Oxygen-evolving photosystem II structures during S1-S2-S3 transitions.

Photosystem II (PSII) catalyses the oxidation of water through a four-step cycle of Si states (i = 0-4) at the Mn4CaO5 cluster1-3, during which an extra oxygen (O6) is incorporated at the S3 state to form a possible dioxygen4-7. Structural changes of the metal cluster and its environment during the S-state transitions have been studied on the microsecond timescale. Here we use pump-probe serial femtosecond crystallography to reveal the structural dynamics of PSII from nanoseconds to milliseconds after illumination with one flash (1F) or two flashes (2F). YZ, a tyrosine residue that connects the reaction centre P680 and the Mn4CaO5 cluster, showed structural changes on a nanosecond timescale, as did its surrounding amino acid residues and water molecules, reflecting the fast transfer of electrons and protons after flash illumination. Notably, one water molecule emerged in the vicinity of Glu189 of the D1 subunit of PSII (D1-E189), and was bound to the Ca2+ ion on a sub-microsecond timescale after 2F illumination. This water molecule disappeared later with the concomitant increase of O6, suggesting that it is the origin of O6. We also observed concerted movements of water molecules in the O1, O4 and Cl-1 channels and their surrounding amino acid residues to complete the sequence of electron transfer, proton release and substrate water delivery. These results provide crucial insights into the structural dynamics of PSII during S-state transitions as well as O-O bond formation.

Theoretical elucidation of the structure, bonding, and reactivity of the CaMn4Ox clusters in the whole Kok cycle for water oxidation embedded in the oxygen evolving center of photosystem II. New molecular and quantum insights into the mechanism of the O-O bond formation.

This paper reviews our historical developments of broken-symmetry (BS) and beyond BS methods that are applicable for theoretical investigations of metalloenzymes such as OEC in PSII. The BS hybrid DFT (HDFT) calculations starting from high-resolution (HR) XRD structure in the most stable S1 state have been performed to elucidate structure and bonding of whole possible intermediates of the CaMn4Ox cluster (1) in the Si (i = 0 ~ 4) states of the Kok cycle. The large-scale HDFT/MM computations starting from HR XRD have been performed to elucidate biomolecular system structures which are crucial for examination of possible water inlet and proton release pathways for water oxidation in OEC of PSII. DLPNO CCSD(T0) computations have been performed for elucidation of scope and reliability of relative energies among the intermediates by HDFT. These computations combined with EXAFS, XRD, XFEL, and EPR experimental results have elucidated the structure, bonding, and reactivity of the key intermediates, which are indispensable for understanding and explanation of the mechanism of water oxidation in OEC of PSII. Interplay between theory and experiments have elucidated important roles of four degrees of freedom, spin, charge, orbital, and nuclear motion for understanding and explanation of the chemical reactivity of 1 embedded in protein matrix, indicating the participations of the Ca(H2O)n ion and tyrosine(Yz)-O radical as a one-electron acceptor for the O-O bond formation. The Ca-assisted Yz-coupled O-O bond formation mechanisms for water oxidation are consistent with recent XES and very recent time-resolved SFX XFEL and FTIR results.

The Nature of the Chemical Bonds of High-Valent Transition-Metal Oxo (M=O) and Peroxo (MOO) Compounds: A Historical Perspective of the Metal Oxyl-Radical Character by the Classical to Quantum Computations.

This review article describes a historical perspective of elucidation of the nature of the chemical bonds of the high-valent transition metal oxo (M=O) and peroxo (M-O-O) compounds in chemistry and biology. The basic concepts and theoretical backgrounds of the broken-symmetry (BS) method are revisited to explain orbital symmetry conservation and orbital symmetry breaking for the theoretical characterization of four different mechanisms of chemical reactions. Beyond BS methods using the natural orbitals (UNO) of the BS solutions, such as UNO CI (CC), are also revisited for the elucidation of the scope and applicability of the BS methods. Several chemical indices have been derived as the conceptual bridges between the BS and beyond BS methods. The BS molecular orbital models have been employed to explain the metal oxyl-radical character of the M=O and M-O-O bonds, which respond to their radical reactivity. The isolobal and isospin analogy between carbonyl oxide R2C-O-O and metal peroxide LFe-O-O has been applied to understand and explain the chameleonic chemical reactivity of these compounds. The isolobal and isospin analogy among Fe=O, O=O, and O have also provided the triplet atomic oxygen (3O) model for non-heme Fe(IV)=O species with strong radical reactivity. The chameleonic reactivity of the compounds I (Cpd I) and II (Cpd II) is also explained by this analogy. The early proposals obtained by these theoretical models have been examined based on recent computational results by hybrid DFT (UHDFT), DLPNO CCSD(T0), CASPT2, and UNO CI (CC) methods and quantum computing (QC).

