Shear-wave velocity for colorectal cancer liver metastases as a potential prognostic factor after chemotherapy: a preliminary study.

AIM: To evaluate whether shear-wave velocity (SWV) can be used for predicting the prognoses of patients with colorectal cancer liver metastases (CRLMs) after chemotherapy. MATERIALS AND METHODS: Our institutional review board approved this prospective study, and written informed consent was obtained. SWV of CRLMs were obtained using point shear-wave elastography using acoustic radiation force impulse from 25 patients prior to and 2, 7, and 14 days after chemotherapy. Progression-free survival (PFS) after chemotherapy was estimated using the Kaplan-Meier method. The Cox proportional hazard regression model was used to determine significant predictive factors for PFS. For measurement reproducibility, an additional 37 patients with CRLMs were enrolled and assessed using intraclass correlation coefficients (ICCs). RESULTS: After chemotherapy, 10 and 15 patients were classified into responder and non-responder groups, respectively. The estimated 1- and 3-year PFS values in the whole cohort were 36% and 8%, respectively. A decrease in the SWV value on day 2 relative to the initial value was a significant predictive factor for better PFS outcome (hazard ratio = 0.20, 95% confidence interval = 0.07-0.57, p=0.003). The estimated 1 and 3-year PFS rates were 66.7% and 22.2%, respectively, in nine patients with decreased SWV values on day 2 and significantly higher than 18.8% and 0% of 16 patients with increased SWV values on day 2. The ICC value of SWV of CRLMs in the additional 37 patients was 0.823 (95% CI = 0.685-0.905), indicating good agreement. CONCLUSION: SWV values of CRLMs could provide prognostic information in patients with CRLMs treated with chemotherapy, as decreased SWV values on day 2 after chemotherapy was a significant predictive factor for better PFS.

Quantitative proteomic analysis of HER2 expression in the selection of gastric cancer patients for trastuzumab treatment.

Background: A wide range of response rates have been reported in HER2-positive gastric cancer (GC) patients treated with trastuzumab. Other HER2-targeted therapies for GC have yet to show efficacy in clinical trials. These findings raise question about the ability of standard HER2 diagnostics to accurately distinguish between GC patients who would and would not benefit from anti-HER2 therapies. Patients and methods: GC patients (n = 237), including a subset from the Trastuzumab in GC (ToGA) trial were divided into three groups based on HER2 status and history of treatment with standard chemotherapy or chemotherapy plus trastuzumab. We applied mass spectrometry-based proteomic analysis to quantify HER2 protein expression in formalin-fixed tumor samples. Using HER2 expression as a continuous variable, we defined a predictive protein level cutoff to identify which patients would benefit from trastuzumab. We compared quantitated protein level with clinical outcome and HER2 status as determined by conventional HER2 diagnostics. Results: Quantitative proteomics detected a 115-fold range of HER2 protein expression among patients diagnosed as HER2 positive by standard methods. A protein level of 1825 amol/µg was predicted to determine benefit from the addition of trastuzumab to chemotherapy. Trastuzumab treated patients with HER2 protein levels above this cutoff had twice the median overall survival (OS) of their counterparts below the cutoff (35.0 versus 17.5 months, P = 0.011). Conversely, trastuzumab-treated patients with HER2 levels below the cutoff had outcomes similar to HER2-positive patients treated with chemotherapy. (Progression-free survival = 7.0 versus 6.5 months: P = 0.504; OS = 17.5 versus 12.6 months: P = 0.520). HER2 levels were not prognostic for response to chemotherapy. Conclusions: Proteomic analysis of HER2 expression demonstrated a quantitative cutoff that improves selection of GC patients for trastuzumab as compared with current diagnostic methods.

A randomised, double-blind, placebo-controlled multi-centre phase III trial of XELIRI/FOLFIRI plus simvastatin for patients with metastatic colorectal cancer.

