Evaluation of mycophenolic acid exposure in a patient with immune-related hepatotoxicity caused by nivolumab and ipilimumab therapy for malignant melanoma: a case report.

BACKGROUND: Guidelines such as the National Comprehensive Cancer Network recommend mycophenolate mofetil (MMF) for the treatment of severe steroid-refractory immune-related hepatotoxicity. Mycophenolic acid (MPA) is an active form of MMF that suppresses T- and B-lymphocyte proliferation and immune-related adverse events caused by immune checkpoint inhibitors. MPA has a narrow therapeutic range (37-70 µg·h/mL) and overexposure increases the risk of leukopenia in transplantation. However, the optimal use of MMF in oncology has not yet been established; thus, monitoring plasma MPA concentrations is necessary to avoid excessive immunosuppression in oncology practice. CASE PRESENTATION: We evaluated plasma MPA concentration in a 75-year-old man with immune-related hepatotoxicity following nivolumab and ipilimumab combination therapy for malignant melanoma. The patient developed severe hepatotoxicity after immunotherapy, and immunosuppressant therapy with corticosteroids was initiated. The patient then developed steroid-refractory immune-related hepatotoxicity; therefore, MMF (1,000 mg twice daily) was co-administered. Seven days after the administration of MMF, the plasma MPA concentration was measured using an enzyme multiplied immunoassay technique. The area under the plasma concentration-time curve for MPA from 0 to 12 h was 41.0 µg·h/mL, and the same dose of MMF was continued. Grade 2 lymphocytopenia, which could be attributed to MMF, was observed during the administration period. Unfortunately, the patient was infected with SARS-CoV-2 and died from respiratory failure. CONCLUSION: Our patient did not exceed the upper limit of MPA levels as an index of the onset of side effects of kidney transplantation and achieved rapid improvement in liver function. Prompt initiation of MMF after assessment of the steroid effect leads to adequate MPA exposure. Therapeutic drug monitoring should be considered when MMF is administered, to avoid overexposure.

Two Cases of Increased Gastrointestinal Polyps in Familial Adenomatous Polyposis following Antiacid Agent Intake.

Introduction: Familial adenomatous polyposis (FAP), a hereditary disorder of the gastrointestinal tract, is an autosomal dominant inherited condition caused by germline mutations in the adenomatous polyposis coli (APC) gene. It is characterized by the development of hundreds to thousands of colorectal adenomatous polyps, which, if left untreated, can eventually develop into colorectal carcinomas. Representative extracolonic tumors in FAP include multiple duodenal adenomas and desmoid tumors. Moreover, multiple fundic gland polyps are frequently identified in the stomachs of patients with FAP. Case Presentation: Herein, we report the two cases. A 52-year-old woman who underwent total colectomy for FAP, and pancreatoduodenectomy was initiated on esomeprazole for the treatment of anastomotic erosion. Esophagogastroduodenoscopy performed 42 months later showed an increased number and size of gastric fundic gland polyps, which subsequently decreased after replacing esomeprazole with ranitidine. Similarly, a 39-year-old woman with FAP was initiated on vonoprazan for the treatment of reflux symptoms. Esophagogastroduodenoscopy and colonoscopy performed 14 months later indicated an increase in the number of gastric fundic gland polyps and colorectal polyps, which subsequently decreased after vonoprazan discontinuation. In these two cases, the increase and decrease in the number and size of fundic gland polyps and colon adenoma were associated with serum gastrin levels. Conclusion: Gastric fundic gland polyps and colon polyps may rapidly increase in number and size due to increased gastrin levels induced by proton pump inhibitor/potassium-competitive acid blocker use. Hence, these drugs should be prescribed with caution.

A case of endoscopic submucosal dissection of esophageal acantholytic Paget's disease with discontinuously spreading and unclear neoplastic extension.

BACKGROUND: Paget's disease (PD) is a carcinoma, in which irregular atypical cells with abundant cytoplasm proliferate mainly within the epithelium and is classified into PD occurring in the breast and extramammary Paget's disease (EMPD) occurring outside the breast. Essentially, extramammary PD is reported as a tumor for which it is difficult for surgeons to properly determine the line of resection. CASE PRESENTATION: An 83-year-old male was admitted to our hospital because of roughness of the esophageal epithelium during the follow-up examination for a gastric ulcer. A preoperative biopsy revealed squamous cell carcinoma; therefore, endoscopic submucosal dissection (ESD) was performed. CONCLUSIONS: The characteristic feature in this patient was the distribution of tumor cells and, accordingly, the difficulty in identifying the neoplastic distribution. In this patient, the odd distribution and growth pattern of the tumor cells made it difficult for the operator to identify the distribution of the lesion preoperatively.