Clinical Impact of Conversion Surgery After Induction Therapy for Esophageal Cancer with Synchronous Distant Metastasis: A Multi-institutional Retrospective Study

BACKGROUND

The standard treatment for advanced esophageal cancer with synchronous distant metastasis is systemic chemotherapy or immunotherapy. Conversion surgery is not established for esophageal cancer with synchronous distant metastasis. This study aimed to investigate the clinical impact of conversion surgery for esophageal cancer with synchronous distant metastasis after induction therapy.

METHODS

This multi-institutional retrospective study enrolled 66 patients with advanced esophageal cancer, including synchronous distant metastasis, who underwent induction chemotherapy or chemoradiotherapy followed by conversion surgery between 2005 and 2021. Short- and long-term outcomes were investigated.

RESULTS

Distant lymph node (LN) metastasis occurred in 51 patients (77%). Distant organ metastasis occurred in 15 (23%) patients. There were 41 patients with metastatic para-aortic LNs, and 10 patients with other metastatic LNs. Organs with distant metastasis included the lung in seven patients, liver in seven patients, and liver and lung in one patient. For 61 patients (92%), R0 resection was achieved. The postoperative complication rate was 47%. The in-hospital mortality rate was 1%, and the 3- and 5-year overall survival (OS) rates for all the patients were 32.4% and 24.4%, respectively. The OS rates were similar between the patients with distant LN metastasis and the patients with distant organ metastasis (3-year OS: 34.9% vs. 26.7%; P = 0.435). Multivariate analysis showed that pathologic nodal status is independently associated with a poor prognosis (hazard ratio, 2.43; P = 0.005).

CONCLUSIONS

Conversion surgery after chemotherapy or chemoradiotherapy for esophageal cancer with synchronous distant metastasis is feasible and promising. It might be effective for improving the long-term prognosis for patients with controlled nodal status.

Prognostic impact of nodal status and lymphovascular invasion in patients undergoing neoadjuvant chemotherapy for esophageal squamous cell carcinoma

Nodal status is well known to be the most important prognostic factor for esophageal cancer patients, even if they are treated with neoadjuvant therapy. To establish an optimal postoperative adjuvant strategy for patients, we aimed to more accurately predict the prognosis of patients and systemic recurrence by using clinicopathological factors, including nodal status, in patients with esophageal cancer who received neoadjuvant chemotherapy. The clinicopathological factors associated with survival and systemic recurrence were investigated in 488 patients with esophageal squamous cell carcinoma who received neoadjuvant chemotherapy. Overall survival differed according to tumor depth, nodal status, tumor regression, and lymphovascular (LV) invasion. In the multivariate analysis, nodal status and LV invasion were identified as independent prognostic factors (P < 0.0001, P = 0.0008). Nodal status was also identified as an independent factor associated with systemic recurrence, although LV invasion was a borderline factor (P = 0.066). In each pN stage, patients with LV invasion showed significantly worse overall survival than those without LV invasion (pN0: P = 0.036, pN1: P = 0.0044, pN2: P = 0.0194, pN3: P = 0.0054). Patients with LV invasion were also more likely to have systemic, and any recurrence than those without LV invasion in each pN stage. Pathological nodal status and LV invasion were the most important predictors of survival and systemic recurrence in patients with esophageal cancer who underwent neoadjuvant chemotherapy followed by surgery. This finding could provide useful information about selecting candidates for adjuvant therapy among these patients. Our analysis showed that LV invasion was an independent prognostic factor in patients with esophageal cancer who underwent neoadjuvant chemotherapy and that combining LV invasion with pathological nodal status makes it possible to stratify the prognosis in those patients.

Significance of Comprehensive Analysis of Preoperative Sarcopenia Based on Muscle Mass, Muscle Strength, and Physical Function for the Prognosis of Patients with Esophageal Cancer

BACKGROUND

The assessment of muscle mass loss, muscle strength, and physical function has been recommended in diagnosing sarcopenia. However, only muscle mass has been assessed in previous studies. Therefore, this study investigated the effect of comprehensively diagnosed preoperative sarcopenia on the prognosis of patients with esophageal cancer.

METHODS

The study analyzed 115 patients with esophageal cancer (age ≥ 65 years) who underwent curative esophagectomy. Preoperative sarcopenia was analyzed using the skeletal mass index (SMI), handgrip strength, and gait speed based on the Asian Working Group for Sarcopenia 2019 criteria. Clinicopathologic factors, incidence of postoperative complications, and overall survival (OS) were compared between the sarcopenia and non-sarcopenia groups. The significance of the three individual parameters also was evaluated.

RESULTS

The evaluation identified 47 (40.9%) patients with low SMI, 31 (27.0%) patients with low handgrip strength, and 6 (5.2%) patients with slow gait speed. Sarcopenia was diagnosed in 23 patients (20%) and associated with older age and advanced pT stage. The incidence of postoperative complications did not differ significantly between the two groups. Among the three parameters, only slow gait speed was associated with Clavien-Dindo grade 2 or greater complications. The sarcopenia group showed significantly worse OS than the non-sarcopenia group. Those with low handgrip strength tended to have worse OS, and those with slow gait speed had significantly worse OS than their counterparts.

CONCLUSIONS

Preoperative sarcopenia diagnosed using skeletal muscle mass, muscle strength, and physical function may have an impact on the survival of patients with esophageal cancer.

Short-term Outcomes of Adjuvant Nivolumab After Neoadjuvant Chemotherapy in Patients With Resected Esophageal Squamous Cell Carcinoma

BACKGROUND/AIM

CheckMate 577 evaluated adjuvant nivolumab therapy after neoadjuvant chemoradiotherapy and surgery for esophageal cancers. However, the efficacy of this treatment in patients who received neoadjuvant chemotherapy remains unknown. This study investigated the short-term outcomes of adjuvant nivolumab therapy in patients with advanced esophageal squamous cell carcinoma post-neoadjuvant chemotherapy.

PATIENTS AND METHODS

Out of 956 patients with thoracic esophageal cancer who underwent radical esophagectomy, 227 who exhibited ypN1-3 after neoadjuvant chemotherapy and surgery were included in this study.

RESULTS

Among 227 patients, 30 received adjuvant nivolumab and 197 received non-nivolumab adjuvant therapy. The nivolumab group displayed a higher number of lymph node metastases compared to the control group. Patients with ypN1-2 tended to have longer recurrence-free survival (RFS) in the nivolumab group than in the non-nivolumab group (p=0.095). In the propensity score-matched cohort, no differences in patient characteristics were observed. Adjuvant nivolumab therapy significantly prolonged RFS in patients who received neoadjuvant chemotherapy (p=0.013). Patients with ypN1-2 in the nivolumab group had significantly longer RFS than their counterparts in the non-nivolumab group (p=0.001), but not in ypN3 (p=0.784). The 1-year postoperative recurrence rates were 59% for the non-nivolumab group and 24% for the nivolumab group (p=0.007). Nivolumab-related adverse events in patients receiving neoadjuvant chemotherapy were mostly consistent across all grades, while the frequency of increased aspartate aminotransferase (AST) levels was relatively higher compared to CheckMate577.

CONCLUSION

Adjuvant nivolumab was more likely to prolong 1-year RFS in patients receiving neoadjuvant chemotherapy, especially in those with ypN1-2, and had acceptable adverse events.

Prognostic value of a novel index combining the prognostic nutritional index and D-dimer levels for gastric cancer after gastrectomy

INTRODUCTION

The prognostic nutritional index and D-dimer level are two useful measures for gastric cancer prognosis. Since they each comprise different factors, it is possible to employ a more useful combined indicator. This study therefore aimed to establish a prognostic nutritional index-D score-which combines the prognostic nutritional index and D-dimer level-and validate its usefulness as a prognostic marker.

METHODS

We collected data from 1,218 patients with gastric cancer who had undergone radical gastrectomy (R0) between January 2004 and December 2015. Patients were divided into three prognostic nutritional index-D score groups based on the following criteria: score 2, low prognostic nutritional index (≤46) and high D-dimer levels (>1.0 µg/ml); score 1, either a low prognostic nutritional index or high D-dimer levels; and score 0, no abnormality. We then defined the PNI-D score as low (score 0 or 1) and high (score 2).

RESULTS

The prognostic nutritional index-D score was significantly associated with overall, recurrence-free, and disease-specific survival (all log-rank P<0.0001). The 5-year overall survival rates of the patients with prognostic nutritional index-D scores of low and high were 88.1% and 64.7%, respectively; their 5-year recurrence-free survival rates were 86.7% and 61.3%, respectively; and their 5-year disease-specific survival rates were 99.3% and 76.5%, respectively. Cox multivariate analysis revealed that a high prognostic nutritional index-D score was an independent, statistically significant prognostic factor for poor overall (P=0.01) survival in the patients with gastric cancer.

CONCLUSIONS

The prognostic nutritional index-D is an independent prognostic factor for patients with gastric cancer.

Clinical Impact of Early Tumour Shrinkage in Metastatic or Unresectable Oesophageal Cancer Treated with Pembrolizumab plus Chemotherapy

INTRODUCTION

Metastatic or unresectable locally advanced oesophageal cancer remains a disease with high mortality. More recently, pembrolizumab plus chemotherapy has been indicated as the first-line treatment for those patients, but the predictive factors for treatment efficacy remain controversial. This study investigated the clinical utility of early tumour shrinkage (ETS) and depth of response (DpR) in metastatic or unresectable oesophageal cancer treated with pembrolizumab plus CF therapy.

METHODS

ETS and DpR, defined as the percent decreases at the second evaluation and the percentage of the maximal tumour shrinkage during treatment, were measured in 53 eligible patients. The ETS and DpR cut-off values were 20% and 30%, respectively, based on survival outcomes.

