Abstract Malignant Pleural Mesothelioma (MPM) is one of the most clinically aggressive malignancies, with a median survival time of less than 12 months. The monotherapy or combination of therapy with platinum-antifolate chemotherapy agents, may provide survival and life quality improvement in MPM patients. EGFR has been a target for new development drugs that could be used as oncologyc treatment. Nimotuzumab is a humanized antibody, design by Centro de Inmunología Molecular (Habana, Cuba), for treatment EGFR overexpress neoplasms. This antibody was approved for treatment of head and neck cancer and metastasic colorectal cancer. MPM exhibit an important expression of EGFR. In this study, we analyzed the efect of nimotuzumab on two cell lines derived of MPM and a xenograph model of one of them, in atimic nude mouse model. MSTO-211 and H2452 mesothelioma cell lines; MRC-5 normal lung cell line and A431 as EGFR positive cell line were used for all assays. We analyzed the viability of cell lines using violet cristal assays. Apoptosis were analyzed with Anexin-V-Fluos Staining kit accordin to manufacturer instructions. We analyzed the EGFR expression by WB assays. Finally, we generated a xenograft model with MSTO cells in nu/nu mice, and we treated a group with nimotuzumab or cisplatin-gemcitabine one doses/week. Nimotuzumab at any concentration (50, 100, 400 μg/mL) no modified the cellular viability, in both tumor and normal cells, the assays was followed from 24 h to 96 h after exposition. With respect at apoptosis, we no found significant diferences between control and exposured samples at 48 and 72 h after nimotuzumab treatment. In order to analyzed the EGFR expression in mesothelioma cell lines, we obtained protein total extract and then a WB was realized. The total protein from MSTO-211, H2452, A431 and MRC-5 cultures in normal conditions and exposed at nimotuzumab 100 μg/mL by 24h, were obtained; then a PAGE-SDS were realized. We observed that both mesotelioma derived cell lines showed similar EGFR expresion when it compared with A431 in normal culture conditions; while MRC-5 no showed EGFR expresion. When cellular cultures were exposed to nimotuzumab 100 μg/mL by 24h, H2452 and A431 cells showed similar EGFR expression while MSTO-211 showed high expression. Mice nu/nu (n=3) were subcutaneously inoculated in the dorsal right flank with MSTO-211 cells. Treatment was applied to animals when tumors were 50 mm3. First mice group received nimotuzumab, second group received cisplatin-gemcitabine; and third group no received treatmed. Nimotuzumab induced a reduction in tumor volumen and mice survival by 4 weeks more that those in the other groups. In vitro exposition of nimotuzumab in mesotelioma cell lines no affect their viability or induce apoptosis. According with the treatment scheme used in this work, nimotuzumab treatment induce a major survival and low toxicity in mice with mesothelioma pleural malignant xenograph. Citation Format: Saé Muñiz-Hernández, Vanessa Izquierdo-Sánchez, Jorge A. Mendoza-Desión, Carolina González-Torres, Oscar Arrieta. Efect of nimotuzumab on malignant pleural mesothelioma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 25. doi:10.1158/1538-7445.AM2017-25