Characterization of Indole-3-acetic Acid Biosynthesis and the Effects of This Phytohormone on the Proteome of the Plant-Associated Microbe Pantoea sp. YR343.

Indole-3-acetic acid (IAA) plays a central role in plant growth and development, and many plant-associated microbes produce IAA using tryptophan as the precursor. Using genomic analyses, we predicted that Pantoea sp. YR343, a microbe isolated from Populus deltoides, synthesizes IAA using the indole-3-pyruvate (IPA) pathway. To better understand IAA biosynthesis and the effects of IAA exposure on cell physiology, we characterized proteomes of Pantoea sp. YR343 grown in the presence of tryptophan or IAA. Exposure to IAA resulted in upregulation of proteins predicted to function in carbohydrate and amino acid transport and exopolysaccharide (EPS) biosynthesis. Metabolite profiles of wild-type cells showed the production of IPA, IAA, and tryptophol, consistent with an active IPA pathway. Finally, we constructed an Δ ipdC mutant that showed the elimination of tryptophol, consistent with a loss of IpdC activity, but was still able to produce IAA (20% of wild-type levels). Although we failed to detect intermediates from other known IAA biosynthetic pathways, this result suggests the possibility of an alternate pathway or the production of IAA by a nonenzymatic route in Pantoea sp. YR343. The Δ ipdC mutant was able to efficiently colonize poplar, suggesting that an active IPA pathway is not required for plant association.

Feasibility Study of a Network Meta-Analysis and Unanchored Population-Adjusted Indirect Treatment Comparison of Niraparib, Olaparib, and Bevacizumab as Maintenance Therapies in Patients with Newly Diagnosed Advanced Ovarian Cancer.

Selecting a first-line (1L) maintenance option for ovarian cancer is challenging given the variety of therapies, differing trials, and the lack of head-to-head data for angiogenesis and poly(ADP-ribose) polymerase (PARP) inhibitors. Thus, indirect treatment comparisons (ITCs) can aid treatment decision making. This study assessed the feasibility of two ITCs, a network meta-analysis (NMA) and a population-adjusted ITC (PAIC), comparing the efficacy of the PARP inhibitor niraparib in the PRIMA trial (NCT02655016) with other 1L maintenance treatments. A systematic literature review was conducted to identify trials using the Cochrane Handbook for Systematic Reviews of Interventions to assess differences in trial design, population characteristics, treatment arms, and outcome measures. All 12 trials identified were excluded from the NMA due to the absence of a common comparator and differences in survival measures and/or inclusion criteria. The PAIC comparing PRIMA and PAOLA-1 trials was also not feasible due to differences in inclusion criteria, survival measures, and the previous receipt of chemotherapy/bevacizumab. Neither ITC met recommended guidelines for analysis; the results of such comparisons would not be considered appropriate evidence when selecting 1L maintenance options in ovarian cancer. ITCs in this setting should be performed cautiously, as many factors can preclude objective trial comparisons.

Ad hoc Analysis of the Phase III ENGOT-OV16/NOVA Study: Niraparib Efficacy in Germline BRCA Wild-type Recurrent Ovarian Cancer with Homologous Recombination Repair Defects.

In this analysis, we examined the relationship between progression-free survival (PFS) and mutation status of 18 homologous recombination repair (HRR) genes in patients in the non-germline BRCA-mutated (non-gBRCAm) cohort of the ENGOT-OV16/NOVA trial (NCT01847274), which evaluated niraparib maintenance therapy for patients with recurrent ovarian cancer. This post hoc exploratory biomarker analysis was performed using tumor samples collected from 331 patients enrolled in the phase III ENGOT-OV16/NOVA trial's non-gBRCAm cohort. Niraparib demonstrated PFS benefit in patients with either somatic BRCA-mutated (sBRCAm; HR, 0.27; 95% confidence interval, CI, 0.08-0.88) or BRCA wild-type (BRCAwt; HR, 0.47; 95% CI, 0.34-0.64) tumors. Patients with BRCAwt tumors with other non-BRCA HRR mutations also derived benefit from niraparib (HR, 0.31; 95% CI, 0.13-0.77), as did patients with BRCAwt/HRRwt (HRR wild-type) tumors (HR, 0.49; 95% CI, 0.35-0.70). When patients with BRCAwt/HRRwt tumors were further categorized by genomic instability score (GIS), clinical benefit was observed in patients with homologous recombination-deficient (GIS ≥ 42; HR, 0.33; 95% CI, 0.18-0.61) and in patients with homologous recombination-proficient (HRp; GIS < 42; HR, 0.60; 95% CI, 0.36-0.99) disease. Although patients with sBRCAm, other non-BRCA HRR mutations, or GIS ≥ 42 benefited the most from niraparib treatment, PFS benefit was also seen in HRp (GIS < 42) patients without HRR mutations. These results support the use of niraparib in patients with recurrent ovarian cancer regardless of BRCA/HRR mutation status or myChoice CDx GIS. Significance: We retrospectively evaluated the mutational profile of HRR genes in tumor samples from 331 patients from the non-germline BRCA-mutated cohort of the phase III NOVA trial of patients with platinum-sensitive high-grade serous ovarian cancer. Patients with non-BRCA HRR mutations generally benefited from second-line maintenance treatment with niraparib compared with placebo.

Discovery of an inhibitor of Z-alpha1 antitrypsin polymerization.

Polymerization of the Z variant alpha-1-antitrypsin (Z-α1AT) results in the most common and severe form of α1AT deficiency (α1ATD), a debilitating genetic disorder whose clinical manifestations range from asymptomatic to fatal liver and/or lung disease. As the altered conformation of Z-α1AT and its attendant aggregation are responsible for pathogenesis, the polymerization process per se has become a major target for the development of therapeutics. Based on the ability of Z-α1AT to aggregate by recruiting the reactive center loop (RCL) of another Z-α1AT into its s4A cavity, we developed a high-throughput screening assay that uses a modified 6-mer peptide mimicking the RCL to screen for inhibitors of Z-α1AT polymer growth. A subset of compounds from the Library of Pharmacologically Active Compounds (LOPAC) with molecular weights ranging from 300 to 700 Da, was used to evaluate the assay's capabilities. The inhibitor S-(4-nitrobenzyl)-6-thioguanosine was identified as a lead compound and its ability to prevent Z-α1AT polymerization confirmed by secondary assays. To further investigate the binding location of S-(4-nitrobenzyl)-6-thioguanosine, an in silico strategy was pursued and the intermediate α1AT M* state modeled to allow molecular docking simulations and explore various potential binding sites. Docking results predict that S-(4-nitrobenzyl)-6-thioguanosine can bind at the s4A cavity and at the edge of ß-sheet A. The former binding site would directly block RCL insertion whereas the latter site would prevent ß-sheet A from expanding between s3A/s5A, and thus indirectly impede RCL insertion. Altogether, our investigations have revealed a novel compound that inhibits the formation of Z-α1AT polymers, as well as in vitro and in silico strategies for identifying and characterizing additional blocking molecules of Z-α1AT polymerization.