RESULTS

Twenty-seven patients (51%) were treatment-naïve, while 26 (49%) had received any treatment before initiating pembrolizumab plus CF therapy. The median progression-free survival (PFS) and overall survival (OS) for ETS ≥20% and <20% were 12.7 and 5.5 months and 14.4 and 8.2 months, and 12.7 and 4.9 months and 14.4 and 8.0 months for DpR ≥30% and <30%, respectively. ETS <20% showed early tumour growth, whereas ETS ≥20% had a good response rate with sufficient longer response duration. In addition, an ETS cut-off of 20% predicted the best overall response and was not associated with prior treatment. In multivariable analysis, ETS ≥20% and DpR ≥30% were independent factors of longer PFS.

CONCLUSION

Our findings suggest that an ETS is a promising on-treatment marker for early prediction of further sensitivity to pembrolizumab plus CF therapy.

Clinicopathological Characteristics and Survival Outcomes in Patients with Advanced Esophageal Squamous Cell Carcinoma Who Were Intraoperatively Diagnosed Non-Curative

INTRODUCTION

Curative esophagectomy is not always possible in patients with locally advanced esophageal cancer. However, few studies have investigated patients who underwent non-curative surgery with intraoperative judgment. This study aimed to investigate patient characteristics and clinical outcomes for patients undergoing non-curative surgery and compare them between non-resectional and non-radical surgery.

METHODS

Among 989 consecutive patients with thoracic esophageal squamous cell carcinoma who were preoperatively expected for curative esophagectomy, 66 who were eligible for non-curative surgery were included in this study.

RESULTS

Intraoperative diagnosis of T4b accounted for 93% of the reasons for the failure of curative surgery. In those patients, esophageal cancer locally invaded into the aortobronchial constriction (70%), trachea (25%), or pulmonary vein (5%). Lymph node metastasis mainly invaded into the trachea (50%) or bronchus (28%). The overall survival of patients with non-curative surgery was 51.5%, 25.7%, and 10.4% at 6, 12, and 24 months after surgery, respectively. Although there were no differences in preoperative patient characteristics between non-resectional and non-radical surgery, distant metastasis, especially pleural dissemination, was significantly observed in T4b patients due to esophageal cancer with non-radical surgery than those with non-resectional surgery (35% vs. 15%, p = 0.002). Even in patients with non-curative surgery, R1 resection and postoperative chemoradiotherapy were identified as independent factors for survival 1 year after surgery (p = 0.047, and 0.019).

CONCLUSIONS

T4b tumor located in aortobronchial constriction or trachea/bronchus makes it difficult to diagnose whether it is resectable or unresectable. Moreover, surgical procedures and perioperative treatment were deeply associated with the clinical outcomes.

Adjuvant Chemotherapy With S-1 Plus Docetaxel Versus S-1 Plus Oxaliplatin in Stage III Gastric Cancer

BACKGROUND/AIM

The Japanese Gastric Cancer Treatment Guidelines recommend doublet chemotherapy (S-1 plus another chemotherapy) over S-1 alone for patients with pStage III gastric cancer who underwent radical gastrectomy. However, no consensus exists on adjuvant regimens for patients with pStage III gastric cancer. Therefore, we conducted a comparative study to evaluate the tolerability, safety, and survival outcomes of docetaxel plus S-1 (DS) and S-1 plus oxaliplatin (SOX) therapies as adjuvant chemotherapy for patients with pStage III gastric cancer.

PATIENTS AND METHODS

We retrospectively collected data from consecutive patients with gastric cancer who underwent gastrectomy and received DS or SOX therapies postoperatively at the Osaka International Cancer Institute between December 2016 and December 2021. We conducted a propensity score matching analysis to balance clinical backgrounds.

RESULTS

Eighty patients who met the eligibility criteria were analyzed. After matching, 40 patients were included in the study (20 each in the DS and SOX groups). No significant adverse events were observed. The mean ratios of the delivered dose to the planned dose were 74.1% and 86.6% for S-1 and docetaxel in the DS group, respectively, and 75.8% and 76.9% for S-1 and oxaliplatin in the SOX group, respectively. No significant differences were found in recurrence-free and overall survival between the DS and SOX groups (p=0.688 and p=0.772, respectively).

CONCLUSION

DS and SOX therapies as adjuvants were safe and manageable for patients with pStage III gastric cancer who underwent radical gastrectomy. No significant differences were found in prognosis between the two therapies.

Clinical Impact of Enhanced Recovery After Esophagectomy in Patients With Esophageal Cancer

BACKGROUND/AIM

The enhanced recovery after surgery (ERAS) program is expected to improve perioperative outcomes in patients with esophageal cancer. However, how ERAS impacts the postoperative body composition and factors related to compliance rate of ERAS have not been fully investigated.

PATIENTS AND METHODS

The study included 252 consecutive patients with thoracic esophageal cancer who underwent minimally invasive esophagectomy. We compared the postoperative outcomes including body composition between the old perioperative program and the new one that aimed to shorten postoperative length of stay (LOS). Compliance-related clinical factors were also examined.

RESULTS

From 252 patients, 129 underwent the old program and 123 the new program. Postoperative LOS, postoperative complications, and hospital costs were reduced with the new program. Body weight loss was significantly improved with the new program at discharge and 3-months after esophagectomy (94.9% vs. 96.6%, p=0.013, 89.5% vs. 91.1%, p=0.028, respectively). Patients in the new program had better body composition at discharge than those in the old program [body fat mass (91.6% vs. 94.1%), lean body mass (95.2% vs. 97.2), and skeletal muscle mass (95.3% vs. 97.0%)]. Major reasons for incompliance were dysphagia, pneumonia, and anastomotic leakage. Multivariate analysis revealed that age ≥70 years at surgery and sex (male) were independent risk factors for incompliance with the postoperative program.

CONCLUSION

The new ERAS program aimed to shorten postoperative LOS had clinical benefits in body composition early after esophagectomy. Personalized ERAS programs based on age might lead to better postoperative outcomes because of low compliance rates for older patients.

Clinical Impact of Metastatic Lymph Node Size on Therapeutic Effect and Prognosis in Patients with Esophageal Squamous Cell Carcinoma Who Underwent Preoperative Chemotherapy Followed by Esophagectomy

BACKGROUND

Pretreatment metastatic lymph node (LN) size has been reported to be associated with prognosis in esophageal squamous cell carcinoma (ESCC). However, its relationship with response to preoperative chemotherapy or prognosis has not been clarified. We investigated the relationship between metastatic LN size and response to preoperative treatment, and prognosis in patients with metastatic esophageal cancer who underwent surgery.

PATIENTS AND METHODS

A total of 212 clinically node-positive patients who underwent preoperative chemotherapy followed by esophagectomy for ESCC were enrolled. Patients were stratified into three groups on the basis of the length of the short axis of the largest LN in pretreatment computed tomography images: < 10 mm (group A), 10-19 mm (group B), and ≥ 20 mm (group C).

RESULTS

Group A had 90 patients (42%), group B had 103 patients (49%), and group C had 19 patients (9%). Group C had significantly lower percent reduction in total metastatic LN size than groups A and B (22.5% versus 35.7%, P = 0.037). Group C had significantly more metastatic LNs based on histological examination than groups A and B (10.1 versus 2.4, P < 0.001). Group C patients whose LNs responded had significantly fewer metastatic LNs than nonresponders (5.1 versus 11.9, P = 0.042). Group C had significantly poorer overall survival than groups A and B (3-year survival, 25.4% versus 67.3%, P < 0.001). However, group C patients whose LNs responded had better survival than nonresponders (3-year survival, 57.1% versus 0%, P = 0.008).

CONCLUSIONS

Patients with large metastatic LNs have poor response and poor prognosis. However, if a response is obtained, long-term survival can be expected.

Nano-particulate Toll-like Receptor 9 Agonist Potentiates the Antitumor Activity of Anti-Glypican-1 Antibody

BACKGROUND/AIM

Monoclonal antibodies (mAbs) that target tumor antigens have recently been developed. Their antitumor activity is mainly achieved through antibody-dependent cellular cytotoxicity (ADCC) via effector cells such as tumor-infiltrated macrophages and natural killer (NK) cells. CpG oligodeoxynucleotides (ODNs) have potent antitumor activity and are considered to increase the tumor infiltration of macrophages and NK cells; however, a completely solubilized novel CpG-schizophyllan (SPG) complex, K3-SPG, displays more potent antitumor activity. We recently reported the significant antitumor activity of anti-glypican-1 (GPC1) mAb against GPC1-positive esophageal squamous cell carcinoma (ESCC) via ADCC. The aim of this study was to evaluate the potential synergistic antitumor activity of anti-GPC1 mAb and K3-SPG and elucidate the underlying mechanisms using a xenograft model of GPC1-positive human ESCC cells.

MATERIALS AND METHODS

The established human esophageal cancer cell line TE14 was subcutaneously injected into SCID mice. Xenograft mice were treated with anti-GPC1 mAb, K3-SPG, or their combination. Antitumor activity was evaluated by measuring the tumor volume. For FACS analysis, agents were administrated, and tumors were resected 1 day after the final treatment.

RESULTS

Anti-GPC1 mAb or K3-SPG monotherapy showed dose-dependent antitumor activity, and combination therapy with anti-GPC1 mAb and K3-SPG showed antitumor activity (p=0.0859). Flow cytometry revealed significantly increased numbers of macrophages (p=0.0133) and of the ratio of activated NK cells/total NK cells (p=0.0058) following K3-SPG or combination therapy.

CONCLUSION

Combination therapy with K3-SPG and anti-GPC1 mAb or another antitumor mAb may represent a new cancer treatment option acting via ADCC.

The utility of bile juice culture analysis for the management of postoperative infection after pancreaticoduodenectomy

BACKGROUND

Surgical site infections are common after pancreaticoduodenectomy. Our institution routinely performs intraoperative bile culture with pancreaticoduodenectomy. Herein we examined whether antibiotic selection based on bile culture analysis reduced the surgical site infection risk after pancreaticoduodenectomy.