BACKGROUND: The purpose of this randomised phase III trial was to evaluate whether the addition of simvastatin, a synthetic 3-hydroxy-3methyglutaryl coenzyme A reductase inhibitor, to XELIRI/FOLFIRI chemotherapy regimens confers a clinical benefit to patients with previously treated metastatic colorectal cancer. METHODS: We undertook a double-blind, placebo-controlled phase III trial of 269 patients previously treated for metastatic colorectal cancer and enrolled in 5 centres in South Korea. Patients were randomly assigned (1:1) to one of the following groups: FOLFIRI/XELIRI plus simvastatin (40 mg) or FOLFIRI/XELIRI plus placebo. The FOLFIRI regimen consisted of irinotecan at 180 mg m(-2) as a 90-min infusion, leucovorin at 200 mg m(-2) as a 2-h infusion, and a bolus injection of 5-FU 400 mg m(-2) followed by a 46-h continuous infusion of 5-FU at 2400 mg m(-2). The XELIRI regimen consisted of irinotecan at 250 mg m(-2) as a 90-min infusion with capecitabine 1000 mg m(-2) twice daily for 14 days. The primary end point was progression-free survival (PFS). Secondary end points included response rate, duration of response, overall survival (OS), time to progression, and toxicity. RESULTS: Between April 2010 and July 2013, 269 patients were enrolled and assigned to treatment groups (134 simvastatin, 135 placebo). The median PFS was 5.9 months (95% CI, 4.5-7.3) in the XELIRI/FOLFIRI plus simvastatin group and 7.0 months (95% CI, 5.4-8.6) in the XELIRI/FOLFIRI plus placebo group (P=0.937). No significant difference was observed between the two groups with respect to OS (median, 15.9 months (simvastatin) vs 19.9 months (placebo), P=0.826). Grade⩾3 nausea and anorexia were noted slightly more often in patients in the simvastatin arm compared with with the placebo arm (4.5% vs 0.7%, 3.0% vs 0%, respectively). CONCLUSIONS: The addition of 40 mg simvastatin to the XELIRI/FOLFIRI regimens did not improve PFS in patients with previously treated metastatic colorectal cancer nor did it increase toxicity.

CXC chemokine ligand 12a enhances chondrocyte proliferation and maturation during endochondral bone formation.

OBJECTIVE: We investigated the roles of CXC chemokine ligand 12a (CXCL12a), also known as stromal cell-derived factor-1α (SDF-1α), in endochondral bone growth, which can give us important clues to understand the role of CXCL12a in osteoarthritis (OA). METHODS: Primary chondrocytes and tibial explants from embryonic 15.5 day-old mice were cultured with recombinant mouse CXCL12a. To assess the role of CXCL12a in chondrogenic differentiation, we conducted mesenchymal cell micromass culture. RESULTS: In tibia organ cultures, CXCL12a increased total bone length in a dose-dependent manner through proportional effects on cartilage and bone. In accordance with increased length, CXCL12a increased the protein level of proliferation markers, such as cyclin D1 and proliferating cell nuclear antigen (PCNA), in primary chondrocytes as well as in tibia organ culture. In addition, CXCL12a increased the expression of Runx2, Col10 and MMP13 in primary chondrocytes and tibia organ culture system, implying a role of CXCL12a in chondrocyte maturation. Micromass cultures of limb-bud mesenchymal progenitor cells (MPCs) revealed that CXCL12a has a limited effect on early chondrogenesis, but significantly promoted maturation of chondrocytes. CXCL12a induced the phosphorylation of p38 and Erk1/2 MAP kinases and IκB. The increased expression of cyclin D1 by CXCL12a was significantly attenuated by inhibitors of MEK1 and NF-κB. On the other hand, p38 and Erk1/2 MAP kinase and NF-κB signaling were associated with CXCL12a-induced expression of Runx2 and MMP13, the marker of chondrocyte maturation. CONCLUSION: CXCL12a promoted the proliferation and maturation of chondrocytes, which strongly suggest that CXCL12a may have a negative effect on articular cartilage and contribute to OA progression.

Prognostic implication of mucinous histology in colorectal cancer patients treated with adjuvant FOLFOX chemotherapy.

