Abstract P3-11-07: Exploratory biomarker analysis from a phase II, multicenter, randomized trial of eribulin plus gemcitabine(EG) versus paclitaxel plus gemcitabine(PG) as first-line chemotherapy for human epidermal growth factor receptor 2 (HER2)- negative metastatic breast cancer(MBC): Korean cancer study group trial (KCSG BR13-11)

Introduction : A phase II, multicenter, randomized clinical trial of the comparison between eribulin plus gemcitabine (EG) and paclitaxel plus gemcitabine (PG) as first-line chemotherapy for patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) found EG was less neurotoxic, but had similar efficacy of PG. In this study, we performed exploratory biomarker analysis of the impact of genetic alterations on the efficacy according to EG and PG chemotherapy.

Methods : This biomarker study was conducted using tumor samples from 40patients. When tissue collection was possible after disease progression, we performed paired sample analysis. Tumor DNA and RNA were extracted from formalin-fixed, paraffin-embedded tissues. To perform targeted deep sequencing, we used CancerScanTM, a 375 cancer gene panel. And we performed an nCounter expression assay for gene expression analysis using 730 PanCancer panel and 730 Immune panel.

Results: In total, we obtained 44 tissue samples from 40 patients. Twenty two patients were assigned in EG arm and 18 patients were in PG arm. Thirty-eight were at baseline and six after disease progression. Gene expression assay were performed in 44 tissue samples but only 31 samples were possible to be targeted deep sequencing.

We performed differently expressed gene(DEG) analysis for detecting the association between level of gene expression and disease progression. In this analysis, high expression of CCNE1, TGFB4 and BAMBI and low expression of DDB2, CD14 and SHC3 were associated with disease progression among 730 PanCancer panel genes (p<0.05, respectively). In terms of immune panel genes, most of immune related genes were highly expressed in a group without disease progression compared with that with disease progression. Only 2 genes, C8G and CD24 were highly expressed in a group with disease progression. Paired sample analysis showed that expression levels of THBS4 and CD27 decreased after disease progression while those of CCNE2 and FGFR4 increased.

In targeted deep sequencing, FAT3 (42.3%) was most frequently mutated gene followed by PKHD1, PIK3CA and TP53. Among mutated genes, EWSR1 mutation and upstream mutation of ETV1 were associated with disease progression, respectively (p<0.05, respectively). In mutation signature analysis, signature 1 (S, age related), S3(homologous recombination deficiency, HRD), S6 (mismatch repair, MMR), S20(MMR) and S21(microsatellite instability, MSI) were enriched in this population. Mutation signature 3 related to short disease free survival (p=0.0026).

Conclusion: In gene expression analysis, high expression of TGF-B signaling pathway related genes was associated with disease progression while high expression of immune related genes were related to prolonged disease free survival. In mutation analysis, EWSR1 and ETV1 mutations indicated short disease free interval and HRD mutation signature was also related to poor prognosis.

Citation Format: Kim J-Y, Lee EJ, Park KH, Im S-A, Kim S-B, Sohn SH, Lee KS, Chae YS, Lee KH, Kim JH, Im Y-H, Kim T-Y, Lee K-H, Ahn J-H, Kim GM, Park IH, Lee SJ, Han HS, Kim SH, Jung KH, Park YH. Exploratory biomarker analysis from a phase II, multicenter, randomized trial of eribulin plus gemcitabine(EG) versus paclitaxel plus gemcitabine(PG) as first-line chemotherapy for human epidermal growth factor receptor 2 (HER2)- negative metastatic breast cancer(MBC): Korean cancer study group trial (KCSG BR13-11) [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 P3-11-07.

Abstract P4-01-11: Genomic alterations of cell-free DNA in early breast cancer patients with recurrence

Cell-free DNA (cfDNA), as a non-invasive strategy, provides substantial benefit to overcome tumor heterogeneity. Surveillance of recurrence after standard treatment in early breast cancer (BC) using cfDNA, enables to detect minimal residual disease (MRD), also to identify genomic alterations driving recurrences. We aimed to assess the role of cfDNA in detecting MRD by investigating genomic alterations of 1)primary, recurred tumor and 2)cfDNA at time of recurrence using deep targeted sequencing. Fifty-four early BC patients were enrolled prospectively between 2014 and 2017 at time of recurrence. Median disease free interval was 28.5 months (rage 6.2-49.8). 62.7% (32/51) were hormone receptor (HR) positive (28 HRpos/HER2neg, 4 HRpos/HER2pos), 11.8% (6/51) were HRneg/HER2pos and 25.5% (13/51) were triple negative BCs. 59.3% (32/54) patients developed loco-regional recurrence (15 local recurrence only, 13 regional only, 4 with both) and distant metastasis was observed among 40.7% (22/54) patients. Cell-free DNA was extracted from 5cc blood at time of recurrence. Deep targeted sequencing was performed using customized NGS panel –encompassing 426 cancer-related target coding region, 242 fusion and amplification-related region- of cfDNA and FFPE(formalin fixed paraffin embedded) tumor samples archived from surgical resection or biopsy. Deep targeted sequencing data was successfully performed in 72.1% (31/43) plasma samples and sequencing yield was significantly lower when stored for more than 2yrs (46.2% vs 83.3%).

Mutations of cfDNA and tumor (primary, recurred) were analyzed. Mean sequencing depth of cfDNA and FFPE were x425.7 and x777.6 respectively. Median number of pathogenic mutations found in primary tumor, cfDNA and recurred tumor were 27(range 12-99), 25(range 8-85) and 9(range 0-23). Among mutations found in primary tumor, 27.4% were shared mutations (range 8.1%-72.7%) with recurred tumor and 26.1% were shared mutations (range 4.7%-69.2%) observed in cfDNA sample. Among mutations found in recurred tumor, 40.9% were observed in cfDNA (range 17.7-87.5%). In primary tumor, median number of mutations with allelic fraction (MAF)>10% were 12 (range 4-21) and at least one mutation was found in cfDNA at time of recurrence. Among mutations with MAF>10%, 59.4% and 69.1% were found in cfDNA and recurred tumor. Known oncogenic mutations of PIK3CA, TP53, GATA3, AKT1, ESR1, RELN, ERBB2, ERBB3, BRCA1 mutation were found. PIK3CA gene (p.H1047R) was found in two cases both in primary tumor and cfDNA at recurrence (MAF 11.4% vs 5.3% and 12.3% vs 15.4%) suggesting de novo driver mutation. One patient developed regional recurrence during adjuvant aromatase inhibitor with ESR1 V392I mutation in both cfDNA and recurred tumor (MAF 48.1 and 54.5%), while another patient's recurred tumor during aromatase inhibitor harbored ESR1 D538G mutation exclusively in recurred tumor with MAF <1%. Both patients had no ESR1 hotpot mutation in primary tumor.

