — 100 mg once daily on an intermittent two-weeks-on, two-weeks-off cycle. In that group, the objective response rate was 32% (7 partial responses) and the disease control rate was 86%, with a median progression-free survival of about 40 weeks, or roughly 10 months. In a broader group of 47 mesothelioma patients treated at optimized dose levels, the response rate was 26% with a similar 86% disease control rate. For context, standard later-line options in this heavily pretreated setting typically produce response rates in the low double digits and progression-free survival closer to 15 weeks — so these are encouraging early numbers, though they come from a small, single-arm, early-phase study rather than a randomized comparison.

The safety profile was a central part of the story. Most side effects were grade 1–2, and only 8.7% of the full 172-patient population had grade 3–4 treatment-related adverse events, with just 3.5% discontinuing because of side effects. The signature toxicity was proteinuria (protein leaking into the urine), a known class effect of TEAD inhibitors, which proved reversible with dose adjustment and did not cause lasting kidney damage. The intermittent two-on/two-off schedule was specifically designed to manage this effect while preserving activity — a design choice that distinguishes VT3989 from competitors that used continuous daily dosing. Overall survival data have not yet been reported and are expected from the planned phase 3 trial. All of these findings remain investigational; VT3989 is not an approved or established treatment.

Which TEAD Inhibitors Have Been Tested in Mesothelioma?

Three TEAD inhibitors reached clinical testing in mesothelioma, and their diverging fates illustrate why the target has been considered both promising and difficult.

VT3989 (Vivace Therapeutics) is the sole program still advancing. It is a pan-TEAD auto-palmitoylation inhibitor, and — as described above — it produced durable responses and a manageable safety profile in its phase 1/2 trial, earning FDA Orphan Drug and Fast Track designations and a planned phase 3 start in 2026.

IAG933 (Novartis) was the most advanced competitor and used a different mechanism — a YAP/TAZ–TEAD protein–protein-interaction inhibitor given as continuous daily dosing. In a first-in-human phase 1 study (NCT04857372), IAG933 showed only modest single-agent activity in pleural mesothelioma and was limited by dose-limiting toxicities. Novartis discontinued the program in 2025, removing it from its pipeline, citing insufficient activity and tolerability.

IK-930 (Ikena Oncology) was a TEAD1-selective inhibitor evaluated in a phase 1 trial (NCT05228015). It produced no confirmed responses, and Ikena discontinued the program in 2024 as part of a strategic pipeline reduction, redirecting resources to other candidates.

The contrast points to two apparent advantages for VT3989: a pan-TEAD palmitoylation mechanism rather than a paralog-selective or PPI approach, and an intermittent dosing schedule that keeps the class-effect proteinuria in check. None of this guarantees success — a single-arm phase 1/2 signal is not a randomized survival result — but it explains why VT3989 is the program the field is now watching most closely.

Who Might Be Eligible for TEAD Inhibitor Trials?

Because Hippo-pathway disruption is so common in mesothelioma, a broad range of patients could potentially be candidates for TEAD-directed trials — but eligibility is determined by each trial's specific criteria, not by a single test. In the VT3989 study, about 31% of enrolled patients had an NF2 mutation, yet responses occurred in patients both with and without NF2 alterations. As a result, expansion cohorts have enrolled mesothelioma patients regardless of NF2 status, and no companion diagnostic is currently required.

That said, molecular testing of the tumor is increasingly valuable in mesothelioma care, both for understanding a tumor's biology and for matching patients to appropriate trials. Patients considering a TEAD inhibitor trial may benefit from having NF2 and broader Hippo-pathway status assessed as part of comprehensive genomic testing. The pages on molecular and genetic testing and mesothelioma biomarkers explain how this testing works and where it fits in the diagnostic process.

TEAD inhibitor trials generally focus on patients whose disease has progressed after standard therapy — typically after platinum-based chemotherapy and immune checkpoint inhibitors. That places these drugs in the later-line setting, where new options are most urgently needed. How targeted therapies like TEAD inhibitors fit into the broader treatment sequence is covered in latest treatment advances for mesothelioma and immunotherapy for mesothelioma.

How Do Patients Access TEAD Inhibitor Trials?

Because no TEAD inhibitor is FDA-approved, the only way to receive one is through a clinical trial. The VT3989 phase 1/2 study (NCT04665206) has enrolled at major cancer centers including MD Anderson and UCSF, and Vivace's planned phase 3 trial is expected to open additional sites in 2026. The most reliable, up-to-date source for open trials, locations, and eligibility criteria is the U.S. National Library of Medicine's registry at ClinicalTrials.gov, which lists each trial by its NCT number.

