Current options for systemic therapy in mesothelioma

Malignant mesothelioma as a difficult interdisciplinary problem

The authors of the present report review the etiology and clinical symptoms of malignant pleural mesothelioma (MPM) as well as diagnostic techniques (both radiological and biomarkers) used for its detection. Subsequently, they present methods of multimodal treatment (surgery, chemotherapy, and radiotherapy) recommended by the International Mesothelioma Interest Group (IMIG). Finally, they discuss complications and long-term results associated with these methods of MPM treatment.

Multimodality therapy for malignant pleural mesothelioma: surgery plus chemoradiotherapy?

Malignant pleural mesothelioma, well known for its association with asbestos exposure, is an aggressive cancer of the pleura with poor prognosis if left untreated. There is no defined standard of care, but with curative surgery-based multimodality therapy, long-term survival has been documented. In addition to radiation and/or chemotherapy, multimodality therapy includes one of two operations (extrapleural pneumonectomy or radical pleurectomy/decortication) performed with the goal of resecting all gross disease. Ongoing trials are evaluating various treatment strategies involving radical resection, chemotherapy, radiation, intracavitary chemotherapy, photodynamic therapy and immunologic/biologic agents. Improvement in early diagnosis, targeted treatment and adjuvant therapy to control micrometastatic disease are needed to improve outcomes for patients with this challenging disease.

A predictive model for evaluating responsiveness to pemetrexed treatment in patients with advanced colorectal cancer

PURPOSE

To highlight the potential factors that could predict the response rate of patients with metastatic colorectal cancer (mCRC) treated with pemetrexed combined chemotherapy after first- or second-line chemotherapy using the FOLFOX regimen.

MATERIALS AND METHODS

Between January 2007 and July 2014, 54 patients diagnosed and pathologically-confirmed with advanced colorectal cancer in Jiangsu Cancer Hospital and Research Institute, were enrolled. They received pemetrexed at a dose of 500mg/m2 by 10 minute infusion on day 1, repeated every 3 weeks. Doses were modified depending on nadir counts of blood cells. Combined chemotherapeutic agents included irinotecan, lobaplatin, carboplatin, oxaliplatin, gemcitabine, cis-platinum or bevacizumab. Multiple variables (age, sex, hemoglobin, platinum drugs combined, metastasis sites, LDH, ALP, CEA>40 ug/ml) reported earlier were selected.We used logistic regression analysis to evaluate relationships between these and tumor response.

RESULTS

On multivariable analysis, we found that age was significant in predicting the responsiveness to pemetrexed (p<0.05) combined with oxaliplatin. We did not find any other factors which were significantly associated with the response rate to chemotherapy with pemetrexed and irinotecan.

CONCLUSIONS

By multivariate analysis, we found that age had significant impact on the responsiveness of pemetrexed when combined with oxaliplatin. Additional research based on genomic properties of host and tumors are needed to clarify markers for better selection of patients who could benefit from pemetrexed combined chemotherapy.

Suppression of activin A signals inhibits growth of malignant pleural mesothelioma cells

BACKGROUND

Activins control the growth of several tumour types including thoracic malignancies. In the present study, we investigated their expression and function in malignant pleural mesothelioma (MPM).

METHODS

The expression of activins and activin receptors was analysed by quantitative PCR in a panel of MPM cell lines. Activin A expression was further analysed by immunohistochemistry in MPM tissue specimens (N=53). Subsequently, MPM cells were treated with activin A, activin receptor inhibitors or activin-targeting siRNA and the impact on cell viability, proliferation, migration and signalling was assessed.

RESULTS

Concomitant expression of activin subunits and receptors was found in all cell lines, and activin A was overexpressed in most cell lines compared with non-malignant mesothelial cells. Similarly, immunohistochemistry demonstrated intense staining of tumour cells for activin A in a subset of patients. Treatment with activin A induced SMAD2 phosphorylation and stimulated clonogenic growth of mesothelioma cells. In contrast, treatment with kinase inhibitors of activin receptors (SB-431542, A-8301) inhibited MPM cell viability, clonogenicity and migration. Silencing of activin A expression by siRNA oligonucleotides further confirmed these results and led to reduced cyclin D1/3 expression.

