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Generation of a new therapeutic peptide that depletes myeloid-derived suppressor cells in tumor-bearing mice.

Qin H, Lerman B, Sakamaki I, Wei G, Cha SC, Rao SS, Qian J, Hailemichael Y, Nurieva R, Dwyer KC, Roth J, Yi Q, Overwijk WW, Kwak LW - Nat. Med. (2014)

Bottom Line: Peptibody treatment was associated with inhibition of tumor growth in vivo, which was superior to that achieved with Gr-1-specific antibody.Immunoprecipitation of MDSC membrane proteins identified S100 family proteins as candidate targets.Our strategy may be useful to identify new diagnostic and therapeutic surface targets on rare cell subtypes, including human MDSCs.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA. [2] Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA. [3].

ABSTRACT
Immune evasion is an emerging hallmark of cancer progression. However, functional studies to understand the role of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment are limited by the lack of available specific cell surface markers. We adapted a competitive peptide phage display platform to identify candidate peptides binding MDSCs specifically and generated peptide-Fc fusion proteins (peptibodies). In multiple tumor models, intravenous peptibody injection completely depleted blood, splenic and intratumoral MDSCs in tumor-bearing mice without affecting proinflammatory immune cell types, such as dendritic cells. Whereas control Gr-1-specific antibody primarily depleted granulocytic MDSCs, peptibodies depleted both granulocytic and monocytic MDSC subsets. Peptibody treatment was associated with inhibition of tumor growth in vivo, which was superior to that achieved with Gr-1-specific antibody. Immunoprecipitation of MDSC membrane proteins identified S100 family proteins as candidate targets. Our strategy may be useful to identify new diagnostic and therapeutic surface targets on rare cell subtypes, including human MDSCs.

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Peptibodies specifically depleted tumor-induced MDSC in multiple tumor models and inhibited tumor growth in vivo(a–b) Depletion of Gr-1+CD11b+ MDSC in the blood and spleens in EL4-challenged C57BL/6 mice (n = 5 per group) after treatment with 50 μg peptibody i.v. for 3 consecutive days. Control mice received Gr-1 depleting mAb (positive control), irrelevant control peptibody (Pep-irrel) or PBS. Plots are shown for individual representative mice (a) and composite results (b) in a representative experiment out of five, with percentages of MDSC subsets indicated (g = granulocytic, m = monocytic) (mean ± s.e.m). (c–d) Depletion of MDSC in the blood and subcutaneous tumors of EG.7-challenged C57BL/6 mice (n = 5 per group) by peptibody treatment. Percentage of Gr-1+CD11b+ MDSC from ficolled blood and single cell suspensions prepared from harvested tumors is shown for individual representative mice (c) and composite results (mean ± s.e.m) (d) in a representative experiment out of two. (e) Peptibody treatment depleted MDSC in vivo from the blood and spleens of A20 lymphoma-challenged Balb/c mice (data pooled from 2 experiments). (f) Frequencies of Gr-1+CD11b+ MDSC, Ly6G−CD11c+ DC, CD3+ T cells, CD19+ B cells and CD3− CD49b+ NK cells in spleens and Gr-1+CD11b+ immature myeloid cells in the bone marrow from peptibody-treated, EL4-bearing C57BL/6 mice. Data are shown as the mean ± s.e.m of 5 mice per group. (g–h) Inhibition of EL4 tumor growth in C57BL/6 mice following every other day peptibody treatment. Tumor size is shown as the mean ± s.d of 5 mice per group in a representative experiment out of four (g). Tumor mass data are pooled results from 4 independent experiments (h). * P < 0.05, ** P < 0.01 compared with tumor-challenged mice without peptibody treatment (PBS) by two-tailed Student’s t-test.
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Figure 3: Peptibodies specifically depleted tumor-induced MDSC in multiple tumor models and inhibited tumor growth in vivo(a–b) Depletion of Gr-1+CD11b+ MDSC in the blood and spleens in EL4-challenged C57BL/6 mice (n = 5 per group) after treatment with 50 μg peptibody i.v. for 3 consecutive days. Control mice received Gr-1 depleting mAb (positive control), irrelevant control peptibody (Pep-irrel) or PBS. Plots are shown for individual representative mice (a) and composite results (b) in a representative experiment out of five, with percentages of MDSC subsets indicated (g = granulocytic, m = monocytic) (mean ± s.e.m). (c–d) Depletion of MDSC in the blood and subcutaneous tumors of EG.7-challenged C57BL/6 mice (n = 5 per group) by peptibody treatment. Percentage of Gr-1+CD11b+ MDSC from ficolled blood and single cell suspensions prepared from harvested tumors is shown for individual representative mice (c) and composite results (mean ± s.e.m) (d) in a representative experiment out of two. (e) Peptibody treatment depleted MDSC in vivo from the blood and spleens of A20 lymphoma-challenged Balb/c mice (data pooled from 2 experiments). (f) Frequencies of Gr-1+CD11b+ MDSC, Ly6G−CD11c+ DC, CD3+ T cells, CD19+ B cells and CD3− CD49b+ NK cells in spleens and Gr-1+CD11b+ immature myeloid cells in the bone marrow from peptibody-treated, EL4-bearing C57BL/6 mice. Data are shown as the mean ± s.e.m of 5 mice per group. (g–h) Inhibition of EL4 tumor growth in C57BL/6 mice following every other day peptibody treatment. Tumor size is shown as the mean ± s.d of 5 mice per group in a representative experiment out of four (g). Tumor mass data are pooled results from 4 independent experiments (h). * P < 0.05, ** P < 0.01 compared with tumor-challenged mice without peptibody treatment (PBS) by two-tailed Student’s t-test.