Our data showed sequencing yield of 83.3% in plasma samples within 2yr. Pathogenic mutations in primary tumor, especially when MAF>10%, half of them was observed in cfDNA at time of recurrence. ESR1 mutation should be included in cfDNA surveillance for patients undergoing endocrine therapy even absent in primary tumor.

Citation Format: Kim J, Jo WK, Kim KY, Kim BJ, Lee SB, Lee HJ, Yu JH, Kim HJ, Chung IY, Ko BS, Kim S-B, Jung KH, Ahn JH, Chang S, Lee JW, Son BH, Ahn SH. Genomic alterations of cell-free DNA in early breast cancer patients with recurrence [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 P4-01-11.

Abstract P2-02-14: Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer

c-Src (Src) is a proto-oncogene involved in signaling that culminates in the control of multiple biological functions. Src is also one of the most frequently upregulated pathways in triple negative breast cancer (TNBC). Dysregulation of Src has been detected in TNBC and is strongly associated with tumor metastasis and poor prognosis. However, even after promising preclinical studies, Src inhibitors did not show major clinical advantage in unselected TNBC populations. We have previously published that metastatic TNBC has high energy-dependency to mitochondrial fatty acid beta-oxidation (FAO) and FAO activates Src by inducing autophosphorylation at Y419. However, our recent analysis suggests that as observed with the Src inhibitors, TNBC tumors treated with FAO inhibitors also develop drug-resistance and continue tumor growth. Evaluation of their drug resistance mechanism revealed that while short-term inhibition of FAO or Src induces autophagic and apoptotic cell deaths, long-term inhibition results in autophagy-mediated drug resistance and survival. Further analyses suggest that FAO and Src inhibitors activate mitogen-activated protein (MAP) kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway via the induction of cellular reactive oxygen species (ROS) in TNBC. Activated MEK/ERK then induces survival pathways for drug resistance and tumor survival. Validation of in vitro findings using in vivo TNBC models confirmed that combination of FAO/Src inhibitors with MEK/ERK inhibitors can provide significant benefit to overcome the therapeutic resistance of TNBC. These findings open-up new therapeutic opportunities to manage TNBC patients with currently non-targetable metastatic tumors.

Citation Format: Jung KH, Park JH, Sirupangi T, Jia D, Gandhi N, Pudakalakatti S, Elswood J, Porter W, Putluri N, Zhang XH-F, Chen X, Bhattacharya PK, Creighton CJ, Lewis MT, Rosen JM, Wong L-JC, Das GM, Osborne CK, Rimawi MF, Kaipparettu BA. Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer [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 P2-02-14.

Biosynthetic production of fully carbon-13 labeled retinal in E. coli for structural and functional studies of rhodopsins

The isomerization of a covalently bound retinal is an integral part of both microbial and animal rhodopsin function. As such, detailed structure and conformational changes in the retinal binding pocket are of significant interest and are studied in various NMR, FTIR, and Raman spectroscopy experiments, which commonly require isotopic labeling of retinal. Unfortunately, the de novo organic synthesis of an isotopically-labeled retinal is complex and often cost-prohibitive, especially for large scale expression required for solid-state NMR. We present the novel protocol for biosynthetic production of an isotopically labeled retinal ligand concurrently with an apoprotein in E. coli as a cost-effective alternative to the de novo organic synthesis. Previously, the biosynthesis of a retinal precursor, β-carotene, has been introduced into many different organisms. We extended this system to the prototrophic E. coli expression strain BL21 in conjunction with the inducible expression of a β-dioxygenase and proteo-opsin. To demonstrate the applicability of this system, we were able to assign several new carbon resonances for proteorhodopsin-bound retinal by using fully ¹³C-labeled glucose as the sole carbon source. Furthermore, we demonstrated that this biosynthetically produced retinal can be extracted from E. coli cells by applying a hydrophobic solvent layer to the growth medium and reconstituted into an externally produced opsin of any desired labeling pattern.

Fluorescence Enhancement of a Microbial Rhodopsin via Electronic Reprogramming

The engineering of microbial rhodopsins with enhanced fluorescence is of great importance in the expanding field of optogenetics. Here we report the discovery of two mutants (W76S/Y179F and L83Q) of a sensory rhodopsin from the cyanobacterium Anabaena PCC7120 with opposite fluorescence behavior. In fact, while W76S/Y179F displays, with respect to the wild-type protein, a nearly 10-fold increase in red-light emission, the second is not emissive. Thus, the W76S/Y179F, L83Q pair offers an unprecedented opportunity for the investigation of fluorescence enhancement in microbial rhodopsins, which is pursued by combining transient absorption spectroscopy and multiconfigurational quantum chemistry. The results of such an investigation point to an isomerization-blocking electronic effect as the direct cause of instantaneous (subpicosecond) fluorescence enhancement.

Enhancement of radionuclide bio-decontamination by screening highly efficient microalgae for Sr biomineralization

In this study, a new strategy for improving the radionuclide bio-decontamination (RBD) activity of microalgae by screening a better strain with high potential for biomineral production has been proposed. A noninvasive dielectrophoresis (DEP)-based microalgae screening microplatform has been used to select the highly capable microalgae in RBD. Microalgae (Chlorella vulgaris KMMCC9) with a high degree of competence in strontium (Sr) removal were successfully segregated against Chlorella vulgaris KCTC AG10002 that has relatively weak Sr removal activity under an AC electric field. C. vulgaris KMMCC9 with higher Sr biomineral competence (HSC) was also successfully segregated against others with lower Sr biomineral competence (LSC). Furthermore, after the screening and large-scale cultivation of C. vulgaris KMMCC9 with HSC, the microalgae showed highly effective Sr bio-decontamination in both non-radioactive and radioactive Sr contaminated water compared to wild-type (WT).

The Use of a Chimeric Rhodopsin Vector for the Detection of New Proteorhodopsins Based on Color

Student microbial ecology laboratory courses are often conducted as condensed courses in which theory and wet lab work are combined in a very intensive short time period. In last decades, the study of marine microbial ecology is increasingly reliant on molecular-based methods, and as a result many of the research projects conducted in such courses require sequencing that is often not available on site and may take more time than a typical course allows. In this work, we describe a protocol combining molecular and functional methods for analyzing proteorhodopsins (PRs), with visible results in only 4–5 days that do not rely on sequencing. PRs were discovered in oceanic surface waters two decades ago, and have since been observed in different marine environments and diverse taxa, including the abundant alphaproteobacterial SAR11 group. PR subgroups are currently known to absorb green and blue light, and their distribution was previously explained by prevailing light conditions – green pigments at the surface and blue pigments in deeper waters, as blue light travels deeper in the water column. To detect PR in environmental samples, we created a chimeric plasmid suitable for direct expression of PRs using PCR amplification and functional analysis in Escherichia coli cells. Using this assay, we discovered several exceptional cases of PRs whose phenotypes differed from those predicted based on sequence only, including a previously undescribed yellow-light absorbing PRs. We applied this assay in two 10-days marine microbiology courses and found it to greatly enhance students’ laboratory experience, enabling them to gain rapid visual feedback and colorful reward for their work. Furthermore we expect this assay to promote the use of functional assays for the discovery of new rhodopsin variants.