CONCLUSION

Our study suggests that activin A contributes to the malignant phenotype of MPM cells via regulation of cyclin D and may represent a valuable candidate for therapeutic interference.

Temsirolimus inhibits malignant pleural mesothelioma growth in vitro and in vivo: synergism with chemotherapy

INTRODUCTION

Human malignant pleural mesothelioma (MPM) is an asbestos-related malignancy characterized by frequent resistance to chemotherapy and radiotherapy. Here, we investigated the feasibility of mammalian target of rapamycin (mTOR) inhibition by temsirolimus as an antimesothelioma strategy.

METHODS

Phosphorylation of mTOR (p-mTOR) was assessed by immunohistochemistry in MPM surgical specimens (n = 70). Activation of mTOR and impact of mTOR inhibition by temsirolimus was determined in MPM cell lines in vitro (n = 6) and in vivo as xenografts in severe combined immunodeficiency mice (n = 2) either as single agent or in combination with cisplatin.

RESULTS

Strong immunoreactivity for p-mTOR was predominantly detected in epitheloid and biphasic but not sarcomatoid MPM specimens while adjacent normal tissues remained widely unstained. Accordingly, all mesothelioma cell lines harbored activated mTOR, which was further confirmed by hyperphosphorylation of the downstream targets pS6K, S6, and 4EBP1. Temsirolimus potently blocked mTOR-mediated signals and exerted a cytostatic effect on mesothelioma cell lines in vitro cultured both as adherent monolayers and as nonadherent spheroids. Mesothelioma cells with intrinsic or acquired cisplatin resistance exhibited hypersensitivity against temsirolimus. Accordingly, cisplatin and temsirolimus exerted synergistic inhibition of the mTOR downstream signals and enhanced growth inhibition and/or apoptosis induction in mesothelioma cell lines. Finally, temsirolimus was highly active against MPM xenograft models in severe combined immunodeficiency mice both as a single agent and in combination with cisplatin.

CONCLUSION

The mTOR inhibitor temsirolimus is active against mesothelioma in vitro and in vivo and synergizes with chemotherapy. These data suggest mTOR inhibition as a promising novel therapeutic strategy against MPM.

A new standard of care for the management of peritoneal surface malignancy

Cancer dissemination to peritoneal surfaces was, in the past, a lethal condition with a limited survival. Clinical and pharmacologic research have shown that options for both treatment and prevention are now reality. The diseases most commonly treated include peritoneal dissemination from appendiceal malignancy, colorectal malignancy, and peritoneal mesothelioma. Selection factors are important to minimize the number of treated patients who will experience short-term benefit. Treatments involve cytoreductive surgery and perioperative chemotherapy. The intraperitoneal chemotherapy in the operating room is used with heat. Although this combined approach has been criticized, the informed oncologist will seek to identify those patients that may benefit from this more optimistic concept of peritoneal dissemination of cancer.

[Value of tomotherapy in malignant pleural mesothelioma: first clinical results]

INTRODUCTION

There is little clinical data about the place of helicoidal tomotherapy (HT) in the treatment of malignant pleural mesothelioma (MPM). This new form of intensity modulated radiotherapy (IMRT) has great theoretical advantages in large and complex volumes when compared to "traditional" forms of radiotherapy.

PATIENTS AND METHODS

Fourteen patients diagnosed with MPM received adjuvant radiotherapy by HT. The patients were treated at the Curie Institute and the René Gauducheau Centre, starting in August 12007. All patients had a complete initial staging, an extrapleural pneumonectomy (EPP), and a minimum follow-up of six months. The median dose prescribed to the surgical cavity was 50 Gy (48-54 Gy) in 2 Gy (1.80-2.07) fractions. High dose regions received concomitant 57 Gy (54-69 Gy) in 2.16 Gy (2.00-2.30 Gy) fractions.

