Study to Determine the Safety, Tolerability, Pharmacokinetics and Recommended Phase 2 Dose (RP2D) of Livmoniplimab (ABBV-151) as a Single Agent and in Combination With Budigalimab (ABBV-181) in Participants With Locally Advanced or Metastatic Solid Tumors

Inclusion Criteria: * For Dose Escalation only: Participants with an advanced solid tumor who are considered refractory to or intolerant of all existing therapy(ies) known to provide a clinical benefit for their condition. Additionally, participants who have been offered standard therapies and refused, or who are considered ineligible for standard therapies, may be eligible for this study on a case-by-case basis, after discussion with and agreement from the sponsor. Participants with pancreatic adenocarcinoma, urothelial cancer (UC), hepatocellular carcinoma (HCC), or head and neck squamous cell carcinoma (HNSCC) who are being considered for the dose escalation cohorts must also meet the histology specific eligibility criteria described below for dose expansion. * For Dose Expansion only participants must meet criteria specific to the type of cancer: * Pancreatic adenocarcinoma and have disease progression during or after 1 systemic therapy (gemcitabine monotherapy or in combination with other agents, FOLFIRINOX \[or another regimen including both 5-fluorouracil and oxaliplatin\], capecitabine monotherapy or in combination with other agents) administered in the adjuvant, locally advanced, or metastatic setting. If the therapy was used in an adjuvant setting, disease progression must have occurred within 6 months of completing adjuvant therapy. * UC of the bladder and urinary tract and must have progressed following treatment with: * Cohort 4: A platinum-based regimen …