METHODS

A total of 349 patients underwent pancreaticoduodenectomy with intraoperative bile cultures in our institution between 2008 and 2019. Patients were categorized into "group A" (196 patients who underwent pancreaticoduodenectomy between 2008 and 2013) or "group B" (153 patients who underwent pancreaticoduodenectomy between 2018 and 2019). Group A received cefazoline perioperatively and for 2 days postoperatively, whereas group B received piperacillin-tazobactam instead based on the bile culture findings in group A.

RESULTS

In group A, 91 (46.4%) intraoperative bile cultures were positive, and surgical site infections occurred in 61 patients (31.1%). A total of 32 patients had both positive bile culture and surgical site infection, of whom 23 (71.9%) exhibited the same microorganisms in the biliary and surgical site infection cultures. Due to the common finding of cefazoline-resistant Enterococcus spp. and Enterobacter spp. in group A, group B received piperacillin-tazobactam. Surgical site infection incidence in group B was 18.3% (n = 28), which was significantly lower than in group A (P = .006). Cefazoline-resistant Enterococcus spp. and Enterobacter spp., respectively, were cultured in 69.8% and 24.3% of patients with preoperative biliary drainage, compared with 32.2% and 9.7% of patients without preoperative biliary drainage.

CONCLUSION

The perioperative selection of antibiotics based on bile culture findings at pancreaticoduodenectomy can reduce the incidence of surgical site infection.

DUPAN-II normalisation as a biological indicator during preoperative chemoradiation therapy for resectable and borderline resectable pancreatic cancer

BACKGROUND

Duke pancreatic mono-clonal antigen type 2 (DUPAN-II) is a famous tumour maker for pancreatic cancer (PC) as well as carbohydrate antigen 19-9 (CA19-9). We evaluated the clinical implications of DUPAN-II levels as a biological indicator for PC during preoperative chemoradiation therapy (CRT).

METHODS

This retrospective analysis included data from 221 consecutive patients with resectable and borderline resectable PC at diagnosis who underwent preoperative CRT between 2008 and 2017. We focused on 73 patients with elevated pre-CRT DUPAN-II levels (> 230 U/mL; more than 1.5 times the cut-off value for the normal range). Pre- and post-CRT DUPAN-II levels and the changes in DUPAN-II ratio were measured.

RESULTS

Univariate analysis identified normalisation of DUPAN-II levels after CRT as a significant prognostic factor (hazard ratio [HR] = 2.06, confidence interval [CI] = 1.03-4.24, p = 0.042). Total normalisation ratio was 49% (n = 36). Overall survival (OS) in patients with normalised DUPAN-II levels was significantly longer than that in 73 patients with elevated levels (5-year survival, 55% vs. 21%, p = 0.032) and in 60 patients who underwent tumour resection (5-year survival, 59% vs. 26%, p = 0.039).

CONCLUSION

Normalisation of DUPAN-II levels during preoperative CRT was a significant prognostic factor and could be an indicator to monitor treatment efficacy and predict patient prognosis.

IGF1R Inhibition Enhances the Therapeutic Effects of Gq/11 Inhibition in Metastatic Uveal Melanoma Progression

Uveal melanoma (UM) is the most common intraocular tumor in adults, and up to 50% of patients develop metastatic disease, which remains uncurable. Because patients with metastatic UM have an average survival of less than 1 year after diagnosis, there is an urgent need to develop new treatment strategies. Although activating mutations in Gαq or Gα11 proteins are major drivers of pathogenesis, the therapeutic intervention of downstream Gαq/11 targets has been unsuccessful in treating UM, possibly due to alternative signaling pathways and/or resistance mechanisms. Activation of the insulin-like growth factor 1 (IGF1) signaling pathway promotes cell growth, metastasis, and drug resistance in many types of cancers, including UM, where expression of the IGF1 receptor (IGF1R) correlates with a poor prognosis. In this article, we show that direct inhibition of Gαq/11 by the cyclic depsipeptide YM-254890 in combination with inhibition of IGF1R by linsitinib cooperatively inhibits downstream signaling and proliferation of UM cells. We further demonstrate that a 2-week combination treatment of 0.3 to 0.4 mg/kg of YM-254890 administered by intraperitoneal injection and 25 to 40 mg/kg linsitinib administered by oral gavage effectively inhibits the growth of metastatic UM tumors in immunodeficient NOD scid gamma (NSG) mice and identifies the IGF1 pathway as a potential resistance mechanism in response to Gαq/11 inhibition in UM. These data suggest that the combination of Gαq/11 and IGF1R inhibition provides a promising therapeutic strategy to treat metastatic UM.

Modified Collard technique is more effective than circular stapled for cervical esophagogastric anastomosis in prevention of anastomotic stricture: a propensity score-matched study

The anastomotic technique after esophagectomy is of great interest in the prevention of anastomotic complications that adversely affect postoperative recovery. This study aimed to compare the clinical outcomes of modified Collard (MC) and circular stapled (CS) anastomoses after esophagectomy. A total of 504 consecutive patients with thoracic esophageal cancer who underwent esophagectomy and cervical esophagogastric CS or MC anastomosis from January 2013 to December 2019 were enrolled. Out of 504 patients, 134 and 370 underwent CS and MC anastomoses. The frequency of anastomotic leakage and stricture was significantly lesser in the MC group than in the CS group (3.0 vs. 10.5%, P = 0.0014 and 11.1 vs. 34.3%, P &lt; 0.001, respectively). CS anastomosis was an independent risk factor for anastomotic stricture (odds ratio, 4.89; P &lt; 0.001). Oral intake was significantly higher in the group without anastomotic stricture than in the group with anastomotic stricture at 2, 3, and 6 months postoperatively (P &lt; 0.001, P = 0.013, and P &lt; 0.001, respectively). The percentage body weight loss (%BWL) was −12.2% in the group with anastomotic stricture and −7.5% in the group without anastomotic stricture at 3 months postoperatively (P = 0.0012). Anastomotic stricture was an independent factor associated with %BWL (odds ratio, 4.86; P = 0.010). Propensity score-matched analysis, which included 88 pairs of patients, confirmed a significantly lower anastomotic stricture rate in the MC group than in the CS group (10.2 vs. 35.2%, P &lt; 0.001). MC anastomosis is better than CS anastomosis for reducing the frequency of anastomotic stricture, which may be useful for maintaining early postoperative nutritional status.

Recurrence Pattern Comparing Preoperative Chemoradiotherapy and Preoperative Chemotherapy with Docetaxel plus 5-Fluorouracil and Cisplatin for Advanced Esophageal Cancer

BACKGROUND

Preoperative chemoradiation therapy (CRT) or chemotherapy (CT) followed by surgery is currently being administered for advanced esophageal cancer. However, few studies have directly compared CRT and CT for treating locally advanced esophageal carcinoma. This study aimed to assess postoperative recurrence patterns and post-recurrence outcomes in patients with radical esophagectomy after CRT or triplet CT regimen with docetaxel, cisplatin, and 5-fluorouracil (DCF).

METHODS

This study included 325 consecutive patients with thoracic esophageal cancer who received preoperative CRT or DCF followed by curative esophagectomy between January 2010 and December 2019. We compared recurrence patterns after surgery and post-recurrence treatments between CRT and DCF. Locoregional recurrence was defined as recurrences at the primary tumor site or regional lymph nodes. Distant recurrence was defined as non-regional lymph node recurrences, systemic metastases, malignant pleural effusions, or peritoneal metastases.

RESULTS

Among 325 patients, 74 received preoperative CF+RT and 251 received preoperative DCF. A propensity score-matched cohort of 53 with CRT and 53 with DCF was included. CRT patients had tumors located in the upper esophagus and had more advanced cancer than DCF patients; however, no differences in patient characteristics were observed in the matched cohort. CRT patients had better histopathological responses and control of locoregional recurrence than DCF patients. On the other hand, distant recurrence, especially in non-regional lymph node, lung, and pleural dissemination, significantly developed more frequently in CRT patients. Furthermore, CRT patients may have received insufficient post-recurrence treatment owing to fewer treatment options. Therefore, although there was no difference in recurrence rate in the two groups, CRT patients had significantly poorer post-recurrence survival than DCF patients Conclusions. Preoperative DCF could reduce distant recurrence after surgery compared to preoperative CRT. The differences in recurrence patterns can be related to the selection of post-recurrence treatment and their prognosis after recurrence.

Laparoscopic Proximal Gastrectomy with Novel Valvuloplastic Esophagogastrostomy vs. Laparoscopic Total Gastrectomy for Stage I Gastric Cancer: a Propensity Score Matching Analysis

BACKGROUND

Laparoscopic total gastrectomy for early proximal gastric cancer is widely performed. Recently, the number of laparoscopic proximal gastrectomies performed, a surgery limited to early proximal gastric cancer, has gradually increased. However, evidence for the long-term outcomes of laparoscopic total gastrectomy and laparoscopic proximal gastrectomy is insufficient. Therefore, this study aimed to clarify and compare the long-term outcomes of laparoscopic total gastrectomy and laparoscopic proximal gastrectomy with novel valvuloplastic esophagogastrostomy for treatment of clinical stage I proximal gastric cancer.

METHODS

This study included 111 patients who underwent laparoscopic total gastrectomy or laparoscopic proximal gastrectomy for the treatment of upper third clinical stage I gastric cancer between April 2004 and December 2017. After adjusting for propensity score matching analysis, we compared the postoperative complications, nutritional status, and long-term outcomes between the two groups.

RESULTS

After matching the inclusion criteria, 56 patients (28 in each group) were enrolled. No significant differences were noted in the postoperative complications between the two groups. While laparoscopic proximal gastrectomy was associated with lower albumin levels, lower body weight loss was seen by 1 year after surgery and higher hemoglobin levels by 1, 2, and 3 years after surgery. No significant differences were observed in the 3-year overall survival and 3-year recurrence-free survival between the laparoscopic total gastrectomy and laparoscopic proximal gastrectomy groups (P = 0.74 and 0.72, respectively).

