A First-in-Human Study of BG-C0902 Alone and in Combination With Other Therapeutic Agents in Patients With Advanced Solid Tumors

Inclusion Criteria:

• Participants with histologically or cytologically confirmed advanced, metastatic, orunresectable solid tumors not amenable to therapy with curative intent or for whomtreatment is not available or not tolerated.

• Participants must be able to provide archival tissue formalin-fixedparaffin-embedded (FFPE) block containing tumor tissue or approximately 10 to 15freshly cut unstained FFPE slides) or recently obtained fresh tumor biopsy samplesat screening.

• Participants must have ≥ 1 measurable lesion as assessed by RECIST v1.1.

• Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 1, as assessed ≤ 14days before the first dose of study drug.

• Adequate bone marrow and organ function as indicated by the following laboratoryvalues ≤ 14 days before the first dose of study drug

• Female participants of childbearing potential must be willing to use a highlyeffective method of birth control for the duration of the study and for ≥ 7 monthsafter the last dose of study drug. They must also have a negative serum pregnancytest result ≤ 3 days before the first dose of study drug.

• Nonsterile male participants must be willing to use a highly effective method ofbirth control and refrain from sperm donation for the duration of the study and for ≥ 4 months after the last dose of study drug.

Exclusion Criteria:

• History of severe allergic reactions or hypersensitivity to BG-T187 or othermonoclonal antibodies, or to the active ingredient and excipients of the study drugor camptothecins.

• For Phase 1a Part B Safety Expansion and Phase 1b only: Prior treatment with anEGFR-targeting ADC or mesenchymal-epithelial transition (MET)-targetingantibody-drug conjugate (ADC), or any ADC with topoisomerase I (TOPO1) inhibitorpayload.

• Active leptomeningeal disease or uncontrolled, untreated brain metastasis.Participants with a history of treated and, at the time of screening, stable centralnervous system (CNS) metastases are eligible, provided they meet all the following:

1. Brain imaging at screening shows no evidence of interim progression, isclinically stable for ≥ 4 weeks, and has no evidence of new brain metastases

2. Have measurable disease and/or evaluable disease outside CNS

3. No ongoing requirement for corticosteroids as therapy for CNS disease; offcorticosteroids ≥ 14 days before dosing with study drug; anticonvulsants at astable dose are allowed

4. No stereotactic radiation or whole-brain radiation ≤ 14 days before the firstdose of study drug

• History of interstitial lung disease (ILD), or ≥ Grade 2 noninfectious pneumonitis ≤ 2 years before the first dose of the study drug, or has current ILD/noninfectiouspneumonitis, or where suspected active ILD/noninfectious pneumonitis cannot be ruledout by imaging during screening.

• Participants with active or chronic corneal disorder, including but not limited toSjögren's, Fuch's corneal dystrophy, history of corneal transplantation, cornealkeratitis, keratoconjunctivitis, keratopathy, corneal abrasion, inflammation orulceration, other active ocular conditions and any clinically significant cornealdisease that prevents adequate monitoring of drug-induced keratopathy.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.