Mesothelin-Targeted Immunotoxin LMB-100 Alone or in Combination With Nab-Paclitaxel in People With Previously Treated Metastatic and/or Locally Advanced Pancreatic Ductal Adenocarcinoma and Mesothelin Expressing Solid Tumors

Background: LMB-100 is a man-made protein designed to kill cancer cells. LMB-100 targets a cancer marker called mesothelin. Mesothelin is found on the surface of many different tumors, including pancreatic cancer, but is made by a very small number of normal tissues. Other cancers that make mesothelin include mesothelioma, cholangiocarcinoma, thymic carcinoma, ovarian, lung, gastric, endometrial, cervical, and ampullary cancers. After binding to the mesothelin on tumors, LMB-100 can attack and kill cancer cells. Researchers want to see how well it works when given with and without nab-paclitaxel, a drug which treats pancreatic cancer. Objectives: Arm A- To find a safe dose of LMB-100 with a fixed standard dose of nab-paclitaxel in people with advanced pancreatic cancer. To see how well the combination of the two drugs reduce tumor size. Arm B- To find a safe dose of LMB-100 when it is given as a continuous infusion over several days. Eligibility: Arm A- Adults age 18 and older with advanced pancreatic cancer that has worsened after anti-cancer therapy. Arm B- Adults age 18 and older with advanced pancreatic cancer, mesothelioma or other solid tumor that makes mesothelin that has worsened after anti-cancer therapy Design: Participants will be screened with medical history and physical exam. They will give blood, urine, and tissue samples. They will have scans and x-rays. During each 21-day cycle: * For Arm A * Participants will get LMB-100 by an intravenous (IV) catheter on days 1, 3, and 5. This is a tube inserted in a vein, usually in the arm. * Participants will get nab-paclitaxel by IV on days 1 and 8. * For Arm B * Participants will get LMB-100 by an IV catheter as a continuous infusion beginning on day 1 and continuing for 2-4 days * Some participants will also get nab-paclitaxel by IV on days 1 and 8. All participants will get this combination for up to 2 cycles or until their disease worsens or they have intolerable side effects. Participants will have blood and urine tests and scans throughout the study. Participants will have a safety follow-up visit 3-6 weeks after treatment ends. If their disease remains stable or improves, they will be scanned every 6 weeks until their disease gets worse. Even if their disease gets worse, they or their doctor will be called to talk about their cancer status....