The IMmunotherapy Pleural 5-ALA PDT

Inclusion Criteria: * ECOG Performance status (PS) 0-1 (WHO) * Unresectable Malignant Pleural Mesothelioma * suffering from unresectable MPM (n=20), relapsing after one or 2 lines of treatment with platinum-based doublet of chemotherapy (including pemetrexed) \[Note: MPM patients having contra-indications for, or refusing chemotherapy may also be recruited\], and candidate for palliative pleural procedure (i.e. thoracoscopy for pleurodesis by talc or by insertion of indwelled pleural catheter, IPC) * Documented progression after previous 1 or 2 lines of chemotherapy including Platinum/Pemetrexed chemotherapy\* * Measurable disease according to modified RECIST 1.1. for MPM * Malignant pleural lesion assessed to be accessible by local PDT treatment during thoracoscopy, as validated by expert MTB ("MESOCLIN", Lille, France) * Histological diagnosis confirmed by national expert pathology panel ("MESOPATH" - Institut Léon Bérard, Lyon, France) * Weight loss \<10% * available tumor tissue (archival or fresh) * obtention of an informed written consent before any specific procedure of the study * Decision to treat the patient within this clinical trial taken during MPM dedicated multidisciplinary board (RCP MESOCLIN in France ) * Patient affiliated to and covered by social security for standard care * Women of child-bearing potential must use a highly effective method of contraception for 28 days prior to the first dose of investigational product, and must agree to continue using such precautions for 5 months after the final dose of investigational product * Women of child-bearing potential must have a negative pregnancy test within 24h before administration of investigational product * First line patients may also be recruited if they declined or if they have contra-indications for chemotherapy. Exclusion Criteria: * lack of informed written consent; or refusal to sign or to participate * Pregnant, breastfeeding patients, and female patients of childbearing potential who are unwilling or unable to use a highly effective method of contraception as outlined in the protocol for the duration of the study and for at least 5 months after the last dose of nivolumab * Male patients who are unwilling or unable to use contraception methods for the duration of the study and for at least 7 months after the last dose of nivolumab * a previous treatment by anti-PD-1 or anti-PD-L1 antibodies for their cancer or any other cancer in the last 5 years * hypersensitivity to Nivolumab (anti-PD-1 antibodies) * contra-indications for 5-ALA or PDT * contra-indications for thoracoscopy (VATS) * any other comorbidity precluding the feasibility of the therapeutic protocol: uncontrolled cardiac failure, pulmonary hypertension, liver or kidney severe dysfunction (creatinin clearance \<60 ml/min), uncontrolled infection, or other disease according to the investigator * other cancer treated within 5 years before inclusion except baso-cellular skin carcinoma or cervical / bladder in situ carcinoma * inability to receive study information and to give informed consent * patient unable to have a clinical follow-up due to psychological, familial, social or geographical reasons * legal incapacity (people in jail), or under supervision (i.e. guardianship or curatorship) * treatment with experimental drug within 30 days before the start of the study