Definitive Radiation Therapy Is Associated With Improved Survival in Non-Metastatic Malignant Pleural Mesothelioma

Recent Advances of Immune Checkpoint Inhibition and Potential for (Combined) TIGIT Blockade as a New Strategy for Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a fatal cancer type that affects the membranes lining the lungs, and is causally associated with asbestos exposure. Until recently, the first-line treatment consisted of a combination of chemotherapeutics that only had a limited impact on survival, and had not been improved in decades. With the recent approval of combined immune checkpoint inhibition for MPM, promising new immunotherapeutic strategies are now emerging for this disease. In this review, we describe the current preclinical and clinical evidence of various immune checkpoint inhibitors in MPM. We will consider the advantages of combined immune checkpoint blockade in comparison with single agent checkpoint inhibitor drugs. Furthermore, recent evidence suggests a role for T cell immunoglobulin and ITIM domain (TIGIT), an inhibitory immunoreceptor, as a novel target for immunotherapy. As this novel immune checkpoint remains largely unexplored in mesothelioma, we will discuss the potential of TIGIT blockade as an alternative therapeutic approach for MPM. This review will emphasize the necessity for new and improved treatments for MPM, while highlighting the recent advances and future perspectives of combined immune checkpoint blockade, particularly aimed at PD-L1 and TIGIT.

Use of Continuous Positive Airway Pressure (CPAP) to Limit Diaphragm Motion-A Novel Approach for Definitive Radiation Therapy for Inoperable Pleural Mesothelioma: A Pilot Study

Simple Summary

Radiotherapy is an important part of the multimodality approach to treating malignant pleural mesothelioma. In recent studies there is a new trend to treat patients with intact lungs instead of following surgery. This treatment creates significant concerns regarding lung toxicity. We describe two methods to reduce that toxicity. One is the use of constant pulmonary airway pressure (CPAP) to inflate the lungs during treatment. The second is utilizing a novel method of planning and delivering radiotherapy called volumetric modulated arc therapy (VMAT).

Abstract

Malignant pleural mesothelioma (MPM) is a deadly disease and radiotherapy (RT) plays an important role in its management. Recent developments in technique have made it is possible to deliver RT to MPM in the intact lung. However, it is imperative to reduce normal lung doses. We present a pilot study examining the use of CPAP and VMAT radiotherapy to reduce toxicity when treating MPM, involving three consecutive patients with MPM, not amenable to surgery, who were treated according to Helsinki committee approval. Patients were simulated using four-dimentional CT simulation with the assistance of CPAP lung inflation, then were treated using both IMRT and VMAT techniques. Radiation lung dose was optimized based on accepted lung dose constraints. Patients were followed for toxicity as well as local control and survival. Results: Three patients were treated with CPAP-based IMRT treatment. These patients tolerated the treatment and DVH constraints were able to be met. The comparison plans among the four VMAT arcs and the IMRT static field treatment were able to accomplish the treatment planning objectives without significant advantages with either technique. The treatment combined with CPAP reduced the normal lung dose in MPM patients with intact lungs. This technique is worthy of further investigation.

Adjuvant radiation therapy alone is associated with improved overall survival compared to hormonal therapy alone in older women with estrogen receptor positive early stage breast cancer

Background

Breast conserving surgery (BCS) and adjuvant hormonal therapy (HT) without radiation therapy (RT) is an acceptable approach for older women with early stage, estrogen receptor (ER) positive breast cancer. Toxicity and compliance remain issues with HT. Adjuvant RT alone may have better compliance, but its efficacy in the absence of HT is unclear. We aim to assess patterns of adjuvant therapy and survival outcomes among older women with early stage, ER positive (ER+) breast cancer.

Methods

The National Cancer Data Base (NCDB) was used to identify 130,194 women age ≥65 years with invasive ER+, node negative breast cancer diagnosed between 2004 and 2015. All patients underwent BCS. Kaplan‐Meier survival curves were used to examine overall survival (OS). The association between adjuvant therapy and OS was assessed in multivariable Cox proportional hazards regression models.

Results

Unadjusted 5/10‐year OS rates were 90.0%/64.3% for HT and RT, 84.2%/54.9% for RT alone, 78.7%/44.5% for HT alone, and 71.6%/38.0% for no treatment; p<0.001 for all. Compared to HT alone, the 10‐year multivariable hazard ratio (HR) for death for RT alone was 0.86 (95% CI 0.82‐0.91). In propensity‐matched patients who received RT alone or HT alone (n=21,326), RT alone had significantly better survival at 5 (HR_adj: 0.84) and 10 (HR_adj: 0.87) years.

Conclusions

Older women with early stage ER+ breast cancer who undergo BCS and receive both HT and RT have the best survival, while RT as single‐modality therapy had higher rates of OS at 5 and 10 years compared to HT alone.

RapidPlan for Knowledge-Based Planning of Malignant Pleural Mesothelioma

PURPOSE

Treatment planning for malignant pleural mesothelioma is a challenging task due to the relatively large size of the target and the need to spare critical organs that overlap with or are within the target volume. We aimed to develop a knowledge-based model using RapidPlan (RP) for patients with 2 intact lungs.

METHODS AND MATERIALS

Data from 57 patients treated with volumetric modulated arc therapy were chosen for training the dose estimation model at a single dose level. The prescription dose was 50.4 Gy in 1.8 Gy fractions. The model was validated on 23 new patients by comparing the clinical plan to the RP. Time taken to plan the RP was compared with that for the clinical plan.

