Correction to: Therapeutic efficacy, pharmacokinetic profiles, and toxicological activities of humanized antibody-drug conjugate Zt/g4-MMAE targeting RON receptor tyrosine kinase for cancer therapy.

Following publication of the original article [1], the author reported two errors in the authors affiliations.

Prognostic comparison of the longitudinal margin status in distal bile duct cancer: R0 on first bile duct resection versus R0 after additional resection.

BACKGROUND: This study investigated survival differences following intra-operative frozen-section examination of bile duct resection margins and final longitudinal margin status (LMS) in distal bile duct cancer (BDC). METHODS: One hundred and ninety-three patients underwent Whipple's operation for curative resection of distal BDC from 2008 to 2016. Patients were sorted into two and three groups according to LMS of the frozen-sections and the final pathological specimen results: R0 on first bile duct resection (primary R0), R0 after additional resection (secondary R0), and no evidence of residual carcinoma (FR0), carcinoma in situ or high-grade dysplasia (FR1-CIS/HGD), or invasive carcinoma (FR1-INV). Survival and prognostic factors according to LMS were analyzed. RESULTS: The final R0 ratio increased from 82.3% to 90.1% through additional resection. The 5-year overall survival (OS) of primary and secondary R0 were 60.8%, 46.1% (P = 0.969). And disease-free survival of primary and secondary R0 were 54.6%, 54.9% (P = 0.903). The 5-year OS after FR0, FR1-CIS/HGD, FR1-INV were 59.3%, 59.5%, 14.3% (P = 0.842). LMS of the bile duct was an independent prognostic factor by multivariable analyses. CONCLUSIONS: If R0 of final LMS was achieved, it would help to improve survival regardless of R0 through additional resection. And, it should be avoided remaining invasive cancer at the longitudinal margin whenever possible.

Therapeutic efficacy, pharmacokinetic profiles, and toxicological activities of humanized antibody-drug conjugate Zt/g4-MMAE targeting RON receptor tyrosine kinase for cancer therapy.

BACKGROUND: Aberrant expression of the RON receptor tyrosine kinase is a pathogenic feature and a validated drug target in various types of cancers. Currently, therapeutic antibodies targeting RON for cancer therapy are under intensive evaluation. Here we report the development and validation of a novel humanized anti-RON antibody-drug conjugate for cancer therapy. METHODS: Antibody humanization was achieved by grafting sequences of complementarity-determining regions from mouse monoclonal antibody Zt/g4 into human IgG1/κ acceptor frameworks. The selected humanized Zt/g4 subclone H1L3 was conjugated with monomethyl auristatin E using a dipeptide linker to form H-Zt/g4-MMAE. Pharmacokinetic analysis of H-Zt/g4-MMAE was determined using hydrophobic interaction chromatography and a MMAE ADC ELISA kit. Biochemical and biological assays were used for measuring RON expression, internalization, cell viability and death. Therapeutic efficacies of H-Zt/g4-MMAE were validated in vivo using three pancreatic cancer xenograft models. Toxicological activities of H-Zt/g4-MMAE were determined in mouse and cynomolgus monkey. RESULTS: H-Zt/g4-MMAE had a drug to antibody ratio of 3.77:1 and was highly stable in human plasma with a dissociation rate less than 5% within a 20 day period. H-Zt/g4-MMAE displayed a favorable pharmacokinetic profile in both mouse and cynomolgus monkey. In vitro, H-Zt/g4-MMAE induced RON internalization, which results in killing of pancreatic cancer cells with IC50 values at 10-20 nM. In vivo, H-Zt/g4-MMAE inhibited pancreatic cancer xenograft growth with tumoristatic concentrations at 1~3 mg/kg bodyweight. Significantly, H-Zt/g4-MMAE eradicated tumors across multiple xenograft models regardless their chemoresistant and metastatic statuses. Moreover, H-Zt/g4-MMAE inhibited and eradicated xenografts mediated by pancreatic cancer stem-like cells and by primary cells from patient-derived tumors. Toxicologically, H-Zt/g4-MMAE is well tolerated in mice up to 60 mg/kg. In cynomolgus monkey, H-Zt/g4-MMAE up to 30 mg/kg had a manageable and reversible toxicity profile. CONCLUSIONS: H-Zt/g4-MMAE is superior in eradication of pancreatic cancer xenografts with favorable pharmacokinetic profiles and manageable toxicological activities. These findings warrant the transition of H-Zt/g4-MMAE into clinical trials in the future.