RESULTS

Median follow-up was 12.6 months after ending HT. Seven patients received neoadjuvant chemotherapy (cisplatin or carboplatin, and pemetrexed). Eight patients were staged pT3 and five were staged pN1-2. HT was well tolerated. Two patients had suspected G5 radiation pneumonitis within 6 months of ending HT. Of the 12 patients who survived treatment, six relapsed (in average 5.1 months after HT): distant. Four relapses were distant; two relapses were both local and distant. Three patients died after their initial relapse. After initial diagnosis, the median survival was 18.4 months. A learning curve was observed in the optimization of the dosimetric parameters.

CONCLUSION

Helicoidal tomotherapy is a reliable, quite well tolerated, and efficient way of treating MPM patients after an EPP.

A phase I/II study of neoadjuvant chemotherapy with Pemetrexed (Alimta) in rectal cancer

AIM

The aim was to assess the feasibility of preoperative chemotherapy and possible tumour response using Pemetrexed (Alimta) in rectal cancer.

METHOD

The study was a prospective, non-randomized, single-centre phase I/II feasibility trial. 37 patients with resectable rectal cancer were recruited and given three 3-week cycles of preoperative Pemetrexed therapy. Tumour size and stage were assessed by MRI scans before and after chemotherapy. Treatment tolerability and response such as changes in tumour size and symptoms were assessed.

RESULTS

All patients completed the chemotherapy. Whilst mild side effects were frequent (grade 1, 34/37), the risk of severe effects was limited (grade 3 or 4, 4/37). Overall, there was a significant reduction in tumour size (p < 0.001). By RECIST criteria, one patient had tumour progression, 23/36 had stable disease and 12 patients had a response of up to 65%. There was also a significant decrease in the number of pre-treatment symptoms (p < 0.018) including reduction of bleeding and diarrhoea/constipation.

CONCLUSION

Preoperative (Neoadjuvant) treatment with Pemetrexed was feasible in studied patients. Serious side effects were limited and a radiological tumour response or stable disease was seen in a majority of patients.

Synergistic effect of gefitinib and rofecoxib in mesothelioma cells

BACKGROUND

Malignant mesothelioma (MM) is an aggressive tumor that is resistant to conventional modes of treatment with chemotherapy, surgery or radiation. Research into the molecular pathways involved in the development of MM should yield information that will guide therapeutic decisions. Epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) are involved in the carcinogenesis of MM. Combination of COX-2 and EGFR inhibitors, therefore, could be an effective strategy for reducing cell growth in those lines expressing the two molecular markers.

RESULTS

In order to verify the effect of COX-2 and EGFR inhibitors, five MM cell lines NCI-2452, MPP89, Ist-Mes-1, Ist-Mes-2 and MSTO-211 were characterized for COX-2 and EGFR and then treated with respective inhibitors (rofecoxib and gefitinib) alone and in combination. Only MPP89, Ist-Mes-1 and Ist-Mes-2 were sensitive to rofecoxib and showed growth-inhibition upon gefitinib treatment. The combination of two drugs demonstrated synergistic effects on cell killing only in Ist-Mes-2, the cell line that was more sensitive to gefitinib and rofecoxib alone. Down-regulation of COX-2, EGFR, p-EGFR and up-regulation of p21 and p27 were found in Ist-Mes-2, after treatment with single agents and in combination. In contrast, association of two drugs resulted in antagonistic effect in Ist-Mes-1 and MPP89. In these cell lines after rofecoxib exposition, only an evident reduction of p-AKT was observed. No change in p-AKT in Ist-Mes-1 and MPP89 was observed after treatment with gefitinib alone and in combination with rofecoxib.

CONCLUSIONS

Gefitinib and rofecoxib exert cell type-specific effects that vary between different MM cells. Total EGFR expression and downstream signalling does not correlate with gefitinib sensitivity. These data suggest that the effect of gefitinib can be potentiated by rofecoxib in MM cell lines where AKT is not activated.