A 4-1BB ligand (4-1BBL) trimer-containing antigen binding molecule comprising (a) at least one Fab molecule capable of specific binding to PD1 comprising a VH domain comprising (i) HVR-H1 comprising the amino acid sequence of SEQ ID NO:13, (ii) HVR-H2 comprising the amino acid sequence of SEQ ID NO:14, and (iii) HVR-H3 comprising the amino acid sequence of SEQ ID NO:15, and a VL domain comprising (iv) HVR-L1 comprising the amino acid sequence of SEQ ID NO:16, (v) HVR-L2 comprising the amino acid sequence of SEQ ID NO:17, and (vi) HVR-L3 comprising the amino acid sequence of SEQ ID NO:18, and (b) a first polypeptide containing a first heavy chain constant domain (CH1) or a constant light chain domain (CL) and a second polypeptide containing a CL or CH1 domain, respectively, wherein the second polypeptide is linked to the first polypeptide by a disulfide bond between the CH1 and CL domain, wherein the antigen binding molecule is characterized in that the first polypeptide comprises two ectodomains of 4-1BBL comprising the amino acid sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7 and SEQ ID NO:8 that are connected to each other and to the CH1 or CL domain by a peptide linker and in that the second polypeptide comprises one ectodomain of 4-1BBL comprising the amino acid sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7 and SEQ ID NO:8 connected via a peptide linker to the CL or CH1 domain of said polypeptide, and (c) an Fc domain composed of a first and a second subunit capable of stable association, wherein the Fc domain is an IgG1 Fc domain comprising the amino acid substitutions L234A, L235A and P329G (numbering according to Kabat EU index). (a) at least one Fab molecule capable of specific binding to PD1 comprising a VH domain comprising (i) HVR-H1 comprising the amino acid sequence of SEQ ID NO:13, (ii) HVR-H2 comprising the amino acid sequence of SEQ ID NO:14, and (iii) HVR-H3 comprising the amino acid sequence of SEQ ID NO:15, and a VL domain comprising (iv) HVR-L1 comprising the amino acid sequence of SEQ ID NO:16, (v) HVR-L2 comprising the amino acid sequence of SEQ ID NO:17, and (vi) HVR-L3 comprising the amino acid sequence of SEQ ID NO:18, and (b) a first polypeptide containing a first heavy chain constant domain (CH1) or a constant light chain domain (CL) and a second polypeptide containing a CL or CH1 domain, respectively, wherein the second polypeptide is linked to the first polypeptide by a disulfide bond between the CH1 and CL domain, wherein the antigen binding molecule is characterized in that the first polypeptide comprises two ectodomains of 4-1BBL comprising the amino acid sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7 and SEQ ID NO:8 that are connected to each other and to the CH1 or CL domain by a peptide linker and in that the second polypeptide comprises one ectodomain of 4-1BBL comprising the amino acid sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7 and SEQ ID NO:8 connected via a peptide linker to the CL or CH1 domain of said polypeptide, and (c) an Fc domain composed of a first and a second subunit capable of stable association, wherein the Fc domain is an IgG1 Fc domain comprising the amino acid substitutions L234A, L235A and P329G (numbering according to Kabat EU index). <EOS>