CD98 regulates the phosphorylation of HER2 and a bispecific anti-HER2/CD98 antibody inhibits the growth signal of human breast cancer cells.

Human epidermal growth factor receptor (HER) family proteins are currently major targets of therapeutic monoclonal antibodies against various epithelial cancers. However, the resistance of cancer cells to HER family-targeted therapies, which may be caused by cancer heterogeneity and persistent HER phosphorylation, often reduces overall therapeutic effects. We herein showed that a newly discovered molecular complex between CD98 and HER2 affected HER function and cancer cell growth. The immunoprecipitation of the HER2 or HER3 protein from lysates of SKBR3 breast cancer (BrCa) cells revealed the HER2-CD98 or HER3-CD98 complex. The knockdown of CD98 by small interfering RNAs inhibited the phosphorylation of HER2 in SKBR3 cells. A bispecific antibody (BsAb) that recognized the HER2 and CD98 proteins was constructed from a humanized anti-HER2 (SER4) IgG and an anti-CD98 (HBJ127) single chain variable fragment, and this BsAb significantly inhibited the cell growth of SKBR3 cells. Prior to the inhibition of AKT phosphorylation, BsAb inhibited the phosphorylation of HER2, however, significant inhibition of HER2 phosphorylation was not observed in anti-HER2 pertuzumab, trastuzumab, SER4 or anti-CD98 HBJ127 in SKBR3 cells. The dual targeting of HER2 and CD98 has potential as a new therapeutic strategy for BrCa.

Artificial intelligence for surgical safety during laparoscopic gastrectomy for gastric cancer: Indication of anatomical landmarks related to postoperative pancreatic fistula using deep learning.

BACKGROUND: Postoperative pancreatic fistula (POPF) is a critical complication of laparoscopic gastrectomy (LG). However, there are no widely recognized anatomical landmarks to prevent POPF during LG. This study aimed to identify anatomical landmarks related to POPF occurrence during LG for gastric cancer and to develop an artificial intelligence (AI) navigation system for indicating these landmarks. METHODS: Dimpling lines (DLs)-depressions formed between the pancreas and surrounding organs-were defined as anatomical landmarks related to POPF. The DLs for the mesogastrium, intestine, and transverse mesocolon were named DMP, DIP, and DTP, respectively. We included 50 LG cases to develop the AI system (45/50 were used for training and 5/50 for adjusting the hyperparameters of the employed system). Regarding the validation of the AI system, DLs were assessed by an external evaluation committee using a Likert scale, and the pancreas was assessed using the Dice coefficient, with 10 prospectively registered cases. RESULTS: Six expert surgeons confirmed the efficacy of DLs as anatomical landmarks related to POPF in LG. An AI system was developed using a semantic segmentation model that indicated DLs in real-time when this system was synchronized during surgery. Additionally, the distribution of scores for DMP was significantly higher than that of the other DLs (p < 0.001), indicating the relatively high accuracy of this landmark. In addition, the Dice coefficient of the pancreas was 0.70. CONCLUSIONS: The DLs may be used as anatomical landmarks related to POPF occurrence. The developed AI navigation system can help visualize the DLs in real-time during LG.

Efficacy of pancreaticojejunostomy of the pancreatic stump during distal or central pancreatectomy.

BACKGROUND: A stapler is usually used for transection and closure of the pancreas in distal pancreatectomy (DP) or central pancreatectomy (CP). When the pancreas is transected to the right of the portal vein, it is difficult to use a stapler and clinically relevant postoperative pancreatic fistula (CR-POPF) frequently occurs. We report on the efficacy of pancreaticojejunostomy (PJ) of the pancreatic stump for patients in whom stapler use is difficult. METHODS: Patients who underwent DP or CP were enrolled in this study. The pancreas was usually transected by a stapler, and ultrasonic coagulating shears (UCS) were used depending on the tumor situation. When using UCS, hand-sewn closure or PJ was performed for the pancreatic stump. The relationship between clinicopathological factors and the methods of pancreatic transection and closure were investigated. RESULTS: In total, 164 patients underwent DP or CP, and the pancreas was transected with a stapler in 150 patients and UCS in 14 patients. The rate of CR-POPF was higher and the postoperative hospital stay was longer in the UCS group than in the stapler group. PJ of the pancreatic stump, which was performed for 7 patients, did not worsen intraoperative factors. CR-POPF was not seen in these 7 patients, which was significantly less than that with hand-sewn closure. CONCLUSIONS: PJ of the pancreatic stump during DP or CP reduces CR-POPF compared with hand-sewn closure and may be useful especially when the pancreas is transected to the right of the portal vein.

