Inhibition of SUMOylation modulates the immunosuppressive microenvironment of pancreatic cancer

Objective

Pancreatic cancer (PC) is a highly aggressive disease that is poorly responsive to available immunotherapy approaches, such as checkpoint inhibitors. Post-translational protein modification (PTM) by small ubiquitin-like modifier (SUMO) is upregulated in cancer, and high expression of SUMOylation-related factors correlates with poor survival in PC. TAK-981 is a novel inhibitor of SUMOylation that has demonstrated induction of anti-tumor immune responses in preclinical models. Our hypothesis is that TAK-981 will decrease SUMOylated proteins and subsequently modulate the tumor microenvironment to increase anti-tumor immunity.

Methods

In order to recapitulate the microenvironment of human PC, a 3-dimensional organoid cell line derived from a genetically-engineered “KPC” mouse was used. Organoids were injected orthotopically into the head of the pancreas via laparotomy. Once tumors reached 5–7 mm in diameter on ultrasound imaging, mice were randomized to one of two treatment groups: Control/Vehicle versus TAK-981 (15 mg/kg) delivered daily via intraperitoneal injection. Tumors were harvested on day 14 for gene expression analysis by quantitative real time PCR (RT-qPCR).

Results

Tumor growth (Fig. 1) in the TAK-981 15 mg/KG daily group (mean + SD volume = 207 + 109 mm3) was significantly inhibited compared to the vehicle group (595 + 141 mm3, p < 0.01). Immunohistochemical staining for CD 31 (Fig. 2) and Caspase 3 indicated a reduction of angiogenesis and increased apoptosis of tumor cells, consistent with the well-established roles of SUMOylation in angiogenesis and tumorigenesis. Gene expression analysis of tumor lysates showed a 26-fold increase in expression of Interferon beta (p<0.05), and an almost 2-fold increase in expression of genes related to dendritic cell activation, including CD80 (p<0.05) and CD86 (p=0.14) in the TAK-981 group, suggesting a modulation of the immune microenvironment.

Conclusion

Our results suggest that the inhibition of SUMOylation with TAK-981 is associated with improved local tumor control and changes in the immunosuppressive tumor microenvironment. We expect that TAK-981 will improve PC responsiveness to immunotherapy, such as with checkpoint inhibitors.

Inhibition of SUMOylation enhances responses to irreversible electroporation in pancreatic cancer

Objective

The revolutionary results of immunotherapy have not yet translated to pancreatic cancer (PC).

Irreversible electroporation (IRE) is a non-thermal ablative therapy that can generate tumor-specific immune responses, yet not sufficient to eradicate distant metastatic disease. Post-translational protein modification (PTM) by small ubiquitin-like modifier (SUMO) is involved in carcinogenesis and PD-L1 mediated immunosuppression. TAK-981 is a novel inhibitor of SUMOylation that has demonstrated induction anti-tumor immune responses in preclinical models. Our hypothesis is that TAK-981 will augment the effects of IRE in an immunocompetent orthotopic mouse model of PC.

Methods

The PC cell line (KPC4580P) was derived from an autochthonous tumor arising in a genetically engineered mouse model (KPC). The tumors were implanted orthotopically into the pancreas via laparotomy. Once tumors reached 5-7 mm in diameter, mice were randomized to one of four treatment groups: IRE alone, TAK-981 alone, IRE + TAK-981, or no treatment. IRE versus sham laparotomy (150 x 90 microsec pulses at 1500 V/cm) was performed once through second laparotomy. TAK-981 (7.5mg/kg) versus vehicle was delivered via subcutaneous injection twice weekly x four doses, starting on the day of IRE. Tumors were harvested on day 14 for flow cytometric analysis.

Results

Ultrasound was performed on days 8, 14 and 20 after initiation of treatment. Tumor growth in the IRE + TAK-981 group was significantly inhibited compared to sham-treated tumors (Fig. 1, *p=0.0002), and this effect persisted to day 20, even after treatment with TAK-981 was stopped on day 11 (p < 0.01). Flow cytometry revealed a greater than 2-fold increase in CD8+ T-cells (Fig. 2a, *p <0.05) and 4-fold increase in IFN-gamma+ CD8+ T-cells (Fig. 2b, *p=0.01) in tumors treated with the combination relative to sham-treated tumors.

