Mesothelioma Avastin® Cisplatin Pemetrexed Study (MAPS): New Triplet Therapy Shows Significant Improvement in Overall Survival (OS) in Patients with Malignant Pleural Mesothelioma

The following content is based on the article "Bevacizumab for newly diagnosed pleural mesothelioma in the Mesothelioma Avastin Cisplatin Pemetrexed Study (MAPS): a randomised, controlled, open-label, phase 3 trial" written by Professor Gérard Zalcman, M.D., et al. that was published in The Lancet (2015 Dec 21. pii: S0140-6736(15)01238-6. [Epub ahead of print]).

Malignant pleural mesothelioma is a type of cancer that originates in the mesothelium—the tissue lining around the lungs. This rare, yet aggressive, form of cancer is primarily attributed to occupational exposure to asbestos and most often offers patients a poor prognosis.

When pleural mesothelioma is diagnosed at an early stage, resection is often a treatment option for patients. However, for the majority of patients whose diagnoses occur at an advanced stage when resection is not an option, the standard course of therapy for over a decade has been a chemotherapy combination of cisplatin and pemetrexed, as no other studied treatment regimen to date has been able to demonstrate improved OS (overall survival). That is, until now.

Professor Gérard Zalcman, M.D., President of the French Collaborative Thoracic Intergroup and principal investigator of the MAPS study, along with his colleagues, conducted a randomized, controlled, open-label, phase 3 trial in patients (aged 18-75 years) with unresectable malignant pleural mesothelioma who had not previously received any type of chemotherapy treatment. The purpose of the study was to assess the effect on survival of Avastin® (bevacizumab) when added to the current treatment standard of cisplatin in combination with pemetrexed.

448 patients were randomly assigned to receive (intravenously) pemetrexed (500 mg/m²) plus cisplatin (75 mg/m²) with (PCB-223 patients) or without (PC-225 patients) bevacizumab (15 mg/kg) for a period of time ranging from February 13, 2008 through January 5, 2014. The primary endpoint of this study was OS, while progression-free survival (PFS) and safety and quality of life (QoL) served as secondary endpoints.

At the conclusion of this study, OS was statistically longer with PCB (median OS: 18.8 months) than PC (median OS: 16.1 months)—a median gain in survival of 2.7 months representing a statistically significant 24 percent reduction in the risk of death for patients administered PCB. Also, the study demonstrated a significant improvement in PFS for patients in the PCB group vs. the PC group (median PFS: 9.6 months vs. 7.5 months; HR=0.61, p<0.0001). The study’s safety data showed both arms having similar Grade3-4 hematological toxicities (49.6% in the PC arm vs. 47.3% in the PCB arm).

Regarding the study’s findings, Professor Zalcman commented: “For too long, patients with mesothelioma have been underserved in terms of treatment options compared to other types of cancer. These data are an important treatment advance and may offer a potential new standard of care.”