Clinical significance of colonoscopy before laparoscopic bariatric/metabolic surgery in Japanese patients.

PURPOSE: Obesity is known to be associated with colorectal adenoma (CRA) and colorectal cancer (CRC); yet colonoscopy is not considered an essential preoperative evaluation before bariatric/metabolic surgery. The aim of this study was to clarify the clinical significance of preoperative colonoscopy for obese Japanese patients. METHODS: The subjects of this retrospective study were 114 patients who underwent screening colonoscopy before bariatric/metabolic surgery. Multivariate analyses were performed to evaluate the independent predictors of CRA/CRC among the characteristics identified as significant or nearly significant by univariate analyses. RESULTS: Colonoscopy revealed abnormal findings indicating the need for biopsy or polypectomy in 20 of the 114 patients (17.5%), and CRA was diagnosed in 13 patients (11.4%). Three patients (2.6%), who were all ≥ 56 years old, had a CRA ≥ 10 mm in diameter. The multivariate analysis showed that older age and male sex were significant predictors of CRA/CRC, which was identified in 46.2% of the male patients aged ≥ 46 years. CONCLUSION: Our findings suggest that older age and male sex may be risk factors for CRA/CRC in obese Japanese candidates for bariatric/metabolic surgery; thus, preoperative colonoscopy should be considered for these high-risk patients.

Glucose metabolic upregulation via phosphorylation of S6 ribosomal protein affects tumor progression in distal cholangiocarcinoma.

BACKGROUND: The prognosis of distal cholangiocarcinoma (dCCA) remains poor; thus, the identification of new therapeutic targets is warranted. Phosphorylated S6 ribosomal protein indicates a mammalian target of rapamycin complex 1 (mTORC1) activity, and mTORC1 plays a central role in controlling cell growth and regulating glucose metabolism. We aimed to clarify the effect of S6 phosphorylation on tumor progression and the glucose metabolic pathway in dCCA. METHODS: Thirty-nine patients with dCCA who underwent curative resection were enrolled in this study. S6 phosphorylation and the expression of GLUT1 were evaluated by immunohistochemistry, and their relationship with clinical factors was investigated. The effect of S6 phosphorylation on glucose metabolism with PF-04691502 treatment, an inhibitor of S6 phosphorylation, was examined in cancer cell lines by Western blotting and metabolomics analysis. Cell proliferation assays were performed with PF-04691502. RESULTS: S6 phosphorylation and the expression of GLUT1 were significantly higher in patients with an advanced pathological stage. Significant correlations between GLUT1 expression, S6 phosphorylation, and SUV-max of FDG-PET were shown. In addition, cell lines with high S6 phosphorylation levels showed high GLUT1 levels, and the inhibition of S6 phosphorylation reduced the expression of GLUT1 on Western blotting. Metabolic analysis revealed that inhibition of S6 phosphorylation suppressed pathways of glycolysis and the TCA cycle in cell lines, and then, cell proliferation was effectively reduced by PF-04691502. CONCLUSION: Upregulation of glucose metabolism via phosphorylation of S6 ribosomal protein appeared to play a role in tumor progression in dCCA. mTORC1 may be a therapeutic target for dCCA.

Efficacy of laparoscopic liver resection for small hepatocellular carcinoma located in the posterosuperior segments: A multi-institutional study using propensity score matching by the Kyushu Study Group of Liver Surgery.