Mentions: We next determined the effect of peptibody treatment on MDSC in vivo. Intravenous injection of 50 μg Pep-H6 and Pep-G3 completely depleted MDSC in blood and spleens of EL4 tumor-bearing mice, compared with control peptibody (Pep-irrel) or untreated mice (Fig. 3a,b). We found that whereas our peptibodies depleted both monocytic and granulocytic MDSC subsets, Gr-1 mAb depleted granulocytic, but not monocytic, MDSC in both EL4 and EG.7 models. This distinguishing effect of peptibody treatment on monocytic MDSC was especially apparent when blood was first subjected to Ficoll sedimentation to remove granulocytes and granulocytic MDSC (Fig. 3a-d). Importantly, we observed that peptibody treatment depleted intratumoral MDSC in both EG.7 (Fig. 3c,d) and EL4 models (Supplementary Fig. 3). Peptibodies also depleted blood and splenic MDSC in mice bearing A20 lymphomas (Fig. 3e).


Generation of a new therapeutic peptide that depletes myeloid-derived suppressor cells in tumor-bearing mice.

Qin H, Lerman B, Sakamaki I, Wei G, Cha SC, Rao SS, Qian J, Hailemichael Y, Nurieva R, Dwyer KC, Roth J, Yi Q, Overwijk WW, Kwak LW - Nat. Med. (2014)

