PharmaMar has announced data from a Phase 2 study in patients with sarcomatoid/biphasic malignant pleural mesothelioma showing that 41.2% (95% CI: 18.4-67.1) of patients treated with the anticancer drug trabectedin in second line were alive and free of progression at 12 weeks. The median progression-free survival (PFS) in these 17 evaluated patients was 8.3 weeks. There were 5 patients who continue receiving trabectedin beyond 12 weeks.
"Mesothelioma patients usually do not respond to second-line treatments so the preliminary data we observed here is encouraging. This study also adds to the scarce evidence-based science in this disease, as the use of trabectedin is based on its direct effect on tumor-associated macrophages and its efficacy in different tumors, including soft tissue sarcomas." Said Diego Luigi Cortinovis, MD, Medical Oncologist San Gerardo Hospital, Monza, Italy. "Given the aggressiveness of this disease and the poor response of this mesothelioma population, the indication that this treatment might be active in these patients is a major advance and warrants further investigation in a larger population."
The lead author Dr. Diego Luigo Cortinovis, San Gerardo Hospital, Monza, Italy presented the full data at the 51st Annual Meeting of the American Society of Clinical Oncology (ASCO) (Abstract#7561, Poster Board 309).
About the Phase 1b study with PM1183 and doxorubicin
- ATREUS is an Italian multicenter single arm phase II trial (trial number: NCT02194231) sponsored by the Department of Oncology of the Mario Negri Institute for Pharmacological Research (Milan, Italy) that evaluates trabectedin as second line therapy in two separate patient cohorts--a pre-treated epithelioid group, and a smaller naïve or pre-treated biphasic/sarcomatoid groups with two distinct activity endpoints. Subjects were treated with trabectedin at 1.3 mg/m2 infused over 3 hours every 21 days until progression or unacceptable toxicity and treatment response evaluated according to Modified RECIST criteria for MPM.
- The primary endpoint is the PFS at 12 weeks (pproportion of patients free from progression or death at 12 weeks) from the first treatment date, and secondary endpoints include PFS, objective response rate (ORR), overall survival (OS), safety, pain intensity and biological parameters in tumor tissue and blood.
- At 12 weeks, 41.2 percent of the sarcomatoid MPM patients (7 out of 17) patients (95% CI: 18.4-67.1) were alive and free of progression, showing a median PFS of 8.3 weeks (IQR: 6.9-18.4). Five patients (29.4%) continued treatment beyond 12 weeks, receiving trabectedin within a of range 1-10 cycles.
- The evaluated patients included 14 men and 3 women with a median age of 67.7% and 10 patients were smokers. All subjects showed advanced disease (41% and 59% with stage III and IV, respectively) disease and 7 patients did not receive any previous treatment.
- By the time of analysis, 12 patients interrupted treatment because of disease progression, 4 patients stopped treatment due to death and one person withdrew from the trial.
- The most frequent adverse effect was hepatic toxicity, which was observed in 10 patients. Grade 3 or more adverse events were non febrile neutrophil count, which occurred in 2 patients, nausea that affected 3 patients, and single cases were presented with vomiting, mucositis and fever/infection. Grade 1 and 2 fatigue was a frequent and debilitating treatment complication.
- Two serious adverse events, whose causal connection to trabectedin could not be excluded, occurred. One was fatal. Two serious adverse events, possibly related to trabectedin, occurred, and one was fatal.
Mesothelioma is a type of cancer mainly caused by asbestos exposure and patients usually show symptoms after a long period of time. In malignant disease, tumor cells normally form in the thin tissue layer (called pleura) that covers the lung, chest wall, or abdomen. The most common type of malignant disease is epithelial, which forms in the cells that line organs, and there is also a second type called sarcomatoid. The former type is less aggressive and patients have a better prognosis compared to other types . The number of new cases of malignant mesothelioma worldwide has been rising in the last 70 years and the numbers highly vary within and between countries. In the US, there are about 3,000 new cases being diagnosed each year mostly in elderly men , but in Australia and some European countriesthe incidence of mesothelioma may still be rising. In Italy 2004, there were 2.4 new cases per 100.000 people in 2004 . Malignant mesothelioma is characterized by increased chronic inflammation in the tumor microenvironment and the role of tumor associated macrophage (TAM) . The prognosis of patients with mesothelioma is poor with a 5-year survival rate of about 10 percent and a median survival time for those diagnosed with advance disease stage IV of about 12 months .