AIM: Laparoscopic liver resection (LLR) for hepatocellular carcinoma (HCC) located in the posterosuperior segments (PS) have generally been considered more difficult than those for HCC in anterolateral segments (AL), but may be safe and feasible for selected patients with accumulated experience. In the present study, we investigated the effectiveness of LLR for single nodular HCCs ≤3 cm located in PS. METHODS: In total, 473 patients who underwent partial liver resection for single nodular HCCs ≤3 cm at the 18 institutions belonging to the Kyusyu Study Group of Liver Surgery from January 2010 to December 2018 were enrolled. The short-term outcomes of laparoscopic partial liver resection and open liver resection (OLR) for HCCs ≤3 cm, with subgroup analysis of PS and AL, were compared using propensity score-matching analysis. Furthermore, results were also compared between LLR-PS and LLR-AL. RESULTS: The original cohort of patients with HCC ≤3 cm included 328 patients with LLR and 145 with OLR. After matching, 140 patients with LLR and 140 with OLR were analyzed. Significant differences were found between groups in terms of volume of blood loss (median, 55 vs. 287 ml, p < 0.001), postoperative complications (0.71 vs. 8.57%, p = 0.003), and postoperative hospital stay (median, 9 vs. 14 days, p < 0.001). The results of subgroup analysis of PS were similar. Short-term outcomes did not differ significantly between LLR-PS and LLR-AL after matching. CONCLUSIONS: Laparoscopic partial resection could be the preferred option for single nodular HCCs ≤3 cm located in PS.

Impact of AI system on recognition for anatomical landmarks related to reducing bile duct injury during laparoscopic cholecystectomy.

BACKGROUND: According to the National Clinical Database of Japan, the incidence of bile duct injury (BDI) during laparoscopic cholecystectomy has hovered around 0.4% for the last 10 years and has not declined. On the other hand, it has been found that about 60% of BDI occurrences are due to misidentifying anatomical landmarks. However, the authors developed an artificial intelligence (AI) system that gave intraoperative data to recognize the extrahepatic bile duct (EHBD), cystic duct (CD), inferior border of liver S4 (S4), and Rouviere sulcus (RS). The purpose of this research was to evaluate how the AI system affects landmark identification. METHODS: We prepared a 20-s intraoperative video before the serosal incision of Calot's triangle dissection and created a short video with landmarks overwritten by AI. The landmarks were defined as landmark (LM)-EHBD, LM-CD, LM-RS, and LM-S4. Four beginners and four experts were recruited as subjects. After viewing a 20-s intraoperative video, subjects annotated the LM-EHBD and LM-CD. Then, a short video is shown with the AI overwriting landmark instructions; if there is a change in each perspective, the annotation is changed. The subjects answered a three-point scale questionnaire to clarify whether the AI teaching data advanced their confidence in verifying the LM-RS and LM-S4. Four external evaluation committee members investigated the clinical importance. RESULTS: In 43 of 160 (26.9%) images, the subjects transformed their annotations. Annotation changes were primarily observed in the gallbladder line of the LM-EHBD and LM-CD, and 70% of these shifts were considered safer changes. The AI-based teaching data encouraged both beginners and experts to affirm the LM-RS and LM-S4. CONCLUSION: The AI system provided significant awareness to beginners and experts and prompted them to identify anatomical landmarks linked to reducing BDI.

An intraoperative artificial intelligence system identifying anatomical landmarks for laparoscopic cholecystectomy: a prospective clinical feasibility trial (J-SUMMIT-C-01).

