Is there a role for dacomitinib, a second-generation irreversible inhibitor of the epidermal-growth factor receptor tyrosine kinase, in advanced non-small cell lung cancer?

Introduction: Non-small cell lung cancer (NSCLC) is a highly lethal disease. During the past 20 years, the epidermal growth factor receptor (EGFR) has been a relevant target for anticancer drug-design, and a large family of EGFR tyrosine kinase inhibitors (TKI) were designed, which improved therapeutic outcomes compared to conventional chemotherapy in NSCLC patients with specific EGFR mutations. However, resistance to these inhibitors occurs; therefore, the debate on which inhibitor should be used first is still open. Dacomitinib was approved in 2018 for the first-line treatment of NSCLC with EGFR activating mutations. Areas covered: This manuscript reviews the properties of dacomitinib, including the current information from clinical trials and its potential application as stand-alone therapy, or in combination. Expert opinion: Dacomitinib is a second-generation EGFR-TKI that has demonstrated significant improvement in overall survival in a phase III randomized study compared with gefitinib, a first-generation TKI. However, the rapid development and approval of a new generation of TKIs (osimertinib), with better clinical profiles, raises the question of which role can dacomitinib play in NSCLC. Further studies are required to evaluate the efficacy of this drug on brain metastases, as a second-line treatment after third-generation TKIs, or in combination with other types of treatments

The role of Eph receptors in cancer and how to target them: novel approaches in cancer treatment.

Introduction: Erythropoietin-producing human hepatocellular (Eph) receptors are among the largest family of tyrosine kinases that are divided into two classes: EphA and EphB receptors. Over the past two decades, their role in cancer has become more evident. Areas covered: There is a need for new anticancer treatments and more insight in the emerging role of Eph receptors in cancer. Molecular mechanisms underlying the pro-tumorigenic effects of Eph receptors could be exploited for future therapeutic strategies. This review describes the variability in expression levels and different effects on oncogenic and tumor suppressive downstream signaling of Eph receptors in various cancer types, and the small molecules, antibodies and peptides that target these receptors. Expert opinion: The complexity of Eph signaling is a challenge for the definition of clear targets for cancer treatment. Nevertheless, numerous drugs that target EphA2 and EphB4 are currently in clinical trials. However, some Eph targeted drugs also inhibit other tyrosine kinases, so it is unclear to what extent the targeting of Eph receptors contributes to their efficacy. Future research is warranted for an improved understanding of the full network in which Eph receptors function. This will be critical for the improvement of the anticancer effects of drugs that target the Eph receptors

Transport of six tyrosine kinase inhibitors: active or passive ?

Transport of erlotinib, gefitinib, sorafenib, sunitinib, dasatinib and crizotinib can be active or passive, which was studied by measuring uptake at low (4 °C; passive) and normal temperature (37 °C; active and passive) and by the use of specific organic cation transporter (OCT) inhibitors. Intracellular accumulation was determined using Caco-2 as monolayers, while for gut permeation we used differentiated Caco-2 as model for intestinal epithelium in the Transwell system. Sorafenib and crizotinib uptake are likely to be dependent on passive transport. Gefitinib, dasatinib and sunitinib uptake seem to be active. Erlotinib’s transport also seems to be active. This study suggests that hOCTs might be involved in the apical to basolateral transport of gefitinib and crizotinib. Overall it can be concluded that the accumulation and transport of these six TKIs are very different, despite the fact that they are all tyrosine kinase inhibitors

The role of the microbiome in drug resistance in gastrointestinal cancers.

Introduction: The microbiota is recognized for its impact on both human health and disease. The human microbiota is made up of trillions of cells, including bacteria, viruses, and fungi. The largest population of microbes reside in the gut, prompting research for better understanding of the impact of gastrointestinal microbiota in different diseases. Evidence from numerous studies has pointed out the role of commensal microbes as key determinants of cancer pathogenesis. Moreover, gut microbiota may play an important role in chemoresistance; consequently, this knowledge might be important for novel strategies to improve anticancer treatment efficacy. Areas covered: We describe the role of microbiota in different gastrointestinal cancer types (esophageal, gastric, colorectal, hepatocellular and pancreatic-biliary tract cancers). Moreover, we analyzed the impact of the microbiota on resistance to anticancer therapies, and, lastly, we focused on possibilities of microbiota modulation to enhance anticancer therapy efficacy. Expert opinion: Increasing evidence shows that gut microbiota might influence resistance to anticancer treatment, including conventional chemotherapy, immunotherapy, radiotherapy, and surgery. Therefore, a better knowledge of gut microbiota and its interactions with anticancer drugs will enable us to develop novel anticancer treatment strategies and subsequently improve the cancer patients' outcome

Transport of six tyrosine kinase inhibitors: active or passive ?