Real-world data on the efficacy and safety of immune-checkpoint inhibitors in elderly patients with non-small cell lung cancer.

PURPOSE: Immune-checkpoint inhibitors (ICIs) are effective against advanced non-small cell lung cancer (NSCLC). However, whether the efficacy and safety of ICI treatment in elderly patients are similar to those in younger patients is unclear. This study was designed to address this question. METHODS: We enrolled patients who received ICI monotherapy in Japan between December 2015 and December 2017; those ≥75 years of age comprised the elderly group. We compared the efficacy and safety of ICI monotherapy in elderly patients with those in younger patients and explored prognostic factors in elderly patients. RESULTS: We enrolled 676 patients; 137 (20.3%) were assigned to the elderly group. The median age of the elderly and younger groups was 78 (range, 75-85) and 66 (range, 34-74) years. The median progression-free survival (4.8 months vs. 3.3 months, p = 0.1589) and median overall survival (12.3 months vs. 13.0 months, p = 0.5587) were similar between the elderly and younger groups. Multivariate analysis revealed that a significantly better OS in the elderly group was associated with better responses to first- or second-line ICI treatment (p = 0.011) and more immune-related adverse events (irAEs) (p = 0.02). IrAEs that led to ICI discontinuation occurred in 34 of 137 patients (24.8%) in the elderly group, and their survival was significantly higher than that in those who did not have irAEs. CONCLUSION: ICI is also effective in elderly NSCLC patients, and treatment discontinuation due to irAEs may be a good prognostic marker.

Roles of the Flexible Primary Coordination Sphere of the Mn4CaOx Cluster: What Are the Immediate Decay Products of the S3 State?

The primary coordination sphere of the multinuclear cofactor (Mn4CaOx) in the oxygen-evolving complex (OEC) of photosystem II is absolutely conserved to maintain its structure and function. Recent time-resolved serial femtosecond crystallography identified large reorganization of the primary coordination sphere in the S2 to S3 transition, which elicits a cascade of events involving Mn oxidation and water molecule binding to a putative catalytic Mn site. We examined how the crystallographic fields, created by transient conformational states of the OEC at various time points, affect the thermodynamics of various isomers of the Mn cluster using DFT calculations, with an aim of comprehending the functional roles of the flexible primary coordination sphere in the S2 to S3 transition and in the recovery of the S2 state. The results show that the relative movements of surrounding residues change the size and shape of the cavity of the cluster and thereby affect the thermodynamics of various catalytic intermediates as well as the ability to capture a new water molecule at a coordinatively unsaturated site. The implication of these findings is that the protein dynamics may serve to gate the catalytic reaction efficiently by controlling the sequence of Mn oxidation/reduction and water binding/release. This interpretation is consistent with EPR experiments; g ∼ 5 and g ∼ 3 signals obtained after near-infrared (NIR) excitation of the S3 state at 4 K and a g ∼ 5 only signal produced after prolonged incubation of the S3 state at 77 K can be best explained as originating from water-bound S2 clusters (Stotal = 7/2) under a S3 ligand field, i.e., the immediate one-electron reduction products of the oxyl-oxo (Stotal = 6) and hydroxo-oxo (Stotal = 3) species in the S3 state.

First-line osimertinib in elderly patients with epidermal growth factor receptor-mutated advanced non-small cell lung cancer: a retrospective multicenter study (HOT2002).