BACKGROUND: We have implemented Smart Endoscopic Surgery (SES), a surgical system that uses artificial intelligence (AI) to detect the anatomical landmarks that expert surgeons base on to perform certain surgical maneuvers. No report has verified the use of AI-based support systems for surgery in clinical practice, and no evaluation method has been established. To evaluate the detection performance of SES, we have developed and established a new evaluation method by conducting a clinical feasibility trial. METHODS: A single-center prospective clinical feasibility trial was conducted on 10 cases of LC performed at Oita University hospital. Subsequently, an external evaluation committee (EEC) evaluated the AI detection accuracy for each landmark using five-grade rubric evaluation and DICE coefficient. We defined LM-CBD as the expert surgeon's "judge" of the cystic bile duct in endoscopic images. RESULTS: The average detection accuracy on the rubric by the EEC was 4.2 ± 0.8 for the LM-CBD. The DICE coefficient between the AI detection area of the LM-CBD and the EEC members' evaluation was similar to the mean value of the DICE coefficient between the EEC members. The DICE coefficient was high score for the case that was highly evaluated by the EEC on a five-grade scale. CONCLUSION: This is the first feasible clinical trial of an AI system designed for intraoperative use and to evaluate the AI system using an EEC. In the future, this concept of evaluation for the AI system would contribute to the development of new AI navigation systems for surgery.

Development of an artificial intelligence system for real-time intraoperative assessment of the Critical View of Safety in laparoscopic cholecystectomy.

BACKGROUND: The Critical View of Safety (CVS) was proposed in 1995 to prevent bile duct injury during laparoscopic cholecystectomy (LC). The achievement of CVS was evaluated subjectively. This study aimed to develop an artificial intelligence (AI) system to evaluate CVS scores in LC. MATERIALS AND METHODS: AI software was developed to evaluate the achievement of CVS using an algorithm for image classification based on a deep convolutional neural network. Short clips of hepatocystic triangle dissection were converted from 72 LC videos, and 23,793 images were labeled for training data. The learning models were examined using metrics commonly used in machine learning. RESULTS: The mean values of precision, recall, F-measure, specificity, and overall accuracy for all the criteria of the best model were 0.971, 0.737, 0.832, 0.966, and 0.834, respectively. It took approximately 6 fps to obtain scores for a single image. CONCLUSIONS: Using the AI system, we successfully evaluated the achievement of the CVS criteria using still images and videos of hepatocystic triangle dissection in LC. This encourages surgeons to be aware of CVS and is expected to improve surgical safety.

Development of a cross-artificial intelligence system for identifying intraoperative anatomical landmarks and surgical phases during laparoscopic cholecystectomy.

BACKGROUND: Attention to anatomical landmarks in the appropriate surgical phase is important to prevent bile duct injury (BDI) during laparoscopic cholecystectomy (LC). Therefore, we created a cross-AI system that works with two different AI algorithms simultaneously, landmark detection and phase recognition. We assessed whether landmark detection was activated in the appropriate phase by phase recognition during LC and the potential contribution of the cross-AI system in preventing BDI through a clinical feasibility study (J-SUMMIT-C-02). METHODS: A prototype was designed to display landmarks during the preparation phase and Calot's triangle dissection. A prospective clinical feasibility study using the cross-AI system was performed in 20 LC cases. The primary endpoint of this study was the appropriateness of the detection timing of landmarks, which was assessed by an external evaluation committee (EEC). The secondary endpoint was the correctness of landmark detection and the contribution of cross-AI in preventing BDI, which were assessed based on the annotation and 4-point rubric questionnaire. RESULTS: Cross-AI-detected landmarks in 92% of the phases where the EEC considered landmarks necessary. In the questionnaire, each landmark detected by AI had high accuracy, especially the landmarks of the common bile duct and cystic duct, which were assessed at 3.78 and 3.67, respectively. In addition, the contribution to preventing BDI was relatively high at 3.65. CONCLUSIONS: The cross-AI system provided landmark detection at appropriate situations. The surgeons who previewed the model suggested that the landmark information provided by the cross-AI system may be effective in preventing BDI. Therefore, it is suggested that our system could help prevent BDI in practice. Trial registration University Hospital Medical Information Network Research Center Clinical Trial Registration System (UMIN000045731).

Apoptosis-related factors are relevant to progression of pancreatic neuroendocrine tumors.

