Immunotoxins, formulations thereof and their use in medicine

1. A pharmaceutical composition comprising:

(i) a first monoclonal antibody that recognizes CD3 having a heavy chain variable region comprising a complementarity determining region 1 (CDRH1) comprising the amino acid sequence of SEQ ID NO: 5; a complementarity determining region 2 (CDRH2) comprising the amino acid sequence of SEQ ID NO: 6; and a complementarity determining region 3 (CDRH3) comprising the amino acid sequence of SEQ ID NO: 7; and

a light chain variable region comprising a complementarity determining region 1 (CDRL1) comprising the amino acid sequence of SEQ ID NO: 8; a complementarity determining region 2 (CDRL2) comprising the amino acid sequence of SEQ ID NO: 9, and a complementarity determining region 3 (CDRL3) comprising the amino acid sequence of SEQ ID NO: 10, wherein the first antibody is conjugated to at least one ricin toxin A (RTA), and

a second monoclonal antibody that recognizes CD7 having a heavy chain variable region comprising a CDRH1 comprising the amino acid sequence of SEQ ID NO: 15; a CDRH2 comprising the amino acid sequence of SEQ ID NO: 16; and a CDRH3 comprising the amino acid sequence of SEQ ID NO: 17; and

a light chain variable region comprising a CDRL1 comprising the amino acid sequence of SEQ ID NO: 18; a CDRL2 comprising the amino acid sequence of SEQ ID NO: 19, and a CDRL3 comprising the amino acid sequence of SEQ ID NO: 20, wherein the second antibody is conjugated to at least one ricin toxin A (RTA);

(ii) 5 to 20 mM of a citrate buffer;

(iii) 50 to 300 mM of L-arginine or a pharmaceutically acceptable salt thereof;

(iv) 0.01 to 0.1% (w/v) of a polysorbate; and

(v) 120 to 160 mM maltose,

wherein the composition is in water and has a pH in the range 6 to 7.5.

2. The composition of claim 1 , wherein:

the first monoclonal antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 1 and a light chain comprising the amino acid sequence of SEQ ID NO: 2, wherein the first antibody is conjugated to at least one ricin toxin A (RTA), and

the second monoclonal antibody having a heavy chain comprising the amino acid sequence of SEQ ID NO: 11 and a light chain comprising the amino acid sequence of SEQ ID NO: 12, wherein the second antibody is conjugated to at least one ricin toxin A (RTA).

3. The composition of claim 1 , further comprising at least one agent selected from:

100 to 150 mM trehalose;

25 to 75 mM glycine; and

80 to 120 mM mannitol.

4. The composition of claim 1 , wherein the maltose is 130 to 150 mM maltose monohydrate.

5. The composition of claim 1 , comprising 0.05 to 0.5 mg/mL of the first monoclonal antibody and 0.05 to 0.5 mg/mL of the second monoclonal antibody.

6. The composition of claim 1 , comprising 0.2 mg/mL of the first monoclonal antibody and 0.2 mg/mL of the second monoclonal antibody.

7. The composition of claim 1 , comprising 10 mM sodium citrate/citric acid buffer.

8. The composition of claim 1 , comprising 125 mM of L-arginine HCl.

9. The composition of claim 1 , comprising 0.05% (w/v) Tween 20.

10. The composition of claim 1 , comprising 140 mM maltose monohydrate.

11. The composition of claim 1 , wherein the composition is in water for injection and has a pH of 6.5.

12. The composition of claim 1 , wherein the ricin toxin A is ricin, deglycosylated ricin A (dgRTA) or non-glycosylated recombinant ricin A.

13. A lyophilised composition that is a freeze-dried form of the composition of claim 1 and which is suitable for reconstitution with water or an aqueous solution.

14. A method of treating acute Graft versus Host disease (aGVHD) in a human subject, wherein the method comprises:

(a) analysing a sample obtained from the subject for viral infection;

(b) administering the composition of claim 1 to the subject when the subject is determined to exhibit elevated or rising Epstein-Barr virus (EBV) or human cytomegalovirus (CMV) viral titre.

15. The method of claim 14 , wherein the administering comprises multiple infusions of said composition at a dose of 4 mg/m 2 Body Surface Area (BSA).

16. The method of claim 14 , wherein the administering comprises four 4-hour infusions given at 48-hour intervals.

17. The method of claim 14 , wherein at least one of the following is de-immunised:

the first antibody;

the second antibody;

the toxic moiety of the first antibody; and

the toxic moiety of the second antibody.

18. The method of claim 14 , wherein the subject exhibits an EBV or CMV viral titre above 1000 viral DNA copies/ml of blood.

19. The method of claim 14 , wherein the composition suppresses or kills CD3+ or CD7+ T-cells.

20. The method of claim 14 , wherein the composition spares CD8+ anti-viral T-cells relative to CD3+ or CD7+ T-cells.

21. The method of claim 14 , wherein the subject is monitored for viral infection or reactivation by measuring at least one of a viral titre, viral culture, viral antigen detection, viral serology, or immunohistochemistry at least once before administration of said composition.

22. The method of claim 21 , wherein said monitoring comprises measuring plasma viral titre by real-time quantitative PCR.

23. The method of claim 14 , wherein the subject is being or has been treated with prophylactic antiviral medication.

24. A method of preventing chronic GVHD (cGVHD) in a human subject having acute Graft versus Host disease (aGVHD), comprising the step of administering a therapeutically effective amount of the composition of claim 1 .

25. A method of treating acute Graft versus Host disease (aGVHD) in a human subject, wherein the method comprises:

(a) measuring the serum albumin level in a sample obtained from the subject;

(b) administering the composition of claim 1 to the subject when the subject has a serum albumin level of between 10 g/L and 15 g/L.