Latest Treatment Advances for Malignant Mesothelioma (2025–2026): 4 Approved Regimens, 1 Year of Change

Mesothelioma treatment changed more between September 2024 and February 2026 than in the previous decade combined. The FDA approved a fourth first-line systemic regimen in September 2024 — pembrolizumab plus chemotherapy — based on the KEYNOTE-483 trial [5]. Five months later, the Five-Year Clinical Outcomes With Nivolumab Plus Ipilimumab Versus Chemotherapy as First-Line Treatment for Unresectable Pleural Mesothelioma in CheckMate 743 [2] confirmed that dual immunotherapy more than doubles five-year survival versus chemotherapy. And the Extended pleurectomy decortication and chemotherapy versus chemotherapy alone for pleural mesothelioma (MARS 2): a phase 3 randomised controlled trial [4] rewrote the rules on when surgery should — and should not — be offered.

Executive Summary

The mesothelioma treatment landscape now offers four FDA-approved first-line systemic options, up from one in 2019: cisplatin plus pemetrexed, nivolumab plus ipilimumab, pembrolizumab plus chemotherapy (added September 17, 2024), and Tumor Treating Fields with chemotherapy. CheckMate 743's five-year data, published in February 2026, showed 14% five-year survival on dual immunotherapy versus 6% on chemotherapy. The MARS2 trial published in 2024 narrowed surgical candidacy to highly selected early-stage epithelioid patients at high-volume centers, with pleurectomy/decortication preferred over extrapleural pneumonectomy. Pegargiminase (ADI-PEG 20) is at FDA review, mesothelin-targeted CAR-T therapy produced a 72% response rate in early MSK trials, and ASCO and NCCN have updated their guidelines accordingly. For patients diagnosed in 2026, the right treatment depends on cell type, stage, performance status, and access to a specialized center — not on a single standard regimen.

FDA-approved first-line systemic regimens for malignant pleural mesothelioma as of September 2024 [5]

14% vs 6%

Five-year overall survival on nivolumab + ipilimumab versus chemotherapy in CheckMate 743 [2]

17.3 mo

Median overall survival with pembrolizumab plus chemotherapy in KEYNOTE-483 [5]

0% / 4.2%

30-day and 90-day mortality for pleurectomy/decortication in the 2026 Mount Sinai series of 71 selected patients [7]

What Are the Key Treatment Advances for Mesothelioma in 2025–2026?

FDA approved pembrolizumab plus pemetrexed and platinum chemotherapy as a first-line regimen on September 17, 2024 — the first new first-line approval since October 2020 [5]
CheckMate 743 five-year data published in JCO in February 2026: 14% five-year overall survival on nivolumab + ipilimumab versus 6% on chemotherapy alone [2]
For non-epithelioid (sarcomatoid and biphasic) histology, immunotherapy produced 12% five-year survival versus 1% on chemotherapy in CheckMate 743 [2]
The MARS2 phase 3 trial (Lancet Respir Med, 2024) found extended pleurectomy/decortication plus chemotherapy produced worse 2-year survival than chemotherapy alone in unselected patients [4]
NCCN and ASCO 2025 guidelines now restrict surgery to clinically early-stage (T1–3N0) epithelioid patients at experienced centers; pleurectomy/decortication is preferred over extrapleural pneumonectomy [7][6]
The ATOMIC-Meso phase 3 trial of pegargiminase (ADI-PEG 20) plus chemotherapy reported a survival benefit in non-epithelioid mesothelioma; a Biologics License Application is currently under FDA review
Memorial Sloan Kettering's mesothelin-targeted CAR-T plus pembrolizumab phase 1 cohort produced a 72% objective response rate in 11 mesothelioma patients
Tumor Treating Fields (Optune Lua) with pemetrexed and platinum produced 18.2 months median overall survival in the STELLAR trial; FDA-approved via the Humanitarian Device Exemption pathway
A 2026 Mount Sinai pleurectomy/decortication series reported 0% 30-day and 4.2% 90-day mortality in 71 carefully selected patients [7]
The ASCO 2025 guideline update explicitly states that PD-L1 status, tumor mutational burden, and microsatellite instability should not drive mesothelioma treatment selection — histology and performance status do [6]

Why Was the September 2024 KEYNOTE-483 FDA Approval So Significant?

