A phase II study of the combination of gemcitabine and imatinib mesylate in pemetrexed-pretreated patients with malignant pleural mesothelioma

Crosstalk with lung fibroblasts shapes the growth and therapeutic response of mesothelioma cells

Mesothelioma is an aggressive cancer of the mesothelial layer associated with an extensive fibrotic response. The latter is in large part mediated by cancer-associated fibroblasts which mediate tumour progression and poor prognosis. However, understanding of the crosstalk between cancer cells and fibroblasts in this disease is mostly lacking. Here, using co-cultures of patient-derived mesothelioma cell lines and lung fibroblasts, we demonstrate that fibroblast activation is a self-propagated process producing a fibrotic extracellular matrix (ECM) and triggering drug resistance in mesothelioma cells. Following characterisation of mesothelioma cells/fibroblasts signalling crosstalk, we identify several FDA-approved targeted therapies as far more potent than standard-of-care Cisplatin/Pemetrexed in ECM-embedded co-culture spheroid models. In particular, the SRC family kinase inhibitor, Saracatinib, extends overall survival well beyond standard-of-care in a mesothelioma genetically-engineered mouse model. In short, we lay the foundation for the rational design of novel therapeutic strategies targeting mesothelioma/fibroblast communication for the treatment of mesothelioma patients.

Target Therapy in Malignant Pleural Mesothelioma: Hope or Mirage?

Malignant Pleural Mesothelioma (MPM) is a rare neoplasm that is typically diagnosed in a locally advanced stage, making it not eligible for radical surgery and requiring systemic treatment. Chemotherapy with platinum compounds and pemetrexed has been the only approved standard of care for approximately 20 years, without any relevant therapeutic advance until the introduction of immune checkpoint inhibitors. Nevertheless, the prognosis remains poor, with an average survival of only 18 months. Thanks to a better understanding of the molecular mechanisms underlying tumor biology, targeted therapy has become an essential therapeutic option in several solid malignancies. Unfortunately, most of the clinical trials evaluating potentially targeted drugs for MPM have failed. This review aims to present the main findings of the most promising targeted therapies in MPM, and to explore possible reasons leading to treatments failures. The ultimate goal is to determine whether there is still a place for continued preclinical/clinical research in this area.

Co-Delivery of Daunorubicin and Homoharringtonine in Folic Acid Modified-Liposomes for Enhancing Therapeutic Effect on Acute Myeloid Leukemia

Acute myeloid leukemia (AML) remains a threatening disease due to severe complications, drug resistance, and high recurrence rates. Many drug combinations have demonstrated enhanced therapeutic effects in clinical practice. However, it requires complicated dosing regimens and is accompanied by increased toxicity. This study explored the combined effect of two therapeutic agents, daunorubicin (DNR) and homoharringtonine (HHT) in cell viability, apoptosis, and cell cycle in vitro and verified their synergistic effect. We encapsulated the two drugs into liposomes to construct a folic acid-modified co-delivery system (FA-DH-LP) to achieve an effective and safe therapeutic strategy. The FA-DH-LP was prepared by film hydration method. The resultant FA-DH-LP was homogeneously spherical and showed good blood compatibility with high encapsulation efficiency for DNR and HHT. The FA-DH-LP exhibited higher cellular uptake in HL60 and K562 cells and enhanced cytotoxicity than DNR/HHT co-delivery liposomes without folic acid modification (DH-LP) in vitro. In the HL60 subcutaneous xenotransplantation model, FA-DH-LP showed improved tumor targeting ability, anti-leukemia activity and safety profile superior to free combinational drugs and DH-LP after 18-day treatment. The results demonstrated that FA-DH-LP might present a promising delivery strategy to improve the efficacy of the two combinational chemotherapeutics while reducing toxicity.

High tumor cell platelet-derived growth factor receptor beta expression is associated with shorter survival in malignant pleural epithelioid mesothelioma

Malignant pleural mesothelioma (MPM) has a rich stromal component containing mesenchymal fibroblasts. However, the properties and interplay of MPM tumor cells and their surrounding stromal fibroblasts are poorly characterized. Our objective was to spatially profile known mesenchymal markers in both tumor cells and associated fibroblasts and correlate their expression with patient survival. The primary study cohort consisted of 74 MPM patients, including 16 patients who survived at least 60 months. We analyzed location-specific tissue expression of seven fibroblast markers in clinical samples using multiplexed fluorescence immunohistochemistry (mfIHC) and digital image analysis. Effect on survival was assessed using Cox regression analyses. The outcome measurement was all-cause mortality. Univariate analysis revealed that high expression of secreted protein acidic and cysteine rich (SPARC) and fibroblast activation protein in stromal cells was associated with shorter survival. Importantly, high expression of platelet-derived growth factor receptor beta (PDGFRB) in tumor cells, but not in stromal cells, was associated with shorter survival (hazard ratio [HR] = 1.02, p < 0.001). A multivariable survival analysis adjusted for clinical parameters and stromal mfIHC markers revealed that tumor cell PDGFRB and stromal SPARC remained independently associated with survival (HR = 1.01, 95% confidence interval [CI] = 1.00-1.03 and HR = 1.05, 95% CI = 1.00-1.11, respectively). The prognostic effect of PDGFRB was validated with an artificial intelligence-based analysis method and further externally validated in another cohort of 117 MPM patients. In external validation, high tumor cell PDGFRB expression associated with shorter survival, especially in the epithelioid subtype. Our findings suggest PDGFRB and SPARC as potential markers for risk stratification and as targets for therapy.

Synergistic antitumor effect of dual PI3K and mTOR inhibitor NVP-BEZ235 in combination with cisplatin on drug-resistant non-small cell lung cancer cell

Cisplatin resistance is an obstacle for the effective treatment of non-small cell lung cancer (NSCLC). The combined use of two or more chemotherapeutic agents displays advantages for the clinical treatment of drug-resistant lung cancer. The present study aimed to assess the synergy of the dual PI3K/Akt/mTOR signaling pathway inhibitor NVP-BEZ235 and cisplatin, a chemotherapeutic agent, on proliferation, apoptosis, cell cycle arrest and protein expression in cisplatin-resistant NSCLC A549/diamminedichloroplatinum resistance (DDP) cells. Cell proliferation was determined by performing Cell Counting Kit 8 and colony formation assays. Combination index (CI) was used to assess the combinatorial effects of NVP-BEZ235 and cisplatin. Cellular apoptosis and cell cycle arrest were detected via flow cytometry. Western blotting was performed to evaluate protein expression levels relative to β-actin. Cisplatin and NVP-BEZ235 displayed the strongest synergy (CI₅₀=0.23) at the mass ratio of 10:1. The half inhibitory concentrations of cisplatin and NVP-BEZ235 at 10:1 were 1.53 and 0.15 µg/ml, respectively. Compared with the control group, the combination of cisplatin and NVP-BEZ235 induced cell apoptosis and inhibited colony formation. Furthermore, compared with the control group, phosphorylation of Akt and p70S6 Kinase was significantly inhibited and cell cycle was arrested at G₀G₁ phase in the combination treatment group. The expression levels of drug efflux proteins, such as multidrug resistance-associated protein 1 and ATP-binding cassette sub-family G member 2, were significantly decreased when A549/DDP cells were treated with a combination of cisplatin and NVP-BEZ235 compared with the control group. Collectively, the present study indicated that the combined treatment of cisplatin and NVP-BEZ235 displayed synergistic antitumor effects on drug-resistant A549/DDP cells, by which the antiproliferative effects may occur via inhibition of the PI3K/Akt/mTOR signaling pathway and downregulation of drug efflux.