Pembrolizumab plus chemotherapy versus chemotherapy in untreated advanced pleural mesothelioma in Canada, Italy, and France: a phase 3, open-label, randomised controlled trial

Malignant pleural mesothelioma: The disdained member of thoracic oncology!

Pleural mesothelioma is a very aggressive malignancy that arises from the pleural mesothelial cell lining and is linked strongly to prior asbestos exposure. The ban on asbestos has helped to lower the incidence, but in developing countries like India, it is expected to rise. It has an extended latency period usually progressing over decades and presents with nonspecific symptoms. It has a median survival ranging between 10-22 months. The diagnosis of malignant pleural mesothelioma is challenging and is done using computed tomography (CT), magnetic resonance imaging, or positron emission tomography-CT, with the last two predicting the resectability of the tumor better than CT alone. A pleural biopsy along with an array of immunohistochemical markers, such as p16, BRCA1 associated protein 1, and claudin-4, are required for a definitive diagnosis. Several genetic alterations have prognostic significance as well. The current histological subtype identification is indispensable for decision making because of the new therapeutic avenues being explored. The combination of nivolumab and ipilimumab-based immunotherapy outperformed platinum and pemetrexed-based chemotherapy in terms of survival benefit and improved quality of life especially for non-epithelioid subtypes. However, the latter continues to be a robust treatment option for patients with the epithelioid subtype. Surgery is recommended for resectable cases with radiotherapy being indicated in neoadjuvant, adjuvant, and palliative settings along with systemic treatment. This review article provides an overview of epidemiology, etiology, clinical manifestations, diagnostic approaches (including immunohistochemical and genetic markers), staging, and multidisciplinary approaches to current treatment for malignant pleural mesothelioma using surgery, chemotherapy, immunotherapy, and radiotherapy. It also sheds light on some recent studies (EMPHACIS, CALGB30901, Checkmate-743, etc.) that have led to significant developments in recent years with clinically meaningful results.

Randomized trial of anetumab ravtansine and pembrolizumab compared to pembrolizumab for mesothelioma

PURPOSE

The mesothelin-targeting antibody-drug conjugate anetumab ravtansine was evaluated in combination with the programmed cell death-1 (PD-1) inhibitor pembrolizumab based on the common expression of mesothelin and reports of activity in mesothelioma.

PATIENTS AND METHODS

A phase 1 safety run-in of the combination of anetumab ravtansine (6.5 mg/kg iv q3weeks) and pembrolizumab (200 mg, IV q3weeks) was conducted, followed by a phase 2 randomization to the combination or pembrolizumab alone at medical centers across the United States and Canada in the National Cancer Institute's Experimental Therapeutics Clinical Trials Network. Patients with pleural mesothelioma that expressed mesothelin and had previously received platinum-based therapy were eligible.

RESULTS

In phase 1 (n = 12) only one dose limiting toxicity was observed and the rules for dose reduction were not met. In phase 2, there was no difference in the confirmed response rates between the combination group (n = 18, 2 partial responses [PR], 11 %) and the pembrolizumab group (n = 17, 1 PR, 6 %; z = -0.5523, p = 0.29116). The median PFS was 12.2 months (95 % CI 5.1-not evaluable [NE]) for the combination, and 3.9 months for pembrolizumab (95 % CI 2.1-NE)(HR=0.55, p = 0.20). Patients with high baseline levels of soluble mesothelin who received anetumab ravtansine had a median PFS of 5 months.

CONCLUSIONS

The numeric difference in PFS between treatment groups was not statistically significant, likely related to a smaller than planned sample size. High levels of soluble mesothelin should potentially be considered to select against the use of mesothelin-targeting therapies in development that are neutralized by soluble mesothelin.

Treatment patterns and humanistic burden of malignant pleural mesothelioma in Spain

PURPOSE

Malignant pleural mesothelioma (MPM) is an aggressive cancer with long latency and poor prognosis. The real-world treatment patterns and humanistic burden of MPM in an international cohort of patients were recently published. Spanish data are currently lacking and are reported here.

METHODS/PATIENTS

Data were collected from three sources: physician-abstracted demographic, clinical and treatment characteristics of patients with MPM; patient-completed questionnaires on treatment satisfaction, symptoms, caregiver use, and impact of the disease; and caregiver-completed questionnaire reporting their activity and its impact on their daily life.

RESULTS

The 241 patients in Spain were primarily elderly (median age: 67 years), male, retired/unemployed/on long-term sick leave, and diagnosed at stage IV with unresectable disease. Exposure to asbestos was detected (54%, 101/188). First-line treatment (1L) consisted primarily of doublet chemotherapy (86%, 207/241). Of 102 patients who completed 1L at data abstraction, 67 were receiving maintenance therapy, most commonly singlet chemotherapy with pemetrexed. Best supportive care was given to 29 patients, primarily after 1L (86.2%, 25/29). Symptom burden was high and health-related quality of life was poor and declined with progression: mean (SD) EQ-5D score and EQ-5D visual analogue scale score were 0.615 (0.285) and 60.8 (17.1) in 1L and 0.497 (0.370) and 56.1 (19.5) in second line. Overall, 67% of patients (162/241) required daily assistance from their caregiver, who reported an impact on their psychological well-being.

CONCLUSIONS

Patients with MPM in Spain were overall treated according to treatment guidelines at the time. Nevertheless, a considerable burden of disease was reported by patients and caregivers.

Immunotherapy of mesothelioma: the evolving change of a long-standing therapeutic dream

Pleural mesothelioma (PM) is an aggressive and rare disease, characterized by a very poor prognosis. For almost two decades, the world standard treatment regimen for unresectable PM has consisted of a platinum-based drug plus pemetrexed, leading to an overall survival of approximately 12 months. The dramatic therapeutic scenario of PM has recently changed with the entry into the clinic of immune checkpoint inhibition, which has proven to be an effective approach to improve the survival of PM patients. The aim of the present review is to provide a comprehensive overview of the most promising immunotherapeutic-based strategies currently under investigation for advanced PM.

Current State-of-the-Art Therapy for Malignant Pleural Mesothelioma and Future Options Centered on Immunotherapy

Malignant pleural mesothelioma (MPM) is a locally aggressive disease related to asbestos exposure with a median survival for untreated patients of 4-8 months. The combination of chemotherapy based on platinum and antifolate is the standard treatment, and the addition of bevacizumab adds two months to median survival. Recently, in first-line treatment, immunotherapy combining nivolumab with ipilimumab has been shown to be superior to chemotherapy in the CheckMate-743 study in terms of overall survival (18.1 months), leading to its approval by the FDA and EMA. The positive results of this study represent a new standard of treatment for patients with MPM; however, not all patients will benefit from immunotherapy treatment. In an effort to improve the selection of patient candidates for immunotherapy for different tumors, biomarkers that have been associated with a greater possibility of response to treatment have been described. MPM is a type of tumor with low mutational load and neo-antigens, making it a relatively non-immunogenic tumor for T cells and possibly less susceptible to responding to immunotherapy. Different retrospective studies have shown that PD-L1 expression occurs in 20-40% of patients and is associated with a poor prognosis; however, the predictive value of PD-L1 in response to immunotherapy has not been confirmed. The purpose of this work is to review the state of the art of MPM treatment in the year 2023, focusing on the efficacy results of first-line or subsequent immunotherapy studies on patients with MPM and possible chemo-immunotherapy combination strategies. Additionally, potential biomarkers of response to immunotherapy will be reviewed, such as histology, PD-L1, lymphocyte populations, and TMB.