For most of the 2010s, the only FDA-approved first-line regimen for malignant pleural mesothelioma was cisplatin plus pemetrexed, a chemotherapy combination originally approved in 2004 based on the Phase III study of pemetrexed in combination with cisplatin versus cisplatin alone in patients with malignant pleural mesothelioma (EMPHACIS) [3]. Median overall survival in EMPHACIS was 12.1 months on the doublet versus 9.3 months on cisplatin alone — an improvement, but a modest one.

That single-regimen era ended in October 2020 when the FDA approved nivolumab plus ipilimumab based on the First-line nivolumab plus ipilimumab in unresectable malignant pleural mesothelioma (CheckMate 743): a multicentre, randomised, open-label, phase 3 trial [1]. Then on September 17, 2024, the FDA approved a third option: pembrolizumab (Keytruda) combined with pemetrexed and platinum-based chemotherapy for unresectable advanced or metastatic disease [5].

What KEYNOTE-483 Showed

KEYNOTE-483 was a randomized, open-label phase 3 trial that enrolled 440 patients with previously untreated unresectable pleural mesothelioma. The pembrolizumab-plus-chemotherapy arm received up to 2 years of pembrolizumab with up to 6 cycles of pemetrexed plus platinum. The control arm received pemetrexed plus platinum alone.

Median overall survival: 17.3 months versus 16.1 months for chemotherapy alone — a statistically significant improvement [5]
3-year overall survival: 25% versus 17% [5]
Objective response rate: 52% versus 29% [5]
Median progression-free survival: 7.1 months in both arms — a reminder that the immunotherapy benefit shows up most clearly in long-term outcomes [5]

The largest absolute survival benefit was again in non-epithelioid (sarcomatoid and biphasic) histology, where the gain exceeded four months over chemotherapy alone. KEYNOTE-483 was reviewed under the FDA's Project Orbis, a concurrent international review program, allowing the approval to land in multiple regulatory jurisdictions in close succession [5].

"The 2024 KEYNOTE-483 approval mattered for two reasons. It gave clinicians a second immunotherapy-containing regimen — one that combines pembrolizumab with the chemotherapy backbone many patients are already familiar with. And it confirmed something we suspected from CheckMate 743: that immunotherapy works across histologies, not just one subtype."

— David Foster, Executive Director of Client Services, Danziger & De Llano

What Did the CheckMate 743 Five-Year Data Add?

Initial CheckMate 743 results, published in The Lancet in early 2021, showed a median overall survival of 18.1 months on nivolumab plus ipilimumab versus 14.1 months on chemotherapy, with a hazard ratio of 0.74 [1]. The two-year follow-up reported 41% survival on immunotherapy versus 27% on chemotherapy. The three-year analysis, published in Annals of Oncology in 2022, reinforced the durability advantage with 28% of immunotherapy responders still in response at three years compared to 0% on chemotherapy.

The five-year update published in the Journal of Clinical Oncology in February 2026 [2] is what makes the case definitive:

Outcome	Nivolumab + Ipilimumab	Chemotherapy
Median overall survival	18.1 months	14.1 months
Hazard ratio (death)	0.74 (95% CI 0.62–0.88)	—
5-year overall survival (all patients)	14%	6%
5-year overall survival (non-epithelioid)	12%	1%
5-year overall survival (epithelioid)	14%	8%

No new safety signals emerged at five years. The durable survival benefit was preserved across histologic subtypes and PD-L1 expression levels [2]. For patients and families weighing options, this is the longest published follow-up for any first-line mesothelioma regimen — and the difference at five years (14% versus 6%) is the kind of separation that creates long-term survivors rather than just delaying a poor outcome.

How Did MARS2 Change Mesothelioma Surgery Recommendations?

Surgery for mesothelioma has been one of the most contested areas in thoracic oncology. The MARS2 phase 3 trial — published in The Lancet Respiratory Medicine in 2024 — was designed to answer a specific question: does adding extended pleurectomy/decortication to chemotherapy improve survival versus chemotherapy alone? [4]

The answer was unambiguous in this trial population: no. The surgical arm had worse two-year survival (19.3 months versus 24.8 months on chemotherapy alone), more serious adverse events, and worse quality of life [4].

