Background Myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment are potential therapeutic targets in immune checkpoint cancer therapy, particularly for cancers that are unresponsive to anti-PD-1 therapy. It has previously been demonstrated that trefoil factor family 2 (TFF2), a secreted anti-inflammatory peptide, can partially suppress MDSC expansion and partially activate tumor immunity through agonism of the CXCR4 receptor.^1–3 We investigated whether a novel fusion protein, murine TFF2-murine serum albumin (mTFF2-MSA), designated mTNX-1700, has single agent activity and can improve on the therapeutic effects of anti-PD-1 in the Pan02 syngeneic mouse model of advanced pancreatic cancer.

Methods A syngeneic pancreatic mouse model was developed using the Pan02 pancreatic cell line grafted subcutaneously into C57BL/6 mice. We generated a recombinant fusion protein, designated mTFF2-MSA, which contains murine TFF2 fused to murine serum albumin (MSA), for the purpose of increasing half-life and reducing the frequency of dosing. Mice subsequently received mTFF2-MSA, anti-PD-1 antibody (clone RMP1–14) or combination of mTFF2-MSA and anti-PD-1, and tumor volume was measured. At the endpoint, flow cytometry was performed on the tumor, axillary lymph node, blood, and bone marrow, to examine treatment-induced effects on cellular immune profiles.

Results In the Pan02 model, on Day 19 of treatment, tumor growth was suppressed (TGI) by mTFF2-MSA alone, anti-PD-1 alone, and by the combination mTFF2-MSA and anti-PD-1 by 23%, 28% and 36% TGI, respectively. In the blood, as measured by flow cytometry, there was a significant increase in total macrophages and M2 macrophages between the control and all treatment groups, and a decrease in monocytes and neutrophils in the groups dosed with anti-PD-1. In the axillary lymph node, there was a significant decrease in VISTA+ cells in both the CD4+ and CD8+ T-cells, and an increase in T regulatory cells in all treatment groups as compared to the control. In addition, an increase in PD-1+ and Lag3+ in both the CD4+ and CD8+ T-cells in the anti-PD-1 and combination treated groups was observed.

Conclusions mTFF2-MSA exhibits single agent activity and is additive to anti-PD-1 antibody checkpoint inhibition in treating the Pan02 syngeneic mouse model of advanced pancreatic cancer.

References

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2. Dubeykovskaya Z, Si Y, Chen X, Worthley DL, Renz BW, Urbanska AM, Hayakawa Y, Xu T, Westphalen CB, Dubeykovskiy A, Chen D, Friedman RA, Asfaha S, Nagar K, Tailor Y, Muthupalani S, Fox JG, Kitajewski J, Wang TC. Neural innervation stimulates splenic TFF2 to arrest myeloid cell expansion and cancer. Nat Commun. 2016;7:1–11.

3. Dubeykovskaya Z, Duddempudi PK, Deng H, Valenti G, Cuti, KL, Nagar K, Tailor Y, Guha C, Kitajewski J, Wang TC. Therapeutic potential of adenovirus-mediated TFF2-CTP-Flag peptide for treatment of colorectal cancer. Cancer Gene Ther. 2019;26:48–57.