Patients interested in a TEAD inhibitor trial should start by discussing it with their treating oncologist, who can assess whether a trial is medically appropriate and help coordinate referral to a participating center. A specialized mesothelioma treatment center is often the best point of entry, because these centers are more likely to be trial sites and to have the molecular-testing infrastructure that trials require. General guidance on finding and evaluating trials is available on the mesothelioma clinical trials page. As with any investigational therapy, the decision to enroll should be made together with a qualified care team, weighing the potential benefits and the uncertainties that come with early-phase treatment.

Frequently Asked Questions

Is VT3989 approved by the FDA? No. As of mid-2026, VT3989 is investigational and available only through clinical trials. It holds FDA Orphan Drug and Fast Track designations, which can help speed the review process, but neither is an approval. Vivace has announced plans to begin a registrational phase 3 trial in the first half of 2026.

What is the Hippo pathway, and why does it matter in mesothelioma? The Hippo pathway is a growth-control system that normally limits cell division. In most mesotheliomas it is disrupted — most often by loss of the NF2 gene — which allows the proteins YAP and TAZ to partner with TEAD and drive tumor growth. TEAD inhibitors are designed to block that final step.

How well does VT3989 work? In a phase 1/2 trial, VT3989 produced a 32% response rate and 86% disease control rate at the optimized dose in 22 mesothelioma patients, with median progression-free survival of about 40 weeks. These are promising early results in a small group; they demonstrate activity but do not yet prove a survival benefit, which the phase 3 trial will test.

Do I need an NF2 mutation to be eligible? Not necessarily. In the VT3989 trial, responses occurred in patients both with and without NF2 mutations, and expansion cohorts enrolled patients regardless of NF2 status. Molecular testing is still valuable for understanding your tumor and matching you to trials.

What are the side effects of TEAD inhibitors? The main class effect is proteinuria (protein in the urine). In the VT3989 trial most side effects were mild to moderate, grade 3–4 treatment-related events occurred in 8.7% of patients, and the proteinuria was reversible with dose adjustment. An intermittent two-weeks-on / two-weeks-off schedule is used to manage it.

What happened to the other TEAD inhibitors? Two reached the clinic and were discontinued. Ikena's IK-930 was halted in 2024 after producing no confirmed responses, and Novartis's IAG933 was discontinued in 2025 for insufficient activity and tolerability. VT3989 is currently the only TEAD inhibitor still in mesothelioma development.

How can I find a TEAD inhibitor trial? Search ClinicalTrials.gov by NCT number (the VT3989 study is NCT04665206) and discuss options with your oncologist. Specialized mesothelioma centers are the most likely trial sites. See the clinical trials page for guidance.

Quick Statistics

• 0 — TEAD inhibitors FDA-approved for mesothelioma as of mid-2026 (all investigational).
• 32% — VT3989 objective response rate at the optimized dose (n=22), phase 1/2.
• 86% — VT3989 disease control rate at the optimized dose.
• ~40 weeks — median progression-free survival at the optimized dose.
• 172 — total patients in the VT3989 phase 1/2 trial; 135 had mesothelioma.
• 8.7% — patients with grade 3–4 treatment-related adverse events.
• 40–50% — pleural mesotheliomas with NF2 loss; up to ~60% with broader Hippo defects.
• 2 — TEAD inhibitor programs discontinued in mesothelioma (IK-930, IAG933).
• 2026 — year Vivace plans to begin VT3989's registrational phase 3 trial.

External Links

• Danziger & De Llano — Mesothelioma Treatment Overview — plain-language guide to current and emerging mesothelioma treatment options
• Mesothelioma Lawyer Center — treatment, diagnosis, and clinical-trial background for patients and families
• Mesothelioma.net — patient resources on treatment, second opinions, and specialist centers
• ClinicalTrials.gov — VT3989 Study (NCT04665206) — official registry listing with locations and eligibility criteria

Related Pages

• Mesothelioma Molecular and Genetic Testing
• BAP1 Gene Mutation in Mesothelioma
• Latest Treatment Advances for Mesothelioma
• Immunotherapy for Mesothelioma
• Clinical Trials for Mesothelioma
• Histological Subtypes of Mesothelioma