Aptamer targeted therapy potentiates immune checkpoint blockade in triple-negative breast cancer

Abstract

Background: Triple-negative breast cancer (TNBC) is a uniquely aggressive cancer with high rates of relapse due to resistance to chemotherapy. TNBC expresses higher levels of programmed cell death-ligand 1 (PD-L1) compared to other breast cancers, providing the rationale for the recently approved immunotherapy with anti-PD-L1 monoclonal antibodies (mAbs). A huge effort is dedicated to identify actionable biomarkers allowing for combination therapies with immune-checkpoint blockade. Platelet-derived growth factor receptor β (PDGFRβ) is highly expressed in invasive TNBC, both on tumor cells and tumor microenvironment. We recently proved that tumor growth and lung metastases are impaired in mouse models of human TNBC by a high efficacious PDGFRβ aptamer. Hence, we aimed at investigating the effectiveness of a novel combination treatment with the PDGFRβ aptamer and anti-PD-L1 mAbs in TNBC.Methods: The targeting ability of the anti-human PDGFRβ aptamer toward the murine receptor was verified by streptavidin-biotin assays and confocal microscopy, and its inhibitory function by transwell migration assays. The anti-proliferative effects of the PDGFRβ aptamer/anti-PD-L1 mAbs combination was assessed in human MDA-MB-231 and murine 4T1 TNBC cells, both grown as monolayer or co-cultured with lymphocytes. Tumor cell lysis and cytokines secretion by lymphocytes were analyzed by LDH quantification and ELISA, respectively. Orthotopic 4T1 xenografts in syngeneic mice were used for dissecting the effect of aptamer/mAb combination on tumor growth, metastasis and lymphocytes infiltration. Ex vivo analyses through immunohistochemistry, RT-qPCR and immunoblotting were performed. Results: We show that the PDGFRβ aptamer potentiates the anti-proliferative activity of anti-PD-L1 mAbs on both human and murine TNBC cells, according to its human/mouse cross-reactivity. Further, by binding to activated human and mouse lymphocytes, the aptamer enhances the anti-PD-L1 mAb-induced cytotoxicity of lymphocytes against tumor cells. Importantly, the aptamer heightens the antibody efficacy in inhibiting tumor growth and lung metastases in mice. It acts on both tumor cells, inhibiting Akt and ERK1/2 signaling pathways, and immune populations, increasing intratumoral CD8+T cells and reducing FOXP3+Treg cells. Conclusion: Co-treatment of PDGFRβ aptamer with anti-PD-L1 mAbs is a viable strategy, thus providing for the first an evidence of the efficacy of PDGFRβ/PD-L1 co-targeting combination therapy in TNBC.

Optimizing cisplatin delivery to triple-negative breast cancer through novel EGFR aptamer-conjugated polymeric nanovectors

“…Cell and tumor lysates preparation and immunoblot analyses were performed as previously reported [34,35]. Filters were probed with the indicated primary antibodies: anti-EGFR, anti-phospho-44/42 MAPK (extracellular signal-regulated kinase 1/2, ERK1/2, indicated as pERK1/2), anti-caspase 3 and anti-vinculin (Cell Signaling Technology Inc., Danvers, MA), anti-ERK1 (C-16) (Santa Cruz Biotechnology, Santa Cruz, CA), antiphospho-histone H2A.X (Ser139, indicated as γH2AX), clone JBW301 (Upstate Biotechnology, Inc., Lake Placid, NY).…”

Multi-omics tumor profiling technologies to develop precision medicine in multiple myeloma

“…Currently, enormous effort is devoted to identifying novel actionable biomarkers that may allow combination therapies with immune checkpoint blockade in TNBC. Recently, our group demonstrated the efficacy of a novel combination treatment with the previously validated PDGFRβ aptamer [37,73,84] and anti-PD-L1 mAbs in both human and murine in vitro settings, consisting of TNBC cells cultured as monolayer or co-cultured with lymphocytes [92]. Importantly, the PDGFRβ aptamer (intravenous administration) potentiated the efficacy of the anti-PD-L1 antibody in inhibiting tumor growth and lung metastasis formation in a syngeneic 4T1 TNBC mouse model by acting on both tumor cells and immune populations.…”

Mini-Review: Recent Advances in Aptamer Applications

“…high rates of relapse due to resistance to chemotherapy, expresses higher levels of programmed cell death-ligand 1 (PD-L1) compared to other breast cancers, and thus provides the rationale for FDA-approved immunotherapy with anti-PD-L1 monoclonal antibodies (mAbs). Because platelet-derived growth factor receptor β (PDGFRβ) is overexpressed by TNBC cells and tumor microenvironment, Camorani et al 6 developed a PDGFRβ aptamer to investigate a novel combination treatment with the PDGFRβ aptamer and anti-PD-L1 mAbs in TNBC. Importantly, they found that the aptamer increases the antibody efficacy in inhibiting tumor growth and lung metastases in mice by acting on both tumor cells, inhibiting signaling pathways, and increasing intratumoral T cells.…”