Immunomodulatory activity of IR700-labelled affibody targeting HER2.

There is an urgent need to develop therapeutic approaches that can increase the response rate to immuno-oncology agents. Photoimmunotherapy has recently been shown to generate anti-tumour immunological responses by releasing tumour-associated antigens from ablated tumour cell residues, thereby enhancing antigenicity and adjuvanticity. Here, we investigate the feasibility of a novel HER2-targeted affibody-based conjugate (ZHER2:2395-IR700) selectively to induce cancer cell death in vitro and in vivo. The studies in vitro confirmed the specificity of ZHER2:2395-IR700 binding to HER2-positive cells and its ability to produce reactive oxygen species upon light irradiation. A conjugate concentration- and light irradiation-dependent decrease in cell viability was also demonstrated. Furthermore, light-activated ZHER2:2395-IR700 triggered all hallmarks of immunogenic cell death, as defined by the translocation of calreticulin to the cell surface, and the secretion of ATP, HSP70/90 and HMGB1 from dying cancer cells into the medium. Irradiating a co-culture of immature dendritic cells (DCs) and cancer cells exposed to light-activated ZHER2:2395-IR700 enhanced DC maturation, as indicated by augmented expression of CD86 and HLA-DR. In SKOV-3 xenografts, the ZHER2:2395-IR700-based phototherapy delayed tumour growth and increased median overall survival. Collectively, our results strongly suggest that ZHER2:2395-IR700 is a promising new therapeutic conjugate that has great potential to be applicable for photoimmunotherapy-based regimens.

Near-infrared photoimmunotherapy targeting EGFR-Shedding new light on glioblastoma treatment.

Glioblastomas (GBMs) are high-grade brain tumors, differentially driven by alterations (amplification, deletion or missense mutations) in the epidermal growth factor receptor (EGFR), that carry a poor prognosis of just 12-15 months following standard therapy. A combination of interventions targeting tumor-specific cell surface regulators along with convergent downstream signaling pathways may enhance treatment efficacy. Against this background, we investigated a novel photoimmunotherapy approach combining the cytotoxicity of photodynamic therapy with the specificity of immunotherapy. An EGFR-specific affibody (ZEGFR:03115 ) was conjugated to the phthalocyanine dye, IR700DX, which when excited with near-infrared light produces a cytotoxic response. ZEGFR:03115 -IR700DX EGFR-specific binding was confirmed by flow cytometry and confocal microscopy. The conjugate showed effective targeting of EGFR positive GBM cells in the brain. The therapeutic potential of the conjugate was assessed both in vitro, in GBM cell lines and spheroids by the CellTiter-Glo® assay, and in vivo using subcutaneous U87-MGvIII xenografts. In addition, mice were imaged pre- and post-PIT using the IVIS/Spectrum/CT to monitor treatment response. Binding of the conjugate correlated to the level of EGFR expression in GBM cell lines. The cell proliferation assay revealed a receptor-dependent response between the tested cell lines. Inhibition of EGFRvIII+ve tumor growth was observed following administration of the immunoconjugate and irradiation. Importantly, this response was not seen in control tumors. In conclusion, the ZEGFR:03115 -IR700DX showed specific uptake in vitro and enabled imaging of EGFR expression in the orthotopic brain tumor model. Moreover, the proof-of-concept in vivo PIT study demonstrated therapeutic efficacy of the conjugate in subcutaneous glioma xenografts.