No abstract

The tropomyosin receptor kinase (TRK) family of receptor tyrosine kinases are encoded by NTRK genes and have a role in the development and normal functioning of the nervous system. Since the discovery of an oncogenic NTRK gene fusion in colorectal cancer in 1986, over 80 different fusion partner genes have been identified in a wide array of adult and paediatric tumours, providing actionable targets for targeted therapy. This review describes the normal function and physiology of TRK receptors and the biology behind NTRK gene fusions and how they act as oncogenic drivers in cancer. Finally, an overview of the incidence and prevalence of NTRK gene fusions in various types of cancers is discussed.

Background HER2 amplification is detected in 3% of patients with colorectal cancer (CRC), making tumors in the metastatic setting vulnerable to double pharmacological HER2 blockade. Preclinical findings show that it also might impair response to anti‐epidermal growth factor receptor (EGFR) treatment. Subjects and Methods Patients with KRAS exon 2 wild‐type metastatic CRC underwent molecular screening of HER2 positivity by HERACLES criteria (immunohistochemistry 3+ or 2+ in ≥50% of cells, confirmed by fluorescence in situ hybridization). A sample of consecutive HER2‐negative patients was selected as control. A regression modeling strategy was applied to identify predictors explaining the bulk of HER2 positivity and the association with response to previous anti‐EGFR treatment. Results From August 2012 to April 2018, a total of 100 HER2‐positive metastatic CRC tumors were detected out of 1,485 KRAS exon 2 wild‐type screened patients (6.7%). HER2‐positive patients show more frequently lung metastases (odds ratio [OR], 2.04; 95% confidence interval [CI], 1.15–3.61; p = .014) and higher tumor burden (OR, 1.48; 95% CI, 1.10–2.01; p = .011), and tumors were more likely to be left sided (OR, 0.50; 95% CI, 0.22–1.11; p = .088). HER2‐positive patients who received treatment with anti‐EGFR agents (n = 79) showed poorer outcome (objective response rate, 31.2% vs. 46.9%, p = .031; progression‐free survival, 5.7 months vs. 7 months, p = .087). Conclusion Testing for HER2 should be offered to all patients with metastatic CRC because the occurrence of this biomarker is unlikely to be predicted based on main clinicopathological features. Patients with HER2‐amplified metastatic CRC are less likely to respond to anti‐EGFR therapy. Implications for Practice Patients with HER2‐amplified/overexpressed metastatic colorectal cancer (mCRC) harbor a driver actionable molecular alteration that has been shown in preclinical models to hamper efficacy of the anti‐epidermal growth factor receptor (EGFR) targeted therapies. The present study confirmed that this molecular feature was associated with worse objective tumor response and shorter progression‐free survival in response to previous anti‐EGFR therapies. Moreover, it was found that the occurrence of this biomarker is unlikely to be predicted based on main clinicopathological features. Therefore, HER2 status assessment should be included in the molecular diagnostic workup of all mCRC for speedy referral to clinical trials encompassing HER2‐targeted double blockade independently of previous anti‐EGFR treatment.

Starting from a yeast phenotypic screening performed on 21 compounds, we described the identification of two small molecules (9 and 18) able to significantly reduce the S. cerevisiae cell growth, thus miming the effect of GCN5 deletion mutant. Tested on a GCN5-dependent gene transcription assay, compounds 9 and 18 gave a high reduction of the reporter activity. In S. cerevisiae histone H3 terminal tails assay, the H3 acetylation levels were highly reduced by treatment with 0.6-1 mM 9, while 18 was effective only at 1.5 mM. In human leukemia U937 cell line, at 1 mM 9 and 18 showed effects on cell cycle (arrest in G1 phase, 9), apoptosis (9), and granulocytic differentiation (18). When tested on U937 cell nuclear extracts to evaluate their histone acetyltransferase (HAT) inhibitory action, both compounds were able to reduce the enzyme activity when used at 500 microM. Another quinoline, compound 22, was synthesized with the aim to improve the activity observed with 9 and 18. Tested in the HAT assay, 22 was able to reduce the HAT catalytic action at 50 and 25 microM, thereby being comparable to anacardic acid, curcumin, and MB-3 used as references. Finally, in U937 cells, compounds 9 and 18 used at 2.5 mM were able to reduce the extent of the acetylation levels of histone H3 (9) and alpha-tubulin (9 and 18). In the same assay, 22 at lower concentration (100 microM) showed the same hypoacetylating effects with both histone and non-histone substrates.