Target Therapy in Malignant Pleural Mesothelioma: Hope or Mirage?

Evaluation of the combination of gemcitabine, carboplatin, and lactate dehydrogenase A inhibitor on malignant mesothelioma

OBJECTIVES

Lactate dehydrogenase A (LDH-A) catalyzes the last step of glycolysis: supplying cells rapidly but inefficiently with ATP. Many tumors, including malignant mesothelioma (MM), have a high expression of LDH-A, which is associated with cancer aggressiveness. We aimed to determine whether the efficacy of the gemcitabine/carboplatin (Gem + Carbo) combination, widely used to treat this disease, could be increased by inhibition of LDH-A (by NHI-2). To this aim, we analyzed the growth inhibition of pleural and peritoneal MM by multiple combinations.

METHODS

The 72 h sulforhodamine B assay (SRB) was used to test the cytotoxicity of the combination of gemcitabine (in the range 0.1 - 400 nM) and carboplatin (0.01 - 40 µM) with a fixed concentration of NHI-2 (at IC25). We used pleural (H2452) and primary peritoneal (STO, MESO-II) MM cell lines, cultured at normoxic conditions.

RESULTS

NHI-2 did not increase the cytotoxicity of the combination of 100 nM gemcitabine and 10 µM carboplatin in peritoneal MM cell lines. The cell growth inhibition was 10% smaller after the triple combination than the Gem + Carbo treatment.

CONCLUSIONS

Inhibition of LDH-A did not increase the efficacy of gemcitabine and carboplatin in MM under normoxic conditions.

Clinical Next Generation Sequencing Application in Mesothelioma: Finding a Golden Needle in the Haystack

Mesothelioma comprises a group of rare cancers arising from the mesothelium of the pleura, peritoneum, tunica vaginalis testis and pericardium. Mesothelioma is generally associated with asbestos exposure and has a dismal prognosis, with few therapeutic options. Several next generation sequencing (NGS) experiments have been performed on mesothelioma arising at different sites. These studies highlight a genomic landscape mainly characterized by a high prevalence (>20%) of genomic aberrations leading to functional losses in oncosuppressor genes such as BAP1, CDKN2A, NF2, SETD2 and TP53. Nevertheless, to date, evidence of the effect of targeting these alterations with specific drugs is lacking. Conversely, 1-2% of mesothelioma might harbor activating mutations in oncogenes with specifically approved drugs. The goal of this review is to summarize NGS applications in mesothelioma and to provide insights into target therapy of mesothelioma guided by NGS.

Combined inhibition of pyruvate dehydrogenase kinase 1 and lactate dehydrogenase a induces metabolic and signaling reprogramming and enhances lung adenocarcinoma cell killing

Lung adenocarcinoma (LUAD) is one of the most prevalent and aggressive types of lung cancer. Metabolic reprogramming plays a critical role in the development and progression of LUAD. Pyruvate dehydrogenase kinase 1 (PDK1) and lactate dehydrogenase A (LDHA) are two key enzymes involved in glucose metabolism, whilst their aberrant expressions are often associated with tumorigenesis. Herein, we investigated the anticancer effects of combined inhibition of PDK1 and LDHA in LUAD in vitro and in vivo and its underlying mechanisms of action. The combination of a PDK1 inhibitor, 64, and a LDHA inhibitor, NHI-Glc-2, led to a synergistic growth inhibition in 3 different LUAD cell lines and more than additively suppressed tumor growth in the LUAD xenograft H1975 model. This combination also inhibited cellular migration and colony formation, while it induced a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) resulting in mitochondrial depolarization and apoptosis in LUAD cells. These effects were related to modulation of multiple cell signaling pathways, including AMPK, RAS/ERK, and AKT/mTOR. Our findings demonstrate that simultaneous inhibition of multiple glycolytic enzymes (PDK1 and LDHA) is a promising novel therapeutic approach for LUAD.

Mesothelin expression remodeled the immune-matrix tumor microenvironment predicting the risk of death in patients with malignant pleural mesothelioma

Background

The combination of immunobiological agents with immune checkpoint proteins is a promising treatment for malignant pleural mesothelioma (MPM). Mesothelin and anti-PD-L1 antibody-drug conjugates specifically target malignant neoplastic cells, inhibit the migration and invasion of neoplastic cells, and restore the immune landscape. In this study, we confirmed the importance of mesothelin and examined the relationship between mesothelin and the immune landscape of the tumor microenvironment (TME) in two MPM cohorts.

Methods

The discovery cohort included 82 MPM cases. Tissue microarray slides were generated, and samples were processed for hematoxylin & eosin staining, immunohistochemistry, and immunofluorescence assays. The relationship between mesothelin, biomarkers of histogenesis, histological aggressiveness, PD-L1, immune cells (CD4, CD8, CD20, CD68), and collagen type I and type V fibers was evaluated by quantitative digital analyses. The outcome was the survival time until death from disease recurrence. The exploratory cohort included 87 malignant mesothelioma (MESO) patients from The Cancer Genome Atlas database.

Results

Most patients were male (70.7%) with a history of asbestos exposure (53.7%) and with the epithelioid subtype (89%). Surgical resection was performed in 85.4% of patients, and 14.6% received chemotherapy; 59.8% of patients died from disease extension to the mediastinum. Low tumor mesothelin expression was associated with tumor necrosis and nuclear grade 1, whereas high mesothelin expression was significantly associated with the epithelioid histotype and high density of T cells CD8+, macrophages CD68+, and collagen type I fibers. Cox multivariate analysis showed a high risk of death for non-operated patients [hazard ratio (HR), 3.42 (1.15-10.16)] with low tumor mesothelin levels [HR, 2.58 (1.09-6.10)] and high PD-L1 and low infiltration of T cells CD4+ [HR, 3.81 (1.58-9.18)]. In the exploratory cohort, low mesothelin and high COL1A1 and COL5A1 expression were associated with poor overall survival.

Conclusion

Tumor mesothelin expression associated with the TME immune landscape predicts the risk of death for patients with MPM and could be a new target for immunotherapy in MPM.