Table 1.

Description of selected articles.

Article	Study	Objective	Method	Results
Hui-Ming Chen et al. (2021) [31]	Pre-clinical	Role of selected vegetables on antitumor activity in lung cancer (LC).	LC mouse models with and without liver metastases treated with a mix of selected vegetables.	Significant tumor size reduction and survival improvement in mice fed with selected vegetables compared to control mice. Reduction in G-MDSC percentage and M-MDSC immunosuppressive function.
Tao H et al. (2021) [32]	Pre-clinical	Effects of icaritin on the tumor microenvironment.	Mouse models with orthotopic and subcutaneous liver cancer treated with icaritin and anti-PD-1.	Significant tumor size reduction and survival improvement in mice treated with icaritin compared to control mice. Reduction in G-MDSC levels and activity.
Long A et al. (2016) [33]	Pre-clinical	Effects of GD2-CAR-T therapy and all-trans retinoic acid (ATRA) on solid pediatric tumors.	Mouse models with osteosarcoma, Ewing’s sarcoma, rhabdomyosarcoma, and neuroblastoma treated with GD2-CAR-T and ATRA. The control group received only GD2-CAR-T.	ATRA combined with GD2-CAR-T delayed tumor growth and increased survival. MDSC were also decreased.
Rui K et al. (2016) [34]	Pre-clinical	Effects of curdlan on MDSCs.	Mouse models with Lewis LC treated with curdlan for one week before the subcutaneous injection.	Significant reduction in tumor growth, splenic MDSC, arginase, and nitric oxide.
Lesinski G et al. (2015) [35]	Phase II trial.	Efficacy and pharmacokinetics of soy phytochemicals.	Patients with biochemical relapse of prostate cancer, ECOG 0–1. Diet: (1) two soy-enriched bread slices per day for 8 weeks, (2) Legume-free diet for 2 weeks, and (3) two soy- and almond-enriched bread per day for 8 weeks.	Reduction in Th1, regulatory T cells (Treg), Treg/CD8 ratio, M-MDSCs and MDSC-related cytokines. Increase in natural killer cells.
Fleet J et al. (2020) [22]	Pre-clinical	Role of the active form of vitamin D [1,25 (OH)2D] as a regulator of the activity of MDSCs.	Vitamin D receptor (VDR) KO Mouse models treated with 1,25 (OH)2D.	Vitamin D increased VDR levels and reduced MDSC capacity. Arginase levels were higher in VDR KO mice.
Xu P et al. (2020) [36]	Pre-clinical	Action of EGCG on the activity of MDSCs in breast cancer.	4T1 breast cancer-bearing mice treated with increasing doses of EGCG.	Tumor size was smaller in samples treated with EGCG. This compound improved the expression of cell death-related routes in MDSC and reduced the immunosuppressive capacity of MDSCs.