Is There Already a Need of Reckoning on Cancer Immunotherapy?

Analysis of new treatments proposed for malignant pleural mesothelioma raises concerns about the conduction of clinical trials in oncology

In this commentary, using existing clinical trial data and FDA approvals we propose that there is currently a critical need for an appropriate balancing between the financial impact of new cancer drugs and their actual benefit for patients. By adopting "pleural mesothelioma" as our clinical model we summarize the most relevant pertinent and available literature on this topic, and use an analysis of the reliability of the trials submitted for registration and/or recently published as a case in point to raise concerns with respect to appropriate trial design, biomarker based stratification and to highlight the ongoing need for balancing the benefit/cost ratio for both patients and healthcare providers.

Comparison of 3 Randomized Clinical Trials of Frontline Therapies for Malignant Pleural Mesothelioma

IMPORTANCE

Some recently proposed frontline therapies for malignant pleural mesothelioma (MPM) are very costly, yet their impact on quality of life and overall survival of these patients remains arguable. Given the high social toll of this aggressive occupational cancer, it is paramount to establish the real clinical benefit of these treatments.

OBJECTIVE

To directly compare and analyze the statistical robustness of the 3 randomized clinical trials (RCTs) of frontline therapies recommended for MPM since 2003.

DESIGN, SETTING, AND PARTICIPANTS

This comparative effectiveness study assessed the following phase 3 RCTs: the Mesothelioma Cisplatin Pemetrexed Study (MPS) of cisplatin plus pemetrexed vs cisplatin; the Mesothelioma Avastin Cisplatin Pemetrexed Study (MAPS) of cisplatin plus pemetrexed plus bevacizumab vs cisplatin plus pemetrexed; and the CheckMate743 (CM743) study of nivolumab plus ipilimumab vs cisplatin plus pemetrexed. Data collection dates for the RCTs ranged from April 1999 to April 2018. Data for this study were analyzed from February to October 2021.

MAIN OUTCOMES AND MEASURES

Patient selection criteria, superiority of the intervention groups, survival-inferred fragility index, and censoring patterns in each RCT.

RESULTS

A total of 1501 patients were included in the analysis (1170 men [77.9%]; range of median age for treatment groups, 60 [IQR, 19-84] to 69 [IQR, 65-75] years). A virtual comparison of overall survival in MAPS vs the CM743 study showed no statistically significant difference (hazard ratio [HR], 0.97 [95% CI, 0.79-1.20]; P = .79), and the survival-inferred fragility index in the intention-to-treat (ITT) populations was as low as 0.22% of the total sample size in MPS, -0.45% of the total sample size in MAPS, and 0.99% of the total sample size in the CM743 trial. Moreover, reverse restricted mean survival time (RMST) analysis of overall survival using RMST-difference (RMST-D) demonstrated differential censoring in the ITT population of the CM743 trial favoring the control group (0.56 [95% CI, 0.18-0.94]; P = .004) and in the nonepithelioid group (reverse RMST-D, 0.90 [95% CI, 0.001-1.79]; P = .048).

CONCLUSIONS AND RELEVANCE

This comparative effectiveness study found no survival benefit in the CM743 trial over MAPS, despite the inclusion of patients with worse prognosis in the latter trial. Moreover, the statistical conclusions of all the examined trials were shown to be extremely fragile, and the findings of differential censoring in the CM743 trial and in the ITT nonepithelial subset raised additional areas of concern. These findings suggest that selection criteria, fragility, and censoring patterns may affect the original conclusions drawn for the respective trials, casting a shadow on the real benefit. This model of analysis lays a rigorous groundwork extendable to trials of all cancer treatments before their registration.

Novel Therapeutic Targets and Immune Dysfunction in Malignant Pleural Mesothelioma

Advances in the treatment of malignant pleural mesothelioma (MPM) have been disappointing, despite the apparent need for new therapeutic options for this rare and devastating cancer. Drug resistance is common and surgical intervention has brought benefits only to a subset of patients. MPM is a heterogenous disease with a surprisingly low mutation rate and recent sequencing efforts have confirmed alterations in a limited number of tumor suppressors that do not provide apparent insights into the molecular mechanisms that drive this malignancy. There is increasing evidence that epigenetic regulation leads to immune evasion and transformation in MPM. Further, the low efficacy of immune checkpoint inhibitors is consistent with a suppression of genes involved in the anti-tumor immune response. We review three promising emerging therapeutic targets (STAT3, KDM4A, heparanase) and highlight their potential effects on the immune response.