Introduction: Spontaneous hyperinflation (SH) is a recognized but rare complication of intragastric balloon (IGB) placement. Urgent endoscopic removal is critical. Patients may present to centers unfamiliar with IGBs, so all gastroenterologists should be aware of this rare but dangerous complication. Specific removal kits are not always available, and in emergencies, IGBs may be removed with standard endoscopic tools. Case Description/Methods: A 44-year-old woman with obesity had an IGB placed in the Dominican Republic 6 months prior to presentation, with 60-pound weight loss. One week prior, she returned to the Dominican Republic. The IGB was inflated further for additional weight loss. She presents to the ED with 5 days of vomiting >10x/day, severe abdominal pain, and lack of bowel movements for 1 week. Vital signs were normal in the ED. Exam showed soft, distended abdomen, tender in the upper regions, without peritoneal signs. Labs were notable for leukocytosis of 12.0 and lipase of 422 (normal 13-60). CT abdomen/pelvis showed a large IGB (13 x 18 x 15 cm) with internal air-fluid level and no evidence of gastric outlet obstruction. Emergent dual channel upper endoscopy (EGD) was performed (Figure 1). The IGB external catheter was grasped with a snare and rat-tooth forceps and pulled out of the mouth. The internal fluid was suctioned out and cultured. The IGB surface suggested microbial colonization. IGB removal was attempted with the above tools, but there was significant breakdown of the IGB, complicating removal. Two snares were used to grasp each end of the catheter, allowing for completion of IGB removal. There was a large, deep ulcer where the IGB was sitting, likely due to ischemia from the IGB. Fluid culture was negative. Bacterial culture of the IGB showed skin microbiota, and fungal culture showed rare Candida krusei. Post-procedure recovery was unremarkable; she was discharged the next day. Discussion: SH rarely occurs post-IGB placement, and the mechanism of microbial overgrowth with hyperinflation is uncertain. Our patient had no gas-producing organisms cultured from the IGB or its fluid. If there is concern for SH, the IGB should be removed as soon as possible given risk of gastric or esophageal perforation. IGB removal is typically device-dependent and should be done following the manufacturer’s instructions, but in emergent cases, all IGBs can be aspirated with an endoscopic injection needle and removed with standard endoscopic tools.Figure 1.: A: Coronal view of patient’s CT of the abdomen/pelvis with IV and oral contrast, showing significant hyperinflation of intragastric balloon. B: Endoscopic image showing intragastric balloon with appearance of internal microbial colonies and adherence to the gastric wall. C: The intragastric balloon post-removal. The intragastric balloon appears to have internal microbial overgrowth. The balloon was broken during endoscopic removal, making both the internal and external catheters accessible to grasping with a snare. The entire balloon was sent for bacterial and fungal culture.

University of Wisconsin-Madison, USA.

Background Mice bearing B78 melanoma tumors can be cured using an in situ vaccine (ISV) regimen that includes radiation (RT) together with immunocytokine (tumor-targeting mAb conjugated to IL-2). B78 melanoma cells, derived from B16 cells, express minimal to no MHC-I but express MHC-II upon IFN-g/TNF-a stimulation. Although B78 cells are primarily MHC-I-deficient, an increased CD8 T cell infiltration into the tumor microenvironment (TME) has been shown following ISV.1 To further investigate the potential role of specific immune cell lineages in the B78 anti-tumor response to ISV, immune subset depletion studies and flow cytometric analyses were performed. Methods C57BL/6 mice bearing B78 tumors were depleted of immune cell subsets with mAbs (anti-CD4, anti-CD8, anti-NK1.1, or Rat IgG control) for 3 weeks during the course of treatment. Treatment groups included no treatment, RT (12 Gy), or ISV (RT D0 and immunocytokine D5-D9). 6 mice/group (repeated three times) were followed for survival/tumor growth, and flow cytometry studies included 4 mice/group, sacrificed on D8 and D13 following the start of ISV. Results Mice depleted of CD4 T cells during the course of ISV showed a significant reduction of anti-tumor effect as compared to mice treated with ISV/Rat IgG (p Conclusions These studies suggest that CD4 T cells are essential for an anti-tumor response in the B78 melanoma model. In vivo depletion data show that CD4 T cells, but not CD8 or NK cells, are required for a decrease in tumor growth via ISV. Flow cytometric analyses suggest an interplay between CD4 and CD8 T cells as indicated by a decrease in CD8/IFN-g expression following ISV in the absence of CD4 T cells. The role that MHC-I and MHC-II expression plays in this CD4/CD8 T cell anti-tumor response is under investigation. In future studies, B78 melanoma may serve as a critical syngeneic model for development of more effective immunotherapy treatment regimens. Ethics Approval All animal experiments were performed in accordance with protocols approved by Animal Care and Use Committees of the University of Wisconsin-Madison. Reference Morris Z, Guy E, Francis D, et al. In situ tumor vaccination by combining local radiation and tumor-specific antibody or immunocytokine treatments. Cancer Res 2016;76(13):3929-3941.