Despite screening and therapeutic advancements, the global cancer burden is steadily rising, with 1 in 3 men and 1 in 4 women developing cancer in their lifetime. Furthermore, 1 in 8 men and 1 in 11 women will die from untreatable progression of cancer, making cancer one of the leading causes of death worldwide. Small extracellular vesicles (sEVs) have been recently shown to serve as a non-invasive method for potentially identifying cancer. In this work, we describe a comprehensive clinical assay that utilizes cancer-derived sEVs proteins for cancer diagnosis.
Using an isogenic model, we isolated sEVs secreted by normal human bronchial epithelial cells (HBECs) and transformed HBECs(p53/KRAS). Label-free quantification by spectral counting identified 15 extracellular proteins that were upregulated in transformed HBECs compared to normal HBECs. We evaluated the expression of 4 proteins in further cancer lines to establish if these proteins were universally upregulated in cancer, or specific to particular subsets of cancer cells. To address this, we isolated sEVs from a total of 22 cell lines comprising of; non-small cell lung cancer, glioblastoma, colorectal, breast, prostate, melanoma, oesophageal, and ovarian cancer. Interestingly, we found that all 4 markers were upregulated in cancer cell-derived sEVs compared to normal HBEC sEVs, regardless of cancer-type.
Given this, we then isolated sEVs from the serum/plasma of 250 healthy controls and 497 cancer patients who had been diagnosed with cancers of the lung, brain, colorectal, prostate, melanoma, stomach, and oesophagus. Importantly, the combined 4 protein sEVs signature was increased in sEVs derived from cancer subjects compared to healthy controls with an exceptional area under the curve of 0.96, regardless of stage.
The clinical performance of this assay is highly sensitive and specific and detects cancer at early stage 1, thereby providing opportunities for early-detection and improved survival in numerous patients with cancer.