CONCLUSION

Laparoscopic proximal gastrectomy and laparoscopic total gastrectomy for patients with upper third clinical stage I gastric cancer are feasible as regards its safety and outcomes.

The DOLFIN method: a novel laparoscopic Billroth-I gastroduodenostomy for gastric cancer with duodenal invasion

BACKGROUND

Laparoscopic Billroth-I gastroduodenostomy using a delta-shaped anastomosis is safe and feasible. However, it is often difficult to perform in patients who have a short posterior wall of the duodenum. Thus, we have developed a new method named duodenal overlap functional anastomosis with linear stapler (DOLFIN). We hereby report the technical details of the new method and our preliminary experience performing it.

METHODS

After the completion of lymphadenectomy, the duodenum was transected craniocaudally with an endoscopic linear stapler. The hepatoduodenal mesentery was dissected approximately 4 cm along the duodenal bulb, and the anastomosis between the posterior wall of the stomach and the lesser curvature of the duodenum was created. The common entry hole was then transected using an endoscopic linear stapler, and the anastomosis was finally completed.

RESULTS

There were 36 patients with gastric cancer who underwent laparoscopic distal gastrectomy (LDG) or robotic distal gastrectomy (RDG) with B-I reconstruction using DOLFIN. There were no postoperative complications classified as C-D grade 3 or more and complications related to anastomosis, such as anastomotic leak or stenosis.

CONCLUSIONS

Our DOLFIN gastroduodenostomy can be performed safely. In addition, it results in good postoperative outcomes. A long-term comparative study is required to further evaluate the clinical usefulness of this method.

Antemortem diagnosis of pulmonary tumor thrombotic microangiopathy associated with gastric cancer and response to immediate chemotherapy

Pulmonary tumor thrombotic microangiopathy is a rare and fatal complication of cancer that features widespread tumor cell-derived embolisms in the small arteries and arterioles of the lung and is often associated with thrombus formation. We describe the case of a 43-year-old woman who was hospitalized with cough and respiratory distress that lasted for 2 months. Computed tomography findings demonstrated multiple areas of interlobular septal thickening and ground-glass opacities in both lungs. Transthoracic echocardiography demonstrated a D-shaped left ventricle suggesting right heart overload, and pulmonary blood flow scintigraphy revealed multiple small, peripheral, and patchy areas of reduced blood flow. Upper gastrointestinal endoscopy revealed a signet-ring carcinoma. The patient was diagnosed with pulmonary tumor thrombotic microangiopathy based on her clinical presentation and treatment with tegafur, gimeracil oteracil potassium, oxaliplatin, and an anticoagulant was initiated on the 3rd day after admission. The symptoms improved rapidly after treatment initiation. The patient was discharged 28 days after initiation of chemotherapy without the need for supplemental oxygen. This case suggests that the immediate use of chemotherapy and anticoagulants for treating pulmonary tumor thrombotic microangiopathy may improve patient survival.

The clinical impact of modified transpancreatic mattress sutures with polyglactin 910 woven mesh on postoperative pancreatic fistula in distal pancreatectomy

BACKGROUND

We previously reported the stump closure method for the remnant pancreas in distal pancreatectomy, in which soft coagulation and polyglycolic acid felt attached with fibrin glue were utilized. Transpancreatic mattress suture with polyglactin 910 woven mesh was recently reported as a novel stump closure technique. We developed the modified transpancreatic mattress suture with polyglactin 910 woven mesh method, which combined our polyglycolic acid felt method with the transpancreatic mattress suture with polyglactin 910 woven mesh method.

METHODS

The polyglycolic acid felt group included patients undergoing distal pancreatectomy in whom the pancreatic stump was closed with the polyglycolic acid felt method from 2017 to 2018 (n = 54); whereas the modified transpancreatic mattress suture with polyglactin 910 woven mesh group included those whose stump was closed with the modified transpancreatic mattress suture with polyglactin 910 woven mesh method from 2019 to 2020 (n = 51). Perioperative parameters, including grade B/C postoperative pancreatic fistula (clinically relevant postoperative pancreatic fistula), were assessed according to the stump closure method.

RESULTS

The incidence of clinically relevant postoperative pancreatic fistula was significantly lower in the modified transpancreatic mattress suture with polyglactin 910 woven mesh group than in the polyglycolic acid felt group (7.8% vs 22.2%, P = .036). In multivariate analysis, the use of neoadjuvant chemoradiotherapy and the transpancreatic mattress suture with polyglactin 910 woven mesh method were independent factors for preventing clinically relevant postoperative pancreatic fistula (P = .011 and 0.0038, respectively). Moreover, in the modified transpancreatic mattress suture with polyglactin 910 woven mesh group, the incidence of clinically relevant postoperative pancreatic fistula in patients with a thick pancreas (≥13 mm, 6.7%) was comparably as low as that in patients with a thin pancreas (<13 mm, 9.5%).

CONCLUSION

The modified transpancreatic mattress suture with polyglactin 910 woven mesh method is an effective stump closure technique to prevent clinically relevant postoperative pancreatic fistula after distal pancreatectomy. Our results warrant further prospective investigation to evaluate the efficacy of the modified transpancreatic mattress suture with polyglactin 910 woven mesh method compared with other standard closure methods (eg, stapler closure or hand-sewn closure).

Clinical impact of body composition on postoperative outcomes during neoadjuvant chemoradiation therapy for distal bile duct cancer

Body composition changes during neoadjuvant therapy and their clinical significance have not been clarified. The present study aimed to investigate body composition changes during neoadjuvant chemoradiation therapy (NACRT) in patients with distal bile duct cancer and the clinical impact on postoperative complications and the prognosis. A total of 16 patients with distal bile duct cancer who underwent curative resection after NACRT were retrospectively evaluated. The area of skeletal muscle, visceral fat and subcutaneous fat on computed tomography and immunological and nutritional indices were assessed before and after NACRT. All 16 patients completed NACRT followed by pancreaticoduodenectomy without mortality. There was no significant change in the skeletal muscle mass index (SMI) during NACRT. Of the 16 patients, nine (56%) were defined as sarcopenic before NACRT, and eight (50%) met the criteria for sarcopenic after NACRT. The SMI and total fat area were significantly associated with postoperative pancreatic fistula (POPF) (P=0.019 and P=0.007, respectively). The patients with sarcopenia had a shorter disease-free survival time and overall survival time in comparison to patients without sarcopenia (P=0.025 and P=0.115, respectively). In conclusion, NACRT for distal bile duct cancer did not significantly affect the body composition, or the immunological or nutritional indices. Sarcopenia after NACRT was significantly associated with early recurrence in patients with distal bile duct cancer who received NACRT.

Robotic Distal Gastrectomy Reduces Drain Amylase Values in Patients With a Small Pancreas-left Gastric Artery Angle

PURPOSE

Pancreatic fistula is a severe complication after laparoscopic distal gastrectomy (LDG). We previously evaluated the pancreas-left gastric artery angle (PLA) as a risk indicator for developing a pancreatic fistula after LDG. This study evaluated the incidence of pancreatic fistula with robotic distal gastrectomy (RDG) in comparison to LDG from the view of the PLA.

MATERIALS AND METHODS

An association between the PLA and the incidence of pancreatic fistula in 165 patients who underwent either RDG (n=45) or LDG (n=120) was investigated retrospectively.

RESULTS

RDG patients had significantly lower drain amylase values (postoperative day 2) than LDG patients. As opposed to LDG patients, drain amylase values were similar for patients with small (PLA <62 degrees) and large (PLA ≥62 degrees) PLA in RDG patients.

CONCLUSION

Robotic surgery may reduce the risk of postoperative pancreatic fistula in patients with a small PLA.

Salvage Surgery for Recurrent Disease after Definitive Chemoradiotherapy for Esophageal Squamous Cell Carcinoma

BACKGROUND

Outcomes of salvage surgery after failed definitive chemoradiation (CRT) for esophageal cancer have been well defined. However, only a few studies have focused on salvage esophagectomy for recurrent disease after CRT.

METHODS

In 227 patients with esophageal cancer who underwent salvage esophagectomy after definitive CRT, consisting of 116 patients who underwent esophagectomy for persistent disease (the persistent group) and 111 patients who underwent esophagectomy for recurrent disease (the recurrent group), the short- and long-term outcomes were investigated.

RESULTS

The rates of any postoperative complication were similar between the groups (49.1% in the persistent group vs. 49.5% in the recurrent group, p = 0.951), although there was a higher rate of anastomotic leakage in the recurrent group (p = 0.027). Thirty-day mortality was also similar between the groups (1.7% in the persistent group vs. 0.9% in the recurrent group, p = 0.587). The 3-year and 5-year overall survival rates were 33.7% and 28.0% in the persistent group and 48.7% and 41.7% in the recurrent group, respectively (p = 0.0175). In the recurrent group, clinically nodal status before CRT as well as pathologically nodal status and time to relapse were identified as independent prognostic factors. In the persistent group, pT and resection margin were identified as independent factors associated with survival.

CONCLUSIONS

The present study showed that salvage surgery for recurrent disease can provide acceptable short- and long-term outcomes. Considering clinically and pathologically nodal status and time to relapse, adjuvant therapy might be offered for patients who underwent salvage esophagectomy for recurrent disease after definitive CRT.

Risk factors and long‐term postoperative outcomes in patients with postoperative dysphagia after esophagectomy for esophageal cancer

Aim

Dysphagia is one of the most common complications after esophagectomy. However, no study has investigated the long‐term postoperative outcomes in patients with postoperative dysphagia. Here, we aimed to identify risk factors for postoperative dysphagia and to investigate long‐term postoperative outcomes in such patients.

Methods

This study included 304 consecutive patients with thoracic esophageal cancer who underwent curative esophagectomy. They were diagnosed with postoperative dysphagia through a contrast videofluoroscopic swallowing study, and postoperative outcomes were compared based on swallowing function.

