Response Rate Is Associated with Prolonged Survival in Patients with Advanced Non-small Cell Lung Cancer Treated with Gefitinib or Erlotinib

Introduction:Gaining a higher response rate (RR) has usually been determined as a primary end point in phase II trials evaluating the efficacy of new molecular targeted drugs. However, a relationship between clinical response and survival benefit has not been well studied in the patients treated with molecular targeted agents.Methods:Prospective trials of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) monotherapy in non-small cell lung cancer were extracted from MEDLINE, EMBASE, and the annual meetings in 2007 of the American Society of Clinical Oncology, European Cancer Conference, and World Conference on Lung Cancer.Correlation between clinical response and survival was examined using linear regression analysis. We also tried to compare the significance of RR as surrogate markers for survival with that of disease control rate (DCR) by calculating the area under their receiver operating characteristic (ROC) curves.Results:We identified 24 phase II trials and 4 phase III trials with a total of 6171 patients and 30 treatment arms, including 22 arms for the gefitinib group and 8 arms for the erlotinib group. Both RR and DCR strongly correlated with median survival time (MST; p < 0.0001 and p = 0.003, respectively). In an ROC analysis, the area under the ROC curve predicting MST prolongation by RR was 0.918, which was higher than the area under the ROC curve by DCR.Conclusions:We found a significant relationship between RR and MST in clinical trials with EGFR-TKIs. RR could be an independent surrogate marker for MST in the current response criteria in the clinical trials of EGFR-TKIs

Crystal structural analysis of aldoxime dehydratase from Bacillus sp. OxB-1: Importance of surface residues in optimization for crystallization

Matsui D, Muraki N, Chen K, et al. Crystal structural analysis of aldoxime dehydratase from Bacillus sp. OxB-1: Importance of surface residues in optimization for crystallization. Journal of Inorganic Biochemistry . 2022;230: 111770.Aldoxime dehydratase (Oxd) is a heme enzyme that catalyzes aldoxime dehydration to the corresponding nitriles. Unlike many other heme enzymes, Oxd has a unique feature that the substrate binds directly to the heme. Therefore, it is thought that structural differences around the bound heme directly relate to differences in substrate selection. However sufficient structural information to discuss the substrate specificity has not been obtained. Oxd from Bacillus sp. OxB-1 (OxdB) shows unique substrate specificity and enantioselectivity compared to the Oxds whose crystal structures have already been reported. Here, we report the crystal structure of OxdB, which has not been reported previously. Although the crystallization of OxdB has been difficult, by adding a site-specific mutation to Glu85 located on the surface of the protein, we succeeded in crystallizing OxdB without reducing the enzyme activity. The catalytic triad essential for Oxd activity were structurally conserved in OxdB. In addition, the crystal structure of the Michaelis complex of OxdB and the diastereomerically pure substrate Z-2-(3-bromophenyl)-propanal oxime implied the importance of several hydrophobic residues for substrate specificity. Mutational analysis implicated Ala12 and Ala14 in the E/Z selectivity of bulky compounds. The N-terminal region of OxdB was shown to be shorter than those of Oxds from Pseudomonas chlororaphis and Rhodococcus sp. N-771, and have high flexibility. These structural differences possibly result in distinct preferences for aldoxime substrates based on factors such as substrate size. Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved