Clinical Benefit of Avapritinib in KIT-Mutant Gastrointestinal Stromal Tumors: A Post Hoc Analysis of the Phase I NAVIGATOR and Phase I/II CS3007-001 Studies.

PURPOSE: The efficacy of the selective KIT/PDGFRA inhibitor avapritinib (300 mg once daily) was explored in patients with non-PDGFRA-mutant gastrointestinal stromal tumors (GISTs) from the phase I NAVIGATOR and phase I/II CS3007-001 trials. PATIENTS AND METHODS: Adults with unresectable/metastatic, KIT-only-mutant GISTs and progression following ≥1 tyrosine kinase inhibitors (TKIs) were included in this post hoc analysis. Baseline mutational status was identified in tumor and plasma. Primary endpoints were objective response rate (ORR) and progression-free survival (PFS) by blinded independent radiology review per modified RECIST v1.1 in patients harboring KIT activation-loop mutations (KIT exons 17 or 18) without ATP binding-pocket mutations (KIT exons 13 or 14; ALposABPneg), and other KIT mutations (OTHERS). RESULTS: Sixty KIT ALposABPneg and 100 KIT OTHERS predominantly heavily pretreated patients (61.3% with ≥3 prior TKIs) were included. ORR was significantly higher in KIT ALposABPneg than KIT OTHERS patients (unadjusted: 26.7% vs. 12.0%; P = 0.0852; adjusted: 31.4% vs. 12.1%; P = 0.0047). Median PFS (mPFS) was significantly longer in KIT ALposABPneg patients compared with KIT OTHERS patients (unadjusted: 9.1 vs. 3.5 months; P = 0.0002; adjusted: 9.1 vs. 3.4 months; P < 0.0001), and longer in second- versus later-line settings (19.3 vs. 5.6-10.6 months). Benefit with avapritinib was observed in patients with KIT exon 9 mutations in the ≥4 line settings (mPFS: 5.6 and 3.7 months for 4 line and >4 line, respectively). CONCLUSIONS: Avapritinib showed greater antitumor activity in patients with GISTs harboring KIT ALposABPneg mutations versus KIT OTHERS, and may be considered in the former subpopulation. Patients with KIT exon 9 mutations may also benefit in ≥4 line settings.

Effects of Drought Stress on Peramine and Lolitrem B in Epichloë-Endophyte-Infected Perennial Ryegrass.

Perennial ryegrass (Lolium perenne) infected by Epichloë endophytes contains alkaloids that are responsible for toxicosis in many countries. Drought may greatly affect the alkaloids contents of symbionts. The E+ perennial ryegrass was grown in pots with different soil moisture conditions (15%, 30%, 45% and 60% relative saturation moisture content, RSMC) for four months in a greenhouse of Lanzhou University, and then, the aboveground tissues were collected. The levels of peramine and lolitrem B in all plant samples were determined. The results showed that the drought stress significantly (p < 0.05) increased the peramine concentrations of perennial ryegrass but did not affect the lolitrem B concentrations. In addition, the drought stress significantly (p < 0.05) reduced the plant height and dry matter of perennial ryegrass. In conclusion, drought stress affects the peramine concentration in the perennial ryegrass−endophyte symbiont but may not affect the lolitrem B concentration.

Simultaneously enhanced treatment efficiency of simulated hypersaline azo dye wastewater and membrane antifouling by a novel static magnetic field membrane bioreactor (SMFMBR).

Operation performance and membrane fouling of a novel static magnetic field membrane bioreactor (SMFMBR) for treatment of hypersaline azo dye wastewater was investigated. The results showed that SMFMBRs possessed higher efficiency of dye decolorization, COD removal and detoxification than the control MBR without SMF. The (3#) SMFMBR equipped with 305.0 mT (the highest intensity) SMF displayed the best treatment performance among all the four reactors (named as 0#-3#, equipped with SMFs of 0 mT, 95.0 mT, 206.3 mT and 305.0 mT, respectively). Potentially effective microbes belonging to Rhodanobacter, Saccharibacteria genera incertae sedis, Defluviimonas, Cellulomonas, Cutaneotrichosporon, Candida and Pichia were enriched in three SMFMBRs, in both of suspended sludge and bio-cakes. The relative abundance of Candida and Pichia in suspended sludge of 3# SMFMBR was the highest among all the four reactors, suggesting their successful colonization and potentially persistent effect of bioaugmentation. On the other hand, SMF of higher intensity effectively mitigated membrane fouling. Less production of soluble microbial products (SMP) and extracellular polymeric substances (EPS), lower protein/polysaccharide (PN/PS) ratio in SMP and EPS, looser structure of bio-cakes on membrane surface, as well as lower relative abundance of potential fouling causing microbes (mainly bacteria) in microbial communities were determined in 3# SMFMBR than the other three groups.

The Intriguing Effects of Substituents in the N-Phenethyl Moiety of Norhydromorphone: A Bifunctional Opioid from a Set of "Tail Wags Dog" Experiments.