Osimertinib is a standard of care therapy for previously untreated epidermal growth factor receptor mutation-positive non-small cell lung cancer. However, limited data exist regarding the efficacy and safety of osimertinib as a first-line therapy for elderly patients aged 75 years or older. To assess the potential clinical benefits of osimertinib in this population, this retrospective multi-institutional observational study included 132 patients with non-small cell lung cancer (age ≥ 75 years), who received osimertinib as first-line treatment. The proportion of patients with 1-year progression-free survival was 65.8% (95% confidence interval 57.1-73.5). The median progression-free survival was 19.4 (95% confidence interval 15.9-23.9) months. The median overall survival was not reached (95% confidence interval 24.6-not reached). The frequency of pneumonitis was 17.4%, with a grade 3 or higher rate of 9.1%. More than two-thirds of treatment discontinuations due to pneumonitis occurred within 3 months of starting osimertinib, and the prognosis of patients with pneumonitis was unsatisfactory. Osimertinib is one of the effective first-line therapeutic options for patients aged 75 years or older; however, special caution should be exercised due to the potential development of pneumonitis.

Prognostic significance of OX40+ lymphocytes in tumor stroma of surgically resected small-cell lung cancer.

OX40 (CD134) is a co-stimulatory molecule mostly expressed on activated T lymphocytes. Previous reports have shown that OX40 can be an immuno-oncology target and a clinical biomarker for cancers of various organs. In this study, we collected formalin-fixed paraffin-embedded tumor samples from 124 patients with small-cell lung cancer (SCLC) who had undergone surgery. We analyzed the expression profiles of OX40 and other relevant molecules, such as CD4, CD8, and Foxp3, in tumor stroma and cancer nest using immunohistochemistry and investigated their association with survival. High infiltration of OX40+ lymphocytes (OX40high) in tumor stroma was positively associated with relapse-free survival (RFS) and overall survival (OS) compared with low infiltration of OX40+ lymphocytes (OX40low) (RFS, median, 26.0 months [95% confidence interval (CI), not reached (NR)-NR] vs 13.2 months [9.1-17.2], p = .024; OS, NR [95% CI, NR-NR] vs 29.8 months [21.3-38.2], p = .049). Multivariate analysis revealed that OX40high in tumor stroma was an independent indicator of prolonged RFS. Moreover, RFS of patients with OX40high/CD4high in tumor stroma was significantly longer than that of patients with OX40low/CD4low. The RFS of patients with tumor stroma with OX40high/CD8high was significantly longer than that of patients with tumor stroma with OX40low/CD8high, OX40high/CD8low, or OX40low/CD8low. These findings suggest that OX40+ lymphocytes in tumor stroma play a complementary role in regulating the relapse of early-stage SCLC. Reinforcing immunity by coordinating the recruitment of OX40+ lymphocytes with CD4+ and CD8+ T cells in tumor stroma may constitute a potential immunotherapeutic strategy for patients with SCLC.

Prognostic factors in patients with advanced non-small cell lung cancer after long-term Anti-PD-1 therapy (HOT1902).

OBJECTIVES: Limited information is available on the appropriate treatment duration of immune checkpoint inhibitors (ICIs). We aimed to identify candidates who would benefit from ICI discontinuation after one year of treatment for metastatic non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: This retrospective multi-institutional observational study examined medical records of all consecutive patients with advanced or recurrent NSCLC, who started ICI monotherapy at 15 institutions in Japan between December 2015 and December 2017. Patients who received initial ICI therapy for >1 year without progressive disease were defined as the long-term treatment (LT) group; others were defined as the non-long-term treatment (NLT) group. Primary outcomes included the prognostic factors in the LT group, whereas secondary outcomes included efficacy of ICI rechallenge, safety, and survival outcomes in the overall population. RESULTS: In total, 676 patients were enrolled, and 114 (16.9 %) were assigned to the LT group. The median time interval from the start of initial ICI administration to data cutoff was 34.3 months (range, 24.1-47.8); thus, all surviving patients were followed-up for at least 2 years from the start of initial ICI. Median progression-free survival (PFS) was longer in the LT than in the NLT group (33.6 months vs. 2.7 months; p < 0.001). On multivariate analysis, significantly better PFS was associated with smoking (hazard ratio [HR]=0.36, p = 0.04), and complete response (CR; HR=uncomputable, p < 0.001) in the LT group. Thirty-seven patients (5.5 %) received ICI rechallenge, including 10 in the LT group. Among patients receiving rechallenge treatment, the median PFS was 2.2 months, with no difference between the LT and NLT groups. CONCLUSIONS: In the LT group, smoking and achieving CR were significantly associated with better PFS. Since rechallenge treatment was not effective, careful consideration is required for discontinuing ICI. However, these prognostic factors are helpful in considering candidates for ICI discontinuation. TRIAL REGISTRATION: UMIN ID, UMIN000041403.