BACKGROUND: Multidisciplinary therapy centered on antitumor drugs is indicated in patients with unresectable pancreatic neuroendocrine tumors (PanNET). However, the criteria for selection of optimal therapeutic agents is controversial. The aim of this study was to assess the malignancy of PanNET for optimal therapeutic drug selection. METHODS: Forty-seven patients with PanNET who underwent surgery were reviewed retrospectively, and immunohistochemical characteristics, including expression of GLUT1, SSTR2a, SSTR5, Survivin, X-chromosome-linked inhibitor of apoptosis protein (XIAP), and Caspase3 in the resected specimens, were investigated. Relapse-free survival (RFS) and overall survival (OS) were evaluated with regard to the characteristics using the Kaplan-Meier method and compared with the log-rank test. RESULTS: GLUT1 expression showed significant correlation with sex (p = 0.036) and mitotic rate (p = 0.048). Survivin and XIAP expression showed significant correlation with T-stage (p = 0.014 and 0.009), p-Stage (p = 0.028 and 0.045), and mitotic rate (p = 0.023 and 0.007). XIAP expression also significantly influenced OS (p = 0.044). CONCLUSIONS: Survivin and XIAP correlated with grade of malignancy, and expression of XIAP in particular was associated with a poor prognosis. Expression of these proteins may be a useful indicator to select optimal therapeutic agents in PanNET.

Appropriate indications for laparoscopic repeat hepatectomy.

BACKGROUND: Laparoscopic repeat hepatectomy (LRH) has increased, but appropriate indications for LRH are unclear. This study aimed to clarify appropriate indications for LRH. METHODS: We retrospectively compared surgical outcomes between open RH (ORH) (n = 57) and LRH (n = 40) groups. To detect difficult cases of complete pure LRH, we examined patients with unplanned intraoperative hand-assisted laparoscopic surgery (HALS)/open conversion (n = 6). RESULTS: In the LRH versus ORH group, as previous hepatectomy, laparoscopic (75% vs. 12%, p < 0.001) and partial hepatectomy (Hr0) (73% vs. 37%, p = 0.002) were more frequently performed, and as RH procedure, partial hepatectomy (Hr0) (88% vs. 47%, p = 0.0002) was more frequently performed. S1 tumor cases were higher in ORH group (11% vs. 0%), but S2-6 cases were higher in LRH group (73% vs. 49%) (p = 0.02). In LRH group, compared to the pure LRH patients, HALS/open conversion patients underwent significantly more previous hepatectomy with more than lobectomy (Hr2-3) (33% vs. 2.9%, p = 0.033) and more RH procedures with segmentectomy (HrS) (33% vs. 2.9%, p = 0.03). All LRH requiring a repeat hepatic hilar approach were HALS conversions. CONCLUSION: Appropriate indications for LRH were previous hepatectomy was laparoscopic partial hepatectomy (Hr0), and RH procedure was partial hepatectomy (Hr0) for S2-6 tumor location. When RH is more than segmentectomy (HrS) requiring a repeat hepatic hilar approach, planned HALS or ORH may be a better approach than pure LRH.

Down-regulation of dual-specificity phosphatase 6, a negative regulator of oncogenic ERK signaling, by ACA-28 induces apoptosis in NIH/3T3 cells overexpressing HER2/ErbB2.

Dual-specificity phosphatase 6 (DUSP6) is a key negative feedback regulator of the member of the RAS-ERK MAPK signaling pathway that is associated with cellular proliferation and differentiation. Deterioration of DUSP6 expression could therefore result in deregulated growth activity. We have previously discovered ACA-28, a novel anticancer compound with a unique property to stimulate ERK phosphorylation and induce apoptosis in ERK-active melanoma cells. However, the mechanism of cancer cell-specific-apoptosis by ACA-28 remains obscure. Here, we investigated the involvement of DUSP6 in the mechanisms of the ACA-28-mediated apoptosis by using the NIH/3T3 cells overexpressing HER2/ErbB2 (A4-15 cells), as A4-15 exhibited higher ERK phosphorylation and are more susceptible to ACA-28 than NIH/3T3. We showed that A4-15 exhibited high DUSP6 protein levels, which require ERK activation. Notably, the silencing of the DUDSP6 gene by siRNA inhibited proliferation and induced apoptosis in A4-15, but not in NIH/3T3, indicating that A4-15 requires high DUSP6 expression for growth. Importantly, ACA-28 preferentially down-regulated the DUSP6 protein and proliferation in A4-15 via the proteasome, while it stimulated ERK phosphorylation. Collectively, the up-regulation of DUSP6 may exert a growth-promoting role in cancer cells overexpressing HER2. DUSP6 down-regulation in ERK-active cancer cells might have the potential as a novel cancer measure.