Results

In total, 112 patients (37%) were diagnosed with postoperative dysphagia. Older age, low BMI, and recurrent laryngeal nerve palsy were identified as independent risk factors for postoperative dysphagia. In the dysphagia group, a significantly larger number of patients developed in‐hospital pneumonia, and hospital stays were also significantly extended. After discharge, 37 (33%) patients with postoperative dysphagia developed pneumonia. Even more than 1 year after esophagectomy, a significantly larger number of patients (24 patients, 21%) with postoperative dysphagia developed pneumonia compared to those without postoperative dysphagia. Postoperative dysphagia was identified as an independent risk factor for out‐of‐hospital pneumonia. Regarding nutritional status, there was no difference in weight loss 1 year after esophagectomy, but significant weight loss was observed 2 years after esophagectomy in the dysphagia group.

Conclusion

Postoperative dysphagia was associated with both preoperative patient factors and surgical factors. Moreover, patients with postoperative dysphagia had long‐term and short‐term pneumonia risk. The personalization of long‐term follow‐up through more aggressive rehabilitation and nutritional guidance is required for patients with postoperative dysphagia.

Robotic total gastrectomy with thrombectomy and portal vein reconstruction for gastric cancer and portal vein tumor thrombus

Background

Gastric cancer with portal vein tumor thrombus (PVTT) is poor prognosis, and the treatment remains challenging. Regarding surgery, there are only reports of highly invasive laparotomy. We report some techniques of the completely robotic total gastrectomy with thrombectomy and portal vein reconstruction for the patient with gastric cancer and PVTT for the first time.

Case presentation

A 79-year-old man was diagnosed with a 5-cm gastric cancer on the side of the lesser curvature from the middle of the gastric body to the cardia. Computed tomography revealed a massive PVTT extending from the left gastric vein to the portal trunk (28 x 16 mm). There were no other distant metastases. After 3 cycles of the chemotherapy, the PVTT shrank to 19 x 12 mm. After obtaining informed consent from the patient, robotic total gastrectomy with regional lymphadenectomy and thrombectomy were performed. We used the da Vinci Xi Surgical System. A 3-cm incision was made at the umbilicus, and a wound retractor was placed. Five additional ports were placed. The right side suprapancreatic lymph nodes were performed at the time of the thrombectomy. It was important to identify the precise extent of the PVTT with intraoperative ultrasonography before the thrombectomy. After PVTT identification, the portal trunk was clamped above and below the tumor thrombus with vascular clips. The membrane on the anterior wall of the portal trunk around the PVTT was carefully incised with da Vinci Scissors. The tumor thrombus was completely enucleated without separation. The incised part of the portal trunk was reconstructed with continuous 5-0 synthetic monofilament nonabsorbable polypropylene sutures. After removing the vascular clamps, we made sure there was no leakage from the portal vein and no tumor thrombus remnants with intraoperative ultrasonography. Robotic total gastrectomy with lymphadenectomy and Roux-en-Y reconstruction were performed. The patient was discharged without complications. The patient has remained alive for 30 months after surgery.

Conclusions

Robotic total gastrectomy with thrombectomy and portal vein reconstruction is a safe, minimally invasive, and precise surgery. It may contribute to improved prognosis of gastric cancer with PVTT when combined with chemotherapy.

Pancreas-left gastric artery angle is associated with postoperative inflammation and drain amylase after laparoscopic gastrectomy

INTRODUCTION

The pancreas often interferes with the surgical field during laparoscopic gastrectomy (LG) and its disorders cause severe postoperative complications. This study aimed to evaluate the association between the anatomical location of the pancreas and surgical outcome and to investigate the optimal surgical position in LG.

METHODS

We newly defined the angle formed between the supra-pancreatic region and the root of the left gastric artery (LGA) as the pancreas-LGA angle (PLA). The association between PLA and surgical outcomes in 107 consecutive patients who underwent laparoscopic distal gastrectomy (LDG) was investigated. Then, the change in PLA before and after insertion of the back pillow in 30 patients with gastric cancer was examined.

RESULTS

The median PLA was 62° (range, 2°-157°). No differences were found in the patient background between patients with small PLA (PLA < 62°; n = 53) and those with large PLA (PLA ≧ 62°; n = 54). The postoperative inflammation response (white blood cells, neutrophils, and C-reactive protein) and amylase concentration in the drainage fluid (D-AMY) were significantly higher in the small PLA group than large PLA group. Multivariable analyses demonstrated that small PLA was an independent risk factor for high D-AMY. After insertion of a back pillow, PLA was noninvasively increased in all patients, and the median PLA was changed to 92° (range, 8°-151°) from 61° (range, 2°-140°). Of 17 patients with small PLA, nine developed large PLA.

CONCLUSIONS

These results suggest that PLA can become one of the indicators of postoperative complications related to anatomical patient factors in LDG.

Orthotopic Human Metastatic Uveal Melanoma Xenograft Mouse Models: Applications for Understanding the Pathophysiology and Therapeutic Management of Metastatic Uveal Melanoma

The propensity of uveal melanoma to metastasize to the liver hinders the accrual of micro-metastatic and end-stage disease tissue samples and restricts the investigation of metastatic uveal melanoma (MUM). Pre-clinical experimental animal models of MUM can help elucidate the pathophysiology of metastatic lesions and provide a tool for designing new therapeutic approaches for MUM. Here, we present an advanced model of hepatic metastases that enables quantitatively visualizing the development of individual hepatic tumor clones and estimating their growth kinetics and colonization efficiency. Similar to clinically observed liver metastases, these models enable the assessment of growth kinetics of the liver micro-metastases and the testing of therapeutic approaches for the treatment of MUM. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Experimental patient-derived xenograft mouse model of metastatic uveal melanoma Basic Protocol 2: Experimental liver micro-metastatic mouse model using splenic injection of metastatic uveal melanoma cells.

Optimal treatment and complications of patients with the perforated upper gastrointestinal tract

PURPOSE

The perforation of the upper gastrointestinal tract is still associated with a high risk of complications and mortality. We aimed to evaluate the optimal treatment and post-treatment complications for this condition.

METHODS

This was a retrospective, single-center study conducted between 2010 and 2019. We analyzed 50 patients with intraperitoneal free air caused by peptic ulcer (44 cases) or cancer (six cases).

RESULTS

All patients initially received either conservative therapy (n = 7) or surgery (n = 43). The nonsurgically cured patients were significantly younger and had mild peritonitis and also had a shorter hospital stay. Two patients were converted to surgery due to worsening symptoms, and one of them was elderly and had a long perforation-to-treatment time. Regarding postoperative complications, patients with Grade II-V (n = 21) were significantly older and had a poorer physical status, longer perforation-to-surgery time, and higher preoperative CRP and lactate than those with Grade 0-I (n = 24). Multivariable analyses identified elevated preoperative lactate as an independent risk factor for postoperative complications. The patients with noncurative surgery for perforated advanced gastric cancer all died within 1 year after surgery.

CONCLUSIONS

Consideration should be given to the nonsurgical indications in elderly and delayed treatment patients and the postoperative outcomes of patients with preoperatively elevated lactate levels.

Abstract 6406: FAK and MEK co-targeting: A new multimodal precision therapy for GNAQ-driven uveal melanoma

Uveal melanoma (UM) is characterized by gain-of-function mutations in GNAQ or GNA11, encoding Gα proteins from the Gq/11 family. UM is the most common eye malignancy in adults. Approximately 50% of UM patients develop liver metastasis (mUM) within 5-10 years after diagnosis, independently of the successful treatment of the primary lesions. mUM is refractory to cytotoxic, targeted, and immunotherapies, with most mUM patients dying within a year. Recent information suggests that GNAQ-oncogenic signaling involves a non-canonical pathway distinct from the activation of PLCβ and PKC-MEK-ERK, which may explain the failure of MEK inhibitors (MEKi) in increasing mUM patient survival. Instead, we found that GNAQ promotes the activation of YAP1, a key oncogenic driver, by a mechanism involving the activation of RhoA by the direct association of Gαq to TRIO, a Rho-GEF (Cancer Cell, 2014). In turn, YAP1 is essential for uveal melanoma cell growth, however no effective and safe YAP1 inhibitors are currently available. Using a novel bioinformatics pipeline, we recently found that PTK2, encoding Focal Adhesion Kinase (FAK), is a synthetic lethal gene with GNAQ activation, and uncovered that GNAQ controls YAP1 through FAK (Cancer Cell, 2019). This study identified FAK as a druggable signaling hub downstream from GNAQ in UM. However, activation of compensatory pathways often results in resistance to targeted agents. Here, we combined the use of CRISPR-Cas9 sgRNA screens with a recently described Cancer Signaling Toolkit approach to identify synthetic lethal interactions enhancing the response to FAKi and signaling networks mediating drug resistance, respectively. Remarkably, both approaches converged to reveal that co-targeting FAK and the MEK-ERK pathway would be a promising combination for treatment of UM. Indeed, MEK-ERK pathway inhibition by multiple approved MEKis (e.g., trametinib), combined with FAK inhibition (VS-4718 or defactinib), showed remarkable synergistic growth inhibitory effects in UM cells. Additionally, the novel RAF/MEK inhibitor RO5126766 also showed synergistic anti-proliferative effects with defactinib. Accordingly, FAKi combination with MEKi exerted cytotoxic effects (apoptotic death) leading to rapid tumor shrinkage in UM xenografts, whereas single drugs were primarily cytostatic. Furthermore, the FAKi/MEKi combination was successful at reducing tumor burden in recently developed liver metastasis UM models. By coupling the unique genetic landscape of UM with the power of unbiased computational pipelines and systems biology genetic screens, our studies revealed that FAK and MEK-ERK co-targeting may provide a new network-based precision therapeutic strategy for mUM treatment. Indeed, the combination of defactinib and RO5126766 is currently being evaluated in patients with various solid tumors (NCT03875820), and could be explored in mUM based on these preclinical findings.