Genome Variations of Evolved Escherichia coli ET8 With a Rhodopsin-Based Phototrophic Metabolism

We reported that the phototrophic metabolism via plasmid-originated Gloeobacter rhodopsin(GR)-expression is improved in Escherichia coli ET5 harboring pKJ606-GR by a genomic point mutation (dgcQ^C1082A ) encoding a transmembrane cell signaling protein (Microb. Cell Fact. 16:111, 2017). Another evolved descendant is isolated from the chemostat, and the genome variation of the strain named ET8 harboring pKJ606-GR is investigated in this study. Whole genome sequencing analysis identifies a single point mutation (C3831976A) located in the non-coding upstream region of kdtA and an IS4 insertional mutation at galU^G706 without any mutations in the plasmid. ET8 strain shows enhanced kdtA transcription and no growth in the D-galactose or lactose sole carbon sourced minimal media. Size of ET8 strain are almost identical to that of the ancestor. Phototrophic growth and proton pumping in ET8 expressing GR (ET8 + GR) are increased 1.5-fold and threefold, respectively, compared with those in the ancestor (W3110 + GR). To verify the effects of the genomic mutations, either the kdtA-upregulation or the galU-disruption is conducted in the ancestor. Both the kdtA-upregulation and the galU-disruption result in the drastic increases of proton-pumping. The physiological properties arising from the genomic variations of the evolved host with the new phototrophic metabolism are further discussed.

Abstract P2-09-21: Molecular alterations and poziotinib, a pan-HER inhibitor efficacy in human epidermal growth factor receptor 2(HER2) positive breast cancers: Combined exploratory biomarker analysis from phase II clinical trial of poziotinib for refractory HER2 positive breast cancer(BC) patients

Introduction: Poziotinib is a novel, pan-HER kinase inhibitor which showed potent anti-tumor activities through irreversible inhibition of HER family tyrosine kinases in preclinical and early clinical studies. Recent the open-label, multicenter phase II trial of poziotinib monotherapy evaluated that poziotinib is a new promising option for patients with HER2-positive metastatic BC who have failed more than two HER2 targeted therapy (NCT02418689). We evaluated genetic profiles of HER2-positive metastatic BC and investigated potential biomarkers of poziotinib for HER2-positive metastatic BC (MBC). Methods: All participants were diagnosed as HER2-positive BCs according to American Society of Clinical Oncology/College of American Pathologists HER2 guideline and provided tissue specimens that would be possible to extract DNA and RNA for next generation sequencing. We performed targeted deep sequencing with a customized 381 cancer gene panel (CancerSCAN™) and analyzed the relationship among the sequencing data, immunohistochemistry and clinical outcome.

Results: From Apr 2015 to Feb 2016, 106 patients were enrolled in the trial from 7 institutes in Korea. Of 106 patients, biomarker data were available for 79 patients. TP53 was the most frequently mutated gene (70.8%) followed by PIK3CA (45.6%). HER2 single nucleotide variant (SNV) was detected in 13 BCs (16.5%) and HER3 SNV was in 9 (11.4%). The score of HER2 immunohistochemistry (IHC) was 3+ in 68 BCs and 2+ with positive in situ hybridization in 11 BCs. In copy number variant (CNV) analysis, HER2 amplification (86.1%) was most frequently observed and followed by CDK12 amplification (58.2%) and APOBEC3B deletion (30.4%). IHC score of HER2 was positively correlated to copy number (CN) of HER2 (P=0.001) but 11 breast cancer tissue did not have copy number amplification of HER2 (13.9%) (Six of HER2 IHC score 2+ and 5 of 3+). The median progression free survival (PFS) was 4.04 months (95% CI, 2.96 - 4.40) for patients who treated with poziotinib in this study. PIK3CA activating mutations were associated with short PFS compared to wild type (WT) and other SNVs (Median PFS of activating mutations vs. WT and others: 2.66 vs. 4.40 (months), P=0.009). HER2 CN amplification was positively correlated to duration of PFS (Median PFS of no amplification vs. 4 ≤ CN < 16 vs. 16 ≤ CN: 2.56 vs. 3.02 vs. 4.86 (months), P=0.032). HER2 SNVs prolonged duration of PFS without statistical significance (Median PFS of HER2 SNVs vs. WT: 4.24 vs. 3.19 (months), P=0.114), but 10 of 13 BCs with HER2 SNV (76.9%) had clinical benefit from poziotinib and 5 BCs (38.5%) had durable response more than 6 months. Conclusion: In this biomarker analysis, SNV of HER2 was frequently observed in HER2 positive MBCs and HER2 CN amplification was detected not in all. High CN amplification of HER2 derived longer PFS than those with low CN. To contrary to this, activating PIK3CA mutations shorten PFS compared to those with WT. In addition, HER2 SNVs might be a potential biomarker of poziotinib in HER2-positive MBC. Further functional study would be warranted.

Citation Format: Kim J-Y, Lee E, Park K, Jung HH, Park W-Y, Lee K-H, Sohn JH, Lee KS, Jung KH, Kim J-H, Lee KH, Im S-A, Park YH. Molecular alterations and poziotinib, a pan-HER inhibitor efficacy in human epidermal growth factor receptor 2(HER2) positive breast cancers: Combined exploratory biomarker analysis from phase II clinical trial of poziotinib for refractory HER2 positive breast cancer(BC) patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-21.