BACKGROUND: There have been controversies in prognostic impact of mucinous histology on colorectal cancer, and its implication in patients treated with adjuvant 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) is unclear. METHODS: Stage II and III colorectal cancer patients who underwent curative resection followed by adjuvant FOLFOX were included. Patients were grouped according to the mucinous content: >50%, mucinous adenocarcinoma (MAC); <50%, adenocarcinoma with intermediated mucinous component (AIM); and without any mucinous component, non-MAC (NMA). Clinicopathological features and disease-free survival (DFS) were compared. RESULTS: Among a total of 521 patients, 27 patients (5.2%) had MAC, 41 patients (7.9%) had AIM, and 453 patients (86.9%) had NMA. Mucinous adenocarcinoma and AIM had higher frequency of proximal location and microsatellite instability, but lower frequency of angiolymphatic invasion. Disease-free survival was significantly worse in the MAC compared with NMA (3-year DFS 57% and 86%, respectively; P<0.001) and AIM (3-year DFS 87%, P=0.01 vs MAC). Multivariate analysis revealed MAC as an independent negative prognostic factor of DFS (adjusted hazard ratio 7.96, 95% confidence interval 3.76-16.8). CONCLUSION: Adenocarcinoma with intermediated mucinous component and MAC have distinct clinicopathological features compared with NMA. Mucinous adenocarcinoma has an adverse prognostic impact on stage II or III colorectal cancer treated with adjuvant FOLFOX.

The beneficial effect of palliative resection in metastatic colorectal cancer.

BACKGROUND: We aimed to determine the role of palliative resection in metastatic colorectal cancer (mCRC) and ascertain which patient populations would benefit most from this treatment. METHODS: A total of 1015 patients diagnosed with mCRC at Seoul National University Hospital between 2000 and 2009 were retrospectively studied. RESULTS: Of the 1015 patients, 168 patients with only liver and/or lung metastasis received curative resection. The remaining 847 patients were treated with palliative chemotherapy and/or palliative resection combined with best supportive care. Palliative resection was performed in 527 (62.2%) cases (complete resection with negative margin (R0) in 93, R1/2 in 434). Resected patients had a more prolonged median overall survival (OS) than unresected patients (21.3 vs 14.1 months; P<0.001). In multivariate analysis, R0 resection was found to be associated with a superior OS compared with R1/2 resection (51.3 vs 19.1 months; P<0.001) and no resection (51.3 vs 14.1 months; P<0.001). When we performed propensity score matching, palliative resection was found to be related to prolonged OS (hazard ratio=0.72, 95% confidence interval=0.59-0.89; P=0.003). CONCLUSION: Palliative resection without residual disease and chemotherapy confers a longer-term survival outcome than palliative chemotherapy alone in mCRC patient subset.

Postoperative chemoradiotherapy for gallbladder cancer.

PURPOSE: The goal of this work was to analyze the outcome of adjuvant chemoradiotherapy for patients with gallbladder cancer who underwent surgical resection and to identify the prognostic factors for these patients. PATIENTS AND METHODS: Between August 1989 and November 2006, 47 patients with gallbladder cancer underwent surgical resection followed by adjuvant radiotherapy. There were 21 males and 26 females, and median age was 60 years (range 44-75 years). Postoperative radiotherapy was delivered to the tumor bed and regional lymph nodes up to 40-50 Gy at 2 Gy/fraction; 41 patients also received intravenous 5-fluorouracil as a radiosensitizer. Median follow-up duration was 48 months for survivors. RESULTS: There were 2 isolated locoregional recurrences, 14 isolated distant metastases, and 7 combined locoregional and distant relapses. The 5-year overall survival rate was 43.7%. According to the extent of resection, the 5-year overall survival rates were 52.8%, 20.0%, and 0% in R0-, R1-, and R2-resected patients, respectively (p = 0.0038). On multivariate analysis incorporating extent of resection, T stage, N stage, performance of lymph node dissection, and histologic differentiation, extent of resection was the only prognostic factor associated with overall survival (p = 0.0075). Among the 37 patients with R0 resection, there was no difference of 5-year overall survival rates in patients with N0, N1, and Nx diseases (46.2%, 60.0%, and 44.4%, respectively, p = 0.6246). As for significant treatment-related morbidity, there was only 1 patient with grade 4 gastric ulcer. CONCLUSION: Adjuvant chemoradiotherapy after R0 resection can achieve a good long-term survival rate in gallbladder cancer patients, even in those with lymph node metastases, and may play a role for patients who underwent R0 resection of primary tumor without lymph node dissection.

Utility of a palatal speech appliance combined with the five-point eight-line segment technique in total tongue reconstruction.