Citation Format: Justine S. Paradis, Monica Acosta, Nadia Arang, Robert Saddawi-Konefka, Ayush Kishore, Takahito Sugase, Xiaodong Feng, Kris C. Wood, Silvia Coma, Mizue Terai, Takami Sato, Jonathan A. Pachter, J. Silvio Gutkind. FAK and MEK co-targeting: A new multimodal precision therapy for GNAQ-driven uveal melanoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6406.

Development and optimization of orthotopic liver metastasis xenograft mouse models in uveal melanoma

BACKGROUND

Patients with metastatic uveal melanoma (MUM) in the liver usually die within 1 year. The development of new treatments for MUM has been limited by the lack of diverse MUM cell lines and appropriate animal models. We previously reported that orthotopic xenograft mouse models established by direct injection of MUM cells into the liver were useful for the analysis associated with tumor microenvironment in the liver. However, considering that patients with UM metastasize to the liver hematogenously, direct liver injection model might not be suitable for investigation on various mechanisms of liver metastasis. Here, we aim to establish new orthotopic xenograft models via hematogenous dissemination of tumor cells to the liver, and to compare their characteristics with the hepatic injection model. We also determine if hepatic tumors could be effectively monitored with non-invasive live imaging.

METHODS

tdtTomate-labeled, patient-derived MUM cells were injected into the liver, spleen or tail vein of immunodeficient NSG mice. Tumor growth was serially assessed with In Vivo Imaging System (IVIS) images once every week. Established hepatic tumors were evaluated with CT scan and then analyzed histologically.

RESULTS

We found that splenic injection could consistently establish hepatic tumors. Non-invasive imaging showed that the splenic injection model had more consistent and stronger fluorescent intensity compared to the hepatic injection model. There were no significant differences in tumor growth between splenic injection with splenectomy and without splenectomy. The splenic injection established hepatic tumors diffusely throughout the liver, while the hepatic injection of tumor cells established a single localized tumor. Long-term monitoring of tumor development showed that tumor growth, tumor distribution in the liver, and overall survival depended on the number of tumor cells injected to the spleen.

CONCLUSION

We established a new orthotopic hepatic metastatic xenograft mouse model by splenic injection of MUM cells. The growth of orthotopic hepatic tumors could be monitored with non-invasive IVIS imaging. Moreover, we evaluated the therapeutic effect of a MEK inhibitor by using this model. Our findings suggest that our new orthotopic liver metastatic mouse model may be useful for preclinical drug screening experiments and for the analysis of liver metastasis mechanisms.

Anti-glypican-1 antibody-drug conjugate is a potential therapy against pancreatic cancer

Background

Pancreatic cancer (PDAC) is the most lethal malignancy. New treatment options for it are urgently required. The aim was to develop an antibody–drug conjugate (ADC) targeting glypican-1 (GPC-1) as a new therapy for PDAC.

Methods

We evaluated GPC-1 expression in resected PDAC specimens and PDAC cell lines. We then measured the antitumour effect of anti-GPC-1 monoclonal antibody conjugated with the cytotoxic agent monomethyl auristatin F (MMAF) in vitro and in vivo.

Results

GPC-1 was overexpressed in most primary PDAC cells and tissues. The PDAC cell lines BxPC-3 and T3M-4 strongly expressed GPC-1 relative to SUIT-2 cells. Compared with control ADC, GPC-1-ADC showed a potent antitumour effect against BxPC-3 and T3M-4, but little activity against SUIT-2 cells. In the xenograft and patient-derived tumour models, GPC-1-ADC significantly and potently inhibited tumour growth in a dose-dependent manner. GPC-1-ADC-mediated G2/M-phase cell cycle arrest was detected in the tumour tissues of GPC-1-ADC-treated mice relative to those of control-ADC-treated mice.

Conclusions

GPC-1-ADC showed significant tumour growth inhibition against GPC-1-positive pancreatic cell lines and patient-derived, GPC-1-positive pancreatic cancer tissues. Our preclinical data demonstrated that targeting GPC-1 with ADC is a promising therapy for patients with GPC-1-positive pancreatic cancer.

TAS-116 inhibits oncogenic KIT signalling on the Golgi in both imatinib-naïve and imatinib-resistant gastrointestinal stromal tumours

BACKGROUND

Despite the effectiveness of imatinib mesylate (IM), most gastrointestinal stromal tumours (GISTs) develop IM resistance, mainly due to the additional kinase-domain mutations accompanied by concomitant reactivation of KIT tyrosine kinase. Heat-shock protein 90 (HSP90) is one of the chaperone molecules required for appropriate folding of proteins such as KIT.

METHODS

We used a novel HSP90 inhibitor, TAS-116, which showed specific binding to HSP90α/β with low toxicity in animal models. The efficacy and mechanism of TAS-116 against IM-resistant GIST were evaluated by using IM-naïve and IM-resistant GIST cell lines. We also evaluated the effects of TAS-116 on the other HSP90 client protein, EGFR, by using lung cell lines.

RESULTS

TAS-116 inhibited growth and induced apoptosis in both IM-naïve and IM-resistant GIST cell lines with KIT activation. We found KIT was activated mainly in intracellular compartments, such as trans-Golgi cisternae, and TAS-116 reduced autophosphorylated KIT in the Golgi apparatus. In IM-resistant GISTs in xenograft mouse models, TAS-116 caused tumour growth inhibition. We found that TAS-116 decreased phosphorylated EGFR levels and inhibited the growth of EGFR-mutated lung cancer cell lines.

CONCLUSION

TAS-116 may be a novel promising drug to overcome tyrosine kinase inhibitor-resistance in both GIST and EGFR-mutated lung cancer.

Stromal fibroblast growth factor 2 reduces the efficacy of bromodomain inhibitors in uveal melanoma

Alterations in transcriptional programs promote tumor development and progression and are targetable by bromodomain and extraterminal (BET) protein inhibitors. However, in a multi‐site clinical trial testing the novel BET inhibitor, PLX51107, in solid cancer patients, liver metastases of uveal melanoma (UM) patients progressed rapidly following treatment. Mechanisms of resistance to BET inhibitors in UM are unknown. We show that fibroblast growth factor 2 (FGF2) rescued UM cells from growth inhibition by BET inhibitors, and FGF2 effects were reversible by FGF receptor (FGFR) inhibitors. BET inhibitors also increased FGFR protein expression in UM cell lines and in patient tumor samples. Hepatic stellate cells (HSCs) secrete FGF2, and HSC‐conditioned medium provided resistance of UM cells to BET inhibitors. PLX51107 was ineffective in vivo, but the combination of a FGFR inhibitor, AZD4547, and PLX51107 significantly suppressed the growth of xenograft UM tumors formed from subcutaneous inoculation of UM cells with HSCs and orthotopically in the liver. These results suggest that co‐targeting of FGFR signaling is required to increase the responses of metastatic UM to BET inhibitors.

Abstract 2319: Accumulation and anti-tumor effect of chimeric antigen receptor (CAR) NK cells in metastasis uveal melanoma

Introduction: Metastatic uveal melanoma (MUM) is resistant to currently available treatments and overall prognosis is poor. MUM is an “immune cold” tumor and immune checkpoint blockades have only a marginal effect on this tumor. To bring immune cells to the tumor site and change the tumor microenvironment, we developed Chimeric Antigen Receptor (CAR)-NK cells targeting high molecular weight melanoma associated antigen (HMW-MAA/CPSG4).

Methods: NK92 cell line derived from NK cell lymphoma was obtained from the American Type Culture Collection (ATCC). NK92 cells were transfected with retroviral pBMN-I vector co-expressing Green Fluorescent Protein (GFP) and anti-HMW-MAA-CD28-CD3z CAR construct. The efficacy of CAR construct transfection was confirmed by expression of His-Tag and F(ab)2 by using BD FACS Celesta flow cytometry. MUM cell line, TJU-UM001, was established from a hepatic metastasis of a uveal melanoma patient in our institution. TJU-UM001 cells have approximately 37,000 HMW-MAA molecules on their surface and are sensitive to NK92 cell killing. Tdtomato-transfected TJU-UM001 cells (106 cells) were intra-hepatically implanted into NOD-scid IL2Rgammanull (NSG) mice. Once establishment of hepatic tumor was confirmed by IVIS 200 imaging system (PerkinElmer) at Red Fluorescent Protein (RFP) excitation 535nm, 3 x 106 CAR-NK92 cells or NK92 cells without CAR constructs were injected into the spleen. Accumulations of GFP+ NK92 cells in the TJU-UM001 tumors in the liver were analyzed under fluorescence microscopy. In a separate experiment, 107 TJU-UM001 cells were subcutaneously implanted into NSG mice. The size of subcutaneous tumor was measured by Caliper. Once tumor became palpable (7-10 mm), 3 x 106 CAR- or non-CAR NK92 cells were directly injected to the MUM tumors. Forty thousand units of human IL-2 were intra-peritoneally injected into mouse once daily for 4 consecutive days after NK92 cell injections.

Results: There were expressions of both His-tag and F(ab)2 on CAR-GFP NK92 cells. GFP and CD54 (ICAM-1) were expressed on 95% and 90% of CAR-GFP NK92 cells, respectively. There was no cross-expression of GFP or human CD54 on mouse cells. Therefore, GFP and CD54 were confirmed to be reliable markers for tracking CAR-GFP NK92 cells in mice. Both CAR- and non-CAR NK92 cells exhibited suppression of TJU-UM001 cell proliferation in in vitro assay. Direct injections of both CAR- and non-CAR NK92 cells showed anti-tumor growth effects on subcutaneously implanted TJU-UM001 tumors. More importantly, via splenic injection, CAR-NK92 cells accumulated selectively in the MUM tumors in the liver, while non-CAR NK92 cells were randomly distributed to normal liver tissue and the MUM tumors. These results support the rationale for hepatic arterial infusion of CAR-NK cells as treatment for uveal melanoma patients with hepatic metastasis.

