Recombinant MVA or MVADELE3L expressing human FLT3L and use thereof as immuno-therapeutic agents against solid tumors

1. A composition comprising a recombinant modified vaccinia Ankara (MVA) virus, wherein the recombinant MVA comprises MVAΔE3L harboring hFlt3L (MVAΔE3L-hFlt3L).

2. The composition of claim 1 wherein the recombinant MVAΔE3L is not harboring nucleic acid encoding or expressing a tumor antigen.

3. The composition of claim 1 further comprising one or more pharmaceutically acceptable excipients, wherein the one or more excipients is selected from the group consisting of solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic agents, absorption delaying agents, and combinations of two or more of the foregoing.

4. The composition of claim 1 wherein the composition further comprises MVA harboring a human Fms-like tyrosine kinase-3 ligand (hFlt3L) (MVA-hFlt3L).

5. The composition of claim 1 further comprising a second amount of a replication competent recombinant attenuated vaccinia virus with deletion of thymidine kinase encoding and expressing human Flt3L.

6. The composition of claim 5 further comprising a third amount of inactivated MVA.

7. A method for treating a malignant solid tumor in a subject in need thereof, the method comprising delivering to the cells of the tumor an effective amount of the recombinant modified vaccinia Ankara (MVA) virus of claim 1 .

8. The method of claim 7 wherein the amount of said virus is effective to bring about one or more of the following: induce the immune system of the subject to mount an immune response against the tumor or enhance or promote an ongoing immune response by the immune system against the tumor; reduce the size of the tumor; eradicate the tumor; inhibit growth of the tumor; inhibit metastasis of the tumor; and reduce or eradicate metastatic tumor.

9. The method of claim 8 wherein the immune response against the tumor accomplishes one or more of the following:

proliferation and activation of CD8 + cytotoxic T cells;

proliferation and activation of CD4 + effector T cells;

increase of the ratio of CD8 + /Treg and of Tconv/Treg;

recruitment of CD45 + cells and CD8 + T cells in the injected and distant tumors;

reduction of tumor-associated macrophages (TAM) in the injected and distant tumors;

influx of Ly6C hi CD11b + inflammatory monocytes and Ly6C hi CD11b − myeloid cells into the injected and distant tumors;

activation and mobilization of cross-presenting CD103 + dendritic cells in the injected and distant tumors via the production of type IFN and proinflammatory cytokines; and

generation of anti-tumor CD8 + T cells and cross-protection against heterologous tumor(s).

10. The method of claim 7 wherein the recombinant MVA is delivered by intratumoral or intravenous injection or a simultaneous or sequential combination of intratumoral and intravenous injection.

11. The method of claim 7 wherein the tumor is melanoma or colon carcinoma.

12. The method of claim 7 wherein delivery of the recombinant MVA is continued for several weeks, months or years, or indefinitely, as long as benefits persist or a maximum tolerated dose is reached.

13. The method of claim 7 wherein the subject is a human.

14. The method of claim 7 wherein the recombinant MVA is delivered at a dosage per administration within the range of about 10 6 -10 10 plaque-forming units (pfu), wherein the delivery is repeated with a frequency within the range of from once per month to two times per week.

15. The method of claim 7 , further comprising conjointly administering to the subject a second amount of an immune checkpoint blocking agent or an immune checkpoint agonist effective to block immune suppressive mechanisms within the tumor.

16. The method of claim 15 wherein the administration of the immune checkpoint blocking agent or immune checkpoint agonist is by parenteral route; or wherein the delivery of the recombinant modified vaccinia Ankara (MVA) virus is by intratumoral injection and the administration of the immune checkpoint blocking agent or immune checkpoint agonist is by intravenous route; or wherein both the delivery of the recombinant modified vaccinia Ankara (MVA) virus and the administration of the immune checkpoint blocking agent or immune checkpoint agonist are by intravenous route; or wherein both the delivery of the recombinant modified vaccinia Ankara (MVA) virus and the administration of the immune checkpoint blocking agent or immune checkpoint agonist are by intratumoral injection.

17. The method of claim 15 wherein the immune checkpoint blocking agent is selected from the group consisting of PD-1 inhibitors, PD-L1 inhibitors, CTLA4 inhibitors, inhibitory antibodies against LAG-3 (lymphocyte activation gene 3), TIM3 (T cell Immunoglobulin and Mucin-3), B7-H3, and TIGIT (T-cell immunoreceptor with Ig and ITIM domains); CD80, CD86, PDL2, B7-H4, II and DLBCL inhibitors, BTLA, and any combination thereof; and the immune checkpoint agonist is selected from the group consisting of anti-ICOS antibody, anti-OX40 antibody, agonist antibody against 4-IBB (CD 137) and against GITR.

18. A kit comprising:

a first component comprising the composition according to claim 1 .

19. A method for treating a malignant tumor in a subject, wherein the subject has been previously treated or dosed with the recombinant modified vaccinia Ankara (MVA) virus of claim 1 in an amount effective to induce the immune system of the subject to mount an immune response against the tumor, the method comprising delivering to the tumor cells of the subject an amount of an immune checkpoint blocking agent effective to block immune suppressive mechanisms within the tumor elicited by tumor cells, stromal cells, or tumor infiltrating immune cells, wherein the immune checkpoint blocking agent comprises CTLA-4, CD80, CD86, PD-1, PDL1, PDL2, LAG3, B7-H3, B7-H4, TIM3, ICOS, II DLBCL inhibitors, BTLA, ipilimumab, nivolumab, pembrolizumab, pidilizumab, AMP-224, MPDL3280A, BMS-936559, MEDI4736, MSB 00107180, or any combination thereof.

20. A recombinant modified vaccinia Ankara virus with deletion of vaccinia virulence factor E3 (MVAΔE3L) modified to express human Fms-like tyrosine kinase 3 ligand (hFlt3L).

21. The kit of claim 18 , further comprising a second component comprising one or both of a replication competent recombinant attenuated vaccinia virus with deletion of thymidine kinase encoding and expressing GM-CSF or human Flt3L, and inactivated MVA, respectively in a second and third amount, said second amount or third amount or both second and third amount contributing to augmenting the induced or enhanced or promoted immune response in said subject.

22. The method of claim 7 , further comprising delivering to the cells of the tumor an effective amount of MVA-hFlt3L.