Abstract P6-06-04: Targeting replication stress in triple negative breast cancer treatment regimen: An emerging approach

Triple-negative breast cancers (TNBCs) represent aggressive heterogeneous subtype of breast cancer with poor clinical outcome. TNBCs have been reported to have high levels of replication stress due to i) various oncogene activations (C-myc or EGFR) ii) germline BRCA mutations iii) “BRCAness” in the absence of BRCA mutations in sporadic TNBCs. Replication stress is known to cause genomic instability, promote tumorigenesis and plays a critical role in therapy resistance in TNBCs. Therefore, targeting replication stress has emerged as an effective approach for better TNBC treatment through further downregulation of the remaining checkpoints to induce catastrophic failure of TNBC cells proliferation. Herein, we evaluated the anticancer efficacy of Carbazole Blue (CB), a synthetic analogue of Carbazole, on TNBC cells growth and progression. Our results demonstrated that CB inhibits short and long term viability of TNBC (MDA-MB-231, MDA-MB-468 and BT549) cells in a dose dependent manner without affecting normal mammary epithelial (MCF-10A) cells. In addition, CB treatment significantly reduced proliferation of TNBC cells, as evidenced by the BrdU proliferation assay. Consistent with this, our results further demonstrated that CB treatment induced G1/S cell cycle arrest and apoptosis in TNBCs. Importantly, systemic delivery of CB using nanoparticle-based delivery approach suppressed breast cancer growth without inducing toxicity, in preclinical orthotopic xenograft and PDX mouse models of TNBC. Furthermore, our gene microarray analysis revealed that CB treatment modulates the expression and activity of several genes known to be involved in DNA replication (CDC6, CDT1, MCMs, Claspin, POLE and PCNA) and associated DNA repair machinery such as (XRCC3, Exo1 and RAD51), which play pivotal roles in replication stress. Our results for the first time highlight the potential use of CB as a novel and potent therapeutic agent for treating TNBCs. As exploiting replication stress to treat cancer is gaining major interest, compound/s that may induce replication stress and inhibit DNA repair ability of cancer cells, has immense translational potential.

Citation Format: Rajamanickam S, Park JH, Bates K, Timilsina S, Eedunuri VK, Onyeagucha B, Subbarayalu P, Abdelfattah N, Jung KH, Favours E, Mohammad TA, Chen H-IH, Vadlamudi RK, Chen Y, Kaipparettu BA, Arbiser JL, Rao MK. Targeting replication stress in triple negative breast cancer treatment regimen: An emerging approach [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-06-04.

Retinal Binding to Apo-Gloeobacter Rhodopsin: The Role of pH and Retinal-Carotenoid Interaction

Over the past few decades, the structure, functions, properties, and molecular mechanisms of retinal proteins have been studied extensively. The newly studied retinal protein Gloeobacter rhodopsin (gR) acts as a light-driven proton pump, transferring a proton from the cytoplasmic region to the extracellular region of a cell following light absorption. It was previously shown that gR can bind the carotenoid salinixanthin (sal). In the present study, we report the effect of pH on the binding of retinal to the apo-protein of gR, in the presence and absence of sal, to form the gR pigment. We found that binding at different pH levels reflects the titration of two different protein residues, one at the lower pK_a 3.5 and another at the higher pK_a 8.4, that affect the pigment's formation. The maximum amount of pigment was formed at pH 5, both with and without the presence of sal. The introduction of sal accelerates the rate of pigment formation by a factor of 190. Furthermore, it is suggested that occupation of the binding site by the retinal chromophore induces protein conformational alterations which in turn affect the carotenoid conformation, which precedes the formation of the retinal-protein covalent bond. Our examination of synthetic retinal analogues in which the ring structure was modified revealed that, in the absence of sal, the retinal ring structure affects the rate of pigment formation and that the intact structure is needed for efficient pigment formation. However, the presence of sal abolishes this effect, and all-trans retinal and its modified ring analogues bind at a similar rate.

Temperature dependence of band gap in MoSe2 grown by molecular beam epitaxy

We report on a temperature-dependent band gap property of epitaxial MoSe₂ ultrathin films. We prepare uniform MoSe₂ films epitaxially grown on graphenized SiC substrates with controlled thicknesses by molecular beam epitaxy. Spectroscopic ellipsometry measurements upon heating sample in ultra-high vacuum showed temperature-dependent optical spectra between room temperature to 850 °C. We observed a gradual energy shift of optical band gap depending on the measurement temperature for different film thicknesses. Fitting with the vibronic model of Huang and Rhys indicates that the constant thermal expansion accounts for the steady decrease of band gap. We also directly probe both optical and stoichiometric changes across the decomposition temperature, which should be useful for developing high-temperature electronic devices and fabrication process with the similar metal chalcogenide films.

An evolutionary optimization of a rhodopsin-based phototrophic metabolism in Escherichia coli

Background

The expression of the Gloeobacter rhodopsin (GR) in a chemotrophic Escherichia coli enables the light-driven phototrophic energy generation. Adaptive laboratory evolution has been used for acquiring desired phenotype of microbial cells and for the elucidation of basic mechanism of molecular evolution. To develop an optimized strain for the artificially acquired phototrophic metabolism, an ancestral E. coli expressing GR was adaptively evolved in a chemostat reactor with constant illumination and limited glucose conditions. This study was emphasized at an unexpected genomic mutation contributed to the improvement of microbial performance.

Results

During the chemostat culture, increase of cell size was observed, which were distinguished from that of the typical rod-shaped ancestral cells. A descendant ET5 strain was randomly isolated from the chemostat culture at 88-days. The phototrophic growth and the light-induced proton pumping of the ET5 strain were twofold and eightfold greater, respectively, than those of the ancestral E. coli strain. Single point mutation of C1082A at dgcQ gene (encoding diguanylate cyclase, also known as the yedQ gene) in the chromosome of ET5 strain was identified from whole genome sequencing analysis. An ancestral E. coli complemented with the same dgcQ mutation from the ET5 was repeated the subsequently enhancements of light-driven phototrophic growth and proton pumping. Intracellular c-di-GMP, the product of the diguanylate cyclase (dgcQ), of the descendant ET5 strain was suddenly increased while that of the ancestral strain was negligible.

Conclusions

Newly acquired phototrophic metabolism of E. coli was further improved via adaptive laboratory evolution by the rise of a point mutation on a transmembrane cell signaling protein followed by increase of signal molecule that eventually led an increase proton pumping and phototrophic growth.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-017-0725-6) contains supplementary material, which is available to authorized users.

