Treatment of Pleural Mesothelioma Update

ASCO Guidelines

Dr. Hedy Kindler joins us on the podcast to discuss the latest update to the treatment of pleural mesothelioma guideline. She discusses the latest changes to the updated recommendations across topics including surgery, immunotherapy, chemotherapy, pathology, and germline testing. Dr. Kindler describes the impact of this guideline and the need for ongoing research in the field.

Read the full guideline update, “Treatment of Pleural Mesothelioma: ASCO Guideline Update” at www.asco.org/thoracic-cancer-guidelines.

TRANSCRIPT

This guideline, clinical tools, and resources are available at http://www.asco.org/thoracic-cancer-guidelines. Read the full text of the guideline and review authors’ disclosures of potential conflicts of interest in the Journal of Clinical Oncology, https://ascopubs.org/doi/10.1200/JCO-24-02425

Brittany Harvey: Hello and welcome to the ASCO Guidelines podcast, one of ASCO's podcasts delivering timely information to keep you up to date on the latest changes, challenges, and advances in oncology. You can find all the shows, including this one at asco.org/podcasts.

My name is Brittany Harvey and today I'm interviewing Dr. Hedy Kindler from the University of Chicago, lead author on “Treatment of Pleural Mesothelioma: ASCO Guideline Update.”

Thank you for being here today, Dr. Kindler.

Dr. Hedy Kindler: Thank you so much.

Brittany Harvey: Then, before we discuss this guideline, I'd like to note that ASCO takes great care in the development of its guidelines in ensuring that the ASCO Conflict of Interest Policy is followed for each guideline. The disclosures of potential conflicts of interest for the guideline panel, including Dr. Kindler, who has joined us here today, are available online with the publication of the guideline in the Journal of Clinical Oncology, which is linked in the show notes.

So then, to jump into the content of this podcast episode, first, Dr. Kindler, can you provide an overview of the purpose and scope of this guideline update on pleural mesothelioma?

Dr. Hedy Kindler: The initial ASCO practice guideline on mesothelioma, which we published in 2018, was quite comprehensive, but since that time incredible progress has been made which has truly transformed the management of this disease. So we felt it was really important to update the guideline now, focusing on four key areas: the role of surgery, new systemic treatments, pathologic insights, and germline testing.

Brittany Harvey: Great. Thank you for highlighting those key areas of the guideline. And so I'd like to next review the key updated recommendations for our listeners. So starting with what are the new updates for surgery?

Dr. Hedy Kindler: So surgery has always been controversial in meso, with significant geographic variation in its use. Now, it's even more controversial. Recent randomized data from the MARS 2 trial, placed in the context of other data we also reviewed in this update, suggest that surgical cytoreduction should not be routinely offered to all patients based solely on anatomic resectability. Surgery should only be offered to highly selected patients with favorable prognostic characteristics. This includes comprehensively staged patients with early-stage epithelioid tumors. Patients should preferably be treated at centers of excellence which have documented low morbidity and mortality, and this should also be done in the context of multimodality therapy and preferably within clinical trials.

Brittany Harvey: Understood. I appreciate you reviewing those recommendations for who surgery should be offered to. So following those, what are the main recommendations for immunotherapy for treating pleural mesothelioma?

Dr. Hedy Kindler: So for a disease in which for 16 years there was only one FDA-approved regimen, pemetrexed and platinum, the pace of recent changes in systemic therapy has been a welcome change with the FDA approval of doublet immunotherapy in October of 2020 and the approval of chemo immunotherapy just a few months ago in September of 2024. Now that we have choices, we've tried to help clinicians determine the optimal treatment regimen for the individual patient. Doublet immunotherapy with ipilimumab and nivolumab should be offered as a first-line systemic option to any mesothelioma patient. For patients with non-epithelioid histology, doublet immunotherapy is hands down the recommended regimen based on the dramatic improvement in survival from 8.8 to 18.1 months for immunotherapy compared with chemo. For patients with previously untreated epithelioid mesothelioma, either ipilimumab-nivolumab immunotherapy or platinum-pemetrexed chemotherapy are reasonable options. Therapy can be individualized based on the patient's comorbidities, acceptance of differing toxicities. and treatment goals. Chemoimmunotherapy with pembrolizumab, pemetrexed, and carboplatin is a newer treatment option for patients with newly diagnosed pleural mesothelioma. This regimen is noteworthy for its very high objective response rate of 62%.

