Immunotherapy for Mesothelioma

Immunotherapy Treatment Profile
Immune Checkpoint Inhibitor Therapy
Category	Medical / Treatment
FDA Approval	October 2, 2020
Approved Regimen	Nivolumab + Ipilimumab
Brand Names	Opdivo + Yervoy
Median OS	18.1 months
3-Year OS Rate	23% (vs. 15% chemo)
Pivotal Trial	CheckMate 743
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Immunotherapy has fundamentally changed the treatment landscape for malignant pleural mesothelioma (MPM). On October 2, 2020, the FDA approved the combination of nivolumab (Opdivo) plus ipilimumab (Yervoy) as the first-line treatment for adults with unresectable MPM — the first new systemic therapy approved for mesothelioma in approximately 16 years, since pemetrexed plus cisplatin gained approval in 2004.

The approval was based on the CheckMate 743 trial, which demonstrated that the nivolumab-ipilimumab combination significantly improved overall survival compared to standard chemotherapy, with a median overall survival of 18.1 months versus 14.1 months. The benefit was particularly striking in patients with non-epithelioid (sarcomatoid and biphasic) histology, where immunotherapy more than doubled survival compared to chemotherapy.

Nivolumab is a PD-1 checkpoint inhibitor and ipilimumab is a CTLA-4 checkpoint inhibitor, both manufactured by Bristol-Myers Squibb. These drugs work by releasing the brakes on the immune system, allowing T cells to recognize and attack mesothelioma tumor cells.

Immunotherapy for mesothelioma at a glance:

• Patients receiving immunotherapy survive 4 months longer than those on chemotherapy — median overall survival of 18.1 months vs. 14.1 months in the CheckMate 743 trial
• Non-epithelioid patients benefit far more from immunotherapy than epithelioid patients — survival more than doubled (18.1 vs. 8.8 months) in sarcomatoid and biphasic subtypes, while epithelioid patients saw a more modest improvement
• Immunotherapy patients are 53% more likely to be alive at 3 years than chemotherapy patients — 23% vs. 15% three-year survival rate, with the gap widening over time
• Dual checkpoint blockade outperforms single-agent immunotherapy — the CheckMate 743 combination succeeded where the PROMISE-meso trial of pembrolizumab alone failed to beat chemotherapy
• Immunotherapy side effects differ from chemotherapy but occur at similar rates — grade 3-4 events in 30% vs. 32%, though immunotherapy causes colitis and hepatitis while chemotherapy causes neutropenia and anemia
• Adding surgery to immunotherapy may nearly double survival over immunotherapy alone — perioperative nivolumab plus ipilimumab achieved 28.6 months median OS vs. 18.1 months for immunotherapy without surgery
• Combination immunotherapy replaced a 16-year-old standard of care — nivolumab plus ipilimumab became the first new first-line approval since pemetrexed plus cisplatin in 2004
• Patients who stop immunotherapy early due to side effects still outlive chemotherapy patients — those discontinuing for adverse events had a median OS of 25.4 months, far exceeding the 14.1-month chemotherapy benchmark
• Immunotherapy responders maintain benefits years after treatment ends — 34% of responders sustained their response for three or more years after stopping therapy, compared to 0% ongoing response in the chemotherapy arm
• Financial assistance can reduce immunotherapy costs from nearly $300,000 to $0 per infusion — BMS Access Support co-pay programs cover eligible commercially insured patients, offsetting the $196,604 incremental cost over chemotherapy