Abstract P6-01-07: Mitochondria-nuclear communication regulates epithelial-mesenchymal transition and metastasis in triple negative breast cancer

For triple negative breast cancer (TNBC), the driver pathways are still poorly understood. Advances in cancer metabolism research over the last decade have enhanced and modified our understanding on Warburg effect. It is now known that mitochondria in tumors are not always defective in their ability to carry out oxidative phosphorylation. Instead, in proliferating cells, mitochondrial energy pathways are reprogrammed to meet the challenges of macromolecular synthesis and to escape from apoptosis. Tumor initiating cells (TICs) maintain cancer stem cell properties and are known to play significant role in TNBC metastasis. Mitochondrial retrograde regulation (MRR) is a bidirectional communication between mitochondria and nucleus. MRR is triggered by mitochondrial functional demands and it responds in a continuous manner to change metabolic needs of the cell. Using transmitochondrial cybrid (cybrid) technology, we generated different cybrid models under common nuclear backgrounds of benign breast epithelium or TNBC. Mitochondria from cells with different cancer potential such as benign breast epithelium, moderately metastatic and highly metastatic breast cancer cell lines were studied under the common nuclear background to understand MRR-regulated TIC properties and cancer pathways. Using genomic, metabolomic, and proteomic approaches, we confirmed the significance of mitochondrial character in the regulation of epithelial mesenchymal transition (EMT), TIC and metastatic properties. Altogether, our results suggest that MRR is critical in TNBC TIC character and stemness.

Citation Format: Park JH, Jung KH, Sirupangi T, Vithayathil S, Jin F, Putluri V, Piyarathna DWB, Yotnda P, Bhat VB, Sreekumar A, Lewis MT, Coarfa C, Putluri N, Creighton CJ, Wong L-JC, Kaipparettu BA. Mitochondria-nuclear communication regulates epithelial-mesenchymal transition and metastasis in triple negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-01-07.

Abstract P1-02-14: Circulating cell-free DNA (CFD) measured by a simple fluorescent assay to predict relapse in triple negative breast cancer patients receiving neoadjuvant chemotherapy: A biomarker substudy of prospective observational study (NCT02001519, NCT02001506)

Background: Prior technique to measure cell free DNA(CFD) is labor-intensive and expensive, while, recently developed fluorescent CFD assay is more simple and convenient.The aim of this study was to evaluate the role of CFD measured by a fluorescent assay as a biomarker of patients with triple negative breast cancer (TNBC) received neoadjuvant chemotherapy

Methods: We prospectively enrolled patients with TNBC, clinical stage II or III (T>1.5cm or lymph node > 1.5cm), who were scheduled for neoadjuvant chemotherapy. Patients received 4 cycles of adriamycin 60 mg/m2 plus cyclophosphamide 600 mg/m2 (AC) followed by 4 cycles of cisplatin or docetaxel, and surgery. Plasma samples were obtained from patients before initial chemotherapy (baseline-CFD) and after 4 cycles of AC neoadjuvant chemotherapy (AC-CFD).

Results: This study included 72 patients who met the inclusion criteria. The mean levels of baseline-CFD and AC-CFD were 239±68 ng/mL and 210±66 ng/mL, respectively, and the CFD level was significantly decreased after AC chemotherapy.( p=0.001) The baseline-CFD was not associated with initial tumor characteristics. (T stage 1-2 vs. 3, p=0.313; N stage 0 vs. 1-3, p=0.317) There was no statistically significant difference between patients with response (CR or PR) to AC chemotherapy and those without response in terms of baseline-CFD, AC-CFD, and change of CFD between two values. (p=0.814, p=0.839, p=0.927) With 33.6 months of median follow up, there were 18 cases of relapse. Relapsed group showed numerically higher level of baseline-CFD, although it was not statistically significant. (relapse, 259 ng/mL; non-relapse, 233 ng/mL; p=0.161) We performed a ROC curve analysis of baseline-CFD for relapse, and found an area under the curve of 0.62 (95% CI, 0.46-0.78) at 222 ng/mL. Patients with baseline-CFD above 222 showed higher relapses than those below 222. (HR, 2.75; 95% CI, 0.96-7.84; p = 0.059)

Conclusions: The baseline-CFD obtained using a simple and convenient fluorescent assay could predict relapse, suggesting baseline-CFD as a potential biomarker for risk stratification of TNBC.

Citation Format: Park K, Woo M, Kim JE, Ahn J-H, Jung KH, Kim S-B. Circulating cell-free DNA (CFD) measured by a simple fluorescent assay to predict relapse in triple negative breast cancer patients receiving neoadjuvant chemotherapy: A biomarker substudy of prospective observational study (NCT02001519, NCT02001506) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-14.

Abstract OT1-01-12: A phase II, multicenter, randomized trial of eribulin plus gemcitabine (EG) vs. paclitaxel plus gemcitabine (PG) in patients with HER2-negative metastatic breast cancer as first-line chemotherapy

Background: Metastatic breast cancer (MBC) is an incurable disease and is needed to improve effective chemotherapy. Paclitaxel plus Gemcitabine (PG) combination chemotherapy is one of the preferred chemotherapeutic regimens for patients with MBC, and was found to be proper as a maintenance chemotherapy regimen with survival benefit and feasible toxicity profile. Eribulin mesylate is a non-taxane inhibitor of microtubule dynamics of the halichondrin class of antineoplastic drugs. A recent pooled analysis of two phase II studies with eribulin showed improved overall survival in in various patient subgroups with advanced/metastatic breast cancer who had previously received an anthracycline and a taxane. Furthermore, eribulin may have rational benefit compared with paclitaxel in terms of neurotoxicity. Therefore, Eribulin plus Gemcitabine (EG) combination chemotherapy may have less neurotoxocity comparing to PG.

Trial Design: Prospective randomized phase 2, open-label, two-arm, multi-center study comparing EG chemotherapy with PG chemotherapy for patients with HER-2 negative MBC as first-line chemotherapy.

Eligibility Criteria: Histologically confirmed breast cancer patients, at least 19 years of age, with no prior history of chemotherapy for metastatic, recurrent breast cancer with evaluable lesions (as per RECIST, 1.1) who have adequate hematologic, renal, and hepatic function. Patients either may or may not have a prior anthracycline containing regimen. Prior hormonal therapy as a treatment of metastatic disease is allowed.

Specific Aims:

The primary efficacy endpoint of the trial is Progression-Free Survival (PFS). The secondary efficacy endpoints are: Time to Treatment Failure (TTF); Overall Survival (OS); neuropathic scale (FACT for Taxane QOL assessment); toxicity; duration of response; Objective Response Rate (ORR); Clinical Benefit Rate. The exploratory endpoint of the study includes pharmacogenetic profile.

Statistical Methods:

The initial sample size of the present study was determined based on the data derived from a previous trial on PG maintenance chemotherapy design; 6-month PFS is 70% for PG chemotherapy. This design was hypothesized that EG chemotherapy would not be inferior to PG chemotherapy. Thus, estimated PFS for each arm is 70%. Based on this estimate, we would plan to recruit a total of 100 patients (50 per arm). Considering drop-out rate of 10%, total 112 MBC patients planned to be enrolled.

Present Accrual and Target Accrual:Enrollment has been completed as of March, 2016 with a target enrollment of 112 patients.