RESULTS

For similar target coverage and plan inhomogeneity, RP significantly improved the sparing of the contralateral lung, heart, stomach, esophagus, and ipsilateral kidney. On average, the contralateral lung V5 Gy and V10 Gy were reduced by 13.9% (P < .001) and 7.9% (P < .001), respectively. The mean heart dose was reduced by 5 Gy (P < .001) and V30 Gy by 9.1% (P < .001). Mean dose to the stomach and esophagus were both reduced by 5 Gy (P < .001), and the ipsilateral kidney V18 Gy by 4.1% (P < .001). Mean total lung dose was reduced by 0.8 Gy with RP, which enabled an increase in prescription dose by 1 fraction Absolute volume of ipsilateral lung was adequately spared by both techniques, while sparing of all other organs, namely the cord, liver, and bowel, was not compromised with RP. Time taken with RP was 20 minutes, 45 seconds versus at least 4 hours for an experienced treatment planner.

CONCLUSIONS

The RP model for malignant pleural mesothelioma showed improved sparing of critical organs with a reduced treatment planning time and increased prescription dose.

Racial Disparities in Treatment Patterns and Survival Among Surgically Treated Malignant Pleural Mesothelioma Patients

Surgery may improve survival in malignant pleural mesothelioma (MPM) patients. We examined treatment and survival in black and white surgical MPM patients using the National Cancer Database (NCDB). Among patients with pleurectomy/decortication (PD) or extrapleural pneumonectomy (EPP), multivariable logistic regressions were used to evaluate racial differences in surgical extent, additional treatment, and 30-/90-day mortality. Multivariable and propensity matched models were used to assess differences in survival. We identified 2550 patients; 2462 white (96.5%), 88 black (3.5%). Black patients were significantly less likely to receive EPP (OR_adj 0.36, 95% CI 0.17-0.78) and trended towards worse 30-/90-day mortality (OR_adj 1.54, 95% CI 0.59-4.03; OR_adj 1.59, 95% CI 0.80-3.17, respectively). There was no difference in survival (HR_adj 0.94, 95% CI 0.71-1.25). Surgery conferred a survival benefit (HR_adj 0.77, 95% CI 0.73-0.82), but it varied by race (HR_adj[white] 0.76, 95% CI 0.72-0.81; HR_adj[black] 0.93, 95% CI 0.67-1.29). With the limitation of a small proportion of surgically resected black MPM patients in this population-based analysis, black patients were noted to undergo less extensive surgery. Although there was an overall survival benefit noted with surgery, this was not consistent across races, despite trends towards worse short-term mortality in black patients.

Prognostic factors of survival in patients with malignant pleural mesothelioma: an analysis of the National Cancer Database

Malignant pleural mesothelioma (MPM) is a rare disease with a very poor prognosis. Previous studies have indicated that women experience longer survival compared with men. We analyzed 16 267 eligible patients (21.3% females) in the National Cancer Database to evaluate which clinical factors are independently predictive of longer survival. After adjusting for all covariates, survival was significantly better in females compared with males [HRadj: 0.81, 95% confidence interval (CI): 0.77-0.85]. Other factors significantly associated with better survival were younger age at diagnosis, higher income, lower comorbidity score, epithelial histology, earlier stage and receipt of surgical or medical treatment. After propensity matching, survival was significantly better for females compared with males [hazard ratio (HR): 0.86, 95% CI: 0.80-0.94]. After propensity matching within the epithelial group, survival remained significantly better for females compared with males (HR: 0.85, 95% CI: 0.74-0.97). This study adds information to the known significant gender survival difference in MPM by disentangling the effect of gender from the effect of age and histology, two known independent factors affecting survival. Circulating estrogen, present in young but not older women, and higher expression of the estrogen receptor beta in epithelial mesothelioma have been suggested to play a role in gender survival differences. These findings may lead to exploring new therapeutic options, such as targeting estrogen receptor beta, and considering hormonal therapy including estrogens for patients with otherwise limited prognosis.

Types of surgery post-neoadjuvant chemotherapy for pleural mesothelioma

Introduction: The surgical arm of the Mesothelioma and Radical Surgery (MARS) trial involved a multimodal approach, with combined therapy consisting of chemotherapy, complete gross resection, and radiation therapy. However, the MARS trial did not compare surgery with chemotherapy, and the survival and quality of life outcomes of this trial's surgical arm were inferior to those of the non-surgical arm. Methods for achieving complete gross resection (macroscopic complete response [MCR]) include extrapleural pneumonectomy (EPP), wherein the pleura, lung, diaphragm, and pericardium are removed en bloc, and pleurectomy/decortication (P/D), wherein the affected lung is preserved. Nonetheless, the most effective therapy remains unclear.Areas covered: Here, surgery post-neoadjuvant chemotherapy for malignant pleural mesothelioma with either EPP or P/D has been discussed, along with trimodal and bimodal therapies.Expert opinion: With the development of post-P/D radiation therapy, it is currently possible to truly compare EPP with P/D. Moreover, R0 resection cannot be achieved with either EPP or P/D; thus, both must incorporate debulking, although the two procedures are largely incompatible. Therefore, there is a need to rebuild the status of surgery as a multimodal therapy.