The aim of this study was to explore a new total tongue reconstruction strategy based on the five-point eight-line segment (FIPELS) technique and a palatal speech appliance, and to evaluate the functional and aesthetic outcomes. Twenty patients with tongue squamous cell carcinoma were included in this study. All patients underwent total tongue resection followed by tongue reconstruction with an anterolateral thigh flap. The patients were divided randomly into two groups according to the reconstruction strategy: FIPELS group (10 patients) and traditional flap design group (10 patients). All 10 patients in the FIPELS group received a palatal speech appliance 1 month after the surgery. A Likert scale was used to assess swallowing function, speech articulation, and the aesthetic outcome of the reconstructed tongue in the traditional and FIPELS (with and without the palatal speech appliance) groups. Compared with the traditional group, swallowing function (1 month, P = 0.016; 3 months, P = 0.021) and the aesthetic outcome (1 month, P = 0.016; 3 months, P = 0.020) were significantly better in the FIPELS group (without the palatal speech appliance); however, there was no significant difference in speech articulation (1 month, P = 0.549; 3 months, P = 0.513). Within the FIPELS group, significantly better speech articulation was obtained with the palatal speech appliance than without it (1 month, P = 0.031; 3 months, P = 0.015).

Structural, optical and electrical properties of nitrogen ion implanted ZnO nanorods.

This study examined the micro-structural and electrical properties of N+-ion-implanted ZnO nanorods. Nitrogen ions with energies of 10-90 keV and beam fluxes of 10(13)-10(16) ions/cm2 were implanted on vertically-aligned ZnO nanorods. Energy dispersive X-ray spectroscopy measurements showed that N+ ions were spread uniformly over the nanorods. Extended X-ray absorption fine structure measurements revealed that the implanted N+s had partially substituted for the oxygen sites. Photoluminescence measurements showed a neutral-donor bound exciton peak at 3.36 eV and a two-electron-satellite peak at 3.33 eV independent of the ion energy and flux. The I-V characteristic curves showed that the current density was not changed by the N+ ion energy and flux much. These results strongly suggested that the N ions substituted for the oxygen sites were neutral.

Phase II study and biomarker analysis of cetuximab combined with modified FOLFOX6 in advanced gastric cancer.

This prospective study was conducted with the Korean Cancer Study Group to evaluate the efficacy and safety of cetuximab combined with modified FOLFOX6 (mFOLFOX6) as first-line treatment in recurrent or metastatic gastric cancer and to identify potential predictive biomarkers. Patients received cetuximab 400 mg m(-2) at week 1 and 250 mg m(-2) weekly thereafter until disease progression. Oxaliplatin (100 mg m(-2)) and leucovorin (100 mg m(-2)) were administered as a 2-h infusion followed by a 46-h continuous infusion of 5-fluorouracil (2400 mg m(-2)) every 2 weeks for a maximum of 12 cycles. Biomarkers potentially associated with efficacy were analysed. Among 38 evaluable patients, confirmed response rate (RR) was 50.0% (95% CI 34.1-65.9). Median time-to-progression (TTP) was 5.5 months (95% CI 4.5-6.5) and overall survival (OS) 9.9 months. Eleven patients having tumour EGFR expression by immunohistochemistry with low serum EGF and TGF-alpha levels showed a 100% RR compared to 37.0% in the remaining 27 patients (P<0.001). Moreover, ligand level increased when disease progressed in seven out of eight patients with EGFR expression and low baseline ligand level. No patient exhibited EGFR amplification or K-ras mutations. Gastric cancer patients with EGFR expression and low ligand levels had better outcomes with cetuximab/mFOLFOX6 treatment.

Age and HER2 expression status affect MRI accuracy in predicting residual tumor extent after neo-adjuvant systemic treatment.

BACKGROUND: Although recent studies suggest high accuracy of breast magnetic resonance imaging (MRI) in predicting residual tumor extent after neo-adjuvant systemic treatment (NST), its use is still controversial. In this study, we aimed to identify predictive factors of MRI accuracy after NST to determine a subgroup of patients in whom the use of MRI provides best additional benefit. MATERIALS AND METHODS: Clinicopathologic and molecular profiles of breast cancer patients were investigated and their relationships with MRI accuracy were analyzed. RESULTS: From January 2006 to February 2008, 195 patients received NST and preoperative MRI. In overall, MRI predicted residual tumor extent with higher accuracy than ultrasonography. Triple-negative (TN) tumors showed highest correlation between MRI-measured and pathologic tumor size (r = 0.781) when compared with other subtypes. Multivariate analysis showed age and HER2 expression status as independent factors predicting MRI accuracy. When patients were classified based on their age and HER2 status, relatively older patients (>45) with HER2-negative tumors showed highest MRI accuracy. This finding was further validated using an independent cohort of 63 consecutive patients. CONCLUSION: Age and HER2 status independently affected MRI accuracy after NST. This observation may guide more tailored approach in using MRI in breast cancer patients undergoing NST.