Contact information:Kyung Hae Jung MD, Ph.D. khjung@amc.seoul.kr

ClinicalTrials.gov Identifier: NCT02263495.

Citation Format: Park YH, Im S-A, Sohn JH, Lee KS, Chae YS, Lee KH, Kim J-H, Im Y-H, Ahn JS, Kim T-Y, Lee K-H, Kim S-B, Ahn J-H, Kim GM, Park IH, Lee SJ, Han HS, Kim SH, Jung KH. A phase II, multicenter, randomized trial of eribulin plus gemcitabine (EG) vs. paclitaxel plus gemcitabine (PG) in patients with HER2-negative metastatic breast cancer as first-line chemotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT1-01-12.

A randomized, multi-center, open-label, phase III study of once-per-cycle DA-3031, a pegylated G-CSF, in comparison with daily filgrastim in patients receiving TAC chemotherapy for breast cancer

PURPOSE

This multi-center, randomized, phase III study was conducted to demonstrate the non-inferiority of DA-3031 compared with daily filgrastim in patients during the first cycle of chemotherapy for breast cancer in terms of the duration of severe neutropenia (DSN).

METHODS

Seventy-four patients with breast cancer who were receiving combination chemotherapy with docetaxel, doxorubicin, and cyclophosphamide (TAC) were enrolled. All participants were randomized to receive either daily subcutaneous injections of filgrastim 100 μg/m²/day for up to 10 days or a single subcutaneous injection of DA-3031 at fixed doses of 6 mg on day 2 of each chemotherapy cycle.

RESULTS

The mean duration of grade 4 (G4) neutropenia in cycle 1 was 2.08 ± 0.85 days for the filgrastim group and 2.28 ± 1.14 days for the DA-3031 group. The difference between groups was 0.2 ± 1.10 days (95 % confidence interval (CI) = -0.26, 0.66), which supported non-inferiority. No statistically significant differences were observed in nadir absolute neutrophil count (ANC) (154.34/mm³ and 161.75/mm³ for the filgrastim and DA-3031 groups, respectively; P = 0.8414) or in time to ANC recovery (10.03 ± 0.75 and 9.83 ± 1.56 days in the filgrastim and DA-3031 groups, respectively; P = 0.0611) during cycle 1. Serious AEs occurred in six (15.8 %) patients receiving filgrastim and in ten (27.8 %) patients receiving DA-3031; however, none was determined to be related to the study drug.

CONCLUSIONS

DA-3031 and daily filgrastim are similar in regard to DSN and safety in breast cancer patients receiving TAC chemotherapy.

Abstract P1-09-09: Role of endocrine therapy in premenopausal patients with hormone receptor-positive metastatic breast cancer, compared with postmenopausal patients: Diachronic analyses from nationwide cohort in Korea (KCSG BR 14-07)

Background

Endocrine therapy (E) has a major role in treatment of hormone receptor (HR)-positive metastatic breast cancer (MBC). However, in contrast to western countries, premenopausal patients (PRE) more prevalent (50% of all breast cancer patients) and have less options of E than postmenopausal patients (POST) in Korea where the use of LHRH agonist in combination aromatase inhibitors (AIs) in PRE is restricted. Recently we have been successfully established nationwide cohort for the patients MBC (575 patients from 26 institutes). This study was designed to evaluate the role of E especially in PRE.

Methods

The patients with MBC were prospectively or retrospectively enrolled between September 2014 and May 2015. Only menopausal status-confirmed patients (296) were analyzed. Postmenopause was defined, based on NCCN guideline. Total duration of treatment was defined as the time from start day of any first treatment to end of any last treatment. Total duration of E was defined as the sum of time duration of each E. Overall survival was calculated from the start day of any treatment for MBC to any causes of death. This work is supported by National Strategic Coordinating Center for Clinical Research (H110C2020).

Results

A total of 296 patients with HR-positive MBC were analyzed [PRE, 169 (57.1%) and POST, 127 (42.9%)]. Except age (mean 44 and 60 years), baseline characteristics including in pathology, HER2 status, initial pathologic stage, de novo metastasis versus recurrence, surgery and adjuvant treatment (chemotherapy, endocrine therapy and radiotherapy) were well balanced. 92 (54.4%) of PRE and 77 (60.6%) of POST received at least one or more E through all treatment course. 41 (24.2%) of PRE and 44 (34.6%) received E as 1st-line treatment (p=0.034). Among PRE who received 1st-line of E, 30 (71.4%) and 9 (21.4%) of PRE received 2nd- and 3rd-line E. 20 (45.4%) and 10 (22.7%) of POST received 2nd- and 3rd- or more line of E. Most of PRE (54%) received tamoxifen+/-goserelin and 32% of PRE received AIs along with ovarian suppression. 71% of POST received AIs. As initial treatment, E was more frequently used in POST than in PRE (34.6% and 24.3%, p=0.053). Overall survival (OS) of all patients was 18.2 months (95% CI, 14.8-21.5). There was no difference in OS between PRE (17.8 months, 10.9-24.8) and POST (18.5 months, 95% CI, 13.2-23.9) (P=0.337). No difference of OS was observed (E, 18.1 moths, 95% CI, 13.0-23.3; chemotherapy 21.2 moths, 95% CI, 16.8-25.5), regardless of initial treatment. Total duration of treatment of PRE and POST were 15.2 and 13.6 months, respectively with no significant difference (p=0.389). PRE (8.3 moths, 95% CI,5.7-10.8) showed the trend toward longer duration of E in comparison with POST (5.5 moths, 95% CI,4.4-6.7), however the difference did not reach statistical significance (p=0.051).

Conclusion

E was more commonly used as 1st-line therapy in POST than in PRE. Although PRE had limited options of E, E was used in long duration of treatment especially in PRE. These findings suggested that E had a role in treatment for PRE with HR-positive MBC and could be used in treatment for PRE with good efficacy.

Citation Format: Kim T-Y, Ahn J-H, Yoon JH, Sohn JH, Kim GM, Lee KH, Park YH, Koh S-J, Lee SE, Chae Y, Lee KS, Lee KE, Won HS, Kim JH, Jeong J, Park KH, Cho EK, Im Y-H, Im S-A, Jung KH. Role of endocrine therapy in premenopausal patients with hormone receptor-positive metastatic breast cancer, compared with postmenopausal patients: Diachronic analyses from nationwide cohort in Korea (KCSG BR 14-07). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-09-09.

Abstract P3-07-34: Predictive role of stromal tumor infiltrating lymphocytes (TILs) in patients with metastatic HER2-positive breast cancer (BC) treated with trastuzumab

Background:Prognostic significance of stromal TILs in metastatic BC has been suggested in various BC subtypes. However, predictive role of stromal TILs for the efficacy of trastuzumab has not been established in patients with HER2-positive BC. This study was performed to evaluate whether the stromal TILs are associated with the efficacy of trastuzumab in patients with metastatic HER2-positve BC.

