Faculty Bibliography

OBJECTIVE:To identify a clinical fistula risk score following distal pancreatectomy. BACKGROUND:Clinically relevant pancreatic fistula (CR-POPF) following distal pancreatectomy (DP) is a dominant contributor to procedural morbidity, yet risk factors attributable to CR-POPF and effective practices to reduce its occurrence remain elusive. METHODS:This multinational, retrospective study of 2026 DPs involved 52 surgeons at 10 institutions (2001-2016). CR-POPFs were defined by 2016 International Study Group criteria, and risk models generated using stepwise logistic regression analysis were evaluated by c-statistic. Mitigation strategies were assessed by regression modeling while controlling for identified risk factors and treating institution. RESULTS:CR-POPF occurred following 306 (15.1%) DPs. Risk factors independently associated with CR-POPF included: age (<60 yrs: OR 1.42, 95% CI 1.05-1.82), obesity (OR 1.54, 95% CI 1.19-2.12), hypoalbuminenia (OR 1.63, 95% CI 1.06-2.51), the absence of epidural anesthesia (OR 1.59, 95% CI 1.17-2.16), neuroendocrine or nonmalignant pathology (OR 1.56, 95% CI 1.18-2.06), concomitant splenectomy (OR 1.99, 95% CI 1.25-3.17), and vascular resection (OR 2.29, 95% CI 1.25-3.17). After adjusting for inherent risk between cases by multivariable regression, the following were not independently associated with CR-POPF: method of transection, suture ligation of the pancreatic duct, staple size, the use of staple line reinforcement, tissue patches, biologic sealants, or prophylactic octreotide. Intraoperative drainage was associated with a greater fistula rate (OR 2.09, 95% CI 1.51-3.78) but reduced fistula severity (P < 0.001). CONCLUSIONS:From this large analysis of pancreatic fistula following DP, CR-POPF occurrence cannot be reliably predicted. Opportunities for developing a risk score model are limited for performing risk-adjusted analyses of mitigation strategies and surgeon performance.

OBJECTIVE:The aim of this study was to investigate the relationship between drain fluid amylase value on the first postoperative day (DFA1) and clinically relevant fistula (CR-POPF) after distal pancreatectomy (DP), and to identify the cut-off of DFA1 that optimizes CR-POPF prediction. BACKGROUND:DFA1 is a well-recognized predictor of CR-POPF after pancreatoduodenectomy, but its role in DP is largely unexplored. METHODS:DFA1 levels were correlated with CR-POPF in 2 independent multi-institutional sets of DP patients: developmental (n = 338; years 2012 to 2017) and validation cohort (n = 166; years 2006 to 2016). Cut-off choice was based on Youden index calculation, and its ability to predict CR-POPF occurrence was tested in a multivariable regression model adjusted for clinical, demographic, operative, and pathological variables. RESULTS:In the developmental set, median DFA1 was 1745 U/L and the CR-POPF rate was 21.9%. DFA1 correlated with CR-POPF with an area under the curve of 0.737 (P < 0.001). A DFA1 of 2000 U/L had the highest Youden index, with 74.3% sensitivity and 62.1% specificity. Patients in the validation cohort displayed different demographic and operative characteristics, lower values of DFA1 (784.5 U/L, P < 0.001), and reduced CR-POPF rate (10.2%, P < 0.001). However, a DFA1 of 2000 U/L had the highest Youden index in this cohort as well, with 64.7% sensitivity and 75.8% specificity. At multivariable analysis, DFA1 ≥2000 U/L was the only factor significantly associated with CR-POPF in both cohorts. CONCLUSION:A DFA1 of 2000 U/L optimizes CR-POPF prediction after DP. These results provide the substrate to define best practices and improve outcomes for patients receiving DP.

BACKGROUND:Immune checkpoint inhibitors are not effective for pancreatic ductal adenocarcinoma (PDAC) as single agents. Vaccine therapy may sensitize PDACs to checkpoint inhibitor treatments. Annexin A2 (ANXA2) is a pro-metastasis protein, previously identified as a relevant PDAC antigen that is expressed by a GM-CSF-secreting allogenic whole pancreatic tumor cell vaccine (GVAX) to induce an anti-ANXA2 antibody response in patients with PDAC. We hypothesized that an ANXA2-targeting vaccine approach not only provokes an immune response but also mounts anti-tumor effects. METHODS:We developed a Listeria-based, ANXA2-targeting cancer immunotherapy (Lm-ANXA2) and investigated its effectiveness within two murine models of PDAC. RESULTS:We show that Lm-ANXA2 prolonged the survival in a transplant model of mouse PDACs. More importantly, priming with the Lm-ANXA2 treatment prior to administration of anti-PD-1 antibodies increased cure rates in the implanted PDAC model and resulted in objective tumor responses and prolonged survival in the genetically engineered spontaneous PDAC model. In tumors treated with Lm-ANXA2 followed by anti-PD-1 antibody, the T cells specific to ANXA2 had significantly increased INFγ expression. CONCLUSIONS:For the first time, a listeria vaccine-based immunotherapy was shown to be able to induce a tumor antigen-specific T cell response within the tumor microenvironment of a "cold" tumor such as PDAC and sensitize the tumor to checkpoint inhibitor therapy. Moreover, this combination immunotherapy led to objective tumor responses and survival benefit in the mice with spontaneously developed PDAC tumors. Therefore, our study supports developing Lm-ANXA2 as a therapeutic agent in combination with anti-PD-1 antibody for PDAC treatment.