How would you treat a patient with metastatic neuroendocrine carcinoma of the gallbladder with early relapse after platinum doublet?

By describing the tumor as a Neuroendocrine carcinoma one implies that the tumor is poorly differentiated and high grade.  This is often described as extra-pulmonary small cell lung cancer or high grade GI NEC.  There are no standard second line regimens.  Options are to treat similarly to a small cell lung cancer or to use a regimen active in second line for the site of origin.  We usually sequence these patients with close attention to MSI and try our best to enroll in a clinical trial.