Downregulation of X-linked inhibitor of apoptosis protein by '7-Benzylidenenaltrexone maleate' sensitizes pancreatic cancer cells to TRAIL-induced apoptosis.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potential biological anticancer agent. However, a wide range of human primary cancers, including pancreatic cancer, display resistance to apoptosis induction by TRAIL. Therefore, this resistance needs to be overcome to allow TRAIL to be successfully used in cancer therapy. In this study, we performed a compound screen to isolate TRAIL sensitizers and found that one of the identified compounds, 7-benzylidenenaltrexone maleate (BNTX), sensitized pancreatic cancer cells to TRAIL-induced apoptotic cell death. The combination of BNTX with TRAIL promoted the release of cytochrome c from mitochondria into cytosol with caspase activation and a resulting increase in annexin V-stained cells. From a mechanistic perspective, we found that BNTX downregulated X-linked inhibitor of apoptosis protein (XIAP) expression when used in combination with TRAIL, and found that TRAIL-induced apoptosis was augmented by siRNA-mediated knockdown of XIAP. We further demonstrated that BNTX promoted the ubiquitin/proteasome-dependent degradation of XIAP protein via protein kinase C (PKC) alpha/AKT pathway inhibition. Moreover, combined treatment by BNTX with TRAIL suppressed growth of pancreatic tumor xenograft of animal model. Therefore, we suggest that inhibitor of apoptosis protein-mediated resistance of pancreatic cancer cells to anticancer therapeutics can be overcome by inhibiting the PKCα/AKT pathway.

Generation and molecular characterization of pancreatic cancer patient-derived xenografts reveals their heterologous nature.

Pancreatic ductal adenocarcinoma (PDAC) is the most challenging type of cancer to treat, with a 5-year survival rate of <10%. Furthermore, because of the large portion of the inoperable cases, it is difficult to obtain specimens to study the biology of the tumors. Therefore, a patient-derived xenograft (PDX) model is an attractive option for preserving and expanding these tumors for translational research. Here we report the generation and characterization of 20 PDX models of PDAC. The success rate of the initial graft was 74% and most tumors were re-transplantable. Histological analysis of the PDXs and primary tumors revealed a conserved expression pattern of p53 and SMAD4; an exome single nucleotide polymorphism (SNP) array and Comprehensive Cancer Panel showed that PDXs retained over 94% of cancer-associated variants. In addition, Polyphen2 and the Sorting Intolerant from Tolerant (SIFT) prediction identified 623 variants among the functional SNPs, highlighting the heterologous nature of pancreatic PDXs; an analysis of 409 tumor suppressor genes and oncogenes in Comprehensive Cancer Panel revealed heterologous cancer gene mutation profiles for each PDX-primary tumor pair. Altogether, we expect these PDX models are a promising platform for screening novel therapeutic agents and diagnostic markers for the detection and eradication of PDAC.

A single-center experience with the laparoscopic Warshaw technique in 122 consecutive patients.

BACKGROUND: Preservation of the spleen in distal pancreatectomy has recently attracted considerable attention. Our current study aimed in the first instance to define the safety of lap-WT in relation to the capacity of this technique to achieve preservation of the spleen and secondly to investigate the effectiveness of a planned lap-WT procedure or early conversion to lap-WT in selected patients with a large tumor attached to the splenic vessels. METHODS: Among 1056 patients who underwent a laparoscopic distal pancreatectomy between January 2005 and December 2014 at our hospital, 122 (24.6 %) underwent lap-WT which were analyzed. The 122 patients were categorized into two groups chronologically (early group: 2005-2012, late group: 2013-2014). RESULTS: The median follow-up was 35 months, and the median operation time was 181 min. The median postoperative hospital stay was 7 days, and the median estimated blood loss was 316 ml. Postoperative complications occurred in 9 patients (7.3 %), including 4 patients (3.2 %) with major pancreatic fistula (ISGPF grade B, C). A reoperation to address postoperative bleeding was needed in one patient. During a median follow-up of 35 months, there were no clinical significant splenic infarctions or gastric varices in any case. All patients were observed conservatively. In patients in the late group who underwent the lap-WT, the mean operating time (171 vs. 205 min, p = 0.001) and mean estimated blood loss (232.1 vs. 370.0 ml, p = 0.017) were significantly less than the early group cases who received lap-WT. CONCLUSIONS: A lap-WT is a safe treatment strategy in select cases when used as a way of preserving the spleen. When splenic vessel preservation is technically challenging, for example when the tumor is enlarged or is attached to the splenic vessels, planned lap-WT or early conversion to lap-WT may be a feasible option.

