Treatment of Pleural Mesothelioma Guidelines Spotlight

Published: May 06, 2025

The American Society of Clinical Oncology’s Treatment of Pleural Mesothelioma guidelines were first published in 2018. Six years later, in 2024, the guidelines received an updated version that addressed new key factors for clinicians to take into consideration based on advancements in treatment and insight.

The updated, 2024 version, published at the beginning of 2025, reflects changes in diagnosis, surgery, immunotherapy, chemotherapy, pathology, and germline mutations. A draft of the update was available for public comment in November 2023.

There were 110 studies compiled as the evidentiary basis for the 2024 update. All of those studies were published between 2016 and 2024. For unchanged recommendations, the previous guideline’s evidence remains as is.

The guidelines were developed by a multidisciplinary Expert Panel through a systemic review of evidence found through PubMed of phase II or III randomized clinical trials, clinical experience, and observational studies.

Here we spotlight the latest updates to the original Treatment of Malignant Pleural Mesothelioma guidelines from the American Society of Clinical Oncology.

Key Treatment of Pleural Mesothelioma Updates:

Diagnosis

1.14 The optimal approach to mesothelioma measurement requires the expertise of a radiologist to identify measurement sites on CT as per modified RECIST 1.1 for mesothelioma. This approach requires calculating the sum of up to 6 measurement sites with at least 0.7 cm thickness, measured perpendicular to the chest wall or mediastinum, with no more than 2 sites on each of 3 CT sections, separated by at least 1 cm axially.

Surgery

2.1 Surgical cytoreduction should not be routinely offered to all patients based solely on anatomic resectability.
2.2 Surgical cytoreduction should only be offered to highly selected patients who have favorable prognostic characteristics including clinical early-stage (T1-3N0) epithelioid tumors.
2.6 In patients who are surgical candidates, neoadjuvant immunotherapy-based treatment may be offered as a treatment option.
2.7 In patients who are surgical candidates, there is insufficient evidence to recommend adjuvant immunotherapy as a treatment option.

Immunotherapy

3.1 In patients with newly diagnosed pleural mesothelioma, ipilimumab plus nivolumab immunotherapy should be offered as a first-line systemic treatment option.
3.2 In patients with newly diagnosed nonepithelioid mesothelioma, ipilimumab plus nivolumab immunotherapy should be offered as the recommended first-line treatment.
3.3 In patients with newly diagnosed epithelioid mesothelioma, ipilimumab plus nivolumab immunotherapy should be offered as a first-line systemic treatment option.
3.4 In patients with newly diagnosed pleural mesothelioma (epithelioid or nonepithelioid), chemoimmunotherapy with pembrolizumab and pemetrexed plus platinum-based chemotherapy may be offered as a first-line systemic treatment option.
3.5 PD-L1, TMB, or MSI should not be used to determine the choice of chemotherapy or immunotherapy in patients with pleural mesothelioma.
3.6 Ipilimumab plus nivolumab immunotherapy should be administered for a duration of up to 2 years in the absence of disease progression or intolerable toxicity.
3.7 In patients previously treated with chemotherapy, double-agent immunotherapy may be offered as a treatment option.
3.8 In patients previously treated with chemotherapy, single-agent immunotherapy may be offered as a treatment option.
3.9 Retreatment with immunotherapy may be offered to patients with initial disease control on immunotherapy whose disease subsequently progressed after completing treatment.
3.10 Patients with severe immunotherapy-related toxicities should discontinue immunotherapy since this does not impair long-term benefit.

Chemotherapy

4.1 In patients with epithelioid histology, pemetrexed plus platinum-based chemotherapy with or without bevacizumab may be offered as a first-line systemic treatment option.
4.2 In patients with nonepithelioid histology who have not received any prior systemic therapy, chemotherapy should not be offered unless there are medical contraindications to immunotherapy.
4.3 In patients with newly diagnosed pleural mesothelioma (epithelioid or nonepithelioid), chemoimmunotherapy with pembrolizumab and pemetrexed plus platinum-based chemotherapy may be offered as a first-line systemic treatment option.
4.4 In patients with nonepithelioid histology who have not received any prior systemic therapy and are not candidates for immunotherapy, the addition of pegargiminase to pemetrexed plus platinum chemotherapy may be offered as a treatment option.
4.5 There is insufficient evidence to make a recommendation on the addition of TTFields to pemetrexed plus platinum-based chemotherapy.
4.6 In patients who have received first-line immunotherapy, pemetrexed plus platinum with or without bevacizumab may be offered as an initial chemotherapy treatment option.
4.7 In patients who have received both immunotherapy and pemetrexed plus platinum-based chemotherapy, vinorelbine or gemcitabine ± ramucirumab may be offered.
4.8 Pemetrexed maintenance chemotherapy following pemetrexed plus platinum chemotherapy is not recommended.
4.9 Gemcitabine switch maintenance chemotherapy following pemetrexed platinum chemotherapy may be offered.
4.10 Gemcitabine with ramucirumab may be offered to patients with disease progression after treatment with platinum pemetrexed chemotherapy.
4.11 Oral vinorelbine may be offered to patients with disease progression after treatment with platinum pemetrexed chemotherapy.
4.12 There is insufficient evidence to make recommendations for the use of biomarkers to predict response to therapy in patients with pleural mesothelioma.

Radiation Therapy

No new recommendations for radiation therapy were included in this update.

Pathology

6.1 This cancer should be called mesothelioma without the prefix malignant because nonmalignant mesothelial entities have been renamed.
6.4 Within the epithelioid subtype, histologic features (ie, nuclear grade, some cytologic features, and architectural patterns) should be reported by pathology because they have prognostic significance.
6.5 The percentage of the sarcomatoid component in biphasic mesothelioma should be reported by pathology because it has prognostic and treatment implications.
6.6 In the absence of a confirmed diagnosis of mesothelioma, mesothelioma in situ should be considered in the differential diagnosis of recurrent unilateral pleural effusion. In the appropriate clinical setting, additional testing (BAP1 and MTAP IHC) should be performed.
6.7 In selected patients in whom tissue is not available or cannot be obtained, cytologic diagnoses may be used for treatment decisions.

Germline Mutations

7.1 All patients with mesothelioma should be offered germline testing.
7.2 Actionable cancer risk genes that have been identified in patients with mesothelioma or that are appropriate based on the patient's personal or family history should be evaluated.
7.3 Because patients with P/LP variant germline variants in BAP1 are likely to have superior survival, individualized treatment including surveillance, platinum-based systemic therapy, and/or resection of multicavitary disease may be offered.
7.4 For patients with mesothelioma and a P/LP germline variant in BAP1 P/LP variant, screening should be offered to detect secondary cancers based on age, sex, and BAP1 tumor predisposition syndrome cancer risks.
7.5 Relatives of patients with known P/LP germline P/LP variants may be at increased risk of developing cancers associated with hereditary syndromes and should be offered genetic counseling regarding the potential risks and benefits of germline genetic testing.
7.6 All patients who are offered germline testing should be offered pretest genetic counseling with a qualified health professional.
7.7 Pretest genetic counseling should include a discussion of potential medicolegal implications of germline testing for mesothelioma.
7.8 There is insufficient evidence to support the use of somatic testing for current standard-of-care therapies.
7.9 All patients with potentially incidental germline findings on somatic tumor panels should be offered genetic counseling with a qualified health professional to discuss potential risks, benefits, and the expected diagnostic yield for germline testing.

View our summary, pocket guide, and patient education information on the ASCO’s Treatment of Malignant Pleural Mesothelioma guidelines.

To view the full, 2025 Treatment of Pleural Mesothelioma guideline update, visit the American Society of Clinical Oncology’s guideline update page.