Artificial intelligence software available for medical devices: surgical phase recognition in laparoscopic cholecystectomy.

BACKGROUND: Surgical process modeling automatically identifies surgical phases, and further improvement in recognition accuracy is expected with deep learning. Surgical tool or time series information has been used to improve the recognition accuracy of a model. However, it is difficult to collect this information continuously intraoperatively. The present study aimed to develop a deep convolution neural network (CNN) model that correctly identifies the surgical phase during laparoscopic cholecystectomy (LC). METHODS: We divided LC into six surgical phases (P1-P6) and one redundant phase (P0). We prepared 115 LC videos and converted them to image frames at 3 fps. Three experienced doctors labeled the surgical phases in all image frames. Our deep CNN model was trained with 106 of the 115 annotation datasets and was evaluated with the remaining datasets. By depending on both the prediction probability and frequency for a certain period, we aimed for highly accurate surgical phase recognition in the operation room. RESULTS: Nine full LC videos were converted into image frames and were fed to our deep CNN model. The average accuracy, precision, and recall were 0.970, 0.855, and 0.863, respectively. CONCLUSION: The deep learning CNN model in this study successfully identified both the six surgical phases and the redundant phase, P0, which may increase the versatility of the surgical process recognition model for clinical use. We believe that this model can be used in artificial intelligence for medical devices. The degree of recognition accuracy is expected to improve with developments in advanced deep learning algorithms.

Risk factors of unplanned intraoperative conversion to hand-assisted laparoscopic surgery or open surgery in laparoscopic liver resection.

BACKGROUND: Laparoscopic liver resection (LLR) is possible in many patients, but pure LLR is sometimes difficult to complete, and unplanned intraoperative hand-assisted laparoscopic surgery (HALS) or open conversion is sometimes necessary. However, appropriate indications and timing for conversion are unclear. This study aimed to clarify the indications for HALS and open conversion from pure LLR. METHODS: We collected data from 208 patients who underwent LLR from January 2010 to February 2021 in our department. We retrospectively examined these data between cases of unplanned intraoperative HALS conversion, open conversion, and pure LLR, and clarified risk factors and indications for HALS or open conversion. RESULTS: There were 191 pure LLRs, nine HALS conversions, and eight open conversions. In the HALS conversion group versus pure LLR group, body mass index (BMI) (27.0 vs. 23.7 kg/m2, p = 0.047), proportions of patients with history of upper abdominal surgery (78% vs. 33%; p = 0.006), repeat hepatectomy (56% vs. 15%; p = 0.002), S7 or S8 tumor location (67% vs. 35%; p = 0.049), and difficulty score (DS) ≥ 7 (56% vs. 19%; p = 0.008) were significantly higher, and surgical time (339 vs. 239 min; p = 0.031) was significantly longer. However, postoperative states were not significantly different between the two groups. The BMI cutoff value for risk of unplanned intraoperative conversion determined by receiver operating characteristic curve analysis was 25 kg/m2, and the proportion of patients with BMI ≥ 25 kg/m2 (89% vs. 31%, p < 0.001) was significantly higher in the HALS conversion versus pure LLR group. In the open conversion group, although there were no significant differences compared to the HALS group in clinicopathological factors except for sex, blood loss was greater (1425 vs. 367 mL; p < 0.001). CONCLUSION: Risk factors for considering HALS during LLR were patients with a history of upper abdominal surgery including repeat hepatectomy, BMI ≥ 25 kg/m2, S7 or S8 tumor location, DS ≥ 7, and prolonged surgical time. Furthermore, uncontrollable intraoperative bleeding was an indication for open conversion.

