[18F]fluorothymidine PET Informs the Synergistic Efficacy of Capecitabine and Trifluridine/Tipiracil in Colon Cancer

Preclinical Imaging in Targeted Cancer Therapies

Preclinical imaging with radiolabeled probes can provide noninvasive tools to test the efficacy of targeted agents in tumors harboring specific genetic alterations and to identify imaging parameters that can be used as pharmacodynamics markers in cancer patients. The present review will primarily focus on preclinical imaging studies that can accelerate the clinical approval of targeted agents and promote the development of imaging biomarkers for clinical applications. Since only subgroups of patients may benefit from treatment with targeted anticancer agents, the identification of a patient population expressing the target is of primary importance for the success of clinical trials. Preclinical imaging studies tested the ability of new radiolabeled compounds to recognize mutant, amplified, or overexpressed targets and some of these tracers were transferred to the clinical setting. More common tracers such as ¹⁸F-Fluorothymidine and ¹⁸F-Fluorodeoxyglucose were employed in animal models to test the inhibition of the target and downstream pathways through the evaluation of early changes of proliferation and glucose metabolism allowing the identification of sensitive and resistant tumors. Furthermore, since the majority of patients treated with targeted anticancer agents will invariably develop resistance, preclinical imaging studies were performed to test the efficacy of reversal agents to overcome resistance. These studies provided consistent evidence that imaging with radiolabeled probes can monitor the reversal of drug resistance by newly designed alternative compounds. Finally, despite many difficulties and challenges, preclinical imaging studies targeting the expression of immune checkpoints proved the principle that it is feasible to select patients for immunotherapy based on imaging findings. In conclusion, preclinical imaging can be considered as an integral part of the complex translational process that moves a newly developed targeted agent from laboratory to clinical application intervening in all clinically relevant steps including patient selection, early monitoring of drug effects and reversal of drug resistance.

The mechanism and tumor inhibitory study of Lagopsis supine ethanol extract on colorectal cancer in nude mice

Background

This study was aimed to determination the tumor inhibitory effect and explore the potential mechanisms of Lagopsis supine ethanol extract (Ls) on colorectal cancer.

Methods

The cell growth inhibition experiment of Ls in colorectal cancer cell lines was determined by MTT method in the time course of 24, 48 and 72 h in four gradient drug concentrations. The protein expression levels of pSTAT3, pJAK2, STAT3, JAK2, Bcl-2 and caspase 3 were measured by Western blot method. The mRNA levels of the downstream genes of STAT3 were detected through semi-quantitative RT PCR. Sixty Balb/c-nude mice were xenograft with HCT116 colorectal cancer cells through subcutaneously. The xenografts were divided into five groups: model group, positive group (capecitabine 300 mg/kg) and three dosages of Ls treated groups (75, 150 and 300 mg/kg). Tumor size and tumor weight were calculated for evaluation the anti-tumor effects. H & E staining and immunohistochemical analysis were used to determine the histopathological changes and the levels of pSTAT3 and pJAK2 in the tumor tissues.

Results

Ls exhibited a significant anti-proliferation effect in HCT116 and SW480 cells in vitro. The protein levels of pSTAT3, pJAK2 and Bcl-2, and the mRNA levels of Bcl-2 and Bak notably reduced with a dose-dependent manner. While the protein levels of caspase 3, and mRNA levels of Bax and caspase-3 remarkably increased in the gradient dosage of Ls in HCT116 cells. HCT116 in vivo xenografts experiment showed that the growth of the tumors significantly inhibited by Ls administration, which with no any significant body weight changes in each experiment group. The histopathology analysis displayed that Ls significantly reduced the inflammatory cells in tumor tissue. Furthermore, Ls also significantly down-regulate the protein levels of pSTAT3 and pJAK2 in the tumor tissues, compared with the model group.

Conclusions

This work shows that Ls inhibited the cell proliferation of colorectal cancer in vitro and significantly reduced the tumor growth in HCT116 xenografts in vivo, which is probably related with the JAK/STAT signal pathway.

Precision treatment in colorectal cancer: Now and the future

Until recently, a one‐drug‐fits‐all model was applied to every patient diagnosed with the same condition. But not every condition is the same, and this has led to many cases of ineffective treatment. Pharmacogenetics is increasingly used to stratify patients for precision medicine treatments, for instance, the UGT1A1*28 polymorphism as a dosage indicator for the use of irinotecan as well as epidermal growth factor receptor (EGFR) immunohistochemistry and KRAS Proto‐Oncogene (KRAS) exon 2 mutation tests for determining the likelihood of treatment response to cetuximab or panitumumab treatment in metastatic colorectal cancer (CRC). The other molecular subtypes, such as KRAS exon 3/4, B‐Raf Proto‐Oncogene, NRAF, PIK3CA, and PETN, were also reported as potential new pharmacogenetic targets for the current and the newly discovered anticancer drugs. In addition to next‐generation sequencing (NGS), primary tumor cells for in vivo and in vitro drug screening, imaging biomarker 3′‐Deoxy‐3′‐18F‐fluorothymidine positron emission tomography, and circulating tumor DNA (ctDNA) detection methods are being developed and may represent the future direction of precision medicine. This review will discuss the current environment of precision medicine, including clinically approved targeted therapies, the latest potential therapeutic agents, and the ongoing pharmacogenetic trials for CRC patients.