Methods of sensitizing cancer to immunotherapy

1. A method of sensitizing medulloblastoma to immunotherapy in a subject in need thereof, comprising:

detecting the expression level of Cdk5 in medulloblastoma cancer cells of the subject;

comparing the detected expression level of Cdk5 to a threshold level; and administering to the subject an amount of a CdK5 inhibitor effective to suppress immune checkpoint Programmed Death Ligand (PD-L1) PD-L1 in the cancer cells and to enhance an immune response to the cancer cells, if the detected expression level of Cdk5 exceeds the threshold level.

2. The method of claim 1 , wherein the Cdk5 inhibitor is selected from the group consisting of Dinaciclib, AT7519, Roscovitine, CYC065, PHA-793887, Milcidib, and SNS-032.

3. The method of claim 1 , further comprising administering a PD-1 binding antagonist and/or a PD-L1 binding antagonist in combination with the Cdk5 inhibitor, the PD-1 binding antagonist and/or a PD-L1 binding antagonist in inhibiting PD-1/PD-L1 interaction.

4. The method of claim 3 , wherein the PD-1 binding and/or PD-L1 binding antagonist is an antibody.

5. The method of claim 4 , wherein the PD-1 binding antagonist and/or PD-L1 binding antagonist is selected from the group consisting of MDX-1106, Merck 3745, CT-011, AMP-224, AMP-514, YW243.55.S70, MPDL3280A, MDX-1105, MEDI-4736, and MSB0010718C.

6. The method of claim 1 , wherein the subject is treated with at least one of tumor removal surgery, chemotherapy, radiation therapy, or immune cells.

7. The method of claim 1 , wherein the Cdk5 inhibitor is CYC065.

8. The method of claim 1 , comprising detecting the level of PD-L1 in medulloblastoma cancer cells of the subject after administering to the subject the Cdk5 inhibitor.

9. The method of claim 1 , wherein the threshold level is at least 1% of medulloblastoma cancer cells expressing Cdk5.