Surgical and oncological outcomes of laparoscopic versus open radical antegrade modular pancreatosplenectomy for pancreatic ductal adenocarcinoma.

PURPOSE: To compare the outcomes of laparoscopic radical antegrade modular pancreatosplenectomy (L-RAMPS) with those of open RAMPS (O-RAMPS) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: We reviewed, retrospectively, the medical records of 50 patients who underwent RAMPS for PDAC without resection of major vessels and adjacent organs between 2007 and 2019, and analyzed the relationship between the operative method and surgical and oncological outcomes. RESULTS: Nineteen of the 50 patients underwent L-RAMPS and 31 patients underwent O-RAMPS. L-RAMPS was associated with significantly less blood loss (P = 0.034) but a longer operative time (P = 0.001) than O-RAMPS. There were no significant differences in patient characteristics, tumor factors, or postoperative course; or in the rates of recurrence-free survival (P = 0.084) or overall survival (P = 0.402) between the L-RAMPS and O-RAMPS groups. CONCLUSION: L-RAMPS for PDAC resulted in less blood loss but a longer operative time than O-RAMPS. Although L-RAMPS may be feasible, the operative time needs to be reduced by standardizing the procedure.

Predictors of early withdrawal from follow-up visits after laparoscopic sleeve gastrectomy in a Japanese institution.

PURPOSE: Postoperative weight loss is related to postoperative adherence to follow-up after bariatric/metabolic surgery, but many patients stop attending follow-up visits early. The aim of this study was to clarify predictors of early withdrawal from follow-up after laparoscopic sleeve gastrectomy (LSG) in a Japanese institution. METHODS: One hundred and fifty-three patients who underwent LSG were retrospectively included in this study. Multivariate analysis was performed to evaluate independent predictors of withdrawal from follow-up visits within 12 months after LSG among significant or nearly significant factors in the univariate analyses. The discrimination power of significant factors was estimated using area under the receiver operating characteristic curve (AUC). RESULTS: Within 12 months after LSG, 25 of the 153 patients withdrew from follow-up visits. The multivariate analysis showed that age was the only significant predictor of withdrawal. The AUC for age was 0.685, and the cut-off value was < 40 years. The younger patients (< 40 years old) had a significantly higher rate of withdrawal compared with the older patients (≥ 40 years) (27.0% vs. 8.9%). CONCLUSION: Older Japanese patients (≥ 40 years old) may be better candidates for LSG. We consider it significant to continue to emphasize the importance of follow-up visits in younger patients after LSG.

In Vitro Tumor Cell-Binding Assay to Select High-Binding Antibody and Predict Therapy Response for Personalized 64Cu-Intraperitoneal Radioimmunotherapy against Peritoneal Dissemination of Pancreatic Cancer: A Feasibility Study.

Peritoneal dissemination of pancreatic cancer has a poor prognosis. We have reported that intraperitoneal radioimmunotherapy using a 64Cu-labeled antibody (64Cu-ipRIT) is a promising adjuvant therapy option to prevent this complication. To achieve personalized 64Cu-ipRIT, we developed a new in vitro tumor cell-binding assay (64Cu-TuBA) system with a panel containing nine candidate 64Cu-labeled antibodies targeting seven antigens (EGFR, HER2, HER3, TfR, EpCAM, LAT1, and CD98), which are reportedly overexpressed in patients with pancreatic cancer. We investigated the feasibility of 64Cu-TuBA to select the highest-binding antibody for individual cancer cell lines and predict the treatment response in vivo for 64Cu-ipRIT. 64Cu-TuBA was performed using six human pancreatic cancer cell lines. For three cell lines, an in vivo treatment study was performed with 64Cu-ipRIT using high-, middle-, or low-binding antibodies in each peritoneal dissemination mouse model. The high-binding antibodies significantly prolonged survival in each mouse model, while low-and middle-binding antibodies were ineffective. There was a correlation between in vitro cell binding and in vivo therapeutic efficacy. Our findings suggest that 64Cu-TuBA can be used for patient selection to enable personalized 64Cu-ipRIT. Tumor cells isolated from surgically resected tumor tissues would be suitable for analysis with the 64Cu-TuBA system in future clinical studies.

