Reversible Interlayer Sliding and Conductivity Changes in Adaptive Tetrathiafulvalene-Based Covalent Organic Frameworks

Ordered interlayer stacking is intrinsic in two-dimensional covalent organic frameworks (2D COFs) and has strong implications on COF's optoelectronic properties. Reversible interlayer sliding, corresponding to shearing of 2D layers along their basal plane, is an appealing dynamic control of both structures and properties, yet it remains unexplored in the 2D COF field. Herein, we demonstrate that the reversible interlayer sliding can be realized in an imine-linked tetrathiafulvalene (TTF)-based COF TTF-DMTA. The solvent treatment induces crystalline phase changes between the proposed staircase-like sql net structure and a slightly slipped eclipsed sql net structure. The solvation-induced crystallinity changes correlate well with reversible spectroscopic and electrical conductivity changes as demonstrated in oriented COF thin films. In contrast, no reversible switching is observed in a related TTF-TA COF, which differs from TTF-DMTA in terms of the absence of methoxy groups on the phenylene linkers. This work represents the first 2D COF example of which eclipsed and staircase-like aggregated states are interchangeably accessed via interlayer sliding, an uncharted structural feature that may enable applications such as chemiresistive sensors.

[Reliability and validity of the chronic obstructive pulmonary disease morning symptom diary Chinese version]

Objective: To describe the development of the Chronic Obstructive Pulmonary Disease Morning Symptom Diary (COPD-MSD) Chinese version and to test its reliability and validity. Methods: The COPD-MSD Chinese version was developed by the standard cross-cultural translation principle. A hundred and eight patients with COPD in stable condition from the Second Xiangya Hospital were assessed by interview with COPD-MSD Chinese version, and underwent mMRC, CAT scores and pulmonary function test.The reliability and validity were evaluated by performing correlation analysis.The stages of COPD determined by lung function were compared to observe the value of COPD-MSD Chinese version in determining disease severity. Results: The Cronbach's alpha and retest reliability of the total scale were 0.908 and 0.927, respectively.The explanatory factor analysis was conducted using orthogonal rotation through the maximum variation principle components extraction which revealed the presence of 5 components with eigen values exceeding 1, explaining totally 74.257% of the variance, and the total score of the COPD-MSD Chinese version was significantly correlated with the mMRC and CAT scores (r=0.44 and 0.56,P<0.01), indicating that the scale of the convergence validity was good. The COPD-MSD Chinese version scores varied significantly in patients with different severity of COPD(χ(2)=9.808, P<0.05). Conclusion: The COPD-MSD Chinese version showed good reliability and validity and could be used in clinical assessment of morning symptoms in Chinese COPD patients.

[Prevalence and quality of spirometry and the impact of spirometry training in Hunan, People's Republic of China]

Objective: To explore quality of spirometry in Hunan province and the impact of education on it. Methods: Cross-sectional study and a prospective randomized cohort study. (1) A total of 460 public hospitals in Hunan province were investigated. Research assistants collected 20 consecutive reports of pulmonary ventilation test reports (PVTRs) and basal information of those hospitals which owned spirometry. (2) To measure the effect of education, 28 randomly selected 2(nd) level hospitals which owned spirometry were randomized to intervention and control group (1∶1). The intervention group received a short-time training which included face-to-face lectures and a hand-by-hand operation training course, while the control group received usual care. PVTRs were investigated 3 months after the intervention. All PVTRs were classified to grade A, B, C, D and E according to the Chinese pulmonary ventilation test (PVT) guidelines. Results: The recovery rate was 100%. The spirometry-equipped ratio was 1.6% (2/129) at 1(st) level hospitals, 39.0% (105/269) at 2(nd) level hospitals, 100% (62/62) at 3(rd) level hospitals in Hunan province. There were 100% (2/2), 91.4% (96/105) and 93.5% (58/62) utilization rate at 1(st), 2(nd) and 3(rd) level hospitals. Common reasons for not owning a spirometer were equipment cost and insufficient insurance. Lack of knowledge about spirometry and inadequate benefits were the top two reasons for low utilization rate. There were 3 120 PVTRs from 156 hospitals which used spirometry, a total of 50.4% (1 574/3 120) PVTRs got grade A, a total of 14.8% (462/3 120) PVTRs were judged as unreliable (grade D, E). There were 560 PVTRs and 28 questionnaires, respectively, before and after intervention. The technicians' knowledge improved after education compared to before (9.8±0.6 vs 8.6±1.1) (P<0.05). And 75.0% (210/280) PVTRs got A grade in the intervention group, which was significantly higher than those in the control group (75.0% vs 37.9%, P<0.05). While none of PVTRs was unreliable, which was lower than that in the control group (0 vs 14.6%, P<0.05). Conclusions: The equipment ratio and the utilization rate of spirometry are still low and imbalanced among three levels hospitals in Hunan. The short-time training is helpful to improve quality of spirometry.

