A Study to Investigate ALE.P03 as Monotherapy in Adult Patients With Selected Advanced or Metastatic CLDN1+ Solid Tumors

Inclusion Criteria: * Have histologically and cytologically metastatic confirmed advanced or metastatic colorectal cancer, intrahepatic cholangiocarcinoma, squamous non-small cell lung cancer, urothelial carcinoma, and cervical squamous cell carcinoma. * Have documented radiological disease progression at study entry. * Have provided tissue for CLDN1 (Claudin-1) analysis in a central laboratory. Phase I Dose Escalation: \- Received and being refractory/intolerant to available systemic standard of care (SOC) regimens (based on local institutional guidelines) for advanced disease. Phase I RDE and Phase II: * Received 1-2 available systemic SOC regimens (based on local institutional guidelines) for advanced disease and being refractory or intolerant to treatment. * Patients with actionable oncogenic drivers: received feasible targeted therapy. Applicable for Phase I Dose Escalation, Phase I RDE and Phase II: * Measurable disease per RECIST 1.1, as determined by the site. * Have a performance status of 0 or 1 on the Eastern Cooperative Oncology Groups Performance Status. * Demonstrate adequate bone marrow and organ function as per the protocol. Exclusion Criteria: * SqNSCLC and CSCC: diagnosed with a tumor of predominantly non-squamous histology result or adenocarcinoma. * Has received antineoplastic therapies prior to study intervention within specified time frame. * Has rapidly progressing disease. * Has known active central nervous system metastases and/or carcinomatous meningitis. * Has a history of (non-infectious) interstitial lung disease/pneumonitis that required steroids or current symptomatic or clinically significant pneumonitis requiring steroids and/or immunosuppressive therapies. * Has clinically significant gastrointestinal bleeding. * Has an active infection requiring systemic treatment. * Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the clinical study.