Antitumor effects of novel mAbs against cationic amino acid transporter 1 (CAT1) on human CRC with amplified CAT1 gene.

Copy number alterations detected by comparative genomic hybridization (CGH) can lead to the identification of novel cancer-related genes. We analyzed chromosomal aberrations in a set of 100 human primary colorectal cancers (CRCs) using CGH and found a solute carrier (SLC) 7A1 gene, which encodes cationic amino acid transporter 1 (CAT1) with 14 putative transmembrane domains, in a chromosome region (13q12.3) with a high frequency of gene amplifications. SLC7A1/CAT1 is a transporter responsible for the uptake of cationic amino acids (arginine, lysine, and ornithine) essential for cellular growth. Microarray and PCR analyses have revealed that mRNA transcribed from CAT1 is overexpressed in more than 70% of human CRC samples, and RNA interference-mediated knockdown of CAT1 inhibited the cell growth of CRCs. Rats were immunized with rat hepatoma cells expressing CAT1 tagged with green fluorescent protein (GFP), and rat splenocytes were fused with mouse myeloma cells. Five rat monoclonal antibodies (mAbs) (CA1 ~ CA5) reacting with HEK293 cells expressing CAT1-GFP in a GFP expression-dependent manner were selected from established hybridoma clones. Novel anti-CAT1 mAbs selectively reacted with human CRC tumor tissues compared with adjacent normal tissues according to immuno-histochemical staining and bound strongly to numerous human cancer cell lines by flow cytometry. Anti-CAT1 mAbs exhibited internalization activity, antibody-dependent cellular cytotoxicity, and migration inhibition activity against CRC cell lines. Furthermore, CA2 inhibited the in vivo growth of human HT29 and SW-C4 CRC tumors in nude mice. This study suggested CAT1 to be a promising target for mAb therapy against CRCs.

Altered binding avidities and improved growth inhibitory effects of novel anti-HER3 mAb against human cancers in the presence of HER1-or HER2-targeted drugs.

HER1-and HER2-targeted drugs are effective in cancer therapy, especially against lung, breast and colon malignancies; however, resistance of cancer cells to HER1-and HER2-targeted therapies is becoming a serious problem. The avidity/affinity constant (KA) and growth inhibitory effect of anti-HER3 rat monoclonal antibodies (mAb, Ab1∼Ab6) in the presence of therapeutic mAb or low-molecular-weight inhibitors against HER family proteins were analyzed by flow cytometry-based Scatchard plots (Splot) and cell proliferation assay. The KA of Ab3 and Ab6, but not Ab1 or Ab4, split into dual (high and low) modes of KA, and Ab6 exhibited greater anti-proliferative effects against LS-174T colon cancer cells in the presence of Pertuzumab (anti-HER2 mAb). A high KA by Ab6 and Ab6-mediated increased growth inhibition were observed against NCI-H1838 lung or BT474 breast cancer cells, respectively, in the presence of Panitumumab (anti-HER1 mAb) or Perutuzumab. A high KA by Ab6 and Ab6-mediated increased anti-proliferative effects against NCI-H1838 or BT474 were also respectively observed in the presence of Erlotinib (HER1 inhibitor) or Lapatinib (HER1/HER2 inhibitor). In HER1-knockout (KO) NCI-H1838, the reactivity and KA of Ab4 increased compared with in parent NCI-H1838. In HER1-KO or HER3-KO SW1116 colon cancer cells, dual modes of KA with Pertuzumab were noted, and the combination Ab6 and Pertuzumab promoted growth inhibition of HER1-KO, but not of parent SW1116.