Abstract GS5-05: Resistance to neoadjuvant chemotherapy in triple negative breast cancer mediated by a reversible drug-tolerant state

Approximately 50% of patients with localized triple negative breast cancer (TNBC) have substantial residual cancer burden following treatment with neoadjuvant chemotherapy (NACT), resulting in distant metastasis and death for most of these patients. While genomic and phenotypic intra-tumor heterogeneity are pervasive features of TNBCs at the time of diagnosis, the functional contributions of heterogeneous tumor cell populations to chemoresistance have not been elucidated.

To investigate tumor evolution accompanying NACT, we employed orthotopic patient-derived xenograft (PDX) models of treatment-naïve TNBC, which retain intra-tumor heterogeneity characteristic of human TNBC. We discovered that some PDX models initially exhibited partial sensitivity to standard front-line NACT (Adriamycin plus Cytoxan, AC). Following AC, residual tumors were resistant to chemotherapy but repopulated tumors with chemo-sensitive cells if left untreated, indicating that tumor cells possessed inherent plasticity. To identify the tumor cell subpopulation(s) conferring chemoresistance, we conducted barcode-mediated clonal tracking in three independent PDX models by introducing a high-complexity pooled lentiviral barcode library into PDX tumor cells which were then orthotopically engrafted into recipient mice. Strikingly, residual tumors maintained the same heterogeneous clonal architecture as naïve tumors. Concordantly, whole-exome sequencing revealed conservation of genomic subclonal architecture throughout treatment. These results were corroborated by genomic sequencing of serial biopsies pre- and post-AC obtained directly from TNBC patients enrolled on an ongoing clinical trial at MD Anderson (ARTEMIS; NCT02276443). Together, these studies revealed that genomically distinct pre-treatment subclones were equally capable of surviving AC to reconstitute tumors after treatment.

To identify functional addictions of residual tumor cells, we conducted histologic and transcriptomic profiling. Residual tumors following AC-treatment exhibited extensive fibrotic desmoplasia and tumor cell pleomorphism in both PDX models and in serial biopsies obtained from TNBC patients enrolled on the ARTEMIS trial. Strikingly, these AC-induced features were reverted upon regrowth of residual tumors in PDXs and in patients' tumors. Similarly, residual tumors exhibited unique transcriptomic features, many of which are also de-regulated in cohorts of human TNBCs undergoing chemotherapy treatment. These features were nearly completely reverted after tumors regrew, suggesting that the residual tumor state may be a unique and transient therapeutic window. Gene set enrichment analyses revealed that residual tumors had increased activation of oxidative phosphorylation and decreased glycolytic signaling. Pharmacologic targeting of oxidative phosphorylation with a small-molecule inhibitor of mitochondrial electron transport chain complex I (IACS-010759) significantly delayed the regrowth of AC-treated residual tumors in three independent PDX models. Collectively, these studies reveal that a reversible phenotypic state can confer chemoresistance in the absence of genomic selection and that the residual tumor state is a novel therapeutic window for chemo-refractory TNBC.

Citation Format: Echeverria GV, Ge Z, Seth S, Jeter-Jones SL, Zhang X, Zhou X, Cai S, Tu Y, McCoy A, Peoples M, Lau R, Shao J, Sun Y, Bristow C, Carugo A, Ma X, Harris A, Wu Y, Moulder S, Symmans WF, Marszalek JR, Heffernan TP, Chang JT, Piwnica-Worms H. Resistance to neoadjuvant chemotherapy in triple negative breast cancer mediated by a reversible drug-tolerant state [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS5-05.