Delta-like 1 homolog (DLK1) as a possible therapeutic target and its application to radioimmunotherapy using 125I-labelled anti-DLK1 antibody in lung cancer models (HOT1801 and FIGHT004).

OBJECTIVES: Delta-like 1 homolog (DLK1) is a non-canonical Notch ligand known to be expressed in several cancers but whose role in lung cancer is not yet fully understood. We sought to confirm DLK1 expression in small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC), and to examine DLK1's clinical significance. Furthermore, we examined the possible utility of DLK1 as a novel target in radioimmunotherapy (RIT). METHODS: We retrospectively assessed the correlation between clinical features and DLK1 expression by immunohistochemistry in resected specimens from 112 patients with SCLC and 101 patients with NSCLC. Moreover, we performed cell and animal experiments, and examined the possibility of RIT targeting DLK1 in SCLC using iodine-125 (125I) -labeled anti-DLK1 antibody, knowing that 125I can be replaced with the alpha-particle-emitter astatine-211 (211At). RESULTS: In SCLC and NSCLC, 20.5 % (23/112) and 16.8 % (17/101) of patients (respectively) had DLK1-positive tumors. In NSCLC, DLK1 expression was associated with recurrence-free survival (P < 0.01) but not with overall survival. In SCLC, there was no association between DLK1 expression and survival. In addition, 125I-labeled anti-DLK1 antibody specifically targeted DLK1 on human SCLC tumor cell lines. Furthermore, 125I-labeled anti-DLK1 antibody was incorporated into tumor tissue in a mouse model. CONCLUSION: A proportion of SCLC and NSCLC exhibits DLK1 expression. As a clinical feature, DLK1 expression could be a promising prognostic factor for recurrence in patients with resected NSCLC. In addition, DLK1 could serve as a new therapeutic target, including RIT, as suggested by our pilot study using a radiolabeled anti-DLK1 antibody in SCLC.

Five-year follow-up results from phase II studies of nivolumab in Japanese patients with previously treated advanced non-small cell lung cancer: pooled analysis of the ONO-4538-05 and ONO-4538-06 studies.

BACKGROUND: Two phase II studies in Japan examined the efficacy and safety of nivolumab, a programmed cell death 1 receptor inhibitor, in patients with advanced squamous and non-squamous non-small cell lung cancer (ONO-4538-05 and ONO-4538-06). We examined the long-term efficacy and safety of nivolumab in these patients treated for up to 5 years. METHODS: Patients with squamous (N = 35) or non-squamous (N = 76) non-small cell lung cancer received nivolumab (3 mg/kg every 2 weeks) until disease progression/death. Overall survival and progression-free survival were assessed at 5 years after starting treatment in separate and pooled analyses. Safety was evaluated in terms of treatment-related adverse events. RESULTS: A total of 17 patients were alive at the database lock (26 July 2019). The median overall survival (95% confidence interval) and 5-year survival rate were 16.3 (12.4-25.2) months and 14.3% in squamous patients, 17.1 (13.3-23.0) months and 19.4% in non-squamous patients and 17.1 (14.2-20.6) months and 17.8% in the pooled analysis, respectively. Programmed death ligand-1 expression tended to be greater among 5-year survivors than in non-survivors (P = 0.0703). Overall survival prolonged with increasing programmed death ligand-1 expression, with 5-year survival rates of 11.8, 21.8 and 41.7% in patients with programmed death ligand-1 expression of <1, ≥1-<50 and ≥50%, respectively. Treatment-related adverse events in ≥10% of patients (pooled analysis) included rash (15.3%), malaise (14.4%), decreased appetite (14.4%), pyrexia (14.4%) and nausea (10.8%). CONCLUSIONS: Long-term survival with nivolumab was observed in patients with squamous or non-squamous non-small cell lung cancer. No new safety signals were reported after ≥5 years of follow-up.