Brittany Harvey: It's great to have those new options to improve outcomes for patients.

Beyond the chemoimmunotherapy recommendation that you just described, what are the highlights for chemotherapy recommendations?

Dr. Hedy Kindler: So pemetrexed platinum-based chemotherapy with or without bevacizumab still plays a role in this disease and should be offered as a first-line treatment option in patients with epithelioid histology. This regimen is not recommended in patients with non-epithelioid disease unless they have medical contraindications to immunotherapy. Pemetrexed maintenance chemotherapy following pemetrexed-platinum chemotherapy is not recommended.

Brittany Harvey: Thank you for reviewing those recommendations as well.

So then next, what are the important changes regarding pathology?

Dr. Hedy Kindler: Well, one fun fact is that we've changed the name of the disease. It's no longer malignant mesothelioma. Now it's just mesothelioma. Since the non-malignant mesothelial entities have been renamed, all mesos are now considered malignant, so there's no need to use the prefix malignant in the disease name. Mesothelioma should be reported as epithelioid, sarcomatoid, or biphasic because these subtypes have a clear prognostic and predictive value. Knowing the subtype helps us decide on whether chemotherapy or immunotherapy is the optimal treatment for a patient, so it must be reported. Additionally, within the epithelioid subtype, histologic features, including nuclear grade, some cytologic features, and architectural patterns should be reported by pathology because they have prognostic significance. Pathologists have recently identified a premalignant entity, mesothelioma in situ, which can be found in patients with long standing pleural effusions and should be considered in the differential diagnosis. In the appropriate clinical setting, additional testing, including BAP1 and MTAP IHC should be performed.

Brittany Harvey: Definitely. These pathologic recommendations are important for treatment selection. So in that same vein, in the final section of the recommendations, what are the updated recommendations from the panel regarding germline testing?

Dr. Hedy Kindler: This is one of our most important recommendations, that universal germline testing should be offered to all mesothelioma patients. The proportion of patients with mesothelioma who have pathogenic or likely pathogenic germline variants is similar to other diseases in which universal germline genetic testing and counseling are now the standard of care. This is most commonly observed in the tumor suppressor gene BAP1 and this not only affects cancer risk in patients and their family members, but also has key prognostic significance. For example, pleural mesothelioma patients with BAP1 germline mutations who receive platinum-based chemotherapy live significantly longer, 7.9 years compared to 2.4 years for those without these mutations. Thus, we recommend that all patients with mesothelioma should be offered universal germline genetic counseling and/or germline testing.

Brittany Harvey: So there were a large amount of new and updated recommendations in this update. So in your view Dr. Kindler, what is the both importance of this update and how will it impact both clinicians and patients with pleural mesothelioma?

Dr. Hedy Kindler: Even as we were researching and writing this update, new data kept emerging which we needed to include. So it's clearly a time of great progress in the management of this disease. We've comprehensively reviewed and analyzed the extensive emerging data and provided clinicians with a roadmap for how to incorporate these new advances into their management of this disease.

Brittany Harvey: Absolutely, that is key for optimal patient care.

So you've just mentioned emerging data and rapid evidence generation, so what future research developments are being monitored for changes in the treatment of pleural mesothelioma?

Dr. Hedy Kindler: Despite these recent advances in disease management, mesothelioma continues to be a lethal cancer, and there's clearly a need to develop better treatments. This includes ongoing studies of novel immunotherapeutic agents such as bispecific antibodies, cell therapy using chimeric antigen receptors targeting mesothelioma tumor antigens, and precision medicine approaches to target tumor suppressor genes.

Finally, strategies for early cancer detection and prevention are vital for individuals predisposed to develop mesothelioma due to BAP1 and other germline mutations, as well as for those who are occupationally or environmentally exposed to asbestos.

Brittany Harvey: Absolutely. We'll look forward to these new updates to continue development in the field.

So thank you so much for this mountain of work to update this guideline, and thank you for your time today, Dr. Kindler.

Dr. Hedy Kindler: Thank you so much. It's been a pleasure. Thank you for asking me to do this.

Brittany Harvey: And thank you to all of our listeners for tuning in to the ASCO Guidelines podcast. To read the full guideline update, go to www.asco.org/thoracic-cancer-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app available in the Apple App Store or the Google Play Store. If you have enjoyed what you've heard today, please rate and review the podcast and be sure to subscribe so you never miss an episode.

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