849 - Selective killing of circulating tumor cells prevents metastasis and extends survival

Background

Distant metastasis is initiated by circulating tumor cells (CTCs), which are considered to be a determining factor for the degree of metastasis and the survival of cancer patients. Although CTC-based diagnostic approaches are being rapidly developed, limited studies have proven the benefits of CTC elimination, with most studies providing only hypothetical inference because of unpredictable nature and dynamics of CTCs.

Methods

We modified photodynamic therapy to specifically eliminate green fluorescent protein (GFP)-expressing CTCs and evaluated the therapeutic efficacy of CTC elimination via in vitro and in vivo experiments.

Results

When circulating blood is illuminated with a blue laser (λ = 473 nm), the combination of GFP and photosensitizers induces a selective elimination of GFP-expressing CTCs, with limited effect on normal cells. In GFP-expressing cancer cell-infused mice model, numbers of circulating tumor cells were significantly reduced after blue laser illumination. In GFP-expressing cancer cell transplanted mice models, the treatment suppressed distant metastasis and extended the survival of the tumor-bearing mice.

Conclusions

This study using novel photodynamic modality is the first experimental study to demonstrate that selective killing of CTCs delays distant metastasis significantly and ultimately improves survival. In addition, this study directly suggests CTCs are a core seed to be metastasized into secondary organs.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Kyung Hee University.

Funding

National R&D Program for Cancer Control, Ministry of Health and Welfare, Republic of Korea (HA17C0039) Kyung Hee University (KHU-20170844).

Disclosure

Y.R. Kim: CEO: Oncocross. All other authors have declared no conflicts of interest.