Furthermore, the design of PolyPEPI1018 excludes peptides containing self-epitopes, thus reducing the risk of autoimmune and/or hypersensitivity reactions to a minimum. Treos Bio ZRT OBERTO -101 Amendment 3 Product: PolyPEPI 1018 Colorectal Cancer Vaccine Page 28 of 81 CONFIDENTIAL 2 STUDY OBJECTIVE S 2.1 Primary Objectives The primary objective of this study is : • To evaluate the safety and tolerability of a multiple doses of PolyPEPI1018 as an add - on to maintenance therapy in subjects with metastatic colorectal cancer (mCRC) 2.2 Secondary Objectives The secondary objectives of th is study are: • To identify PEPIs (Personal EPItopes capable of inducing T cell responses in an individual) from PolyPEPI1018 in each study subject • To evaluate the immunogenicity of PolyPEPI1018 by measuring both effector and memory T cell responses • To evaluate initial efficacy of PolyPEPI1018 by evaluating Objective Response Rate (ORR) 2.3 Exploratory Objectives The exploratory objectives of this study are: • To explore the correlation between PEPIs and T cell responses • To explore the correlation between PEPIs and tumor infiltrating lymphocytes • To explore the correlation between T cell responses and tumor infiltrating lymphocytes • To explore the correlation between PEPIs and ORR • To explore the correlation between T cell responses and ORR Treos Bio ZRT OBERTO -101 Amendment 3 Product: PolyPEPI 1018 Colorectal Cancer Vaccine Page 29 of 81 CONFIDENTIAL 3 STUDY DESIGN 3.1 Overall Study Design This is a Phase 1, open-label, non-randomized, multicenter study to evaluate the safety, tolerability, immunogenicity and efficacy of multiple subcutaneous (SC) injections of PolyPEPI1018 as an add-on immunotherapy to the standard-of- care maintenance therapy in approximately 10 subjects with mCRC. This is an amended Study Design only in the USA: 5 subjects in Italy are under evaluat ion after only a single SC injection of the same vaccine, as originally planned.