Method:Between June 2006 and March 2013, a total of 60 women with recurrent or metastatic HER2-positive BC treated with trastuzumab were included in this retrospective analysis. In these patients, trastuzumab was administered either as single agent or combination with taxanes. Stromal TILs were assessed using immunohistochemistry in surgical specimen (n=39, 65%) and biopsy specimen of metastatic lesion (n=21, 35%) by the academic pathologist (HJL). Primary endpoint of this study was progression-free survival (PFS), and secondary endpoints were response rate and overall survival (OS).

Result:Median age was 54 year old (range, 36-76), and all patients had invasive ductal carcinoma. Hormone receptor was positive in 34 patients (57%) and 18 patients (30%) initially presented with metastatic disease. Nine patients (15%) received cytotoxic chemotherapy without trastuzumab before the administration of trastuzumab. Patients were grouped according to the TILs (< 10% [n=50] and >10% [n=10]), and there was no significant difference in age (p=0.68), histologic grade (p=1.00), metastatic sites (p>0.05), and number of lines of chemotherapy before the administration of trastuzumab(p=0.33) among patients with low and high stromal TILs. High TILs were more common in hormone receptor (HR)-negative tumor compared with HR–positive tumor (31% vs 6%; p=0.02). In overall, median PFS and OS were 15.0 months (95% CI, 9.7-20.2) and 35.0 months (95% CI, 29.8-40.2), respectively. Median PFS in patients with high stromal TILs were numerically longer than that in those with low TILs (22.0 months [95% CI, 9.6-34.4] vs 14.0 months [95% CI, 9.6-18.4]; p=0.057). There was no difference in response rates (p=0.43) and OS (p=0.94) according to the stromal TILs. FcR genotype was not significantly correlated with objective response rate, PFS and OS.

Conclusion:This study suggests that the stromal TILs might be associated with the clinical outcomes of HER2-targeted therapy in patients with metastatic HER2-positive BC. Our finding should be validated in future studies based on a large sample size.

Keywords: Breast cancer, tumor infiltrating lymphocyte. Trastzumab, HER2.

Citation Format: Yoon JA, Yoo C, Lee HJ, Kim K-P, Kim J, Ahn J-H, Jung KH, Gong G, Kim S-B. Predictive role of stromal tumor infiltrating lymphocytes (TILs) in patients with metastatic HER2-positive breast cancer (BC) treated with trastuzumab. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-34.

Abstract P1-14-15: A randomized phase lll trial of neoadjuvant sequential chemotherapy with 4 cycles of adriamycin plus cyclophosphamide followed by 4 cycles of docetaxel (AC4-D4) versus shorter 3 cycles of FEC followed by 3 cycles of docetaxel (FEC3-D3) in node-positive breast cancer (Neo-Shorter): First report of efficacy & toxicity profile

Background: The addition of a taxane to anthracycline-based chemotherapy provided an improved outcome in neoadjuant setting. Two neoadjuvant chemotherapy with 4 cycles of AC followed by 4 cycles of docetaxel (AC4-D4) and 3 cycles of FEC followed by 3 cycles of docetaxel (FEC3-D3) are widely used. Short duration of chemotherapy, 6 cycles rather than 8 cycles might be an attractive approach.

Methods: This is a randomized, single-center, prospective, parallel group, comparative phase III trial (NCT02001506). Patients (pts) with breast cancer of clinically stage II or III, or sized  1.5 cm with histologically proven lymph-node involvement were included. Pts were stratified according to hormone receptor and HER2 expression status and randomized to AC4-D4 and 3 cycles of FEC3-D3 treatment. The primary endpoint was pathological complete response, defined as the absence of invasive disease in the breast and axillary lymph nodes, analyzed by intention to treat.

Results: At the time of submission, a total of 207 pts were enrolled; 1 pt failed screening; 25 pts dropped out (5 pts in AC4-D4 arm and 2 pts in FEC3-D3 arm discontinue treatment due to progressive disease); 39 pts are still receiving neoadjuvant chemotherapy; 142 pts, who received surgery, were included for this analysis. In AC4-D4 arm, among 64 pts, 57 pts achieved clinical response (6 complete response [CR] and 51 partial response [PR]) and among them 9 pts achieved pathologic complete response [pCR]. In FEC3-D3 arm, among 78 pts, 66 pts achieved clinical response (7 CR and 59 PR) and among them 11 pts achieved pCR. Addition of docetaxel increased clinical response in both arms. The most common adverse event was febrile neutropenia. Without prophylactic G-CSF, grade ≥3 febrile neutropenia (FN) occurred 23/661 cycles (3.5%) in AC4-D4 arm and 23/552 cycles (4.2%) in FEC3-D3 arm, respectively. Grade 3 and 4 toxicities other than FN were reported at expected levels in both groups. Sixty-one severe adverse events were reported; 33 (including 23 FN) in AC4-D4 arm and 28 (including 23 FN) in FEC3-D3 arm.

Conclusion: Compared to AC4-D4, shorter duration of FEC3-D3 neoadjuvant chemotherapy showed similar efficacy of pCR rate of 14.0% (versus 14.1% in AC4-D4 arm). The most common and important adverse event was febrile neutropenia in both arms. Updated study findings will be provided.

Citation Format: Kim JE, Ahn J-H, Jung KH, Lee HJ, Gong G-Y, Lee E-M, Ha EJ, Son B-H, Ahn S-H, Ahn SD, Kim H-H, Shin HJ, Kim S-B. A randomized phase lll trial of neoadjuvant sequential chemotherapy with 4 cycles of adriamycin plus cyclophosphamide followed by 4 cycles of docetaxel (AC4-D4) versus shorter 3 cycles of FEC followed by 3 cycles of docetaxel (FEC3-D3) in node-positive breast cancer (Neo-Shorter): First report of efficacy & toxicity profile. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-15.

Abstract P6-10-03: Does participation in clinical trials influence on survival in patients with metastatic breast cancer?

Background

Recently, many clinical trials (TRIAL) especially incorporated with molecular-targeted agents are being conducted in treatment for breast cancer worldwide. However, the relation of participating clinical trials with survival has not been actively studied. This study was designed to evaluate whether participation in clinical trials could improve overall survival (OS) or not in patients with metastatic breast cancer (MBC), compared with conventional treatment.