Enucleation for benign or low-grade malignant lesions of the pancreas: Single-center experience with 65 consecutive patients.

INTRODUCTION: Standard resection for benign and borderline neoplasms of the pancreas is associated with a substantial risk of postoperative morbidity and long-term functional impairment, whereas enucleation leads to less morbidity and preserves healthy parenchyma as well as pancreatic function. The aim of this study was to evaluate the postoperative clinical outcomes and long-term functional and oncologic results after pancreatic enucleation, and to compare the clinical results of laparoscopic and open enucleation. METHODS: From March 2005 to December 2013, 65 cases of enucleation of benign tumors in the pancreas were identified through a retrospective review of medical records. RESULTS: Most of the patients were women (73.8 %), and the median age was 52.7 years (interquartile range 43.1-60.9 years). Median tumor size was 2.5 cm (interquartile range 1.6-3.8 cm). The most common indication for enucleation was pancreatic neuroendocrine tumor (24, 36.9%). A clinically relevant pancreatic fistula (International Study Group on Pancreatic Fistula grade B, C) was reported in 6 patients (9.2%). The patients with tumors of the pancreatic neck had more complications after enucleation than those with tumors at other locations (3/4, 75%). There were no differences of clinical outcomes between open and laparoscopic enucleation groups. At a median follow-up of 58.7 months there was one case of new-onset diabetes, and there were no recurrences or deaths. CONCLUSION: Enucleation is a safe and effective procedure for the treatment of benign and borderline pancreatic neoplasms. It preserves pancreatic function and is not associated with recurrence. The incidence of postoperative complications, including pancreatic fistula, is acceptable. Laparoscopic enucleation seems to be a feasible and safe approach associated with favorable perioperative outcomes for the selected patients.

Laparoscopic central pancreatectomy for benign or low-grade malignant lesions in the pancreatic neck and proximal body.

INTRODUCTION: Laparoscopic central pancreatectomy (LCP) is a parenchyma-sparing minimally invasive surgical technique for removal of benign or low-grade malignant lesions from the neck and proximal body of the pancreas. The aim of this study was to compare the short- and long-term clinical outcomes of LCP with those of other pancreatectomies. METHODS: During the study period, January 2007 to December 2010 (median follow-up 40.6 months), 287 pancreatectomies were performed for lesions in the neck and proximal body of the pancreas. To compare the clinical outcomes of LCP and other pancreatectomies, 26 cases of LCP, 14 cases of open central pancreatectomy (OCP), and 96 cases of extended laparoscopic distal pancreatectomy (E-LDP) were selected. RESULTS: Tumor sizes in the LCP (2.2 cm) and OCP (2.9 cm) groups were smaller than in the E-LDP (4.0 cm) group. Mean operation time in the LCP group (350.2 min) was longer than in the OCP (270.3 min) and E-LDP groups (210.6 min). There were more surgical complications in the LCP (38.5 %) and OCP groups (50 %) than in the E-LDP group (14.6 %). Mean duration of postoperative hospital stay was 13.8 days for the LCP group, which was significantly shorter than for the OCP group (22.4 days). New-onset diabetes was less frequent after LCP than after E-LDP (11.5 vs. 30.8 %). CONCLUSIONS: In selected patients with small and benign tumors in the pancreatic neck and proximal body LCP leads to increased postoperative morbidity but earlier postoperative recovery than OCP, and excellent postoperative pancreatic function (compared with E-LDP). LCP should, therefore, be considered a valid therapeutic option for selected patients.