Somatic mutations in the epidermal growth factor receptor (EGFR) gene are present in approximately 20% (in Caucasians) to 40% (in East Asians) of adenocarcinomas of the lung. Targeted therapy for these lung cancers has been established based on evidence regarding mainly common mutations; that is, exon 19 deletions (Del19) and L858R. EGFR‐tyrosine kinase inhibitors (TKI), gefitinib, erlotinib or afatinib showed high objective response rates (ORR) of approximately 60%. Several studies suggested that Del19 might be more sensitive to EGFR‐TKI than L858R. On the other hand, it has been difficult to establish evidence for other less common mutations, accounting for 12% of all EGFR mutations, because there are many variants and many studies have excluded patients with these uncommon mutations. However, recent studies revealed that these rare genotypes could be targetable if appropriate TKI are selected. For example, G719X (X denotes A, S, C and so on), Del18, E709K, insertions in exon 19 (Ins19), S768I or L861Q showed moderate sensitivities to gefitinib or erlotinb with ORR of 30%–50%. However, afatinib appeared to be especially effective for these tumors. Although Ins20s (except for insFQEA) have been regarded as resistant mutations, osimertinib may be effective for rare subtypes of them and nazartinib (EGF816) is promising for the majority of them. For the further development of targeted therapy in all EGFR mutations, it is important to precisely detect targetable mutations, to select the most appropriate TKI for each mutation, and to continue investigating in vitro studies and collecting clinical data on even rare mutations.

Polyketides are among the major classes of bioactive natural products used to treat microbial infections, cancer, and other diseases. Here we describe a pathway to chloroethylmalonyl-CoA as a polyketide synthase building block in the biosynthesis of salinosporamide A, a marine microbial metabolite whose chlorine atom is crucial for potent proteasome inhibition and anticancer activity. S-adenosyl-L-methionine (SAM) is converted to 5-chloro-5-deoxyadenosine (5-ClDA) in a reaction catalyzed by a SAMdependent chlorinase as previously reported. By using a combination of gene deletions, biochemical analyses, and chemical complementation experiments with putative intermediates, we now provide evidence that 5-ClDA is converted to chloroethylmalonyl-CoA in a 7-step route via the penultimate intermediate 4-chlorocrotonyl-CoA. Because halogenation often increases the bioactivity of drugs, the availability of a halogenated polyketide building block may be useful in molecular engineering approaches toward polyketide scaffolds.actinomycete ͉ biological halogenation ͉ marine natural product ͉ proteasome inhibitor ͉ Salinispora tropica

Background: MNNG HOS transforming gene (MET) exon 14 mutations in lung cancer, including exon 14 skipping and point mutations, have been attracting the attention of thoracic oncologists as new therapeutic targets. Tumors with these mutations almost always acquire resistance, which also occurs in other oncogene-addicted lung cancers. However, the resistance mechanisms and treatment strategies are not fully understood.Methods: We generated Ba/F3 cells expressing MET exon 14 mutations by retroviral gene transfer. The sensitivities of these cells to eight MET-tyrosine kinase inhibitors (TKIs) were determined using a colorimetric assay. In addition, using N-ethyl-N-nitrosourea mutagenesis, we generated resistant clones, searched for secondary MET mutations, and then examined the sensitivities of these resistant cells to different TKIs.Results: Ba/F3 cells transfected with MET mutations grew in the absence of interleukin-3, indicating their oncogenic activity. These cells were sensitive to all MET-TKIs except tivantinib. We identified a variety of secondary mutations. D1228 and Y1230 were common sites for resistance mutations for type I TKIs, which bind the active form of MET, whereas L1195 and F1200 were common sites for type II TKIs, which bind the inactive form. In general, resistance mutations against type I were sensitive to type II, and vice versa.Conclusions: MET-TKIs inhibited the growth of cells with MET exon 14 mutations. We also identified mutation sites specific for TKI types as resistance mechanisms and complementary activities between type I and type II inhibitors against those mutations. These finding should provide relevant clinical implication for treating patients with lung cancer harboring MET exon 14 mutations.

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Dedicated to Professor Albert Eschenmoser on the occasion of his 75th birthday Using the diastereoisomeric triols 1a ± d (Fig. 1) and examples summarized in Fig. 2, the central C-atom of acyclic 1,3,5-triols is demonstrated to exhibit a distinctive chemical shift that is dependent on the 1,3-and 3,5-relative configuration, but is independent of the functionalities present outside of this structural motif. These NMR characteristics are then used to predict the relative configuration of several natural products (Fig. 7). In addition, an example is given to show the possibility of assembling an NMR database for a larger array of functional groups from NMR databases of smaller arrays of functional groups. Through our work on palytoxin [1], AAL toxins/fumonisins [2], maitotoxin [3], and universal NMR databases [4], we have experimentally demonstrated that steric and/or stereoelectronic interactions between the structural motifs connected either directly or with a one-CH 2 bridge are significant, whereas interactions between the structural motifs connected with a two-or more-CH 2 bridge are almost negligible. On this basis, we have noticed that 1,3,5-trisubstituted acyclic compounds, represented by A, may exhibit a unique characteristic: the central C-atom may exhibit a distinctive chemical shift which is dependent on the X 1 /X 2 -and X 2 /X 3 -relative configuration, but is independent of the functionalities present outside of this structural motif 1 ). One might be concerned that, through the substituents X 1 and X 3 , functional groups present outside of the 1,3,5-trisubstituted moiety might indirectly affect the chemical shifts of these nuclei. However, upon a close examination of the cases previously studied in our laboratories, we speculate that such indirect steric and/or stereoelectronic effects on the chemical shifts in question is negligibly small [2 ± 4].To test this hypothesis, we have chosen a 1,3,5-triol system (X 1 X 2 X 3 OH in A) as an example, synthesized the four possible diastereoisomers Helvetica Chimica Acta ± Vol. 83 (2000) 2562 1 ) This analysis may be applicable for the chemical shift of the H-atom attached to the central C-atom.