Bangwei Cao

Nowadays, colorectal cancer is the fourth most common type of tumor all over the world. When diagnosed, ∼50%-60% of tumors have metastasized, thus resulting in a grim prognosis. Chemotherapy is regarded as standard treatment for patients with colorectal cancer, however, limitations of chemotherapy cannot be ignored, such as low selectivity, insufficient concentrations in tumor tissues, and systemic toxicity. Recently, six targeted drugs have been approved by the U.S. Food and Drug Administration (FDA) for treatment of metastatic colorectal cancer (mCRC), including bevacizumab, aflibercept, regorafenib, cetuximab, and panitumumab. The development of these drugs marked significant advancement in the field of mCRC therapy. The addition of biologic agents to chemotherapy has prolonged the median overall survival. Now, many investigational drugs are under clinical trials, of which programmed death (PD)-1/L1 has drawn much attention. In this review, new biologic agents under clinical trials such as MEK/MET/RAS/RAF/PD-1 inhibitors with potentials for mCRC treatment are concluded by describing targeted drugs approved by FDA, to offer new insights into global trends and future development.

Objective: To isolate exosomes from the serum of colon cancer patients and identify RNAs in the small vesicles. Methods: ExoQuick-TC Exosome Precipitation Solution was used for exosome isolation and the shapes of exosomes were observed under a transmission electron microscope. Mass spectrometry was used to identify the classification of miRNAs encapsulated in exosomes, and the expression levels of miRNA-21,-133a, and -181b in exosomes were detected by RT-PCR. Results: Exosomes isolated from serum of colon cancer patients were circular-or oval-shaped and vary in size with a diameter of 40-100 nm. Mass spectrometry shows that the main RNAs in exosomes are small RNAs; the levels of these small RNAs in exosomes are significantly higher compared with fresh serum. There is still a tiny amount of small RNAs in exosome-free serum, but the amounts are significantly lower than that in exosomes. No more RNAs were detected in the repeated freezing and thawing serum, but there were still some RNAs detectable in the exosomes extracted from these serums. MiRNA-21, -133a and -181b can be detected in exosomes, and the level of miRNA-21 is associated with early diagnosis of colon cancer.