Aim of this study is to provide the "proof of concept" of efficacy and tolerability of lurbinectedin monotherapy in progressive malignant mesotheliomas.

Malignant mesothelioma arises from the mesothelial cells of the pleural, peritoneal or pericardial lining and is often associated with asbestos exposition. There is no cure for most malignant mesotheliomas and the scope of all three major oncological therapeutic procedures (surgery, radiotherapy and chemotherapy) is to reduce/eliminate symptoms as well as to prolong progression free survival (PFS) and/or overall survival (OS). While progressive patients are still in good health able to undertake a second-line treatment, there is no standard treatment for progressive disease.

Lurbinectedin is a novel compound structurally related to trabectedin and with similar mode of action. Pre-clinical data showed a better safety profile than trabectedin. Lurbinectedin has been already tested in different Phase I-II trials showing promising activity in ovarian, pancreatic, breast, small and non-small cell lung cancer as well as in other tumor types, with objective responses averaging 30%, disease stabilization up to 75% and having manageable toxicity. Although lurbinectedin has not been widely tested in mesotheliomas, some mesothelioma patients have been already treated with lurbinectedin where again promising activity has been observed.

Inclusion Criteria:

• Written informed consent according to ICH/GCP regulations before registration and prior to any trial specific procedures
• Histologically confirmed malignant mesothelioma (all histologies are eligible)
• Progression on or after one line of platinum-based combination chemotherapy. Any previous treatment with surgery or radiotherapy is allowed
• ≤ 1 line of treatment with an immune checkpoint inhibitor
• Prior systemic treatment stopped at least 4 weeks before registration
• Measurable or evaluable disease according to the modified RECIST criteria for malignant pleural mesothelioma
• Age ≥ 18 years
• ECOG performance status ≤ 1
• Adequate bone marrow function: hemoglobin ≥ 90 g/L; absolute neutrophil count ≥ 2 x 109/L, platelet count ≥ 100 x 109/L
• Adequate hepatic function: total bilirubin ≤ 1.5 ULN (except for patients with Gilbert's disease ≤ 3.0 x ULN); aspartate aminotransferase and alanine aminotransferase ≤ 3.0 x ULN; albumin ≥ 30 g/L
• Adequate renal function: creatinine clearance ≥ 30 mL/min/1.73, calculated according to the corrected formula of Cockcroft-Gault
• Women with child-bearing potential are using effective contraception, are not pregnant or lactating and agree not to become pregnant during trial treatment and during 6 months thereafter. A negative pregnancy test before registration (within 7 days) into the trial is required for all women with child-bearing potential
• Men agree not to father a child during trial treatment and during 6 months after last treatment infusion.

Exclusion Criteria:

• Known brain or leptomeningeal metastases
• History of another hematologic or primary solid tumor (except for curatively treated basal or squamous cell carcinoma of the skin, properly treated in situ malignant melanoma, in situ carcinoma of the uterine cervix or pT1-2 prostate cancer with Gleason score ≤6) within five years prior to registration
• More than one previous line of chemotherapy. Re-challenge is not allowed
• Prior treatment with lurbinectedin or trabectedin
• Treatment with any other experimental drug within 4 weeks before registration
• Concomitant use of other anti-cancer drugs, anti-cancer surgical intervention or radiotherapy except for local pain control and/or other local symptoms (e.g. pleurodesis due to dyspnea)
• Grade > 1 from any AE derived from previous treatment; alopecia any grade, grade ≤ 2 peripheral neuropathy and clinically not significant elevation of GGT grade ≤ 2 (according to the NCI-CTCAE v4.03) are allowed
• Treatment with cortisone (prednisolone > 10 mg or equivalent) for immune-mediated side effects from previous immunotherapy (if applicable)
• Severe or uncontrolled cardiovascular disease (congestive heart failure NYHA III or IV), unstable angina pectoris, history of myocardial infarction within the last six months, serious arrhythmias requiring medication (with exception of atrial fibrillation or paroxysmal supraventricular tachycardia)
• Severe or uncontrolled endocrinopathy due to previous immune checkpoint inhibitor treatment (if applicable)
• Known history of human immunodeficiency virus or active chronic hepatitis C or hepatitis B virus infection or any uncontrolled active systemic infection requiring intravenous antimicrobial treatment
• Known hypersensitivity to the trial drug or to any component of the trial drug
• Any other serious underlying medical, psychiatric, psychological, familial or geographical condition, which in the judgment of the investigator may interfere with the planned staging, treatment and follow-up, affect patient compliance or place the patient at high risk from treatment-related complications.