Detection of somatic TP53 mutation in surgically resected small-cell lung cancer by targeted exome sequencing: association with longer relapse-free survival.

OBJECTIVES: Few reports have explored clinical biomarkers, including those identified by targeted exome sequencing (TES) of surgically resected small-cell lung cancer (SCLC) and correlation with patient survival. PATIENTS AND METHODS: We collected formalin-fixed paraffin-embedded tumor samples from 127 patients with SCLC who had undergone surgery and analysed nonsynonymous somatic gene mutation profiles by TES of 26 cancer-related genes using next-generation sequencing (NGS) and web databases (UMIN Registration No. 000010117). RESULTS: We detected 38 nonsynonymous somatic tumor protein p53 (TP53) mutations in 43 (54.4%) patients. Among these TP53 lesions, we identified clinically relevant mutations including those encoding Y220C, R248W, R249M, M237I, and R273L substitutions in the p53 protein. These mutations have been reported to be associated with certain clinical outcomes or biology in other types of malignancies but not in SCLC. Moreover, nonsynonymous somatic mutations of TP53 were positively associated with relapse-free survival (RFS) (median, 17.33 months [95% confidence interval (CI), 3.86-30.79] in a mutation-positive group vs 10.39 months (6.96-13.82) in a mutation-negative group, p = 0.042). Multivariate analysis revealed that nonsynonymous somatic TP53 mutation was an independent factor of prolongation of RFS (hazard ratio: 0.51, 95% CI: 0.29-0.89, p = 0.019) but not overall survival (OS). CONCLUSION: These data suggested that TES may play a critical role for promoting reverse-translational studies, including investigations of the biology of TP53 mutations in different stages of SCLC. Accumulation of the data using cancer panels with a broader range of genes, including TP53, is expected to be useful for future clinical applications for patients with SCLC.

A randomized phase II trial of cisplatin plus gemcitabine versus carboplatin plus gemcitabine in patients with completely resected non-small cell lung cancer: Hokkaido Lung Cancer Clinical Study Group Trial (HOT0703).

PURPOSE: This study evaluated the efficacy and safety of platinum plus gemcitabine (P/G) combinations as postoperative adjuvant chemotherapies for non-small cell lung cancer. METHODS: Patients with postoperative stage IB-IIIA non-small cell lung cancer were randomly assigned to receive either cisplatin plus gemcitabine (GP arm) or carboplatin plus gemcitabine (GC arm) every 3 weeks for four cycles. The primary endpoint was 2-year disease-free survival (DFS). Secondary endpoints were safety, feasibility, overall survival (OS), and biomarker analyses. RESULTS: A total of 102 patients were randomized (stage IB, 22%; II, 36%; IIIA, 42%; histology: 74% adenocarcinoma). Of the 51 patients in each arm, 37 (73%) completed 4 cycles. During follow-up (median 5.8 years; range 0.1-9.7 years), estimated DFS and OS rates at 2 years were 59.6% and 86.3% with GP and 68.0% and 86.3% with GC, respectively. No significant difference in DFS was noted between arms (P = 0.163), although 3-, 4-, and 5-year DFS rates were higher with GC. Hematological toxic effects were comparable and non-hematological toxic effects were infrequent. DFS was significantly higher in the excision repair cross-complementation group 1 (ERCC1)-low group than in the ERCC1-high group for the GP arm (P = 0.045). CONCLUSION: Both P/G combination regimens were feasible and well-tolerated, and thus may represent valid options for postoperative adjuvant treatment of non-small cell lung cancer. Although no significant differences in DFS were evident between regimens, the present data favor the adoption of GC for further evaluation. CLINICAL TRIAL REGISTRATION: UMIN-CTR ( https://www.umin.ac.jp/ctr/ ) identifier: UMIN000000913.

Synthesis of Pd-Ru solid-solution nanoparticles by pulsed plasma in liquid method.

We have synthesized solid-solution nanoparticles (Pd : Ru = 1 : 3, 1 : 1 and 3 : 1) in an immiscible Pd-Ru system by the pulsed plasma in liquid method using Pd-Ru mixture bulk electrodes. The particle sizes of the floated and sedimented samples were measured to be <10 and <20 nm, respectively, via high-resolution transmission electron microscopy (HR-TEM). The lattice parameters of nanoparticles followed the Vegard's law, and the energy-dispersive X-ray spectroscopy (EDX) results almost coincided with those obtained for the starting bulk mixtures. The solid-solution structures and local structure were confirmed via HR-TEM, X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS).

