Key Inclusion Criteria:
* Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1.
* Histologically or cytologically-documented, incurable locally advanced or metastatic solid tumor of one of the following types:
* Cohort A: oesophageal squamous-cell carcinoma that was refractory or intolerant to fluoropyrimidine-based, platinum-based, and taxane-based chemotherapy.
* Cohort B: gastric adenocarcinoma that was refractory or intolerant to fluoropyrimidine-based, platinum-based, and taxane-based chemotherapy.
* Cohort C: cervical cancer that was refractory or intolerant to platinum-based and taxane-based chemotherapy.
* Cohort D: biliary tract cancer, including intrahepatic cholangiocarcinoma (IHCC), extrahepatic cholangiocarcinoma (EHCC), and gallbladder cancer (GBC), with exception of ampullary carcinoma, progressed during or after first line platinum-based or fluoropyrimidine-based chemotherapy.
* Cohort E: lung adenocarcinoma with activating genomic alterations (EGFR/ ALK/ ROS1/ BRAF/ MET/ RET) that was refractory or intolerant to targeted tyrosine kinase inhibitors (TKIs) and had not received platinum-based chemotherapy for unresectable local advanced or metastatic disease, and no suitable or willing to receive platinum-based chemotherapy.
* Measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) in accordance with RECIST v 1.1, bone-only disease is not measurable and is not permitted.
* Availability of archival tumor tissue or newly acquired biopsy (unstaining tumor slides, recommended from metastasis sites).
* Adequate bone marrow, hepatic and renal function.
* Recovered from all prior treatment-related toxicities to Grade 1 or less by NCI-CTCAE v 5.0 (except alopecia or peripheral neuropathy that may be Grade 2 or less).
* Individuals must have completed all prior cancer treatments at least 2 weeks prior to the first dose including chemotherapy , radiotherapy and major surgery. Prior antibody treatment for cancer must have been completed at least 3 weeks prior to the first dose.
* Individuals must have at least a 3-month life expectancy.
Key Exclusion Criteria:
* Previous treatment with topoisomerase I inhibitors as a free form or as other formulations.
* Previous treatment with Trop-2 targeted therapy.
* Individuals with a history of or current central nervous system (CNS) metastases.
* Known additional malignancy within 3 years prior to enrollment with the exception of curatively treated basal cell carcinoma of the skin, squamous cell carcinoma of the skin and/or curatively resected in situ cancers.
* Individuals known to be human immunodeficiency virus positive.
* Individuals with active hepatitis B virus (HBV), or hepatitis C virus (HCV) infection. Hepatitis B core antibody (HBcAb) testing is required and if positive, then HBV DNA testing will be performed and if positive the individual will be excluded.
* Known history of unstable angina, myocardial infarction (MI), or chronic heart failure present within 6 months of first dose or clinically significant cardiac arrhythmia (other than stable atrial fibrillation) requiring anti-arrhythmia therapy or left ventricular ejection fraction \< 50%.
* Known history of clinically significant active chronic obstructive pulmonary disease, or other moderate-to-severe chronic respiratory illness present within 6 months of the first dose.
* Infection requiring systematic antibiotic use within 1 week of the first dose.
* Individuals with active chronic inflammatory bowel disease (ulcerative colitis, Crohn disease) and individuals with a history of bowel obstruction or gastrointestinal (GI) perforation.
* High dose systemic corticosteroids within 2 weeks prior to the first dose (however, low dose corticosteroids ≤ 10 mg prednisone or equivalent daily are permitted provided the dose is stable for 4 weeks).
* Individuals who have received a live vaccine within 30 days of first dose.
Note: Other protocol defined Inclusion/Exclusion criteria may apply.
