Pembrolizumab in MSI-high Pancreatic Sarcomatoid Carcinoma

We report the outcome of a patient with MSI-high metastatic pancreatic sarcomatoid carcinoma refractory to multiple lines of chemotherapy treated successfully with pembrolizumab. In November 2015, our patient presented with epigastric pain leading to radiologic workup. A lesion in the pancreas as well as liver metastasis were diagnosed; liver biopsy revealed a poorly differentiated sarcomatoid carcinoma. After having received every approved chemotherapy for pancreatic cancer his disease eventually progressed so that we reached out for novel therapeutic strategies. Because of the tumor being MSI high, treatment with pembrolizumab was commenced in May 2017. Clinical response with better overall quality of life was soon reported and repeated CT scans showed an ongoing partial response leading to a near complete remission in the latest scan obtained. Adverse events during the course of therapy included immune mediated arthralgia grade 1, colitis grade 2 and pneumonitis grade 1 which were managed by administration of glucocorticoids without interruption of immunotherapy. To our knowledge, this is the first case of a patient with MSI high metastatic sarcomatoid carcinoma of the pancreas successfully treated with immunotherapy for more than three years.