Peptibodies specifically depleted tumor-induced MDSC in multiple tumor models and inhibited tumor growth in vivo(a–b) Depletion of Gr-1+CD11b+ MDSC in the blood and spleens in EL4-challenged C57BL/6 mice (n = 5 per group) after treatment with 50 μg peptibody i.v. for 3 consecutive days. Control mice received Gr-1 depleting mAb (positive control), irrelevant control peptibody (Pep-irrel) or PBS. Plots are shown for individual representative mice (a) and composite results (b) in a representative experiment out of five, with percentages of MDSC subsets indicated (g = granulocytic, m = monocytic) (mean ± s.e.m). (c–d) Depletion of MDSC in the blood and subcutaneous tumors of EG.7-challenged C57BL/6 mice (n = 5 per group) by peptibody treatment. Percentage of Gr-1+CD11b+ MDSC from ficolled blood and single cell suspensions prepared from harvested tumors is shown for individual representative mice (c) and composite results (mean ± s.e.m) (d) in a representative experiment out of two. (e) Peptibody treatment depleted MDSC in vivo from the blood and spleens of A20 lymphoma-challenged Balb/c mice (data pooled from 2 experiments). (f) Frequencies of Gr-1+CD11b+ MDSC, Ly6G−CD11c+ DC, CD3+ T cells, CD19+ B cells and CD3− CD49b+ NK cells in spleens and Gr-1+CD11b+ immature myeloid cells in the bone marrow from peptibody-treated, EL4-bearing C57BL/6 mice. Data are shown as the mean ± s.e.m of 5 mice per group. (g–h) Inhibition of EL4 tumor growth in C57BL/6 mice following every other day peptibody treatment. Tumor size is shown as the mean ± s.d of 5 mice per group in a representative experiment out of four (g). Tumor mass data are pooled results from 4 independent experiments (h). * P < 0.05, ** P < 0.01 compared with tumor-challenged mice without peptibody treatment (PBS) by two-tailed Student’s t-test.
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Figure 3: Peptibodies specifically depleted tumor-induced MDSC in multiple tumor models and inhibited tumor growth in vivo(a–b) Depletion of Gr-1+CD11b+ MDSC in the blood and spleens in EL4-challenged C57BL/6 mice (n = 5 per group) after treatment with 50 μg peptibody i.v. for 3 consecutive days. Control mice received Gr-1 depleting mAb (positive control), irrelevant control peptibody (Pep-irrel) or PBS. Plots are shown for individual representative mice (a) and composite results (b) in a representative experiment out of five, with percentages of MDSC subsets indicated (g = granulocytic, m = monocytic) (mean ± s.e.m). (c–d) Depletion of MDSC in the blood and subcutaneous tumors of EG.7-challenged C57BL/6 mice (n = 5 per group) by peptibody treatment. Percentage of Gr-1+CD11b+ MDSC from ficolled blood and single cell suspensions prepared from harvested tumors is shown for individual representative mice (c) and composite results (mean ± s.e.m) (d) in a representative experiment out of two. (e) Peptibody treatment depleted MDSC in vivo from the blood and spleens of A20 lymphoma-challenged Balb/c mice (data pooled from 2 experiments). (f) Frequencies of Gr-1+CD11b+ MDSC, Ly6G−CD11c+ DC, CD3+ T cells, CD19+ B cells and CD3− CD49b+ NK cells in spleens and Gr-1+CD11b+ immature myeloid cells in the bone marrow from peptibody-treated, EL4-bearing C57BL/6 mice. Data are shown as the mean ± s.e.m of 5 mice per group. (g–h) Inhibition of EL4 tumor growth in C57BL/6 mice following every other day peptibody treatment. Tumor size is shown as the mean ± s.d of 5 mice per group in a representative experiment out of four (g). Tumor mass data are pooled results from 4 independent experiments (h). * P < 0.05, ** P < 0.01 compared with tumor-challenged mice without peptibody treatment (PBS) by two-tailed Student’s t-test.
Mentions: We next determined the effect of peptibody treatment on MDSC in vivo. Intravenous injection of 50 μg Pep-H6 and Pep-G3 completely depleted MDSC in blood and spleens of EL4 tumor-bearing mice, compared with control peptibody (Pep-irrel) or untreated mice (Fig. 3a,b). We found that whereas our peptibodies depleted both monocytic and granulocytic MDSC subsets, Gr-1 mAb depleted granulocytic, but not monocytic, MDSC in both EL4 and EG.7 models. This distinguishing effect of peptibody treatment on monocytic MDSC was especially apparent when blood was first subjected to Ficoll sedimentation to remove granulocytes and granulocytic MDSC (Fig. 3a-d). Importantly, we observed that peptibody treatment depleted intratumoral MDSC in both EG.7 (Fig. 3c,d) and EL4 models (Supplementary Fig. 3). Peptibodies also depleted blood and splenic MDSC in mice bearing A20 lymphomas (Fig. 3e).

Bottom Line: Peptibody treatment was associated with inhibition of tumor growth in vivo, which was superior to that achieved with Gr-1-specific antibody.Immunoprecipitation of MDSC membrane proteins identified S100 family proteins as candidate targets.Our strategy may be useful to identify new diagnostic and therapeutic surface targets on rare cell subtypes, including human MDSCs.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA. [2] Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA. [3].

ABSTRACT
Immune evasion is an emerging hallmark of cancer progression. However, functional studies to understand the role of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment are limited by the lack of available specific cell surface markers. We adapted a competitive peptide phage display platform to identify candidate peptides binding MDSCs specifically and generated peptide-Fc fusion proteins (peptibodies). In multiple tumor models, intravenous peptibody injection completely depleted blood, splenic and intratumoral MDSCs in tumor-bearing mice without affecting proinflammatory immune cell types, such as dendritic cells. Whereas control Gr-1-specific antibody primarily depleted granulocytic MDSCs, peptibodies depleted both granulocytic and monocytic MDSC subsets. Peptibody treatment was associated with inhibition of tumor growth in vivo, which was superior to that achieved with Gr-1-specific antibody. Immunoprecipitation of MDSC membrane proteins identified S100 family proteins as candidate targets. Our strategy may be useful to identify new diagnostic and therapeutic surface targets on rare cell subtypes, including human MDSCs.

Show MeSH
Related in: MedlinePlus