Review of malignant pleural mesothelioma survival after talc pleurodesis or surgery

Real-world outcomes for patients with pleural mesothelioma: A multisite retrospective cohort study

AIM

To evaluate the real-world treatment patterns and outcomes for patients with pleural mesothelioma (PM) in the era of immunotherapy.

METHODS

This retrospective audit included patients with PM diagnosed within three tertiary referral centers in Queensland, Australia from January 2017 to July 2023. Patient and treatment characteristics and outcomes were recorded. Data was analyzed using descriptive statistics and the Kaplan-Meier survival method.

RESULTS

A total of 90 patients were included: 84% were male, the median age was 75 years (range 70-79) and 85% had baseline Eastern Group Cooperative Group of 0-1. Subtypes included 54% epithelioid, 17% biphasic, 12% sarcomatoid, and 17% unspecified/unknown. First-line treatment was received by 57/90 patients (63%) and 33/90 patients (37%) received the best supportive care (BSC). Chemotherapy was most used (63%) overall, but first-line immunotherapy was more commonly used since ipilimumab/nivolumab was reimbursed by the Australian Pharmaceutical Benefits Scheme in July 2021. After first-line treatment, only 40% received second-line treatment and 60% received BSC. 12-month overall survival (OS) and progression-free survival for all patients were 53% (95% confidence interval [CI]: 43-65) and 25% (95% CI 15-40) respectively. 12-month OS was 72%, 64%, and 29% for immunotherapy, chemotherapy, and BSC, respectively. There was no significant difference in survival between chemotherapy and immunotherapy (hazard ratio 1.28, 95% CI: 0.65-2.5, p = 0.5).

CONCLUSION

In our unselected real-world cohort, both chemotherapy and immunotherapy are active against PM, but the prognosis remains guarded. There remains a need for better treatment options, especially in the first-line setting. Enrolment in clinical trials is crucial to improving outcomes in this debilitating disease.

ALPPL2 Is a Highly Specific and Targetable Tumor Cell Surface Antigen

Identification of tumor-specific cell surface antigens has proven challenging, as the vast majority of tumor-associated antigens are also expressed in normal tissues. In mesothelioma, we identified a highly specific tumor cell surface antigen that can be targeted for therapy development. Mesothelioma is caused by malignant transformation of the mesothelium, is incurable, and can be categorized into three histologic subtypes: epithelioid, biphasic, and sarcomatoid. To identity novel mesothelioma cell surface antigens with broad subtype coverage and high tissue specificity, we have previously selected phage antibody display libraries on live mesothelioma cells and tissues following counterselection on normal cells and identified a panel of human antibodies that bind all subtypes of mesothelioma, but not normal mesothelium. One of the antibodies, M25, showed high specificity against an antigen we identify here as ALPPL2. IHC on normal human tissues found that ALPPL2 is expressed only on placental trophoblasts, but not on any other normal tissues. This significant tissue specificity and broad tumor type coverage suggest that ALPPL2 could be an excellent cell surface target for therapeutic development against mesothelioma. To evaluate therapeutic potential of ALPPL2 targeting, an ALPPL2-targeted antibody-drug conjugate was developed and demonstrated potent and specific tumor killing in vitro and in vivo against both epithelioid and sarcomatoid mesothelioma. Thus, ALPPL2 belongs to a rare class of cell surface antigens classified as truly tumor specific and is well suited for therapy development against ALPPL2-expressing tumors. SIGNIFICANCE: These findings identify ALPP2 as a true tumor-specific cell surface antigen whose tissue specificity enables the development of novel therapies.

Effusion cytology of malignant mesothelioma enables earlier diagnosis and recognizes patients with better prognosis

A conclusive diagnosis of malignant mesothelioma (MM) can be based on effusion cytology using the guidelines for the cytopathologic diagnosis of epithelioid and mixed-type MM. Briefly, the diagnosis is obtained when the mesothelial phenotype of malignant cells is established by ancillary techniques. This study is based on the comparison of the overall survival rates of patients with MM when diagnosed by effusion cytology, histopathology, or a combination of both. A total of 144 patients were diagnosed with epithelioid and mixed-type pleural MM at Karolinska University Hospital between 2004 and 2013. The diagnosis was obtained by histopathology in 74 cases and by cytological examination of pleural effusion in 70 cases. In 29 of the latter cases, a diagnostic biopsy was obtained simultaneously. A total of 104 patients received chemotherapy. All diagnoses were supported by clinical findings, including computer tomography scans. The median time between first symptoms and diagnosis was similar for cytology and histopathology. However, a delay of more than 6 months after first symptoms was seen in many patients in the histopathology group, resulting in late onset of treatment. The overall survival and proportion of long-term survival were significantly better for cases diagnosed by cytology. Similarly, a better survival, following a cytological diagnosis, was also seen in patients who were only provided the best supportive care. Accurate cytological diagnosis enables conclusive diagnosis of MM. Our finding enables the initiation of treatment as soon as the cytological diagnosis is established, avoiding further delay and deterioration of patient survival and possibilities for treatment.

Predictions of Mortality from Pleural Mesothelioma in Italy After the Ban of Asbestos Use

Even if the epidemic of malignant pleural mesothelioma (MPM) is still far from being over worldwide, the health effects of regulations banning asbestos can be evaluated in the countries that implemented them early. Estimates of MPM future burden can be useful to inform and support the implementation of anti-asbestos health policies all around the world. With this aim we described the trends of MPM deaths in Italy (1970-2014) and predicted the future number of cases in both sexes (2015-2039), with consideration of the national asbestos ban that was issued in 1992. The Italian National Statistical Institute (ISTAT) provided MPM mortality figures. Cases ranging from 25 to 89 years of age were included in the analysis. For each five-year period from 1970 to 2014, mortality rates were calculated and age-period-cohort Poisson models were used to predict future burden of MPM cases until 2039. During the period 1970-2014 a total number of 28,907 MPM deaths were observed. MPM deaths increased constantly over the study period, ranging from 1356 cases in 1970-1974 to 5844 cases in 2010-2014. The peak of MPM cases is expected to be reached in the period 2020-2024 (about 7000 cases). The decrease will be slow: about 26,000 MPM cases are expected to occur in Italy during the next 20 years (2020-2039). The MPM epidemic in Italy is far from being concluded despite the national ban implemented in 1992, and the peak is expected in 2020-2024, in both sexes. Our results are consistent with international literature.

Extrapleural pneumonectomy: still indicated?

The optimal treatment of malignant pleural mesothelioma (MPM) has not yet been established and is still under investigation. Surgery is one of the pillars in the multimodality approach with the purpose of removing as much as visible tumor as possible and to relieve symptoms. To date, two major surgical procedures are available for removal or debulking of MPM that is considered to be resectable: [extended (e)] pleurectomy/decortication (P/D) and extrapleural pneumonectomy (EPP). Historically, EPP was regarded as the only way to achieve a macroscopic complete resection. However, in the last years, there is a shift in literature towards (e)P/D as the preferred surgical procedure whenever possible as several retrospective studies and meta-analyses showed a similar or lower long-term survival and higher perioperative mortality and postoperative morbidity in patients who been treated with EPP. On the other hand, no randomized-controlled trials regarding surgical treatment with (e)P/D or EPP exist and therefore level A evidence favoring one surgical procedure is lacking. In this review we provide a nuanced and well-considered answer to the question whether EPP is still indicated in the surgical treatment of MPM.