Key Facts

Metric	Finding
FDA Approval	October 2, 2020 — nivolumab + ipilimumab for unresectable MPM, the first new systemic therapy in 16 years
CheckMate 743 Enrollment	605 patients randomized (303 immunotherapy, 302 chemotherapy) across multiple international centers; lead investigator Paul Baas, Netherlands Cancer Institute
Median Overall Survival	18.1 months (immunotherapy) vs. 14.1 months (chemotherapy); HR 0.74 (96.6% CI: 0.60–0.91), representing a 26% reduction in risk of death
3-Year Overall Survival	23% (immunotherapy) vs. 15% (chemotherapy); 3-year PFS rate 14% vs. 1%
Non-Epithelioid Subtype Benefit	Median OS 18.1 months vs. 8.8 months (HR 0.46; 95% CI: 0.31–0.68) — survival more than doubled for sarcomatoid and biphasic histology
Epithelioid Subtype Benefit	Median OS 18.7 months vs. 16.5 months — a modest improvement favoring immunotherapy
Objective Response Rate	40% (immunotherapy) vs. 43% (chemotherapy); however, 28% of immunotherapy responders had ongoing response at 3 years vs. 0% for chemotherapy
Grade 3-4 Adverse Events	30% (immunotherapy) vs. 32% (chemotherapy); treatment discontinuation 20% vs. 8%; immune-mediated events include colitis, hepatitis, pneumonitis
CONFIRM Trial (Second-Line)	First randomized trial to show improved OS with nivolumab vs. placebo in relapsed mesothelioma; PD-L1 was not predictive or prognostic
Perioperative Immunotherapy	Neoadjuvant nivolumab + ipilimumab before surgery: median OS 28.6 months, median PFS 19.8 months (Nature Medicine 2025 phase 2 trial)
Active Recruiting Trials (2026)	32 immunotherapy trials among 93 total mesothelioma trials actively recruiting; 52 US-based; 5 CAR-T cell therapy trials recruiting
Treatment Cost	Approximately $292,319 (immunotherapy) vs. $95,715 (chemotherapy); incremental cost of $196,604 for 0.53 additional QALYs; BMS co-pay assistance may reduce patient cost to $0

What Is the FDA-Approved Immunotherapy for Mesothelioma?

The FDA-approved immunotherapy regimen for unresectable malignant pleural mesothelioma consists of two immune checkpoint inhibitors given in combination:

Nivolumab (Opdivo): A PD-1 checkpoint inhibitor administered at 3 mg/kg intravenously every 2 weeks. PD-1 is a protein on T cells that normally acts as an "off switch" — when tumor cells express PD-L1 (the ligand for PD-1), they can deactivate attacking T cells. Nivolumab blocks this interaction, allowing T cells to remain active against tumor cells.

Ipilimumab (Yervoy): A CTLA-4 checkpoint inhibitor administered at 1 mg/kg intravenously every 6 weeks. CTLA-4 is another immune checkpoint that normally dampens T cell activation early in the immune response. By blocking CTLA-4, ipilimumab enhances and broadens the T cell response against the tumor.

Treatment continues for up to 24 months or until disease progression or unacceptable toxicity. Prior to this approval, the only FDA-approved first-line systemic therapy was the chemotherapy combination of pemetrexed plus cisplatin, approved in 2004.

What Did the CheckMate 743 Trial Show?

CheckMate 743 (NCT02899299) was the open-label, multicenter, randomized phase 3 trial that led to FDA approval. It was the first immunotherapy trial to demonstrate improved overall survival in first-line mesothelioma treatment.

Trial Design

A total of 605 patients were randomized: 303 to nivolumab plus ipilimumab and 302 to standard chemotherapy (pemetrexed plus cisplatin or carboplatin). The study was powered at 90% to detect a hazard ratio of 0.72 with a 5% type-I error. The primary endpoint was overall survival. Lead investigator was Paul Baas of The Netherlands Cancer Institute.

Primary Results

Outcome	Nivolumab + Ipilimumab	Chemotherapy
Median Overall Survival	18.1 months (95% CI: 16.8–21.4)	14.1 months (95% CI: 12.4–16.2)
Hazard Ratio	0.74 (96.6% CI: 0.60–0.91) — 26% reduction in death risk
2-Year OS Rate	41%	27%
3-Year OS Rate	23%	15%
3-Year PFS Rate	14%	1%
Objective Response Rate	40%	43%

At three years, 28% of responders in the immunotherapy arm had an ongoing response, versus 0% in the chemotherapy arm. Patients who discontinued immunotherapy due to adverse events still had a favorable median OS of 25.4 months, and 34% of responders maintained their responses for three or more years after discontinuation.

Histology-Specific Results

The most clinically significant finding was the dramatically different benefit by histological subtype:

Epithelioid subtype: Median OS 18.7 months vs. 16.5 months (modest improvement) Non-epithelioid subtype: Median OS 18.1 months vs. 8.8 months (HR 0.46; 95% CI: 0.31–0.68) — more than doubled survival

This finding is particularly important because non-epithelioid mesothelioma (sarcomatoid and biphasic subtypes) has historically been poorly responsive to chemotherapy. Immunotherapy demonstrated its greatest relative benefit in this difficult-to-treat population, making it the clear treatment of choice for non-epithelioid disease.

