Abstract Cancer arises from the accumulation of genomic alterations and epigenetic changes that constitute a hallmark of cancer. Owing to the molecular heterogeneity in cancer, only a minor fraction of patients profit from approved therapies. Available targeted therapies can only address alterations common to a particular type of cancer and induce transient effects due to the generation of resistant sub-clones. In contrast, the IVAC MUTANOME project aims to immunologically target multiple cancer mutations uniquely expressed in a given patient's tumor. The IVAC MUTANOME approach should be applicable to the majority of patients irrespective of the tumor entity and offers the potential to exploit the whole tumor mutanome of a given patient using a multi-target approach. The IVAC approach is supported by (i) the availability of technologies that allow fast discovery and validation of individual mutations based on sequencing of whole exome and (ii) an innovative vaccine platform based on RNA-technology supporting fast manufacturing and release of patient-specific vaccines targeting multiple immunogenic mutations within weeks. The phase I study to test the individualized cancer immunotherapeutics for the treatment of malignant melanoma was approved and initiated in 2013 (NCT02035956). With that, the IVAC MUTANOME trial is the first trial in Europe that introduces a fully personalized mutanome vaccine for cancer. The objectives of the clinical trial are to study the feasibility, safety, tolerability and immunogenicity of the IVAC MUTANOME approach for malignant melanoma. Feasibility will be shown by the proven ability to provide the fully personalized IVAC MUANOME vaccine to patients. Recruitment of a patient in the trial repetitively triggers the IVAC MUTANOME process covering (i) the receipt of tumor and blood sample specimens, (ii) the identification, prioritization and confirmation of mutations, (iii) testing of pre-existing immunity against private tumor mutations, (iv) the final selection of mutated sequences, (iv) design, production of a DNA lead structure, (v) GMP manufacturing and release of the patient-specific mRNA, (vi) shipment to the clinical trial site, and (vii) the administration of the IMP to patients. The IVAC MUTANOME recruitment status, manufacturing experiences and treatment status of this first-in-class clinical trial as well as novel data on the immune assessment incl. vaccine-induced mutation-specific T cell responses of the first patients treated will be presented. Citation Format: Bjoern-Philipp Kloke, Cedrik M. Britten, Carmen Loquai, Martin Löwer, Sebastian Attig, Valesca Bukur, Nicole Bidmon, Evelyna Derhovanessian, Jan Diekmann, Mustafa Diken, Angela Filbry, Stephan Grabbe, Sandra Heesch, Christoph Hoeller, David Langer, Uli Luxemburger, Matthias Miller, Felicitas Mueller, Tina Mueller-Brenne, Inga Ortseifer, Burkhard Otte, Anna Paruzynski, Sebastian Petri, Richard Rae, Christine Seck, Kristina Spieß, Arbel D. Tadmor, Jochen Utikal, Klaus Kuehlke, John Castle, Alexandra Kemmer-Brueck, Isabel Vogler, Andreas N. Kuhn, Sebastian Kreiter, Oezlem Tuereci, Ugur Sahin. IVAC MUTANOME: Individualized vaccines for the treatment of cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT202. doi:10.1158/1538-7445.AM2015-CT202