EGFR exon 20 insertions in advanced non-small cell lung cancer: A new history begins

Although targeted therapy is standard of care in a large subset of oncogenic addicted non-small cell lung cancers (NSCLC), until recently, this therapeutic approach has not been feasible for all genomic alterations such as for those tumors harboring Epidermal Growth Factor Receptor (EGFR) exon 20 insertion (ex20ins) mutations. Despite being the third most common EGFR mutation, a limited efficacy of first- and second-generation EGFR tyrosine kinase inhibitors (TKI) exists. This is related to the heterogeneity at the molecular level in EGFR ex20ins mutation variants and the finding that this mutation promotes active kinase conformation but does not increase the affinity for EGFR TKI. As a result, the prognosis of this population is diminished. Therefore, chemotherapy remained the most suitable strategy in this subset of EGFR mutant NSCLC patients. Recently, new treatment strategies have been reported in this landscape, either with new EGFR TKI or bispecific antibodies, which may establish a new standard of care in the coming future for these patients. Future research should focus on elucidating the oncogenic degree of all EGFR ex20ins variants, the potential role of combination strategies either with chemotherapy or immune checkpoint inhibitors, and the most appropriate first-line treatment strategy in this subgroup. Finally, the knowledge of mechanisms of acquired resistance to these new agents upon progression is a priority for personalising treatment at that time. It is in this framework, that we provide a thorough overview on this subject.     

Endothelin and bradykinin: ‘brothers-in-arms’ in Chagas vasculopathies?

Reports of Chagas disease are increasing in non-endemic populations across the globe. Apart from vector eradication and prevention efforts by public health organizations, current pharmacological interventions are sparse and show important side effects. In this issue of the BJP, Andrade et al. elegantly demonstrate a new pharmacological paradigm whereby Trypanosoma cruzi host cell invasion requires significant cross-talk between receptors for kinins and endothelins. It is shown, for example, that acting via both ET(A) and ET(B) receptors, endothelin-1 (ET-1) cooperates with the (TLR2/CXCR2/B(2) kinin receptor) complex to activate inflammatory processes in response to invading trypomastigotes. This study by Andrade et al. prompts, however, several important questions, summarized in this Commentary, such as the putative role of chymase-dependent production of ET-1, the contentious protective role of ACE inhibitors in Chagasic patients, the unexplored role of de novo formed B(1) receptors for kinins triggered by cytokines and the putative role of compartmentalized calcium pools in host cell invasion by trypomastigotes.     

Inhibition of Epidermal Growth Factor Receptor and Vascular Endothelial Growth Factor Receptor Phosphorylation on Tumor-Associated Endothelial Cells Leads to Treatment of Orthotopic Human Colon Cancer in Nude Mice

The purpose of our study was to determine whether the dual inhibition of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) signaling pathways in tumor-associated endothelial cells can inhibit the progressive growth of human colon carcinoma in the cecum of nude mice. SW620CE2 human colon cancer cells growing in culture and orthotopically in the cecum of nude mice expressed a high level of transforming growth factor alpha (TGF-α) and vascular endothelial growth factor (VEGF) but were negative for EGFR, human epidermal growth factor receptor 2 (HER2), and VEGFR. Double immunofluorescence staining revealed that tumor-associated endothelial cells expressed EGFR, VEGFR2, phosphorylated EGFR (pEGFR), and phosphorylated VEGFR (pVEGFR). Treatment of mice with either 7H-pyrrolo [2,3-d]-pyrimidine lead scaffold (AEE788; an inhibitor of EGFR and VEGFR tyrosine kinase) or CPT-11 as single agents significantly inhibited the growth of cecal tumors (P < .01); this decrease was even more pronounced with AEE788 combined with CPT-11 (P < .001). AEE788 alone or combined with CPT-11 also inhibited the expression of pEGFR and pVEGFR on tumor-associated endothelial cells, significantly decreased vascularization and tumor cell proliferation, and increased the level of apoptosis in both tumor-associated endothelial cells and tumor cells. These data demonstrate that targeting EGFR and VEGFR signaling on tumor-associated endothelial cells provides a viable approach for the treatment of colon cancer.     

