Method for increasing the percentage of monomeric antibody Fab-dsFv multimeric species
The present invention provides method for increasing the percentage of monomer in a composition of recombinantly expressed antibody molecules characterised in that the antibody molecule comprises at least one Fv with specificity for an antigen of interest comprising one VH and one VL wherein said VH and VL are connected directly or indirectly via one or more linkers and are stabilised by a disulfide bond therebetween, said method comprises a) a thermal conversion step of holding the composition comprising the antibody molecule at a temperature in the range 30 to 60° C. for a period of at least 1 hour, wherein step a) is performed in the presence of a reducing agent or after treatment with a reducing agent.
1. A method for increasing the percentage of monomer in a composition of recombinantly expressed antibody molecules characterised in that the antibody molecule comprises at least one Fv with specificity for an antigen of interest comprising one VH and one VL wherein said VH and VL are connected directly via one or more linkers and are stabilised by a disulfide bond therebetween, said method comprising:
a) a thermal conversion step of holding the composition comprising an antibody selected from the group consisting of a dsscFv, a Fab-2xdsscFv, a Fab-dsscFv-dsFv, a Fab-dsscFv-sdAb, a Fab-dsscFv-scFv and a Fab-dsscFv at a temperature in the range 45 to 55° C. for a period of at least 1 hour,
b) wherein step a) is performed in the presence of a reducing agent or after treatment with a reducing agent.
2. The method according to claim 1 , wherein the temperature is 50° C.
3. The method according to claim 1 , wherein the reducing agent is selected from glutathione (GSH), ethylsulfite, 2-mercaptoethanol (BME), 2-mercaptoethylamine (BMEA), cysteine-HCl and dithiothreitol (DTT).
4. The method according to claim 1 , wherein the concentration of reducing agent is in the range 1 mM to 100 mM. hours.
5. The method according to claim 1 , wherein the period is in the range 1 to 70 hours.
6. The method according to claim 1 , wherein:
a) step a) is performed at a temperature in the range 45 to 55° C., for a period of 4 to 6 hours and in step b) the reducing agent is BMEA or BME and is at a concentration in the range 60 to 90 mM; or
b) step a) is performed at a temperature of 50° C., for a period of 5 hours and in step b) the reducing agent is BMEA or BME and is at a concentration 70 to 80 mM.
7. The method according to claim 1 , wherein the reducing agent is employed in the presence of an amino acid.
8. The method according to claim 7 , wherein the amino acid is selected from arginine, lysine and proline.
9. The method according to claim 7 , wherein the concentration of amino acid is in the range 0.01 to 1.0 M.
10. The method according to claim 1 , wherein the antibody is at a concentration in the range 0.5 g/L to 5 g/L in the composition.
11. The method according to claim 1 , wherein the thermal step is performed in the presence of concomitant stirring.
12. The method according to claim 11 , wherein the stirring in the range 100 to 1200 rpm.
13. The method according to claim 1 , wherein reducing agent is:
a) added to the recombinant antibody composition before the temperature is raised to 45 to 55° C.; or b) added to the recombinant antibody composition after the temperature is raised to 45 to 55° C.
14. The method according to claim 1 , comprising a further step of downstream purification.
15. The method according to claim 14 , wherein downstream purification comprises chromatography.
16. The method according to claim 15 , wherein the chromatography is hydrophobic interaction chromatography or ion exchange chromatography.
17. The method according to claim 1 , wherein the VH and VL which are connected directly via one or more linkers and are stabilised by a disulfide bond therebetween, are a complementary VH/VL pair which form an antigen binding site.
18. The method according to claim 1 , wherein the reducing agent comprises a single thiol group.
19. The method according to claim 18 , wherein the reducing agent is selected from glutathione (GSH), 2-mercaptoethanol (BME), 2-mercaptoethylamine (BMEA), and cysteine-HCl.
20. The method according to claim 1 , wherein the antibody is a Fab-2xdsscFv or a Fab-dsscFv.