Table 1.

Clinical trials targeting MDSCs directly or indirectly in HGGs.

Tumor Type	Drug	Target	Combination Strategy	Status	Clinical Trial Identifier	Effects on Clinical Outcome	References
Glioblastoma	Capecitabine	Tumor cells	Bevacizumab	Active, recruiting	NCT02669173	Reduction in MDSC frequencies and increase in cytotoxic immune cells is observed in GBM patients	[134]
Glioblastoma	Atezolizumab	PDL1	Ipatasertib	Active, recruiting	NCT03673787	Early results show reduction of regulatory T-cells and increase in effector T-cells in solid tumor patients	[140]
Glioblastoma	IMA 950 (multi tumor-associated peptides vaccine)	Immune cells	Vaccine adjuvant Poly ICLC	Completed	NCT01920191	Sustained CD8 and CD4 T-cell responses leads to an increase in medial survival of GBM patients by 19 months	[141,142]
Advanced solid tumors (including malignant glioma)	Cabiralizumab	CSFR1	Nivolumab	Completed	NCT02526017	Decreases circulating monocytes in solid tumor patients. Some adverse effects such as increase in creatine kinase and serum liver enzymes are reported	[143,144]