Multicenter Trial of ESK981 in Patients With Select Solid Tumors

Eligibility Criteria: * Patients with histological or cytological confirmation of advanced cancer per specific cohort. * Cohort 1: Pancreatic adenocarcinoma or adenosquamous carcinoma who have progressed or deemed intolerant of the standard of care chemotherapy regimens. * Cohort 2: Pancreatic or gastrointestinal neuroendocrine tumor or carcinoma with Ki-67 \> 20% who have progressed or deemed intolerant of at least first-line standard of care systemic therapy. * Cohort 3: The subject has histologically proven prostate cancer who have progressed or deemed intolerant of at least first-line standard of care systemic therapy with radiologic evidence of metastases and at least one of the following: * Small cell or neuroendocrine morphology on the basis of tissue sample. * Prostate adenocarcinoma with IHC staining for neuroendocrine markers (e.g., chromogranin and synaptophysin). * Presence of visceral metastases or high-volume disease (\> 4 sites of metastases) with a PSA ≤ 5. * Serum chromogranin A level ≥ 5x upper limit of normal (ULN) and/or serum neuron specific enolase (NSE) ≥ 2x ULN. * Trans-differentiated carcinoma or poorly-differentiated carcinoma * Eastern Cooperative Oncology Group (ECOG) performance status 0 - 2 * Must be ≥ 18 years of age. * Evaluable disease determined using guidelines of Response Evaluation Criteria in Solid Tumors (RECIST version 1.1) * Ability to understand and willingness to sign IRB-approved informed consent. * Will…