(-)-N-Phenethyl analogs of optically pure N-norhydromorphone were synthesized and pharmacologically evaluated in several in vitro assays (opioid receptor binding, stimulation of [35S]GTPγS binding, forskolin-induced cAMP accumulation assay, and MOR-mediated ß-arrestin recruitment assays). "Body" and "tail" interactions with opioid receptors (a subset of Portoghese's message-address theory) were used for molecular modeling and simulations, where the "address" can be considered the "body" of the hydromorphone molecule and the "message" delivered by the substituent (tail) on the aromatic ring of the N-phenethyl moiety. One compound, N-p-chloro-phenethynorhydromorphone ((7aR,12bS)-3-(4-chlorophenethyl)-9-hydroxy-2,3,4,4a,5,6-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7(7aH)-one, 2i), was found to have nanomolar binding affinity at MOR and DOR. It was a potent partial agonist at MOR and a full potent agonist at DOR with a δ/µ potency ratio of 1.2 in the ([35S]GTPγS) assay. Bifunctional opioids that interact with MOR and DOR, the latter as agonists or antagonists, have been reported to have fewer side-effects than MOR agonists. The p-chlorophenethyl compound 2i was evaluated for its effect on respiration in both mice and squirrel monkeys. Compound 2i did not depress respiration (using normal air) in mice or squirrel monkeys. However, under conditions of hypercapnia (using air mixed with 5% CO2), respiration was depressed in squirrel monkeys.

Effects of Seasonal Variation on the Alkaloids of Different Ecotypes of Epichloë Endophyte-Festuca sinensis Associations.

The Epichloë endophyte-Festuca sinensis association produces alkaloids which can protect the host plant from biotic and abiotic stresses. Alkaloid concentrations depend on the genetic predisposition of grass and endophyte, and are affected by the environment. Endophyte infected F. sinensis of six ecotypes were grown in experimental field and greenhouse for 2 years. Their aboveground plant tissues were collected each season to test for peramine, lolitrem B, and ergot concentrations. The results showed that seasonal changes affected the peramine, lolitrem B and ergot concentrations of Epichloë endophyte-F. sinensis associations; and these three different alkaloids responded differently to seasonal variation. The peramine concentration of six ecotypes of F. sinensis decreased significantly (p < 0.05) from spring to autumn. The lolitrem B concentration of F. sinensis was higher in autumn than in other seasons. Ergot concentrations of five ecotypes (41, 57, 84, 99, and 141) of F. sinensis peaked in the summer, and lowered in spring and autumn. In addition, the ecotype has insignificant effect (p > 0.05) on the peramine and lolitrem B concentrations of F. sinensis, but it has a significant impact (p < 0.05) on the ergot concentrations. We concluded that the seasonal variation and ecotypes can influence the alkaloids produced by the F. sinensis-endophyte associations, but the effects of seasonal conditions on the alkaloid concentrations are more pronounced than ecotypes.

Quinone skeleton as a new class of irreversible inhibitors against Staphylococcus aureus sortase A.

Sortase A (SrtA) anchors surface proteins to the cell wall and aids biofilm formation during infection, which functions as a key virulence factor of important Gram-positive pathogens, such as Staphylococcus aureus. At present researchers need a way in which to validate whether or not SrtA is a druggable target alternative to the conventional antibiotic targets in the mechanism. In this study, we performed a high-throughput screening and identified a new class of potential inhibitors of S. aureus SrtA, which are derived from natural products and contain the quinone skeleton. Compound 283 functions as an irreversible inhibitor that covalently alkylates the active site Cys184 of SrtA. NMR analysis confirms the direct interaction of the small-molecule inhibitor towards SrtA protein. The anchoring of protein A (SpA) to the cell wall and the biofilm formation are significantly attenuated when the S. aureus Newman strain is cultured in the presence of inhibitor. Our study indicates that compound 283 could be a potential hit for the development of new anti-virulence agents against S. aureus infections by covalently targeting SrtA.

Characterization of Gain-of-Function Mutant Provides New Insights into ClpP Structure.

ATP-dependent Clp protease (ClpP), a highly conserved serine protease in vast bacteria, could be converted into a noncontrollable enzyme capable of degrading mature proteins in the presence of acyldepsipeptides (ADEPs). Here, we design such a gain-of-function mutant of Staphylococcus aureus ClpP (SaClpP) capable of triggering the same level of dysfunctional activity that occurs upon ADEPs treatment. The SaClpPY63A mutant degrades FtsZ in vivo and inhibits staphylococcal growth. The crystal structure of SaClpPY63A indicates that Asn42 would be an important domino to fall for further activation of ClpP. Indeed, the SaClpPN42AY63A mutant demonstrates promoted self-activated proteolysis, which is a result of an enlarged entrance pore as observed in cryo-electron microscopy images. In addition, the expression of the engineered clpP allele phenocopies treatment with ADEPs; inhibition of cell division occurs as does showing sterilizing with rifampicin antibiotics. Collectively, we show that the gain-of-function SaClpPN42AY63A mutant becomes a fairly nonspecific protease and kills persisters by degrading over 500 proteins, thus providing new insights into the structure of the ClpP protease.

Development of Heat Shock Protein (Hsp90) Inhibitors To Combat Resistance to Tyrosine Kinase Inhibitors through Hsp90-Kinase Interactions.

