Lenvatinib and Pembrolizumab Maintenance Therapy for the Treatment of Patients of Advanced Unresectable Pancreatic Cancer

Inclusion Criteria: * Documented informed consent by the participant * Willingness to provide tissue and blood samples for correlative studies * Age: \>= 18 years * Eastern Cooperative Oncology Group (ECOG) performance status =\< 1 * Must have a confirmed histologic or cytologic diagnosis of advanced unresectable pancreatic ductal adenocarcinoma (PDA) * Must have received at least 16 weeks of 1st or 2nd line therapy and achieved partial response or stable disease (by computed tomography \[CT\] or magnetic resonance imaging \[MRI\]) with no signs of progression within 30 days before start of treatment * Last chemotherapy treatment must be within 30 days prior to start of treatment * No prior therapy with an anti-PD-1, anti-PD-L1, or anti PD L2 agent or with an agent directed to another stimulatory or co-inhibitory T-cell receptor (e.g., CTLA-4, OX 40, CD137) * Measurable or evaluable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) version (v) 1.1. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions * Participants must have recovered from all adverse events (AEs) due to previous therapies to =\< grade 1 or baseline, with the following exception: participants with =\< grade 2 neuropathy are eligible * Note: Participants who have entered the follow-up phase of an investigational study may participate as long as it has been 4 weeks after the last dose of the previous investig…