Conclusion

Our results suggest that the combination of IRE with TAK-981 is associated with better local tumor control and a significant increase of CD8+ T-cells and IFN-gamma+ CD8+ T-cells. We expect that this combination might contribute systemic immune responses that would prevent or even eradicate distant metastasis. Given that immunosuppression mediated by PD-L1 is regulated by ubiquitination and is seen in 50% of PC tumors, targeting PTM with TAK-981 might also render PC responsive to immunotherapy with checkpoint inhibitors.

Roux-en-Y drainage of the pancreatic stump decreases pancreatic fistula after distal pancreatic resection

Clinically relevant fistula after distal pancreatic resection occurs in 5-30% of patients, prolonging recovery and considerably increasing in-hospital stay and costs. We tested whether routine drainage of the pancreatic stump into a Roux-en-Y limb after distal pancreatic resection decreased the incidence of fistula. From October 2001, data of all patients undergoing pancreatic distal resection were entered in a prospective database. From June 2003 after resection, the main pancreatic duct and the pancreatic stump were oversewn, and in addition, anastomosed into a jejunal Roux-en-Y limb by a single-layer suture (n = 23). A drain was placed near the anastomosis, and all patients received octreotide for 5-7 days postoperatively. The volume of the drained fluid was registered daily, and concentration of amylase was measured and recorded every other day. Patient demographics, hospital stay, pancreatic fistula incidence (> or =30 ml amylase-rich fluid/day on/after postoperative day 10), perioperative morbidity, and follow-up after discharge were compared with our initial series of patients (treated October 2001-May 2003) who underwent oversewing only (n = 20). Indications, patient demographics, blood loss, and tolerance of an oral diet were similar. There were four (20%) pancreatic fistulas in the "oversewn" group and none in the anastomosis group (p < 0.05). Nonsurgical morbidity, in-hospital stay, and follow-up were comparable in both groups.

Hydrocortisone treatment of early SIRS in acute experimental pancreatitis

This work studied the effects of hydrocortisone treatment in experimental acute pancreatitis on cytokines, phospholipase A2, and breakdown products of arachidonic acid and survival. Edematous and necrotizing pancreatitis were induced in Wistar rats by cerulein hyperstimulation and retrograde intraductal infusion of sodium taurocholate, respectively. Hydrocortisone (10 mg/kg) was administered intravenously 10 minutes after induction of acute pancreatitis. Serum was assayed for phospholipase A2; interleukin (IL) 1beta, IL-6, IL-10, thromboxane B2; Prostaglandin E2; and leukotriene B4 at five different time points. A significant release of inflammatory mediators was seen only in the severe model. Hydrocortisone powerfully suppressed arachidonic acid breakdown products and only mildly attenuated the systemic increase of phospholipase A2 and pro- and antiinflammatory cytokines. The mortality rate after 72 hr in the severe model was 86%. Hydrocortisone treatment reduced mortality to 13% (P = 0.001; Fisher's exact test). Hydrocortisone seems to be effective in the treatment of the early systemic inflammatory response syndrome associated with severe acute pancreatitis.

Late mortality in patients with severe acute pancreatitis

BACKGROUND

Mortality due to severe or necrotizing acute pancreatitis most often results from multiorgan dysfunction syndrome (MODS) occurring either early (within the first 14 days) or 2 weeks or more after the onset of symptoms due to septic complications. The aim of this study was to analyse the course of the disease in patients who died from severe acute pancreatitis.

METHODS

Between January 1994 and August 2000 details of 263 consecutive patients with acute pancreatitis were entered prospectively into a database. All patients were treated in an intermediate or intensive care unit.

RESULTS

The overall mortality rate was 4 per cent (ten of 263 patients). The mortality rate was 9 per cent (ten of 106) in patients with necrotizing disease. No patient died within the first 2 weeks of disease onset. The median day of death was 91 (range 15-209). Six patients died from septic MODS. Ranson score, Acute Physiology and Chronic Health Evaluation (APACHE) II score during the first week of disease, pre-existing co-morbidity, body mass index, infection and extent of necrosis were significantly associated with death (P < 0.01 for all parameters). However, only infection of the necrotic pancreas was an independent risk factor in the multivariate analysis.

CONCLUSION

Early deaths in patients with severe acute pancreatitis are rare, mainly as a result of modern intensive care treatment. Nine of the ten deaths occurred more than 3 weeks after disease onset. Infection of pancreatic necrosis was the main risk factor for death.