An oxyl/oxo mechanism for oxygen-oxygen coupling in PSII revealed by an x-ray free-electron laser.

Photosynthetic water oxidation is catalyzed by the Mn4CaO5 cluster of photosystem II (PSII) with linear progression through five S-state intermediates (S0 to S4). To reveal the mechanism of water oxidation, we analyzed structures of PSII in the S1, S2, and S3 states by x-ray free-electron laser serial crystallography. No insertion of water was found in S2, but flipping of D1 Glu189 upon transition to S3 leads to the opening of a water channel and provides a space for incorporation of an additional oxygen ligand, resulting in an open cubane Mn4CaO6 cluster with an oxyl/oxo bridge. Structural changes of PSII between the different S states reveal cooperative action of substrate water access, proton release, and dioxygen formation in photosynthetic water oxidation.

A prospective phase II study of carboplatin and nab-paclitaxel in patients with advanced non-small cell lung cancer and concomitant interstitial lung disease (HOT1302).

OBJECTIVES: Patients with concomitant advanced non-small cell lung cancer (NSCLC) and interstitial lung disease (ILD) are excluded from most clinical chemotherapy trials because of the high risk of exacerbating the latter condition. This study prospectively investigated the efficacy and safety of albumin-bound paclitaxel (nab-paclitaxel) in combination with carboplatin in patients with both advanced NSCLC and ILD. PATIENTS AND METHODS: The enrolled patients had treatment-naïve, advanced NSCLC with ILD. Patients received 100 mg/m2nab-paclitaxel weekly and carboplatin at an area under the concentration-time curve of 6 once every 3 weeks for 4-6 cycles. The primary endpoint was the overall response rate (ORR); secondary endpoints included toxicity, progression-free survival (PFS), and overall survival (OS). RESULTS: Thirty-six patients were enrolled between April 2014 and September 2017. Sixteen patients (44.4%) had adenocarcinoma, 15 (41.7%) had squamous cell carcinoma (Sq), and 5 (13.9%) had non-small cell carcinoma. The median number of cycles administered were 4 (range: 1-6). The ORR was 55.6% (95% confidence interval [CI]: 39.6-70.5). The median PFS and OS were 5.3 months (95% CI: 3.9-8.2) and 15.4 months (95% CI: 9.4-18.7), respectively. A greater proportion of patients with Sq experienced improvements than did those with non-Sq: ORRs, 66.7% (95% CI: 41.7-84.8) vs. 47.6% (95% CI: 28.3-67.6) (P = 0.254); median PFS, 8.2 months (95% CI: 4.0-10.2) vs. 4.1 months (95% CI: 3.3-5.4) (HR, 0.60 [95% CI, 0.30-1.20]; P = 0.15); and median OS, 16.8 months (95% CI: 9.8-not reached) vs. 11.9 months (95% CI: 7.3-17.4) (HR, 0.56 [95% CI, 0.24-1.28]; P = 0.17). Two patients (5.6%) experienced grade ≥2 pneumonitis and 1 patient (2.8%) died. CONCLUSION: Weekly nab-paclitaxel combined with carboplatin showed favorable efficacy with acceptable toxicity in patients with both advanced NSCLC and ILD.

Three-year follow-up results from phase II studies of nivolumab in Japanese patients with previously treated advanced non-small cell lung cancer: Pooled analysis of ONO-4538-05 and ONO-4538-06 studies.