What the Field Concluded

High-volume mesothelioma centers strongly contested the interpretation, arguing that MARS2 enrolled unselected patients — including non-epithelioid and node-positive cases — who should not have been offered surgery in the first place. The 2025 NCCN and ASCO guideline updates settled on a careful middle position [6][7]:

Surgery should only be considered for patients with clinically early-stage (T1–3N0) epithelioid tumors
Surgery should be performed only at experienced, high-volume mesothelioma centers
If surgery is offered, pleurectomy/decortication (P/D) is preferred over extrapleural pneumonectomy (EPP)
IMRT radiotherapy is no longer advised after extrapleural pneumonectomy; palliative radiation remains appropriate

The shift from EPP to P/D has been building for years. A February 2026 ASCO Post report on a Mount Sinai series of 71 carefully selected pleurectomy/decortication patients reported 0% 30-day mortality and only 4.2% 90-day mortality — figures dramatically better than the unselected MARS2 surgical cohort [7]. The lesson is consistent across the data: when surgery is performed on the right patient at the right center, outcomes are very different from when it is performed on unselected patients at lower-volume hospitals.

"After MARS2, the question is no longer 'should this patient have surgery' — it's 'is this patient one of the narrow group who genuinely benefits, and are they at a center that does enough of these operations to do it safely?' For most patients with mesothelioma in 2026, the answer to the surgery question is now no."

— David Foster, Executive Director of Client Services, Danziger & De Llano

What Emerging Therapies Are Closest to Changing the Standard of Care?

Three categories of novel therapy are at the most advanced stages of development and could reshape treatment within the next one to two years.

ADI-PEG 20 (Pegargiminase) — Metabolic Therapy

Roughly half of mesotheliomas lack expression of argininosuccinate synthetase 1 (ASS1), an enzyme that lets cells synthesize their own arginine. Tumors without ASS1 are dependent on circulating arginine to survive. ADI-PEG 20 (pegargiminase) depletes that circulating arginine, effectively starving susceptible cancer cells.

The ATOMIC-Meso phase 3 trial randomized chemotherapy-naïve mesothelioma patients to pegargiminase plus chemotherapy versus chemotherapy alone and reported a median overall survival of 9.3 versus 7.7 months. The benefit was most pronounced in non-epithelioid disease, with some patients achieving multi-year survival — historically very uncommon for sarcomatoid tumors. A Biologics License Application is currently under FDA review; if approved, pegargiminase would become the first metabolic therapy for mesothelioma.

Mesothelin-Targeted CAR-T Cell Therapy

Mesothelin is a glycoprotein overexpressed on more than 90% of mesothelioma cells, making it an attractive target for engineered T-cell therapies. Memorial Sloan Kettering's phase 1 trial of intrapleurally delivered mesothelin-targeted CAR-T cells combined with pembrolizumab produced a 72% objective response rate in 11 mesothelioma patients, including two durable complete metabolic responses on PET imaging. A phase 2 trial of the same combination is ongoing at MSK.

A separate engineered cell therapy — gavocabtagene autoleucel (gavo-cel), a mesothelin-targeting T-cell receptor fusion construct — produced a 20% objective response rate and 77% disease control rate at the recommended phase 2 dose in a 32-patient phase 1 trial. Gavo-cel has FDA Orphan Drug designation for mesothelioma, and a phase 2 trial (EVEREST-2) is enrolling.

Tumor Treating Fields (Optune Lua)

Tumor Treating Fields delivers low-intensity alternating electric fields at 150 kHz through transducer arrays worn on the torso for at least 18 hours per day. The STELLAR phase 2 trial combined TTFields with pemetrexed plus platinum chemotherapy in 80 patients with unresectable pleural mesothelioma and reported a median overall survival of 18.2 months and median progression-free survival of 7.6 months.

