Identification of Dinaciclib and Ganetespib as Anti-inflammatory Drugs Using a Novel HTP Screening Assay that Targets IFNγ-dependent PD-L1 Expression

Shira Hagbi-Levi ^1* Michal Abraham ² Lika Gamaev ¹ Inbal Mishaelian ¹ Ophir Hay ¹ Elina Zorde- Khevalevsky ¹ Ori Wald ¹ Hanna Wald ¹ Devorah Olam ¹ Lola Weiss ¹ Amnon Peled ^1*

• ¹ Goldyne Savad Institute of Gene Therapy, Hadassah Medical Center, Jerusalem, Israel
• ² AlonBio Ltd., Ness Ziona, Israel

IFNγ plays both positive and negative roles in the regulation of innate and adaptive immune responses against tumors and virally infected tissues by up-regulating CXCL10 and PD-L1 expression. To identify novel pathways and drugs that regulate the IFNγ-dependent PD-L1, we expressed GFP under the control of mouse PD-L1 promotor in mouse cancer cells that up regulate PD-L1 and CXCL10 in response to IFNγ stimulation. Using these cells, we screened an FDA approved library of 1496 small molecules known for their ability to inhibit IFNγ-dependent increase in PD-L1.We identified 46 drugs that up regulated and 4 that down regulated IFNγ-dependent PD-L1 expression. We discovered that in addition to the known JAK inhibitors Ruxolitinib and Baricitinib, Dinaciclib, a CDK1/2/5/9 inhibitor, and Ganetespib, a Hsp90 inhibitor, significantly inhibit both PD-L1 and CXCL10 expression in the model cells. Furthermore, both drugs suppressed IFNγ-dependent CXCL10 and PD-L1 expression in-vitro in primary human lung cells and human cancer cells. These drugs also significantly inhibited delayed-type hypersensitivity (DTH) in-vivo in an inflammation mouse model. Our novel screening platform can therefore be used in the future to identify novel immunomodulators and pathways in cancer and inflammation, expanding therapeutic horizons.