Circulating DNA for detection of gastric cancer.

OBJECTIVE: Gastric cancer (GC) is one of the most common malignant tumors worldwide, particularly, prevalent in China. Despite the decreasing incidence of GC in China, the 5-year survival rate is still not over 30% yet. Therefore, early diagnosis and therapeutic outcome evaluation of GC remains as the issue to be resolved in a clinical setting. MATERIALS AND METHODS: Recent studies have found the presence of a certain amount of circulating DNA in the peripheral blood of patients with malignant tumor and shown that these free DNA bear tumor-specific genetic information. The circulating DNA detection includes quantitative and qualitative methods and analysis. Combined monitoring of changes in circulating DNA levels and aberrant alteration of relevant tumor genes is likely to provide comprehensive real-time information to patients. RESULTS: Under normal conditions, oncogene presents in the form of proto-oncogene such as K-ras, which is in non-carcinogenic status under the influence of tumor suppressor gene. When tumor suppressor gene is damaged or mutated of oncogene itself is induced for instance P53, oncogene is then activated and induces tumorigenesis. However, compared to gene mutation detection, the detection of DNA methylation is relatively more well-developed and stable. CONCLUSIONS: This article reviews the current status of the research on circulating DNA in the diagnosis, assessment of response to therapy and prognostic evaluation in GC. In addition, the advantage, current issue and prospect of using circulating DNA as tumor marker are also analyzed.

Is c-Met oncoprotein expression an adverse prognosticator in extrahepatic bile duct cancer treated with curative resection followed by adjuvant chemoradiotherapy?

PURPOSE: To analyze the expression of c-Met, and to investigate correlations between the expression of c-Met, clinicopathologic variables, and survival in patients undergoing curative surgery followed by adjuvant chemoradiotherapy for extrahepatic bile duct (EHBD) cancer. METHODS: Ninety EHBD cancer patients who underwent curative resection followed by adjuvant chemoradiotherapy were enrolled. Expression of c-Met was assessed with immunohistochemical staining on tissue microarray. The correlation between clinicopathologic variables and survival outcomes was evaluated using Kaplan-Meier method and Cox proportional hazard model. RESULTS: On univariate analysis, 66 patients (76.7 %) showed c-Met expression. c-Met expression had a significant impact on 5-year overall survival (OS) (43.0 % in c-Met(+) vs. 25.0 % in c-Met(-), p = 0.0324), but not on loco-regional relapse-free survival or distant metastasis-free survival (DMFS). However, on multivariate analysis incorporating tumor location and nodal involvement, survival difference was not maintained (p = 0.2940). Tumor location was the only independent prognostic factor predicting OS (p = 0.0089). Hilar location tumors, nodal involvement, and poorly differentiated tumors were all identified as independent prognostic factors predicting inferior DMFS (p = 0.0030, 0.0013, and 0.0037, respectively). CONCLUSIONS: This study showed that c-Met expression was not associated with survival outcomes in EHBD cancer patients undergoing curative resection followed by adjuvant chemoradiotherapy. Further studies are needed to fully elucidate the prognostic value of c-Met expression in these patients.

Testican-1-mediated epithelial-mesenchymal transition signaling confers acquired resistance to lapatinib in HER2-positive gastric cancer.