Protective effects of endothelin-A receptor antagonist BQ123 against LPS-induced oxidative stress in lungs

The aim of this study was to assess whether endothelin-A receptor (ET(A)-R) blocker, BQ123, influences lung edema, lipid peroxidation TBARS), hydrogen peroxide (H(2)O(2)), TNF-α concentration or the glutathione redox system in the lung homogenates obtained from LPS-induced endotoxic shock rats. The study was performed on male Wistar rats (n = 6 per group) divided into groups: (1) saline, (2) LPS (15 mg/kg)-saline, (3) BQ123 (0.5 mg/kg)-LPS, (4) BQ123 (1 mg/kg)-LPS. The ET(A)-R antagonist was injected intravenously 30 min before LPS administration. Five hours after saline or LPS administration, animals were sacrificed and lungs were isolated for indices of lung edema, oxidative stress and TNF-α concentration. Injection of LPS alone resulted in lung edema development and a marked increase in TNF-α (p < 0.02), TBARS (p < 0.02), and H(2)O(2) (p < 0.01) concentrations as well as a depletion of total glutathione (p < 0.01). Administration of BQ123 (1 mg/kg), before LPS challenge, led to a significant reduction in TNF-α and H(2)O(2) concentrations (p < 0.05) and elevation of both total glutathione and the GSH/GSSG ratio (p < 0.05). However, it did not prevent LPS-induced TBARS increase and lung edema formation. Interestingly, a lower dose of BQ123 was much more effective in decreasing H(2)O(2), TBARS, as well as TNF-α levels (p < 0.02, p < 0.05, p < 0.05, respectively). That dose was also effective in prevention of lung edema development (p < 0.01). Taken together, the obtained results indicate that BQ123 is highly effective in decreasing LPS-induced oxidative stress in lungs. Moreover, the dose of 0.5 mg/kg of the antagonist showed to be more effective in decreasing free radical generation and lung edema in endotoxemic rats.     

Renal vascular effects of the selective endothelin receptor antagonists in anaesthetized rats

1. Endothelin (ET) is a potent vasoconstrictor peptide which has been shown to have an important role in the regulation of systemic and renal haemodynamics. In order to elucidate the role of endogenous ET in the kidney, we examined the effects of ET receptor antagonists on systemic and renal vasculature in normotensive anaesthetized rats.
2. Intravenous injection of a selective ET_A receptor antagonist, {"type":"entrez-nucleotide","attrs":{"text":"FR139317","term_id":"258103156","term_text":"FR139317"}}FR139317 (0.5 μmol kg⁻¹, for 20 min) induced a very small fall in blood pressure. Similarly, a non-selective ET_A/ET_B receptor antagonist, TAK-044 (12.5 μmol kg⁻¹, for 20 min) slightly decreased blood pressure. A selective ET_B receptor antagonist, BQ-788 (0.5 μmol kg⁻¹, for 20 min) had no effect on blood pressure.
3. {"type":"entrez-nucleotide","attrs":{"text":"FR139317","term_id":"258103156","term_text":"FR139317"}}FR139317 and TAK-044 did not affect renal blood flow or calculated renal vascular resistance. In contrast, BQ-788 significantly reduced renal blood flow by 18.2±2.4% and increased renal vascular resistance. Furthermore, the renal vascular action of BQ-788 was not observed when combined with {"type":"entrez-nucleotide","attrs":{"text":"FR139317","term_id":"258103156","term_text":"FR139317"}}FR139317.
4. Pretreatment with a nitric oxide (NO) synthase inhibitor N^ω-nitro-L-arginine methyl ester (L-NAME, 37 μmol kg⁻¹, i.v.) and a cyclo-oxygenase inhibitor ibuprofen (44 μmol kg⁻¹, i.v.) completely abolished the BQ-788-mediated renal vasoconstriction.
5. These results indicate that activation of ET_B receptors by endogenous ET acts as a physiological brake for the ET_A-mediated renal vasoconstriction; this effect appears to be mediated by stimulation of NO and/or vasodilator prostaglandin(s) release.

     

Pharmacological characterization of endothelin-induced rat pulmonary arterial dilatation

1. The aim of study was to characterize endothelin (ET)-induced vasodilatation in isolated extrapulmonary rat arteries (EPA) and in intrapulmonary arteries (IPA) preconstricted with 1 μM phenylephrine.
2. The ET-3 (1 nM–100 nM)- and ET-1 (10 nM–100 nM)-induced transient vasodilatations in EPA were more potent than those in IPA. The vasodilatation induced by ET-3 (100 nM) was larger than that induced by ET-1 (100 nM).
3. Both the ET_B antagonist, BQ788 (3 μM) and or endothelium denudation, but not the ET_A antagonist, BQ123 (3 μM), abolished the vasodilatation induced by ET-1 or ET-3 (100 nM each) in EPA and in IPA. The ATP-sensitive K+channel blocker, glibenclamide (20 μM) and the nitric oxide synthase inhibitor, N^G-monomethyl-L-arginine (L-NMMA, 1 mM) suppressed the ET-induced vasodilatation in EPA and in IPA.
4. We conclude that the vasodilatation induced by endothelins is markedly reduced in rat isolated IPA, and suggest that the endothelial ET_B-mediated vasodilatation varies depending on rat pulmonary arterial regions. Furthermore, ET_B-mediated vasodilatation involves activation of ATP-sensitive K⁺ channels and of nitric oxide synthase in rat isolated EPA and IPA.

     

Statin-induced necrotizing autoimmune myopathy: An uncommon complication of a commonly used medication

A well-known side effect of statin therapy is myopathy. We report a case of statin induced necrotizing autoimmune myopathy, a rare variant of statin-induced myopathy. A 64-year-old gentleman on atorvastatin presented with muscle weakness. Initial laboratory results showed elevated liver function tests, a creatine phosphokinase (CPK) of 8200 IU/L, and positive urine myoglobin. Despite discontinuing atorvastatin, his CPK remained persistently elevated. Muscle biopsy was consistent with necrotizing myopathy. Anti-HMG CoA reductase antibody was strongly positive. Steroids followed by intravenous immunoglobulin were given. The patient’s muscle weakness, CPK, and liver functions gradually improved, and he was eventually discharged on oral steroids. Statin induced necrotizing autoimmune myopathy should be considered when discontinuing statin does not lead to muscle recovery and improvement in CPK. Diagnosis is confirmed by positive anti-HMG-CoA reductase autoantibody.     

Endothelin-1 Induces CXCL1 and CXCL8 Secretion in Human Melanoma Cells

The endothelin pathway plays a critical role in melanoma tumor progression by a variety of mechanisms that enhance tumor cell growth, invasion, and metastasis. Here, we investigate the effect of this pathway on CXC chemokine expression in human melanoma cells and melanocytes. As determined by ELISA, endothelin-1 (ET-1) induces CXCL1 and CXCL8 secretion in three human melanoma cell lines in a concentration-dependent fashion. These responses are mediated by the endothelin-B receptor and are sustained over a 40 h time course. ET-1 does not induce CXCL1 secretion in primary human melanocytes but ET-3, an endothelin isoform, induces a low level of CXCL1 secretion in certain cultures. Neither ET-1 nor ET-3 induces secretion of CXCL8 in primary human melanocytes; thus, this response may be specific for melanocytic cells that have undergone malignant transformation. We have previously demonstrated that ET-1 induces changes in the expression of adhesion molecules in melanoma cells such that invasion and metastasis are favored. This study demonstrates that ET-1 additionally induces secretion of CXC chemokines critical for melanoma metastasis and tumor progression.