Citation Format: Bao Quoc Lam, Takahito Sugase, Mizue Terai, Meggie Danielson, Nadezhda Anikeyeva, Melissa A. Wilson, Yuri Sykulev, Takami Sato. Accumulation and anti-tumor effect of chimeric antigen receptor (CAR) NK cells in metastasis uveal melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2319.

Stromal fibroblast growth factor 2 reduces the efficacy of bromodomain inhibitors in uveal melanoma

Alterations in transcriptional programs promote tumor development and progression and are targetable by bromodomain and extraterminal (BET) protein inhibitors. However, in a multi-site clinical trial testing the novel BET inhibitor, PLX51107, in solid cancer patients, liver metastases of uveal melanoma (UM) patients progressed rapidly following treatment. Mechanisms of resistance to BET inhibitors in UM are unknown. We show that fibroblast growth factor 2 (FGF2) rescued UM cells from growth inhibition by BET inhibitors, and FGF2 effects were reversible by FGF receptor (FGFR) inhibitors. BET inhibitors also increased FGFR protein expression in UM cell lines and in patient tumor samples. Hepatic stellate cells (HSCs) secrete FGF2, and HSC-conditioned medium provided resistance of UM cells to BET inhibitors. PLX51107 was ineffective in vivo, but the combination of a FGFR inhibitor, AZD4547, and PLX51107 significantly suppressed the growth of xenograft UM tumors formed from subcutaneous inoculation of UM cells with HSCs and orthotopically in the liver. These results suggest that co-targeting of FGFR signaling is required to increase the responses of metastatic UM to BET inhibitors.

Lipolysis-stimulated lipoprotein receptor overexpression is a novel predictor of poor clinical prognosis and a potential therapeutic target in gastric cancer

The prognosis of patients with advanced gastric cancer (GC) remains poor despite the recent advances in molecular targeted therapies, and the search for biomarkers that can predict prognosis and additional new agents with acceptable toxicity profiles are needed. Lipolysis-stimulated lipoprotein receptor (LSR) is a lipoprotein receptor that binds to triglyceride-rich lipoproteins and related to some malignancies. Herein, we examined the association between LSR expression and the prognosis of patients with GC, and investigated the antitumor effect of a previously developed anti-human LSR monoclonal antibody (#1-25). We first performed immunohistochemical analysis of LSR protein expression in GC and normal tissues, and then examined its association with the prognosis of 110 patients with GC. LSR was overexpressed in most of primary GC and metastatic tumors, but not in normal tissues. Patients with strong LSR expression (N = 80, 72.7%) had significantly poorer overall survival (OS) than those with weak expression (P = 0.017). Multivariate analysis identified strong LSR (as well as pT) as independent and significant prognostic factors for OS. Next, we demonstrated that very low density lipoprotein (VLDL) treatment increases cell proliferation in LSR-expressing GC cell lines in vitro; LSR inhibition using #1-25 inhibited VLDL-induced proliferation by suppressing JAK/STAT and PI3K signaling. In vivo, we demonstrated a marked antitumor effect of #1-25 in 2 distinct GC cell line xenograft mice models. Our findings suggest that LSR plays a key functional role in GC development, and that this antigen can be therapeutically targeted to improve GC treatment.

Abstract 816: Antibody-drug conjugate targeting glypican-1 shows potent antitumor effect in pancreatic cancer

Pancreatic cancer is the most lethal malignancy; thus developing new treatment options is urgently required. We confirmed that enhanced expression of glypican-1 (GPC1) was observed in pancreatic cancer. In this study, we aimed to develop novel antibody-drug conjugate (ADC) targeting GPC1 as a new therapy for pancreatic cancer. By the immunohistochemical analysis, enhanced expression of GPC1 was observed in pancreatic cancer. Among pancreatic cancer cell lines, BxPC3 and T3M4 cells expressed high expression of GPC1 compared to SUIT2 cells. We developed new anti-GPC1 monoclonal antibody (mAb) and selected a clone having highly internalizing activity. The anti-GPC1 mAb was conjugated with cytotoxic agent monomethyl auristatin F (MMAF). Compared with the control ADC, this GPC1-ADC showed potent antitumor effect toward BxPC3 and T3M4, while little activity in SUIT2 cells. In BxPC3 xenograft model, GPC1-ADC had significant and potent tumor growth inhibition in a dose dependent manner. In addition, using patient derived tumor xenograft (PDX) model with GPC1-positive pancreatic cancer, GPC1-ADC also showed significant tumor growth inhibition. In the tumor tissue, GPC1-ADC-mediated G2/M phase cell cycle arrest was detected in GPC1-ADC treated mice compared to control-ADC treated mice. In summary, our newly developed GPC1-ADC showed significant tumor growth inhibition against not only GPC1-positive pancreatic cell line but also patient derived GPC1-positive pancreatic cancer. Our preclinical data demonstrated that targeting GPC1 by ADC is a promising therapy for patients with GPC1-positive pancreatic cancer.

Citation Format: Satoshi Serada, Takahiko Nishigaki, Takahito Sugase, Yurina Saito, Tsuyoshi Takahashi, Kosuke Hiramatsu, Minoru Fujimoto, Masaki Mori, Yuichiro Doki, Tetsuji Naka. Antibody-drug conjugate targeting glypican-1 shows potent antitumor effect in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 816.

Histological changes of superficial esophageal squamous cell carcinoma after preoperative chemotherapy

INTRODUCTION

We aimed to analyze the clinical and histological effects of chemotherapy in superficial esophageal squamous cell carcinoma (SESCC).

METHODS

We analyzed tumor samples from five patients with cT1bN1M0 who underwent subtotal esophagectomy following two courses of a new triplet chemotherapy regimen including docetaxel, cisplatin, and 5-fluorouracil (DCF). To assess the histological effects of chemotherapy, resected specimens were analyzed by macroscopic examination, hematoxylin & eosin (HE) staining, immunohistochemical (IHC) staining (p53, Ki-67 and cytokeratin) and periodic acid-Schiff (PAS) staining.

RESULTS

All five patients had a pathological T stage of T0/1a-LPM/1a-MM/1b (1/2/1/1) and histological grade of grade1a/1b/2/3 (1/1/2/1). Endoscopic examination revealed substantial shrinkage of lugol-voiding lesions (LVLs) in all cases. One case showed complete LVL disappearance, and resected specimen examination confirmed pathological complete response (pCR). IHC and PAS staining revealed that most initial LVLs were PAS-negative. Obvious viable cells were confirmed in two cases. The other three cases exhibited nuclear atypia and strong expression of p53 and Ki-67 in the basal layer of mucosa or lamina propria mucosae, even though the superficial layer of mucosa showed no obvious LVLs with PAS-positive. p53-positive lesions were also observed in Ki-67-positive. This indicated discordance between the endoscopic findings and histopathological evaluation.

CONCLUSION

DCF chemotherapy alone had a substantial therapeutic effect on SESCC in all cases. However, despite the normal appearance of the mucosal surface, viable cancer cells remained below the basal layer of mucosa. Careful attention should be paid when diagnosing clinical CR, or securing a resection margin of SESCC after DCF chemotherapy.

Intratumoral Delivery of an Adenoviral Vector Carrying the SOCS-1 Gene Enhances T-Cell-Mediated Antitumor Immunity By Suppressing PD-L1

Ovarian cancer is the leading cause of gynecologic cancer-related deaths and novel therapeutic strategies are required. Programmed cell death 1 and programmed cell death ligand 1 (PD-L1), which are key mediators of host immune tolerance, are associated with ovarian cancer progression. Recent evidence indicates the importance of IFNγ-induced PD-L1 for immune tolerance in ovarian cancer. This study aimed to reveal the therapeutic potential of suppressor of cytokine signaling 1 (SOCS-1), an endogenous inhibitor of the Janus kinase (JAK)-STAT signaling pathway, for the treatment of ovarian cancer. IHC assessment revealed that patients with ovarian cancer with high intratumoral STAT1 activation exhibited poor prognosis compared with patients with low STAT1 activation (P < 0.05). Stimulation of OVISE, OVTOKO, OV2944-HM-1 (HM-1), and CT26 cell lines with IFNγ induced STAT1 phosphorylation and PD-L1 expression. Adenovirus-mediated SOCS-1 gene delivery (AdSOCS-1) in HM-1 and CT26 cells in vitro potently inhibited IFNγ-induced STAT1 phosphorylation and PD-L1 upregulation, similar to the addition of JAK inhibitor I, but failed to inhibit their proliferation. Notably, intratumoral injection of AdSOCS-1, but not AdLacZ, significantly inhibited the tumor growth of HM-1 and CT26 cells subcutaneously transplanted in immunocompetent syngeneic mice. AdSOCS-1 reduced PD-L1 expression on tumors and restored the activation of tumor-infiltrating CD8⁺ T cells. Moreover, the antitumor effect of AdSOCS-1 was significantly attenuated by PD-L1 Fc-fusion protein administration in vivo, suggesting that the effect of AdSOCS-1 is mainly attributable to enhancement of tumor immunity. This study highlights the potential clinical utility of SOCS-1 as an immune checkpoint inhibitor. Mol Cancer Ther; 17(9); 1941-50. ©2018 AACR.

Glypican-1 targeted antibody-based therapy induces preclinical antitumor activity against esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) has a poor prognosis despite the development of multimodal therapy. Expression of glypican-1 (GPC1) has been reported to be elevated in a subset of patients with ESCC and associated with chemoresistance. This study aimed to determine the association of GPC1 with ESCC growth and potential usefulness of the GPC1 targeted therapy by monoclonal antibody (mAb) in ESCC. Expression of GPC1 was higher in ESCC tumor tissues than in adjacent non-tumoral tissues and normal tissues. Knockdown of GPC1 decreased growth of ESCC cells and induced apoptosis via inhibition of EGFR, AKT and p44/42-MAPK signaling pathways in vitro. Anti-GPC1 mAb strongly inhibited tumor growth via antibody-dependent cellular cytotoxicity dependent and independent manner in GPC1-positive ESCC xenograft models. Anti-GPC1 mAb also inhibited tumor growth of GPC1 positive ESCC patients derived tumor xenograft models. Furthermore, anti-GPC1 mAb showed a significant tumor growth inhibition with decreased angiogenesis compared with IgG treated controls in ESCC xenografted mice. Treatment with anti-GPC1 mAb was not toxic in mice. Anti-GPC1 mAb may have a potent anti-tumor effect and represent a novel treatment option for patients with GPC1-positive ESCC.