Human epidermal growth factor receptor 2 (HER2)-directed treatment using trastuzumab has shown clinical benefit in HER2-positive gastric cancer. Clinical trials using lapatinib in HER2-positive gastric cancer are also currently underway. As with other molecularly targeted agents, the emergence of acquired resistance to HER2-directed treatment is an imminent therapeutic problem for HER2-positive gastric cancer. In order to investigate the mechanisms of acquired resistance to HER2-directed treatment in gastric cancer, we generated lapatinib-resistant gastric cancer cell lines (SNU216 LR) in vitro by chronic exposure of a HER2-positive gastric cancer cell line (SNU216) to lapatinib. The resultant SNU216 LR cells were also resistant to gefitinib, cetuximab, trastuzumab, afatinib and dacomitinib. Interestingly, SNU216 LR cells displayed an epithelial-mesenchymal transition (EMT) phenotype and maintained the activation of MET, HER3, Stat3, Akt and mitogen-activated protein kinase signaling in the presence of lapatinib. Using gene expression arrays, we identified the upregulation of a variety of EMT-related genes and extracellular matrix molecules, such as Testican-1, in SNU216 LR cells. We showed that the inhibition of Testican-1 by small interfering RNA decreased Testican-1-induced, MET-dependent, downstream signaling, and restored sensitivity to lapatinib in these cells. Furthermore, treatment with XAV939 selectively inhibited ß-catenin-mediated transcription and Testican-1-induced EMT signaling, leading to G1 arrest. Taken together, these data support the potential role of EMT in acquired resistance to HER2-directed treatment in HER2-positive gastric cancer, and provide insights into strategies for preventing and/or overcoming this resistance in patients.

Novel fusion transcripts in human gastric cancer revealed by transcriptome analysis.

Gene fusion is involved in the development of various types of malignancies. Recent advances in sequencing technology have facilitated identification of gene fusions and have stimulated the research of this field in cancer. In the present study, we performed next-generation transcriptome sequencing in order to discover novel gene fusions in gastric cancer. A total of 282 fusion transcript candidates were detected from 12 gastric cancer cell lines by bioinformatic filtering. Among the candidates, we have validated 19 fusion transcripts, which are 7 inter-chromosomal and 12 intra-chromosomal fusions. A novel DUS4L-BCAP29 fusion transcript was found in 2 out of 12 cell lines and 10 out of 13 gastric cancer tissues. Knockdown of DUS4L-BCAP29 transcript using siRNA inhibited cell proliferation. Soft agar assay further confirmed that this novel fusion transcript has tumorigenic potential. We also identified that microRNA-coding gene PVT1, which is amplified in double minute chromosomes in SNU-16 cells, is recurrently involved in gene fusion. PVT1 produced six different fusion transcripts involving four different genes as fusion partners. Our findings provide better insight into transcriptional and genetic alterations of gastric cancer: namely, the tumorigenic effects of transcriptional read-through and a candidate region for genetic instability.

X-ray absorption fine structure study of cobalt ion distribution in ferromagnetic Zn(1-x)Co(x)O films.

We examined the distribution of Co ions in ferromagnetic n-type Zn(1-x)Co(x)O semiconducting films with Co concentrations of 0.0-0.07 using x-ray absorption fine structure (XAFS) measurements at the Co and Zn K edges. Extended XAFS (EXAFS) revealed that Co ions mainly occupied the zinc sites in the films. X-ray absorption near edge structure (XANES) spectra demonstrated that the pre-edge peak of the Co K edge was substantially affected by the second neighboring Co ions in the zinc sites due to their environmental potential distortion. From the pre-edge peak and EXAFS analysis using ab initio calculations, we found that Co ions uniformly occupied the zinc sites of the Zn0.93Co0.07O film, whereas the Co ions of the Zn0.97Co0.03O and Zn0.95Co0.05O films were substituted at the zinc sites with a non-uniform distribution. The ferromagnetic properties of the Zn0.93Co0.07O film may be induced by direct interaction between the magnetic dipoles of the Co ions with a mean distance of 4.3 Å, or by the Co conduction-electron mediation.

Local structural properties of CuI at low temperatures.

This study examined the local structural properties of CuI at low temperatures of 10-300 K by x-ray diffraction (XRD) and extended x-ray absorption fine structure (EXAFS) measurements at the Cu K edge. The XRD data were refined using two models, split (distorted zinc-blende structure) and non-split (zinc-blende structure), using a conventional Rietveld refinement combined with a maximum entropy method (MEM). MEM/Rietveld analyses showed that both the split and non-split models could fit the data. EXAFS revealed the split model fit to be better than the non-split model. The split distance of Cu-I pairs was approximately 0.03 Å at 15 K and increased to 0.07 Å at 300 K. XRD and EXAFS combined together suggested that the CuI crystal was in a metastable state with a distorted zinc-blende structure at low temperatures.