Safety Profile

The safety profile was consistent with known profiles of nivolumab and ipilimumab in other tumor types. Grade 3-4 treatment-related adverse events occurred in approximately 30% of immunotherapy patients versus 32% of chemotherapy patients, though the types differed — immune-mediated events (colitis, hepatitis, pneumonitis) in the immunotherapy arm versus hematological toxicity (neutropenia, anemia) in the chemotherapy arm. Treatment discontinuation due to adverse events was 20% for immunotherapy versus 8% for chemotherapy.

A key biomarker finding from the 3-year update: a high score of a 4-gene inflammatory expression signature appeared to correlate with improved survival benefit from immunotherapy, potentially offering a patient selection tool for future clinical practice.

What Other Immunotherapy Trials Have Been Conducted?

CONFIRM Trial (Phase 3, Second-Line)

The CONFIRM trial was a randomized phase 3 study comparing nivolumab versus placebo in patients with relapsed mesothelioma (both pleural and peritoneal) who had received at least one prior line of platinum-based chemotherapy. It was the first randomized trial to demonstrate improved overall survival in relapsed mesothelioma. Both co-primary endpoints (OS and PFS) were met. Notably, PD-L1 was not found to be predictive or prognostic in CONFIRM, suggesting that PD-L1 testing should not be used to select patients for second-line nivolumab.

PROMISE-meso Trial (Phase 3, Second-Line)

The PROMISE-meso trial compared pembrolizumab (200 mg fixed dose every 3 weeks) versus single-agent chemotherapy (gemcitabine or vinorelbine) in 144 patients with relapsed MPM. This trial was negative — pembrolizumab did not improve progression-free survival or overall survival compared to chemotherapy in an unselected patient population. The result highlighted that single-agent PD-1 blockade is insufficient as monotherapy in second-line unselected mesothelioma and reinforced the importance of combination approaches or biomarker-driven selection.

DREAM and PrE0505 Trials (Phase 2, First-Line)

The DREAM trial (Australia) and PrE0505 trial (United States) were single-arm phase 2 trials that tested durvalumab (anti-PD-L1) combined with standard chemotherapy (cisplatin plus pemetrexed) as first-line treatment. Both showed promising results — DREAM reported median OS of 18.4 months with a 48% objective response rate, while PrE0505 reported median OS of approximately 20.4 months with a 56.4% partial response rate. These results provided the rationale for DREAM3R, a phase 3 trial of 480 patients comparing durvalumab plus chemotherapy versus chemotherapy alone.

BEAT-meso Trial (Phase 3)

The BEAT-meso trial was an international randomized phase 3 trial comparing atezolizumab (anti-PD-L1) plus bevacizumab plus chemotherapy versus bevacizumab plus chemotherapy alone in 400 patients. The primary endpoint was not met — median OS was 20.5 months versus 18.1 months (HR 0.84, p=0.14, not significant). However, the addition of atezolizumab did significantly improve progression-free survival (9.2 vs. 7.6 months; HR 0.72, p=0.0021).

What Role Do BAP1, TMB, and Other Biomarkers Play?

BAP1 Mutations

BAP1 (BRCA1-associated protein 1) is the most commonly mutated gene in mesothelioma, found in approximately 45.6% of cases. Other common mutations include CDKN2A (21.7%), TP53 (17.1%), and NF2 (14.3%).

BAP1 deficiency has been found to enrich immune pathways in the tumor microenvironment, increasing interferon-alpha and interferon-gamma signatures, activating dendritic cells, and increasing checkpoint receptor expression. BAP1-deficient mesothelioma tumors may therefore be more responsive to immunotherapy, though this relationship requires further prospective validation.

Tumor Mutational Burden

Mesothelioma has a low tumor mutational burden (TMB) compared to other cancers that respond well to immunotherapy, such as melanoma or non-small cell lung cancer. Despite this low TMB, the CheckMate 743 results demonstrate that combination immunotherapy can still be effective. In the NIBIT-MESO-1 trial, patients with TMB higher than the median of 8.3 mutations per megabase had significantly longer survival (41.3 months vs. 17.4 months; p=0.02), suggesting TMB may help identify patients most likely to benefit.