BACKGROUND: Nivolumab is a programmed cell death 1 (PD-1) receptor inhibitor antibody that enhances immune system antitumor activity. It is associated with longer overall survival (OS) than the standard treatment of docetaxel in patients with previously treated advanced squamous (SQ) and non-squamous (non-SQ) non-small cell lung cancer (NSCLC). We previously conducted two phase II studies of nivolumab in Japanese patients with SQ (ONO-4538-05) and non-SQ (ONO-4538-06) NSCLC, showing overall response rates (ORRs) (95% CI) of 25.7% (14.2-42.1) and 22.4% (14.5-32.9), respectively, with acceptable toxicity. In this analysis, we more precisely estimated the long-term safety and efficacy in patients with SQ and non-SQ NSCLC by pooling data from these two trials. METHODS: SQ (N = 35) and non-SQ (N = 76) NSCLC patients received nivolumab (3 mg/kg, every 2 weeks) until progression or discontinuation. OS was estimated using the Kaplan-Meier method. A pooled analysis of SQ and non-SQ patients was also performed. RESULTS: In SQ NSCLC patients, the median OS (95% CI) was 16.3 months (12.4-25.2), and the estimated 1-year, 2-year, and 3-year survival rates were 71.4% (53.4-83.5), 37.1% (21.6-52.7), and 20.0% (8.8-34.4), respectively. In non-SQ NSCLC patients, median OS was 17.1 months (13.3-23.0), and the estimated 1-, 2-, and 3-year survival rates were 68.0% (56.2-77.3), 37.4% (26.5-48.1), and 31.9% (21.7-42.5), respectively. When SQ NSCLC and non-SQ NSCLC data were pooled, the median OS was 17.1 months (14.2-20.6), and the estimated 1-, 2-, and 3-year survival rates were 69.1% (59.6-76.8), 37.3% (28.3-46.2), and 28.1% (20.0-36.7), respectively. Twenty (76.9%) of 26 responders lived for 3 or more years. Nivolumab was well tolerated and no new safety signals were found. CONCLUSION: Treatment with nivolumab improved long-term survival and was well tolerated in patients with SQ and non-SQ NSCLC. TRIAL REGISTRATION: JapicCTI-132072; JapicCTI-132073.

Analysis of DLL3 and ASCL1 in Surgically Resected Small Cell Lung Cancer (HOT1702).

BACKGROUND: Delta-like protein 3 (DLL3) is a Notch ligand that has an important role in the tumorigenesis of small cell lung cancer (SCLC). Recently, rovalpituzumab tesirine (Rova-T), a DLL3-targeted antibody-drug conjugate, has been developed for treating SCLC. DLL3 is a transcriptional target of the achaete-scute homolog-1 (ASCL1) transcription factor, which is involved in pulmonary neuroendocrine cell development. However, the relationship between DLL3 and/or ASCL1 expression and the clinical features of SCLC remains unknown, especially for early-stage resected SCLC. This study aimed to investigate the expression of DLL3 and ASCL1 in resected SCLC samples using immunohistochemical analysis. MATERIALS AND METHODS: We collected 95 surgically resected SCLC samples, which were formalin fixed and paraffin embedded. Immunohistochemistry staining was performed to investigate the correlation between the expression of either DLL3 or ASCL1 and clinicopathological features of study patients. RESULTS: Seventy-seven (83%) of 93 immunohistochemically evaluable samples were positive for DLL3 (expression in ≥1% of tumor cells), and DLL3-high expression (≥75%) was observed in 44 samples (47%). Sixty-one (64%) of 95 samples were positive for ASCL1 (expression in ≥5% of tumor cells). A positive correlation was observed between DLL3 and ASCL1 expression. DLL3 and ASCL1 expression were not associated with survival in SCLC patients. DLL3 was more prevalent in patients with advanced clinical disease. CONCLUSION: DLL3 and ASCL1 were highly expressed in patients with surgically resected SCLC. DLL3 and ASCL1 may be targets for the treatment of SCLC. IMPLICATIONS FOR PRACTICE: This article examines the relationship between delta-like protein 3 (DLL3) and achaete-scute homolog-1 (ASCL1) protein expression with the clinical features of 95 surgically resected small cell lung cancer (SCLC). DLL3 is attracting attention because rovalpituzumab tesirine (Rova-T), a DLL3-targeted antibody-drug conjugate, was developed recently. DLL3 and ASCL1 were highly expressed in patients with surgically resected SCLC. DLL3 and ASCL1 may be targets for the treatment of early-stage SCLC, including with Rova-T.

Phase II trial of S-1 plus cisplatin combined with bevacizumab for advanced non-squamous non-small cell lung cancer (TCOG LC-1202).