Transport of erlotinib, gefitinib, sorafenib, sunitinib, dasatinib and crizotinib can be active or passive, which was studied by measuring uptake at low (4 °C; passive) and normal temperature (37 °C; active and passive) and by the use of specific organic cation transporter (OCT) inhibitors. Intracellular accumulation was determined using Caco-2 as monolayers, while for gut permeation we used differentiated Caco-2 as model for intestinal epithelium in the Transwell system. Sorafenib and crizotinib uptake are likely to be dependent on passive transport. Gefitinib, dasatinib and sunitinib uptake seem to be active. Erlotinib’s transport also seems to be active. This study suggests that hOCTs might be involved in the apical to basolateral transport of gefitinib and crizotinib. Overall it can be concluded that the accumulation and transport of these six TKIs are very different, despite the fact that they are all tyrosine kinase inhibitors

EORTC-related new drug discovery and development activities: role of the Pharmacology and Molecular Mechanisms Group

Abstract The EORTC Pharmacology and Molecular Mechanism Group (PAMM) focuses on applied research to translate basic/fundamental research discoveries in cancer biology into new drug discovery and development. PAMM provides a unique platform on the pharmacology, pharmacokinetics, pharmacodynamics of drug effects, molecular mechanisms of anticancer agents, and drug-related molecular pathology. For these purposes the group stimulates the interaction between basic scientists and clinicians in order to perform translational research on the pharmacology and molecular mechanisms of anticancer agents in Europe. The group has extensive expertise in various disciplines of pharmacology and has developed standards for studies performed in conjunction with clinical trials equivalent to those of good laboratory practice (GLP). The group serves as master organization for other EORTC (sub-)committees in the maximal interest of these groups and of the EORTC as a whole. PAMM merged with Preclinical Therapeutics Models Group (PTMG) in 2000 and with the Screening and Pharmacology Group (SPG) in 2003. The latter group continued as the Drug Discovery Committee within PAMM. The groups have always been involved in the development of anticancer agents, evolving from platinum analogs, anthracyclines, nitrosoureas, antifolates in the 1980's, to drugs derived from natural sources (trabectedin, taxanes) in the 1990's, and anti-signaling drugs, DNA alkylators, in the last decade. Several of these drugs have been registered. Mechanistic studies focused on drug activation/inactivation, target (DNA, receptors) in relation to efficacy and toxicity such as with several antimetabolites (5-fluorouracil, methotrexate), topoisomerase inhibitors (irinotecan), tyrosine kinase inhibitors (imatinib), acridones (C-1311), etc. The group recently included pharmacogenetics in the identification of genetic polymorphisms in order to use this information for personalized therapy

Adaptation of a human gut epithelial model in relation to the assessment of clinical pharmacokinetic parameters for selected tyrosine kinase inhibitors

The absorption, efflux and transport properties of two of the most commonly used tyrosine kinase inhibitors (TKIs), Erlotinib (E) and Gefitinib (G) were investigated using an adapted workable methodology of a 3-day Caco-2 cell monolayer transwell system, a standard model to test drug permeability and uptake of orally administered compounds. Monolayer integrity was tested using trans-epithelial electrical resistance (TEER) measurements, while drug concentrations were determined with a validated LC-MS/ MS technique. Addition of 5 % bovine serum albumin (BSA) maintained drug concentrations at 20 µM through the avoidance of chelate formation, (nevertheless, a reduced accumulative mass transport of the protein bound drug was observed). Investigation with Ko143 (a specific blocker of ABCG2) or NaN3 (a metabolic inhibitor) indicated an interplay between active transport and passive diffusion for gefitinib, while active transport proved to be absent for erlotinib (p < 0.05). The mechanism indicates that ABCG2 is partially involved with accumulation of gefitinib in the cell. This adapted methodology is well suited for absorption, efflux and transport studies and may be extended to investigate the dominant mechanism involved in the transport of TKIs

Novel targeted strategies to overcome resistance in small-cell lung cancer: focus on PARP inhibitors and rovalpituzumab tesirine

ABSTRACTIntroduction: Small-cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumour, and its outcome is strongly conditioned by the rapid onset of resistance to conventional chemothera..

CYB5A (Cytochrome B5 Type A (microsomal))

Review on Cytochrome B5 Type A, with data on DNA/RNA, on the protein encoded and the diseases in which the gene has been implicated

Subcellular localization of several structurally different tyrosine kinase inhibitors

Protein tyrosine kinases form an important target for a new class of anticancer drugs, the tyrosine kinase inhibitors (TKIs). Recently we demonstrated that sunitinib, an inhibitor of the membrane-associated vascular endothelial growth factor receptor (VEGFR), is trapped in lysosomes which isolates the drug from its intended target. Therefore we investigated whether this also holds for other TKIs, targeted against different protein kinases. For this purpose we used the ProteoExtractR kit, which enables a subcellular extraction separating cellular proteins into four distinct fractions covering the cytosol, membranes and membrane organelles (including lysosomes), nuclear proteins and the cytoskeleton. Since TKIs are 98-100 % protein bound we used this property to study their subcellular distribution and used Caco-2 cells as a model. As expected after 2 hours exposure sunitinib was trapped in cytosol (58 %) and organelles (42 % including lysosomes). Crizotinib, an inhibitor of ALK-EML4, showed a similar distribution. However, erlotinib, an inhibitor of the epidermal growth factor receptor (EGFR) showed a very low cellular accumulation and was limited to the organelle fraction. In contrast, the other EGFR inhibitor, gefitinib was predominantly located in the cytosolic (39 %) and membrane fraction (44 %). Sorafenib, another VEGFR inhibitor was predominantly located in the organelle fraction (85 %) and cytosol (15 %) after 2 hours, while after 24 hours distribution decreased (9.9 fold) with a slight shift. Dasatinib, an inhibitor of BCR-Abl was located only in the cytosol (100 %). In general localization after 24 hours was comparable, albeit several small changes were seen. In conclusion protein fractionation with the ProteoExtractR Subcellular Proteome Extraction kit demonstrated large differences in TKI levels in various cellular organelles, with a pattern in agreement with lysosomal accumulation of sunitinib