What Immunotherapy Trials Are Currently Recruiting?

As of January 2026, there are 93 mesothelioma clinical trials actively recruiting patients, of which 32 (34%) are immunotherapy trials and 52 are based in the United States.

Key actively recruiting immunotherapy trials include:

Trial	NCT Number	Phase	Intervention
Neoadjuvant Durvalumab + Tremelimumab	NCT05932199	Phase Ib/IIa	Durvalumab + tremelimumab +/- chemo (Baylor)
Immunotherapy Before Surgery for Sarcomatoid Meso	NCT05647265	Phase 2	Neoadjuvant immunotherapy + surgery
Partial Pleurectomy for Unresectable MPM	NCT07126509	—	Surgery +/- immunotherapy
Pembrolizumab + Chemo + Image-Guided Surgery	—	Phase 2	Pembrolizumab + chemo + surgery

Additionally, 5 CAR-T cell therapy trials are actively recruiting mesothelioma patients, representing an emerging frontier in cellular immunotherapy for this disease.

Perioperative Immunotherapy (2025 Update)

A phase 2 trial published in Nature Medicine (2025) evaluated neoadjuvant immunotherapy before surgery for resectable mesothelioma. Patients receiving nivolumab plus ipilimumab before surgery had a median PFS of 19.8 months and median OS of 28.6 months — substantially better than nivolumab alone (median PFS 9.6 months, median OS 19.3 months). Extended pleurectomy/decortication was performed in 81.8% of patients. These results suggest that perioperative immunotherapy may significantly improve outcomes in surgically resectable disease.

What Does Immunotherapy Cost and How Do Patients Access It?

Cost-Effectiveness

A Markov model analysis from a US payer perspective found that the total cost of nivolumab plus ipilimumab treatment was approximately $292,319 compared to $95,715 for chemotherapy — an incremental cost of $196,604 for 0.53 additional quality-adjusted life years (QALYs). At a willingness-to-pay threshold of $207,659 per QALY, the combination was not considered cost-effective unless drug prices were reduced by approximately 34%.

Patient Assistance Programs

BMS Access Support offers benefit investigation, prior authorization assistance, appeal process support, and co-pay assistance programs for eligible commercially insured patients who may pay as little as $0 per infusion, subject to an annual maximum benefit.

"For mesothelioma patients, understanding all available treatment options — including immunotherapy clinical trials — is essential. These advances represent real hope for improved survival, particularly for those with non-epithelioid disease where chemotherapy alone offered limited benefit."

— David Foster, Patient Advocate, Danziger & De Llano

Frequently Asked Questions

Who is eligible for immunotherapy treatment for mesothelioma?

The FDA-approved nivolumab plus ipilimumab combination is indicated for adults with unresectable malignant pleural mesothelioma as a first-line treatment. Patients must have a confirmed MPM diagnosis and disease that cannot be removed by surgery. There is no PD-L1 expression requirement — the CONFIRM trial found that PD-L1 status was not predictive of benefit, so testing is not required for patient selection.

What are the most common side effects of immunotherapy for mesothelioma?

Immunotherapy side effects differ substantially from chemotherapy. The most significant are immune-mediated adverse events including colitis, hepatitis, and pneumonitis, with grade 3-4 events occurring in approximately 30% of patients. By contrast, chemotherapy primarily causes hematological toxicities such as neutropenia and anemia. Approximately 20% of immunotherapy patients discontinue treatment due to adverse events, compared to 8% on chemotherapy.

Can immunotherapy be combined with surgery for mesothelioma?

Yes. A 2025 phase 2 trial published in Nature Medicine showed that neoadjuvant nivolumab plus ipilimumab given before surgical resection achieved a median overall survival of 28.6 months and median progression-free survival of 19.8 months. Extended pleurectomy/decortication was performed in 81.8% of patients. These results were substantially better than immunotherapy alone (18.1 months median OS in CheckMate 743).

How does immunotherapy compare to chemotherapy for non-epithelioid mesothelioma?

Immunotherapy provides a dramatically greater benefit for non-epithelioid (sarcomatoid and biphasic) mesothelioma than for epithelioid disease. Non-epithelioid patients treated with immunotherapy had a median overall survival of 18.1 months versus just 8.8 months on chemotherapy — more than doubling survival. This makes immunotherapy the clear treatment of choice for non-epithelioid mesothelioma, which historically responded poorly to chemotherapy.