The FDA approved Optune Lua (formerly NovoTTF-100L) for first-line use in combination with pemetrexed and platinum chemotherapy through the Humanitarian Device Exemption pathway, a regulatory route reserved for devices treating rare conditions. STELLAR was a single-arm trial, so the FDA considers the efficacy formally "unproven" by the standard randomized-controlled-trial criterion. More than 75 U.S. cancer centers are now certified to prescribe Optune Lua. Skin reactions at the array site are the most common adverse event, affecting roughly 71% of patients.

For a continuously updated catalog of current trials by treatment type, see the mesothelioma clinical trials reference at WikiMesothelioma [9]. Our previous coverage of the 2026 clinical trial pipeline beyond standard treatment details the next wave of phase 2 and phase 3 studies.

What Does the ASCO and NCCN Guidance Say for 2025–2026?

The 2025 ASCO update on pleural mesothelioma treatment — drawing on 110 studies published between 2016 and 2024 — and the parallel NCCN Version 1.2025 guidelines now provide histology-specific recommendations rather than a single algorithm [6]:

Histology	Preferred First-Line	Alternative
Non-epithelioid (sarcomatoid or biphasic)	Nivolumab + ipilimumab	Pembrolizumab + pemetrexed/platinum
Epithelioid	Nivolumab + ipilimumab or pembrolizumab + chemotherapy	Pemetrexed + platinum (with bevacizumab in selected cases)
Immunotherapy contraindicated	Pemetrexed + platinum	Pegargiminase + chemotherapy (non-epithelioid, conditional)

Several specific changes are worth highlighting. PD-L1, tumor mutational burden, and microsatellite instability testing should not drive mesothelioma treatment selection — the guideline is explicit on this point. Histologic subtype and performance status are what matter. All mesothelioma patients should now be offered germline BAP1 testing, framed as a high-evidence, strong recommendation. And the guideline drops the word "malignant" from the disease name: mesothelioma is, by definition, malignant — the qualifier is redundant.

Why Does Where You Get Treated Matter?

For a rare cancer like mesothelioma — roughly 3,000 cases diagnosed annually in the United States — treatment-center experience is a survival variable in its own right. Research published by the National Cancer Institute and reflected in NCCN guidance shows that five-year survival rates at NCI-designated comprehensive cancer centers are substantially higher than at community hospitals for rare cancers where surgical volume, multidisciplinary expertise, and trial access all matter [6].

This is particularly true for surgical decisions. The contrast between the Mount Sinai series (0% 30-day mortality in 71 selected pleurectomy/decortication patients) and the unselected MARS2 surgical cohort (substantially higher mortality and morbidity) is not a coincidence — it reflects what happens when patient selection and surgical volume are right [7][4]. For patients evaluating where to receive care, the question is not just "does this hospital offer mesothelioma treatment" but "how many of these operations does the surgical team perform per year, and what are their outcomes."

For a list of high-volume centers and their specialties, see the Mesothelioma.net treatment center directory [12] and the WikiMesothelioma treatment options reference [8]. Our guide to what to expect at your first mesothelioma specialist appointment walks through the questions to ask when comparing centers.

How Does the Treatment Landscape Affect Legal Claims?

The cost of modern mesothelioma treatment has risen sharply alongside its complexity. First-year costs for an immunotherapy-containing regimen can run from $150,000 to more than $1 million when surgery, radiation, scans, and inpatient care are included. Most patients require help from a combination of insurance, asbestos trust funds, and personal-injury settlements to access the full menu of options described above.

The legal framework for asbestos claims is built around that reality. Asbestos trust funds — established by bankrupt former asbestos manufacturers — distribute set scheduled values for documented mesothelioma diagnoses, and personal-injury or wrongful-death lawsuits against solvent defendants can produce verdicts and settlements that fund both treatment and family security. The 2025–2026 treatment advances make access to these resources more important, not less: there are now four FDA-approved regimens to consider, multiple specialized centers worth traveling to, and active clinical trials that may be a fit. Working with a firm experienced in mesothelioma litigation — like Danziger & De Llano [11] — helps families move quickly through trust-fund claims and litigation so that the focus stays on treatment decisions.

For background on how asbestos compensation works, our trust fund filing guide and our first 30 days legal-steps overview both cover what patients and families should do alongside choosing a treatment center.

What Should Patients Do With This Information?