Overexpression of leucine-rich α2-glycoprotein-1 is a prognostic marker and enhances tumor migration in gastric cancer

Gastric cancer is one of the most common malignant tumors. Although improvement in chemotherapy has been achieved, the clinical prognosis of advanced gastric cancer remains poor. Therefore, it is increasingly important to predict the prognosis and determine whether patients should or should not receive neoadjuvant or adjuvant chemotherapy. Leucine‐rich α2‐glycoprotein‐1 (LRG1) is overexpressed during inflammation and is associated with various malignancies. In this study, we assessed LRG1 expression in cancer specimens and in the sera of patients with cancer to clarify the usefulness of LRG1 as a biomarker in gastric cancer. This study enrolled 239 (for immunohistochemical staining; IHC) and 184 (for ELISA) patients with gastric cancer. Results of IHC showed that LRG1 expression was significantly associated with histological type, lymphatic and venous invasion, tumor and node factors, and disease stage. Overall survival was significantly worse in the high LRG1 expression group than in the low LRG1 group (P = 0.0003). Cox multivariate analysis of overall survival revealed that LRG1 expression was an independent prognostic factor (P = 0.0258). Serum LRG1 was significantly higher in gastric cancer patients than in healthy volunteers, and increased as the pathological stage progressed. Furthermore, a significant correlation was revealed between serum LRG1 level and LRG1 expression with IHC (P < 0.0001). Inhibition of LRG1 significantly decreased cell proliferation in vitro (migratory and invasive capacity of gastric cancer cells). These results suggest that LRG1 expression in tumors and serum may be a useful prognostic marker in gastric cancer patients.

Metachronous solitary splenic metastasis arising from early gastric cancer: a case report and literature review

BACKGROUND

The metastasis of malignant tumors to the spleen is rare, and only a small percentage of cases can be treated surgically, as splenic metastases generally occur in the context of multivisceral metastatic cancer at a terminal stage. We report a rare case of metachronous solitary splenic metastasis arising from early gastric cancer.

CASE PRESENTATION

A 75-year-old man was initially referred to our hospital for examination of gastric cancer, diagnosed at a medical check-up. Esophagogastroduodenoscopy showed a slightly elevated lesion with a central irregular depression in the upper-third of the stomach. Biopsy specimens of the lesion showed a moderately-differentiated adenocarcinoma, and abdominal computed tomography showed no evidence of distant metastases. Endoscopic submucosal dissection was performed, with histological confirmation of a moderately-differentiated adenocarcinoma invading the submucosal layer. The patient subsequently underwent laparoscopic total gastrectomy with regional lymph node dissection, resulting in no residual carcinoma and no lymph node metastasis. Computed tomography, 28 months later, showed a well-defined mass measuring 4.2 cm in diameter in the spleen, and the patient underwent a splenectomy, since there was no evidence of further metastatic lesions in any other organs. Histological examination confirmed the diagnosis of a poorly-differentiated adenocarcinoma originating from the previous gastric cancer. The patient was alive 2 months after surgical resection of the splenic metastasis without any recurrence.

CONCLUSION

To the best of our knowledge, this is only the second case of a solitary splenic metastasis from early gastric cancer to be reported in the English literature. The present case suggests surgical resection may be the preferred treatment of choice for patients with a solitary splenic metastasis from gastric cancer.

Abstract 5085: SOCS-1 gene therapy combined with radiation therapy has a potent antitumor effect for esophageal squamous cell carcinoma

INTRODUCTION Radiation therapy (RT) is one of the main strategies for esophageal squamous cell carcinoma (ESCC) besides surgery and chemotherapy. Although RT has shown remarkable clinical benefits for ESCC patients, there remains the resistance for RT. Recently, some reports show that STAT3 activation is induced by irradiation and can result in treatment-resistance for radiotherapy in various cancer. Suppressor of cytokine signaling-1 (SOCS-1) has been cloned as a negative regulator of various cytokine signaling. We previously reported that overexpression of SOCS-1 showed a potent anti-tumor effect for ESCC through targeting of JAK/STAT and FAK/ERK signaling pathway. Since these results, SOCS-1 might have a possibility to overcome the resistance of RT. The aim of this study is to evaluate the antitumor effect of SOCS-1 gene therapy using adenoviral vector (AdSOCS-1) combined with RT.

METHODS At first, we evaluated RT resistance by the STAT3 in ESCC cell lines by using pEB-Multi-constitutive-STAT3(c-STAT3) vector. We examined the colony forming assay between parent (TE8, TE9, TE11, TE14) and stably expression of c-STAT3 cells. Next, we evaluated cell growth inhibition effect of AdSOCS-1 gene therapy combined with RT in vitro and in vivo. As in vivo model, we examined the combined effect of RT (2Gy) and AdSOCS-1 gene therapy by using TE14 xenograft mice (ICR nu/nu mice).

RESULTS At first, ESCC cell with stably expression of c-STAT3 showed a significant increase in colony forming ability after RT as compared with parent and mock cell. It suggested that activation of STAT3 might be related to RT resistance in ESCC cell. Furthermore, ESCC cells with RT were induced the secretion of IL-6, and the activation level of STAT3 was elevated by multiple RT. In addition, they increased the expression of anti-apoptosis protein (mcl-1, survivin), and might have a RT resistance. Next, we confirmed that combination therapy with RT and AdSOCS-1 had better proliferation inhibitory effect and decreasing of colony forming ability. In addition, we showed that AdSOCS-1 gene therapy inhibited the induction of the expression of anti-apoptosis protein (mcl-1, survivin) by RT and induced apoptosis synergistically. As in vivo model, the combination therapy group showed a significant anti-tumor effect compared to the RT alone group and AdSOCS-1 gene therapy alone group.

CONCLUSIONS The activation of STAT3 is involved in resistance to radiation therapy in esophageal squamous cell carcinoma, and SOCS-1 gene therapy combined with radiation therapy may have a potent anti-tumor effect.

Note: This abstract was not presented at the meeting.

Citation Format: Takahito Sugase, Tsuyoshi Takahashi, Satoshi Serada, Minoru Fujimoto, Koji Tanaka, Yashuhiro Miyazaki, Tomoki Makino, Yukinori Kurokawa, Makoto Yamasaki, Kiyokazu Nakajima, Shuji Takiguchi, Masaki Mori, Yuichiro Doki, Tetsuji Naka. SOCS-1 gene therapy combined with radiation therapy has a potent antitumor effect for esophageal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5085. doi:10.1158/1538-7445.AM2017-5085

Suppressor of cytokine signaling-1 gene therapy induces potent antitumor effect in patient-derived esophageal squamous cell carcinoma xenograft mice

Chronic inflammation is involved in cancer growth in esophageal squamous cell carcinoma (ESCC), which is a highly refractory cancer with poor prognosis. This study investigated the antitumor effect and mechanisms of SOCS1 gene therapy for ESCC. Patients with ESCC showed epigenetics silencing of SOCS1 gene by methylation in the CpG islands. We infected 10 ESCC cells with an adenovirus-expressing SOCS1 (AdSOCS1) to examine the antitumor effect and mechanism of SOCS1 overexpression. SOCS1 overexpression markedly decreased the proliferation of all ESCC cell lines and induced apoptosis. Also, SOCS1 inhibited the proliferation of ESCC cells via multiple signaling pathways including Janus kinase (JAK)/signal transducer and activator of transcription (STAT) and focal adhesion kinase (FAK)/p44/42 mitogen-activated protein kinase (p44/42 MAPK). Additionally, we established two xenograft mouse models in which TE14 ESCC cells or ESCC patient-derived tissues (PDX) were subcutaneously implanted. Mice were intra-tumorally injected with AdSOCS1 or control adenovirus vector (AdLacZ). In mice, tumor volumes and tumor weights were significantly lower in mice treated with AdSOCS1 than that with AdLacZ as similar mechanism to the in vitro findings. The Ki-67 index of tumors treated with AdSOCS1 was significantly lower than that with AdLacZ, and SOCS1 gene therapy induced apoptosis. These findings demonstrated that overexpression of SOCS1 has a potent antitumor effect against ESCC both in vitro and in vivo including PDX mice. SOCS1 gene therapy may be a promising approach for the treatment of ESCC.

Clinicopathological Characteristics, Surgery and Survival Outcomes of Patients with Duodenal Gastrointestinal Stromal Tumors

BACKGROUND

Duodenal gastrointestinal stromal tumors (GISTs) are a rare subset of GISTs (3-5%), and their clinicopathological features have not been fully described. The purpose of this retrospective study was to examine these characteristics and compare the operative procedures.

METHODS

Twenty-five patients with duodenal GIST underwent complete resection, local resection (LR) or pancreaticoduodenectomy (PD) from 1990 to 2014 at our 2 hospitals. We analyzed patient characteristics, treatments, histological examinations, postoperative complications and survival outcomes.

RESULTS

Twelve patients (48%) with no symptoms were incidentally diagnosed for unrelated reasons. Sixteen patients (64%) had c-kit mutations while 6 (24%) were wild-type, including 4 with a history of neurofibromatosis type 1. Comparing LR (n = 16) and PD (n = 9), the recurrence-free survival rate was significantly worse for PD. On multivariate analysis, however, tumor size was an independent and significant prognostic factor, but not operative procedure. There was no body weight change with LR, but body weight decreased by 7% with PD.

CONCLUSION

Duodenal GISTs had different characteristic genetic mutations compared to other GISTs. LR for duodenal GISTs appears to be oncologically and nutritionally feasible.