Animal model considerations for chordoma research: reproducing the tumor microenvironment in vivo with humanized mice.

Animal models have been commonly used in immunotherapy research to study the cell response to external agents and to assess the effectiveness and safety of new therapies. Over the past few decades, immunocompromised (also called immunodeficient) mice allowed researchers to grow human tumor cells without the impact of the host's immune system. However, while this model is very valuable to understand the tumor biology and to understand the underlying mechanism of immunotherapy, the results may not always directly translate to humans. The tumor microenvironment has significant implications for tumor engraftment, growth, invasion, etc., and the immune system plays a critical role in shaping the tumor microenvironment. Human immunocompetent mice, also named humanized mice, are engineered mice that possess functional human immune cells. This in vivo model can be used to effectively study the effect of the human immune system to a human implanted tumor. Moreover, this can effectively mimic the response to treatment. This section is an overview of the current understanding of the different humanized mice that could be utilized to mimic the tumor microenvironment in chordoma.

Is Cystogastrostomy a Definitive Operation for Pancreatitis Associated Pancreatic Fluid Collections?

BACKGROUND: Pancreatic-enteric drainage procedures have become standard therapy for symptomatic pancreatic pseudocysts and walled-off pancreatic necrosis. The need for pancreatic resection after cyst-enteric drainage procedure in the event of recurrence is not well studied. This study aimed to quantify the percentage of patients requiring resection due to recurrence after surgical cystogastrostomy and identify predictors of drainage failure. METHODS: A single-institution retrospective review was conducted to identify all patients undergoing surgical cystogastrostomy between 2012 and 2020. Demographic, disease, and treatment characteristics were identified. Failure of surgical drainage was defined as the need for subsequent pancreatic resection due to recurrence. Characteristics between failure and nonfailure groups were compared with identifying predictors of treatment failure. RESULTS: Twenty-four cystogastrostomies were performed during the study period. Three patients (12.5%) required a subsequent distal pancreatectomy after surgical drainage. There was no difference in comorbidities between drainage alone and failure of drainage groups. Mean cyst size seemed to be larger in patients that underwent drainage alone versus those that needed subsequent resection (15.2 vs 10.3 cm, P =0.05). Estimated blood loss at initial operation was similar between groups (126 vs 166 mL, P =0.36). CONCLUSION: Surgical pancreatic drainage was successful in the initial management of pancreatic fluid collections. We did not identify any predictors of failure of initial drainage. There was a trend suggesting smaller cyst size may be associated with cystgastrostomy failure. Resection with distal pancreatectomy for walled-off pancreatic necrosis and pancreatic pseudocysts can be reserved for cases of failure of drainage.