BACKGROUND: S-1 plus cisplatin is a standard chemotherapy regimen for advanced non-small cell lung cancer (NSCLC). The addition of bevacizumab has been shown to significantly improve overall survival (OS) in patients with advanced non-squamous (NSq) NSCLC who received carboplatin plus paclitaxel, however, failed to show an OS advantage in patients who received cisplatin plus gemcitabine. METHODS: Chemotherapy-naive patients with Stage IIIB, IV or recurrent non-SQ NSCLC were treated with a 3-week cycle of S-1 80 mg/m2 on days 1-14, cisplatin 60 mg/m2 on day 8 and bevacizumab 15 mg/kg on day 8 for 4-6 cycles. Patients without progressive disease (PD) received maintenance bevacizumab 15 mg/kg on day 1 with a 3-week cycle and S-1 80 mg/m2 every other day. The primary endpoint was progression-free survival (PFS). Secondary endpoints were objective response rate (ORR), OS, toxicity profile and Quality of life (QOL). RESULTS: From June 2013 to January 2015, 39 eligible patients were enrolled from eight institutions. Thirty-one patients (79%) completed four cycles of induction chemotherapy, and maintenance chemotherapy was initiated in 23 patients (59%). Median PFS, OS and ORR were 7.3 months (95% CI: 5.9-8.7), 21.4 months (95% CI: 14.7-not reached) and 64%, respectively. The most common grade 3/4 toxicities were leukopenia (12.8%), neutropenia (23.0%) and hypertension (28.2%). QOL analyses showed detrimental effects after initiation of the regimen. CONCLUSIONS: S-1 plus cisplatin in combination with bevacizumab met the primary endpoint in patients with advanced NSq-NSCLC. RR was anticipated to be high with acceptable toxicities.

Theoretical and computational investigations of geometrical, electronic and spin structures of the CaMn4 OX (X = 5, 6) cluster in the Kok cycle Si (i = 0-3) of oxygen evolving complex of photosystem II.

The optimized geometries of the CaMn4 OX (X = 5, 6) cluster in the oxygen evolving complex (OEC) of photosystem II (PSII) by large-scale quantum mechanics (QM) and molecular mechanics (MM) calculations are compared with recent serial femtosecond crystallography (SFX) results for the Si (i = 0-3) states. The valence states of four Mn ions by the QM/MM calculations are also examined in relation to the experimental results by the X-ray emission spectroscopy (XES) for the Si intermediates. Geometrical and valence structures of right-opened Mn-hydroxide, Mn-oxo and Mn-peroxide intermediates in the S3 state are investigated in detail in relation to recent SFX and XES experiments for the S3 state. Interplay between theory and experiment indicates that the Mn-oxo intermediate is a new possible candidate for the S3 state. Implications of the computational results are discussed in relation to possible mechanisms of the oxygenoxygen bond formation for water oxidation in OEC of PSII.

Spin, Valence, and Structural Isomerism in the S3 State of the Oxygen-Evolving Complex of Photosystem II as a Manifestation of Multimetallic Cooperativity.

Photosynthetic water oxidation is catalyzed by a Mn4CaO5-cluster in photosystem II through an S-state cycle. Understanding the roles of heterogeneity in each S-state, as identified recently by the EPR spectroscopy, is very important to gain a complete description of the catalytic mechanism. We performed herein hybrid DFT calculations within the broken-symmetry formalism and associated analyses of Heisenberg spin models to study the electronic and spin structures of various isomeric structural motifs (hydroxo-oxo, oxyl-oxo, peroxo, and superoxo species) in the S3 state. Our extensive study reveals several factors that affect the spin ground state: (1) (formal) Mn oxidation state; (2) metal-ligand covalency; (3) coordination geometry; and (4) structural change of the Mn cluster induced by alternations in Mn···Mn distances. Some combination of these effects could selectively stabilize/destabilize some spin states. We found that the high spin state ( Stotal = 6) of the oxyl-oxo species can be causative for catalytic function, which manifests through mixing of the metal-ligand character in magnetic orbitals at relatively short O5···O6 distances (<2.0 Å) and long MnA···O5 distances (>2.0 Å). These results will serve as a basis to conceptually identify and rationalize the physicochemical synergisms that can be evoked by the unique "distorted chair" topology of the cluster through cooperative Jahn-Teller effects on multimetallic centers.