Mechanistic insight into RET kinase inhibitors targeting the DFG-out conformation in RET-rearranged cancer

Oncogenic fusion events have been identified in a broad range of tumors. Among them, RET rearrangements represent distinct and potentially druggable targets that are recurrently found in lung adenocarcinomas. Here, we provide further evidence that current anti-RET drugs may not be potent enough to induce durable responses in such tumors. We report that potent inhibitors such as AD80 or ponatinib that stably bind in the DFG-out conformation of RET may overcome these limitations and selectively kill RET-rearranged tumors. Using chemical genomics in conjunction with phosphoproteomic analyses in RET-rearranged cells we identify the CCDC6-RETI788N mutation and drug-induced MAPK pathway reactivation as possible mechanisms, by which tumors may escape the activity of RET inhibitors. Our data provide mechanistic insight into the druggability of RET kinase fusions that may be of help for the development of effective therapies targeting such tumors

Trifunctional coating

The invention is directed to a coating, and to an article comprising said coating and to a method of forming a coating. More in particular, the invention relates to a coating that relates to an antifouling, cell-binding and antimicrobial coating. The coating of the invention comprises a) an inner coating layer formed from an inner coating composition, the inner coating composition comprising, i) an inner polymerisable compound comprising a polymerisable group, ii) an antimicrobial agent, and iii) an initiator, and b) an outer coating layer formed from an outer coating composition, the outer coating composition comprising i) inorganic particles with a polymerisable group and a hydrophilic polymer chain attached to one or more of the inorganic particles, ii) a cell-binding moiety, iii) an initiator, and iv) optionally, an outer polymerisable compound comprising a polymerisable group

Trifunctional coating

The invention is directed to a coating, and to an article comprising said coating and to a method of forming a coating. More in particular, the invention relates to a coating that relates to an antifouling, cell-binding and antimicrobial coating. The coating of the invention comprises a) an inner coating layer formed from an inner coating composition, the inner coating composition comprising, i) an inner polymerisable compound comprising a polymerisable group, ii) an antimicrobial agent, and iii) an initiator, and b) an outer coating layer formed from an outer coating composition, the outer coating composition comprising i) inorganic particles with a polymerisable group and a hydrophilic polymer chain attached to one or more of the inorganic particles, ii) a cell-binding moiety, iii) an initiator, and iv) optionally, an outer polymerisable compound comprising a polymerisable group

Sphingosine-1-phosphate stimulates the functional capacity of progenitor cells by activation of the CXCR4-dependent signaling pathway via the S1P(3) receptor

OBJECTIVE - Sphingosine-1-phosphate (S1P) is a bioactive lipid, which influences migration and proliferation of endothelial cells through activation of S1P receptors and has been shown to support SDF-1 induced migration and bone marrow homing of CD34 progenitors. METHODS AND RESULTS - Here, we show that incubation of patient-derived endothelial progenitor cells (EPCs) with S1P or its synthetic analog FTY720 improved blood flow recovery in ischemic hind limbs. Likewise, recovery of blood flow was dramatically reduced after induction of hindlimb ischemia in mice deficient for the S1P receptor 3 (S1P3). S1P3 bone marrow-derived mononuclear cells (BMCs) failed to augment neovascularization after hind limb ischemia. Of note, treatment of BMCs derived from S1P3 mice with S1P did not rescue blood flow recovery. Mechanistically, S1P and FTY720 induced phosphorylation of CXCR4, activated the Src kinase, and stimulated phosphorylation of JAK2. The contribution of CXCR4 for S1P-mediated effects was further supported by the findings that S1P preincubation failed to stimulate invasion capacity and in vivo blood flow recovery of BMCs from CXCR4 mice. The activation of CXCR4 was dependent on the Src kinase family as demonstrated by preincubation with the Src inhibitor PP2. The activation of the CXCR4 signaling by S1P is mediated via the S1P3 receptor, since S1P-induced Src phosphorylation was abrogated in EPC from S1P3 mice. CONCLUSIONS - S1P agonists might serve as sensitizers of CXCR4-mediated signaling and may be applied in clinical progenitor cell therapy to improve EPC or BMC function in patients with coronary artery disease

Sphingosine-1-phosphate stimulates the functional capacity of progenitor cells by activation of the CXCR4-dependent signaling pathway via the S1P3 receptor