Heat shock protein 90 (Hsp90) is a ubiquitous chaperone of all of the oncogenic tyrosine kinases. Many Hsp90 inhibitors, alone or in combination, have shown significant antitumor efficacy against the kinase-positive naïve and mutant models. However, clinical trials of these inhibitors are unsuccessful due to insufficient clinical benefits and nonoptimal safety profiles. Recently, much progress has been reported on the Hsp90-cochaperone-client complex, which will undoubtedly assist in the understanding of the interactions between Hsp90 and its clients. Meanwhile, Hsp90 inhibitors have shown promise against patients' resistance caused by early generation tyrosine kinase inhibitors (TKIs), and at least 13 Hsp90 inhibitors are being reevaluated in the clinic. In this regard, the objectives of the current perspective are to summarize the structure and function of the Hsp90-cochaperone-client complex, to analyze the structural and functional insights into the Hsp90-client interactions to address several existing unresolved problems with Hsp90 inhibitors, and to highlight the preclinical and clinical studies of Hsp90 inhibitors as an effective treatment against resistance to tyrosine kinase inhibitors.

Alectinib: a novel second generation anaplastic lymphoma kinase (ALK) inhibitor for overcoming clinically-acquired resistance.

The development of inhibitors for the tyrosine anaplastic lymphoma kinase (ALK) has advanced rapidly, driven by biology and medicinal chemistry. The first generation ALK inhibitor crizotinib was granted US FDA approval with only four years of preclinical and clinical testing. Although this drug offers significant clinical benefit to the ALK-positive patients, resistance has been developed through a variety of mechanisms. In addition to ceritinib, alectinib is another second-generation ALK inhibitor launched in 2014 in Japan. This drug has a unique chemical structure bearing a 5H-benzo[b]carbazol-11(6H)-one structural scaffold with an IC50 value of 1.9 nmol/L, and is highly potent against ALK bearing the gatekeeper mutation L1196M with an IC50 of 1.56 nmol/L. In the clinic, alectinib is highly efficacious in treatment of ALK-positive non-small cell lung cancer (NSCLC), and retains potency to combat crizotinib-resistant ALK mutations L1196M, F1174L, R1275Q and C1156Y.

Pd-catalyzed α-selective C(sp3)-H acetoxylation of amides through an unusual cyclopalladation mechanism.

We report the first example of Pd-catalyzed site-selective α-C(sp(3))-H oxidation/acetoxylation of amides through an unusual [4,6]-bicyclic metallacycle intermediate with 1-aminoanthraquinone as a new bidentate directing group. In addition to the distinct mechanism and high efficiency, the reaction is highly appealing due to the ample commercial source, low-cost, as well as easy removal and recycling of the auxiliary group.

Substituent-enabled oxidative dehydrogenative cross-coupling of 1,4-naphthoquinones with alkenes.

A Rh-catalyzed oxidative dehydrogenative cross-coupling of 1,4-naphthquinones with alkenes was achieved by using a substituent-enabled C(sp(2))-H functionalization (SEF) strategy. The method shows high functional group tolerance, broad substrate scope, and great potential for further functional transformations.

Naphthoquinone-directed C-H annulation and C(sp³)-H bond cleavage: one-pot synthesis of tetracyclic naphthoxazoles.

One-pot synthesis of tetracyclic naphthoxazole derivatives from electron-deficient naphthoquinones and alkynes was achieved via Rh(III)-catalyzed C-H activation and C(sp(3))-H bond cleavage for the first time. This approach proceeds through a tandem cascade process involving substrate tautomerization, C-H activation, oxidative addition, cyclization, and aromatization. In addition, broad substrate scope, simple starting materials, and steric tolerance make this strategy of great practicality.

Development of cell-active N6-methyladenosine RNA demethylase FTO inhibitor.

The direct nucleic acid repair dioxygenase FTO is an enzyme that demethylates N(6)-methyladenosine (m(6)A) residues in mRNA in vitro and inside cells. FTO is the first RNA demethylase discovered that also serves a major regulatory function in mammals. Together with structure-based virtual screening and biochemical analyses, we report the first identification of several small-molecule inhibitors of human FTO demethylase. The most potent compound, the natural product rhein, which is neither a structural mimic of 2-oxoglutarate nor a chelator of metal ion, competitively binds to the FTO active site in vitro. Rhein also exhibits good inhibitory activity on m(6)A demethylation inside cells. These studies shed light on the development of powerful probes and new therapies for use in RNA biology and drug discovery.

InBr3-catalyzed glycosidation of glycals with arylamines: an alternative approach to access 4-aminocyclopent-2-enones.

To turn side products into major products, a novel strategy to access biologically active 4-aminocyclopent-2-enones was developed. These compounds were originally identified as side products but became major products when 3,5-dimethylpyran-3,4-diol 7a was used as the substrate and 30% InBr(3) as the catalyst. Aryl- or heteroarylamines as well as variously substituted glycals can be used in this reaction, and the corresponding 4-aminocyclopent-2-enones were obtained in moderate to good yields. These compounds can be further used to prepare 4-aminocarbocyclic nucleosides.