Method

Korean Cancer Study Group (KCSG) has successfully established Nationwide Cohort in KOREA to conduct diachronic analysis (KCSG BR 14-07). Clinical data for patients with MBC were collected from this Cohort. OS was defined as the time duration from first diagnosis of metastasis to any cause of death. This work is supported by National Strategic Coordinating Center for Clinical Research (H110C2020).

Results

A total of 575 patients with metastatic breast from 26 institutes in KOREA cancer MBC were consequently enrolled between September 2014 and May 2015. 156 (27.1%) of patients were enrolled to at least one or more clinical trials and 419 patients received only conventional treatment (CONV). Age, hormone status, HER2 status, initial pathologic stage, metastasis versus recurrence, adjuvant treatment, ECOG performance status (PS) (0, 1 vs 2 or more) were similar between TRIAL and CONV. 30% of trials were associated with HER2-targeted agents. As initial treatment, chemotherapy was more frequently used in TRIAL (85.9%) than in CONV (79.0%) (P=0.038). Number of regimens of chemotherapy was greater in TRIAL (2.9+/-1.8) than CONV (2.1+/-1.6) (P<0.001). Number of regimens of endocrine therapy (E) was similar between TRIAL (1.4+/-0.6) and CONV (1.5+/-0.7) (P=0.474). Overall survival of all patients was 16.2 months (95% CI, 14.1-18.1). TRIAL showed significant prolongation of survival, compared with CONV [21.1 (95% CI, 17.7-24.6) vs 15.1 months (95% CI, 13.1-17.2); P=0.005]. The differences in OS was constantly observed in HER2-positive [23.8 (16.7-30.9) vs 17.2 months (95% CI, 12.4-21.9); P=0.018] and Triple-negative [15.4 (10.5-20.3) vs 12.0 months (95% CI, 10.2-13.8); P=0.025]. In multivariate analysis, initial metastasis, hormone status, ECOG PS did not influence on OS between TRIAL and CONV (P=0.849)

Conclusion

Participating in clinical trials could be associated with prolongation of survival. This results constantly maintained in HER2-positive and triple-negative MBC. These findings suggested that clinical trials are useful for the patients with MBC, even if the patients do not complete the standard treatment.

Citation Format: Kim T-Y, Sohn JH, Kim S-B, Yoon JH, Kim GM, Lee KH, Koh S-J, Park YH, Lee SE, Chae Y, Lee KS, Lee KE, Won HS, Kim JH, Jeong J, Park KH, Cho EK, Im Y-H, Im S-A, Jung KH. Does participation in clinical trials influence on survival in patients with metastatic breast cancer?. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-10-03.

Abstract OT3-01-10: A prospective, open-label, single-arm, multi-center, phase II exploratory study to evaluate the efficacy and safety of poziotinib (NOV120101) in patients with HER2-positive metastatic breast cancer who have received at least two prior HER2-directed regimens

Background: Poziotinib is a novel, oral, irreversible pan-HER inhibitor that has shown promising clinical activity in Phase 1 studies of patients (pts) with advance HER2 positive breast cancer who have failed at least 2 prior lines of HER2-directed therapy. A Phase 2 study of poziotinib was initiated in Korea in March 2015 in pts with HER2+ metastatic breast cancer. This phase 2 study is designed to seek accelerated approval for poziotinib for the treatment of metastatic breast cancer in Korea.

Trial Design: Prospective Phase 2, open-label, single-arm, multi-center study in pts with recurrent, Stage IV breast cancer with HER2-overexpression who had received at least 2 prior HER2-directed regimens

Eligibility Criteria: Histologically confirmed breast cancer patients, at least 19 years of age, with confirmed HER2 positive evaluable tumors (per RECIST, 1.1) who have adequate hematologic, renal, and hepatic function and have failed at least two HER2-directed regimens that included a taxane-containing anticancer chemotherapy, with a life expectancy of at least 12 weeks.

Specific Aims: The Primary Efficacy Endpoint of the study was Progression-Free Survival (PFS). The Secondary Efficacy Endpoints included: PFS rate at 12 weeks post-dose; Objective Response Rate (ORR) including Complete Response (CR) and Partial Response (PR) rates; Disease Control Rate (DCR) including CR, PR, and Stable Disease (SD); Duration of Disease Control; Overall Survival (OS); Time to Progression (TTP); Time to Objective Response and Duration of Objective Response. The Exploratory Endpoints included: Population Pharmacokinetic (PK) Profile and Exploratory Genomic and Biomarker Analyses.

Statistical Methods: In the randomized, multicenter, 2-arm, open-label study of trastuzumab emtansine (TH3RESA18), the median PFS was shown to be 3.3 months in subjects with optimal treatment per Investigator's Choice. This ongoing study with poziotinib expects a median PFS of 4.5 months based on data from a previous Phase 1 study of poziotinib (NOV120101). Based on the following assumptions, a 5% one-sided significance level, and 80% power, and 2 months of accrual and 12 months of follow-up, 66 subjects will be required. Accounting for a 10% drop-out rate, a total of 74 subjects will be recruited into this ongoing Phase 2 study.

Present Accrual and Target Accrual: 17 patients enrolled as of May 20, 2015 with a total target enrollment of 74 patients

Contact information:

ClinicalTrials.gov Identifier: NCT02418689.

Citation Format: Park Y-H, Jung KH, Sohn JH, Lee KS, Lee KH, Kim J-H, Kim J-Y, Jung J, Han H, Park W-Y, Im S-A. A prospective, open-label, single-arm, multi-center, phase II exploratory study to evaluate the efficacy and safety of poziotinib (NOV120101) in patients with HER2-positive metastatic breast cancer who have received at least two prior HER2-directed regimens. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT3-01-10.

Structural basis for the slow photocycle and late proton release in Acetabularia rhodopsin I from the marine plant Acetabularia acetabulum

Although many crystal structures of microbial rhodopsins have been solved, those with sufficient resolution to identify the functional water molecules are very limited. In this study, the Acetabularia rhodopsin I (ARI) protein derived from the marine alga A. acetabulum was synthesized on a large scale by the Escherichia coli cell-free membrane-protein production method, and crystal structures of ARI were determined at the second highest (1.52–1.80 Å) resolution for a microbial rhodopsin, following bacteriorhodopsin (BR). Examinations of the photochemical properties of ARI revealed that the photocycle of ARI is slower than that of BR and that its proton-transfer reactions are different from those of BR. In the present structures, a large cavity containing numerous water molecules exists on the extracellular side of ARI, explaining the relatively low pK a of Glu206ARI, which cannot function as an initial proton-releasing residue at any pH. An interhelical hydrogen bond exists between Leu97ARI and Tyr221ARI on the cytoplasmic side, which facilitates the slow photocycle and regulates the pK a of Asp100ARI, a potential proton donor to the Schiff base, in the dark state.