Three practical takeaways for anyone facing a recent diagnosis or evaluating treatment options in 2026:

Confirm your histology before choosing systemic therapy. Whether your tumor is epithelioid, sarcomatoid, or biphasic now drives a meaningfully different first-line recommendation. A confident pathology read — sometimes a second-opinion read at a high-volume center — is the foundation of every other decision.
Get an evaluation at a high-volume mesothelioma center even if your local oncologist is excellent. The biggest survival advantages in modern data come from getting the right surgical decision, the right systemic regimen, and access to trials. All three are easier at centers that see this disease every week.
Ask about clinical trials early, not late. Active phase 2 and phase 3 trials of pegargiminase, mesothelin CAR-T, oncolytic viruses, and perioperative immunotherapy are recruiting now. Eligibility criteria are stricter once a patient has progressed through multiple lines of therapy, so the time to discuss trial options is at the start of treatment, not after a regimen has failed.

"The hardest message to deliver after a mesothelioma diagnosis used to be that the options were limited and the timeline was short. That is no longer the conversation we have in 2026. There is real long-term survival data on the table, four approved first-line regimens, and a deep pipeline of trials. The work now is matching each patient to the right combination — and helping families pay for it without losing the house in the process."

— David Foster, Executive Director of Client Services, Danziger & De Llano

Frequently Asked Questions

What is the latest FDA-approved treatment for malignant mesothelioma?

The most recent FDA approval for mesothelioma is pembrolizumab (Keytruda) combined with pemetrexed and platinum chemotherapy, approved on September 17, 2024 as a first-line regimen for unresectable advanced or metastatic malignant pleural mesothelioma. The approval was based on the KEYNOTE-483 phase 3 trial, which enrolled 440 patients and showed a median overall survival of 17.3 months versus 16.1 months for chemotherapy alone, with a 3-year overall survival rate of 25% versus 17% and an objective response rate of 52% versus 29%. This was the first new first-line FDA approval for mesothelioma in four years, since nivolumab plus ipilimumab in October 2020.

What did the CheckMate 743 five-year data show?

The 5-year follow-up of CheckMate 743, published in the Journal of Clinical Oncology in February 2026, confirmed that dual checkpoint immunotherapy with nivolumab plus ipilimumab produces a durable survival benefit over chemotherapy in unresectable pleural mesothelioma. At 5 years, 14% of patients on immunotherapy were still alive versus 6% on chemotherapy. The benefit was particularly striking in non-epithelioid (sarcomatoid or biphasic) histology, where 12% of immunotherapy patients reached 5 years compared to 1% on chemotherapy. The median overall survival of 18.1 months versus 14.1 months (hazard ratio 0.74) remained stable across the longer follow-up period.

Did the MARS2 trial change how mesothelioma surgery is used?

Yes. The MARS2 phase 3 randomized trial, published in The Lancet Respiratory Medicine in 2024, found that adding extended pleurectomy/decortication to chemotherapy resulted in worse 2-year survival and more serious adverse events compared to chemotherapy alone. The 2025 ASCO and NCCN guideline updates responded by restricting surgery to a much narrower group: highly selected patients with early-stage (T1-3N0) epithelioid tumors treated at experienced high-volume mesothelioma centers. The lung-sparing pleurectomy/decortication (P/D) procedure is now preferred over the more radical extrapleural pneumonectomy (EPP) when surgery is performed.

What emerging mesothelioma treatments are advancing through clinical trials in 2025–2026?

Several novel approaches have produced meaningful results in 2025 and 2026. ADI-PEG 20 (pegargiminase) — a metabolic therapy that depletes circulating arginine to starve tumor cells lacking ASS1 expression — showed a survival benefit in the ATOMIC-Meso phase 3 trial for non-epithelioid disease and is currently under FDA Biologics License Application review. Mesothelin-targeted CAR-T cell therapy at Memorial Sloan Kettering produced a 72% objective response rate in a small phase 1 cohort when combined with pembrolizumab. Tumor Treating Fields (Optune Lua), already FDA-approved through the Humanitarian Device Exemption pathway, produced 18.2 months median overall survival in the STELLAR trial. Oncolytic viruses such as ONCOS-102 are also showing early activity in combination regimens.

