Clec9A binding agents comprising a recombinant heavy-chain only antibody (VHH)

1. A C-type lectin domain family 9 member A (Clec9A) binding agent comprising a recombinant heavy-chain-only antibody (VHH) comprising three complementarity determining regions (CDR1, CDR2, and CDR3), wherein:

CDR1 is the amino acid sequence of SEQ ID NO: 51; CDR2 is the amino acid sequence of SEQ ID NO: 136; and CDR3 is the amino acid sequence of SEQ ID NO: 202.

2. The Clec9A binding agent of claim 1 , wherein the VHH is a humanized VHH.

3. The Clec9A binding agent of claim 2 , comprising an amino acid sequence having at least 98% identity to the amino acid sequence of any one of SEQ ID NO: 332-336; and wherein the CDR1 of the VHH is SEQ ID NO: 51, the CDR2 of the VHH is SEQ ID NO:136 and the CDR3 of the VHH is SEQ ID NO:202.

4. The Clec9A binding agent of claim 3 , wherein the amino acid sequence is selected from SEQ ID NO: 332-336.

5. A recombinant nucleic acid composition comprising an isolated Polynucleotide encoding the Clec9A binding agent of claim 1 .

6. An isolated host cell comprising the nucleic acid of claim 5 .

7. A chimeric protein comprising:

(a) the Clec9A binding agent of claim 1 ; and

(b) a mutated human IFN-α2 comprising one or more mutations at positions R120, M148, R149, and L153 relative to SEQ ID NO: 337 or 338; and

wherein the Clec9A binding agent and the mutated human IFN-α2 are optionally connected with one or more linkers.

8. A chimeric protein comprising:

(a) the Clec9A binding agent of claim 1 ; and

(b) a mutated human IFN-β comprising one or more mutations at positions W22, R27, L32, R35, V148, L151, R152, and Y155 relative to SEQ ID NO: 339; and

wherein the Clec9A binding agent and the mutated human IFN-β are optionally connected with one or more linkers.