OBJECTIVE - Sphingosine-1-phosphate (S1P) is a bioactive lipid, which influences migration and proliferation of endothelial cells through activation of S1P receptors and has been shown to support SDF-1 induced migration and bone marrow homing of CD34 progenitors. METHODS AND RESULTS - Here, we show that incubation of patient-derived endothelial progenitor cells (EPCs) with S1P or its synthetic analog FTY720 improved blood flow recovery in ischemic hind limbs. Likewise, recovery of blood flow was dramatically reduced after induction of hindlimb ischemia in mice deficient for the S1P receptor 3 (S1P3). S1P3 bone marrow-derived mononuclear cells (BMCs) failed to augment neovascularization after hind limb ischemia. Of note, treatment of BMCs derived from S1P3 mice with S1P did not rescue blood flow recovery. Mechanistically, S1P and FTY720 induced phosphorylation of CXCR4, activated the Src kinase, and stimulated phosphorylation of JAK2. The contribution of CXCR4 for S1P-mediated effects was further supported by the findings that S1P preincubation failed to stimulate invasion capacity and in vivo blood flow recovery of BMCs from CXCR4 mice. The activation of CXCR4 was dependent on the Src kinase family as demonstrated by preincubation with the Src inhibitor PP2. The activation of the CXCR4 signaling by S1P is mediated via the S1P3 receptor, since S1P-induced Src phosphorylation was abrogated in EPC from S1P3 mice. CONCLUSIONS - S1P agonists might serve as sensitizers of CXCR4-mediated signaling and may be applied in clinical progenitor cell therapy to improve EPC or BMC function in patients with coronary artery disease

Insight into Targeting Exon20 Insertion Mutations of the Epidermal Growth Factor Receptor with Wild Type-Sparing Inhibitors

Despite the clinical efficacy of epidermal growth factor receptor (EGFR) inhibitors, a subset of patients with non-small cell lung cancer displays insertion mutations in exon20 in EGFR and Her2 with limited treatment options. Here, we present the development and characterization of the novel covalent inhibitors LDC8201 and LDC0496 based on a 1H-pyrrolo[2,3-b]pyridine scaffold. They exhibited intense inhibitory potency toward EGFR and Her2 exon20 insertion mutations as well as selectivity over wild type EGFR and within the kinome. Complex crystal structures with the inhibitors and biochemical and cellular on-target activity document their favorable binding characteristics. Ultimately, we observed tumor shrinkage in mice engrafted with patient-derived EGFR-H773_V774insNPH mutant cells during treatment with LDC8201. Together, these results highlight the potential of covalent pyrrolopyridines as inhibitors to target exon20 insertion mutations

Targeting Drug Resistance in EGFR with Covalent Inhibitors: A Structure-Based Design Approach

Receptor tyrosine kinases represent one of the prime targets in cancer therapy, as the dysregulation of these elementary transducers of extracellular signals, like the epidermal growth factor receptor (EGFR), contributes to the onset of cancer, such as non-small cell lung cancer (NSCLC). Strong efforts were directed to the development of irreversible inhibitors and led to compound CO-1686, which takes advantage of increased residence time at EGFR by alkylating Cys797 and thereby preventing toxic effects. Here, we present a structure-based approach, rationalized by subsequent computational analysis of conformational ligand ensembles in solution, to design novel and irreversible EGFR inhibitors based on a screening hit that was identified in a phenotype screen of 80 NSCLC cell lines against approximately 1500 compounds. Using protein X-ray crystallography, we deciphered the binding mode in engineered cSrc (T338M/S345C), a validated model system for EGFR-T790M, which constituted the basis for further rational design approaches. Chemical synthesis led to further compound collections that revealed increased biochemical potency and, in part, selectivity toward mutated (L858R and L858R/T790M) vs nonmutated EGFR. Further cell-based and kinetic studies were performed to substantiate our initial findings. Utilizing proteolytic digestion and nano-LC-MS/MS analysis, we confirmed the alkylation of Cys797

Overcoming EGFR G724S-mediated osimertinib resistance through unique binding characteristics of second-generation EGFR inhibitors

Acquired resistance to targeted drugs remains a major clinical challenge in lung adenocarcinoma patients. Here, the authors show how the acquired EGFR G724S mutation induces resistance to third-generation EGFR inhibitors and why the mutant kinase remains susceptible to second-generation inhibitors