Modified ubiquitin proteins having a specific binding activity for the extradomain B of fibronectin
The present invention refers to novel hetero-multimeric proteins obtained from modified ubiquitin capable of binding the extradomain B of fibronectin (ED-B) with high affinity. Furthermore, the invention refers to fusion proteins comprising said recombinant protein fused to a pharmaceutically and/or diagnostically active component. The invention is further directed to the use of said proteins in medical treatment methods.
1. A non-naturally occurring protein that binds to the extradomain B (ED-B) of fibronectin, said protein comprising two monomeric ubiquitin units linked together in a head-to-tail arrangement, wherein:
(i) each monomeric ubiquitin unit of said protein has at least 85% amino acid sequence identity to the amino acid sequence of SEQ ID NO: 1; and amino acid substitutions selected from the group consisting of positions corresponding to residues 2, 4, 6, 8, 62, 63, 64, 65, and 66 of SEQ ID NO: 1, and further wherein:
(1) the amino acid substitutions in the first monomeric ubiquitin unit are the amino acid substitutions K6W, L8W, K63R, E64K, S65F, and T66P and the amino acid substitutions in the second monomeric ubiquitin unit are the amino acid substitutions K6T, L8Q, Q62W, K63S, E64N, and T66E, optionally Q2R; or
(2) the amino acid substitutions in the first monomeric ubiquitin unit are the amino acid substitutions Q2T, F4W, K6H, Q62N, K63F, E64K, S65L, and T66S and the amino acid substitutions in the second monomeric ubiquitin unit are the amino acid substitutions K6X, L8X, Q62X, K63X, E64X, S65X, and T66X, optionally Q2X, wherein X can be any amino acid;
(ii) said protein has a specific binding affinity to said ED-B domain of fibronectin of K d =10 −7 -10 −12 M; and
(iii) said protein exhibits a monovalent binding activity with respect to said ED-B domain of fibronectin.
2. The protein according to claim 1 , wherein said first and second monomeric ubiquitin units are linked either directly or by a linker.
3. A fusion protein comprising the protein according to claim 1 fused to a pharmaceutically active component or a diagnostic component, wherein said pharmaceutically active component is a cytokine, a chemokine, a cytotoxic compound, or an enzyme; or wherein said diagnostically active component is a fluorescent compound, a photosensitizer, or a radionuclide.
4. The fusion protein according to claim 3 , wherein said pharmaceutically active component is TNF-alpha.
5. A pharmaceutical composition comprising the protein of claim 1 and one or more pharmaceutically acceptable carriers or excipients.
6. The pharmaceutical composition of claim 5 , further comprising one or more chemotherapeutic agents.
7. The pharmaceutical composition of claim 6 , which is in the form of a combined preparation or in the form of a kit.
8. The protein according to claim 2 , wherein the linker comprises the amino acid sequence of GIG, RIG, SGGGG (SEQ ID NO: 48), SGGGGIG (SEQ ID NO: 49), or SGGGGSGGGGIG (SEQ ID NO: 32).
9. The pharmaceutical composition of claim 6 , wherein the one or more chemotherapeutic agents are selected from the group consisting of melphalan, doxorubicin, cyclophosphamide, dactinomycin, fluorodesoxyuracil, cisplatin, paclitaxel, gemcitabine, a kinase inhibitor, and a radiopharmaceutical.