How many FDA-approved first-line systemic regimens now exist for mesothelioma?

There are now four FDA-approved first-line systemic options for malignant pleural mesothelioma: (1) cisplatin plus pemetrexed (approved 2004 based on the EMPHACIS trial), (2) nivolumab plus ipilimumab (approved October 2020 based on CheckMate 743), (3) pembrolizumab plus pemetrexed and platinum chemotherapy (approved September 2024 based on KEYNOTE-483), and (4) Tumor Treating Fields with chemotherapy (approved via the Humanitarian Device Exemption pathway). The 2025 ASCO and NCCN guidelines also recognize histology-driven preferences — immunotherapy combinations are now preferred for non-epithelioid disease, while either immunotherapy or pemetrexed-based chemotherapy is acceptable for epithelioid tumors.

Should patients seek treatment at a specialized mesothelioma center?

Yes, especially for any decision involving surgery, immunotherapy regimens, or clinical trial enrollment. According to research published by the National Cancer Institute and reflected in NCCN guidelines, 5-year survival rates for patients treated at NCI-designated comprehensive cancer centers can be substantially higher than at community hospitals — particularly for rare cancers like mesothelioma where center volume strongly predicts outcomes. A 2026 Mount Sinai series of carefully selected pleurectomy/decortication patients reported 0% 30-day mortality and only 4.2% 90-day mortality, far below the rates reported in the unselected MARS2 surgical cohort.

Talk to Our Team About Your Treatment and Compensation Options

The 2025–2026 treatment advances have widened the door for mesothelioma patients — but only if you can access the right center, the right regimen, and the right financial support. Our team at Danziger & De Llano has spent more than two decades helping mesothelioma patients and families pursue compensation that funds modern treatment and protects their loved ones.

Take our free case assessment to speak with an advocate today, or call us directly at (855) 699-5441. We work on a contingency basis — you pay nothing unless we recover compensation for you.

References

[1] Baas P, Scherpereel A, Nowak AK, et al. First-line nivolumab plus ipilimumab in unresectable malignant pleural mesothelioma (CheckMate 743): a multicentre, randomised, open-label, phase 3 trial. The Lancet. 2021;397(10272):375–386. PMID: 33485464.
[2] Scherpereel A, Baas P, Nowak AK, et al. Five-Year Clinical Outcomes With Nivolumab Plus Ipilimumab Versus Chemotherapy as First-Line Treatment for Unresectable Pleural Mesothelioma in CheckMate 743. Journal of Clinical Oncology. 2026. PMID: 41734361.
[3] Vogelzang NJ, Rusthoven JJ, Symanowski J, et al. Phase III study of pemetrexed in combination with cisplatin versus cisplatin alone in patients with malignant pleural mesothelioma. Journal of Clinical Oncology. 2003;21(14):2636–2644. PMID: 12860938.
[4] Lim E, Waller D, Lau K, et al. Extended pleurectomy decortication and chemotherapy versus chemotherapy alone for pleural mesothelioma (MARS 2): a phase 3 randomised controlled trial. The Lancet Respiratory Medicine. 2024;12(6):457–466. PMID: 38740044.
[5] U.S. Food and Drug Administration. FDA D.I.S.C.O. Burst Edition: FDA approval of Keytruda (pembrolizumab) with chemotherapy for unresectable advanced or metastatic malignant pleural mesothelioma. September 17, 2024. fda.gov
[6] National Cancer Institute. Mesothelioma Treatment (PDQ) — Health Professional Version. 2025. cancer.gov
[7] ASCO Post. Pleurectomy/Decortication Safe in Select Patients With Pleural Mesothelioma. February 2026. ascopost.com
[8] WikiMesothelioma. Mesothelioma Treatment Options. wikimesothelioma.com/Treatment_Options
[9] WikiMesothelioma. Mesothelioma Clinical Trials. wikimesothelioma.com/Clinical_Trials
[10] WikiMesothelioma. Pleural Mesothelioma. wikimesothelioma.com/Pleural_Mesothelioma
[11] Danziger & De Llano — Mesothelioma Lawyers. dandell.com
[12] Mesothelioma.net. Mesothelioma Treatment Centers. mesothelioma.net