Pancreatic infection in severe pancreatitis: the role of fungus and multiresistant organisms

HYPOTHESIS

Recent controlled clinical studies suggest a positive effect of early antibiotic treatment on late morbidity and mortality in severe acute pancreatitis. However, widespread use of antibiotics may lead to an increased number of fungal infections and multiresistant bacteria, thereby worsening the outcome of the disease.

DESIGN

Single-center prospective study.

SETTING

University hospital, gastrointestinal surgical service.

PATIENTS

One hundred three patients with necrotizing pancreatitis seen consecutively in our service.

INTERVENTIONS

In addition to standard treatment, patients with proven necrotizing pancreatitis received a prophylactic intravenous antibiotic treatment. Pancreatic infection was regarded as an indication for surgery.

MAIN OUTCOME MEASURES

Pancreatic infection, microbiological findings, drug resistance, fungal infections.

RESULTS

Thirty-three patients (32%) had infected necrosis. Gram-negative organisms were isolated from 19 patients (58%), Gram-positive organisms were isolated from 18 patients (55%), fungal organisms were isolated from 8 patients (24%), and multiresistant organisms were isolated from 3 patients (9%). In 7 patients (21%), the organisms cultured from the pancreatic tissue were resistant to the antibiotics given in for prophylaxis. Infection with multiresistant organisms or organisms resistant to the antibiotic used for prophylaxis, but not with fungal infection or Gram-positive or Gram-negative infection, was correlated with a negative outcome.

CONCLUSIONS

Fungal infection under adequate treatment is not associated with a negative outcome. The occurrence of multiresistant organisms seems to be a rare finding (3 of 103 patients). Antibiotic prophylaxis is effective in preventing infection in necrotizing pancreatitis, but optimal choice and duration of administration of the antibiotic agent(s) need to be carefully determined to avoid the sequelae of multiresistant organisms.

[Indications for surgical therapy and operative technique in acute pancreatitis]

Eighty to eighty-five percent of all episodes of acute pancreatitis are mild and self-limiting, subsiding within a few days. In the remaining 15 to 20% of cases, however, severe necrotizing disease complicated by multiple organ dysfunction syndrome (MODS) develops. Early stratification according to disease severity is a cornerstone in the management of patients with acute pancreatitis. Patients suffering from mild disease do not need to be operated upon unless specific conditions such as bile duct stones, a tumour at the papilla of Vater or in the head of the pancreas are present. Patients suffering from severe disease are best managed by early intensive care treatment, including antibiotics penetrating into the pancreas in order to prevent infection of the necrotic tissue. Despite such a treatment infection occurs in up to one third of necrotizing cases, asking for surgical treatment. The latter consists of an organ preserving procedure, combined with a continuous postoperative lavage of the retroperitoneum. In 75% of our patients treated operatively, one surgical intervention was sufficient. Overall mortality in patients with necrotizing pancreatitis ranges, according to the current literature, between 6 and 50% and reaches 8% in our own series.

[Acute pancreatitis--clinical and technical laboratory diagnostic and prognostic assessment]

The incidence of acute pancreatitis within 100,000 inhabitants a year differs between 5 (Bristol) and 80 (USA). Even though the diagnosis of pancreatitis has become easier by the measurement of specific pancreatic enzymes there are still 30-40% of the fatal cases which are first diagnosed at autopsy. It is of utmost importance to assess the diagnosis and the severity of acute pancreatitis in the beginning to identify those patients with severe or necrotising disease who benefit from an early initiated intensive care therapy. Additionally, in view of new therapeutical concepts (e.g. antibiotic therapy in severe forms) and for the evaluation of new drugs, patients should be staged into mild and severe disease as early as possible. In most cases it is not possible to assess the severity clinically on hospital admission. Up to now the "gold standard" are imaging procedures (contrast-enhanced CT and MRI) which should be reserved for the severe cases to estimate the extent of pancreatic necrosis. The ideal predictor in blood or in urine should be objective, reliable, inexpensive, easy to measure, widely available, sensitive and specific. There are a variety of mediators of the "systemic inflammatory response syndrome" which are elevated in this disease (C-reactive protein, antiproteases, enzyme activation peptides like trypsinogen activation peptide (TAP) and carboxypeptidase B activation peptide (CAPAP), PMN-elastase, complement factors, chemokines and interleukins and others). Among all these mediators, C-reactive protein is the parameter best analysed. It has to be taken into account that it is not specific for AP and it's highest efficacy is reached after > 48 hours after the onset of disease. However, because usually a certain time elapses (approximately 24-48 hours) until patients are hospitalised the time delay seems not to a major disadvantage.