How much does immunotherapy for mesothelioma cost?

A US health economic analysis estimated the total cost of nivolumab plus ipilimumab treatment at approximately $292,319, compared to $95,715 for standard chemotherapy — an incremental cost of roughly $196,604. However, Bristol-Myers Squibb offers patient assistance programs through BMS Access Support, which can reduce co-pays to as little as $0 per infusion for eligible commercially insured patients.

How long does immunotherapy treatment for mesothelioma last?

The FDA-approved regimen continues for up to 24 months or until disease progression or unacceptable toxicity. Nivolumab is administered intravenously at 3 mg/kg every 2 weeks, while ipilimumab is given at 1 mg/kg every 6 weeks. Importantly, patients who stop treatment early due to adverse events still achieve favorable outcomes — a median OS of 25.4 months among those who discontinued for side effects.

Are there clinical trials for mesothelioma immunotherapy currently recruiting?

Yes. As of January 2026, 32 immunotherapy trials are actively recruiting among 93 total mesothelioma clinical trials, with 52 based in the United States. Key trials include DREAM3R (testing durvalumab plus chemotherapy in 480 patients), neoadjuvant immunotherapy before surgery trials, and 5 CAR-T cell therapy trials representing an emerging cellular immunotherapy approach.

Does PD-L1 expression predict immunotherapy response in mesothelioma?

Current evidence suggests PD-L1 expression alone is not a reliable predictor. In the CONFIRM trial, PD-L1 was found to be neither predictive nor prognostic for nivolumab benefit in relapsed mesothelioma. However, a 4-gene inflammatory expression signature identified in the CheckMate 743 three-year update showed correlation with improved immunotherapy benefit, potentially offering a future patient selection biomarker.

Get Help

Mesothelioma patients and families can connect with experienced legal and medical advocates:

• Danziger & De Llano provides free case evaluations and can connect families with specialized treatment centers — call (866) 222-9990
• Mesothelioma Lawyer Center offers resources on treatment options and legal rights
• Mesothelioma.net provides comprehensive information on immunotherapy and treatment options

Quick Statistics

• 34% of immunotherapy trials focus specifically on mesothelioma — 32 out of 93 actively recruiting mesothelioma trials involve immune checkpoint inhibitors or cellular immunotherapy
• 52 of 93 active mesothelioma clinical trials are based in the United States — giving US patients broader access to experimental immunotherapy regimens
• BAP1 mutations occur in 45.6% of mesothelioma cases — making it the most frequently mutated gene, with potential implications for immunotherapy responsiveness through enhanced immune pathway activation
• Patients with higher tumor mutational burden survived 41.3 months vs. 17.4 months — above-median TMB (greater than 8.3 mutations per megabase) correlated with significantly longer survival in the NIBIT-MESO-1 trial
• DREAM trial reported a 48% objective response rate with durvalumab plus chemotherapy — providing the rationale for the ongoing 480-patient phase 3 DREAM3R trial
• PrE0505 trial achieved 56.4% partial response rate — durvalumab combined with cisplatin and pemetrexed showed a median OS of approximately 20.4 months in US patients
• BEAT-meso quadruple therapy did not meet its primary OS endpoint — median OS 20.5 vs. 18.1 months (HR 0.84, p=0.14), though PFS was significantly improved at 9.2 vs. 7.6 months (HR 0.72, p=0.0021)
• 81.8% of patients in the perioperative trial underwent extended pleurectomy/decortication — demonstrating that immunotherapy before surgery does not prevent surgical candidacy in most patients
• Nivolumab plus ipilimumab costs approximately 3 times more than chemotherapy — $292,319 vs. $95,715, yielding 0.53 additional quality-adjusted life years at an incremental cost-effectiveness ratio exceeding standard willingness-to-pay thresholds
• CDKN2A, TP53, and NF2 mutations occur in 21.7%, 17.1%, and 14.3% of mesothelioma cases respectively — behind BAP1, these represent the next most common genomic alterations with potential biomarker implications

Related Resources

• Mesothelioma Types and Histology
• Pleurectomy and Decortication (P/D)
• Mesothelioma Diagnosis and Staging
• Asbestos Health Effects
• Mesothelioma Settlements

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