Investigating the potential of the Novel Anti-Cancer compound CTR 20 in enhancing the sensitivity of MDA-MB-231 cells to NK-92 cell-based immunotherapy

Abstract

Triple negative breast cancer (TNBC) accounts for 15-20% of all breast cancers and is currently limited to treatment with chemotherapy administered at the maximum tolerated dose (MTD). However, due to the severe toxicity and the frequent development of chemoresistance, chemotherapy has shown limited therapeutic benefit for TNBC. Various agents with combinational strategies are under current investigation to better target TNBC and improve clinical outcomes. Increasing evidence suggests that anti-cancer agents possess immunomodulatory properties even at lower doses, rendering tumour cells susceptible to immune detection and attack. Recent findings suggest that chemotherapy-induced stress can upregulate natural killer (NK) cell-activating ligands on tumour cells, enhancing their susceptibility to the attack by NK cells of the innate immune system. Therefore, this study investigated the immunogenic potential of two anti-cancer agents in combination with the highly cytotoxic NK-92 cell line: doxorubicin – a widely used anthracycline for breast cancer and CTR 20 – a novel, less-toxic chalcone-based compound synthesized by the Lee laboratory. The overall aim of this study was to determine the therapeutic potential of low-dose chemotherapy in enhancing the presentation of ligands for the NKG2D activating receptor of NK cells, to increase MDA-MB-231 cell susceptibility to NK-92 cell-mediated tumour cell killing. Results demonstrated that low-dose CTR 20 treatment was unsuccessful in rendering MDA-MB-231 cells susceptible to attack by NK-92 cells. Conversely, low-dose doxorubicin treatment successfully upregulated NKG2DL presentation, rendering MDA-MB-231 cells susceptible to NK-92 cytotoxicity without affecting NK-92 degranulation capacity. NK-92 cytotoxicity alone was responsible for inducing a maximum area of tumour cell death of ≈11,000 µm2 /image, whereas the maximum area of tumour cell death following combination therapy with low-dose doxorubicin was ≈13,000 µm2/image, a synergistic increase of 2,000 µm2/image. The findings from this study demonstrate the potential of low-dose doxorubicin treatment to be used incombination with NK-92 cell-mediated immunotherapy to deliver an improved anti-tumour response against TNBC while achieving favourable levels of toxicity.