Eligible adults (≥18) have advanced solid tumors (measurable per RECIST 1.1/RANO 2.0), ECOG 0-1, LVEF ≥50%, and adequate organ function. Exclusions: prior B7-H3/TOP1-ADC therapy, uncontrolled cardiac/pulmonary conditions (e.g., CHF, ILD), active infections (HBV/HCV exceptions), untreated CNS metastases, or unresolved Grade ≥2 toxicity. Contraception is mandatory (7 months for females, 4 for males). Cohort-specific criteria apply (e.g., SCLC: prior platinum therapy; CRPC: progression per PCWG3).

Eligible participants are adults (≥18) with progressing solid tumors after standard therapy, measurable disease per RECIST 1.1, ECOG 0-1, and adequate organ/cardiac function. Key exclusions include prior HER3/topoisomerase I inhibitor ADC therapy (with exceptions), significant cardiac/corneal/pulmonary conditions, active untreated CNS metastases, uncontrolled infections, QTc >470ms, and active hepatitis/HIV. Reproductive requirements mandate contraception for 4-7 months post-treatment.

Phase 1 evaluates safety parameters including dose-limiting toxicities (DLTs) during Cycle 1 and treatment-emergent adverse events (TEAEs)/serious adverse events (SAEs) over approximately 1 year, while determining Maximum Tolerated Dose (MTD) and Recommended Phase 2 Dose (RP2D) of DB-1310. Phase 2a continues monitoring TEAEs/SAEs while assessing efficacy through Objective Response Rate (ORR) per RECIST 1.1 over 1 year.

Pharmacokinetic assessments (AUC, Cmax, Tmax, T1/2) for DB-1310 components are conducted across both phases within 8 treatment cycles (21 days each). Efficacy evaluations include ORR, duration of response (DOR), disease control rate (DCR), progression-free survival (PFS) and overall survival (OS) per RECIST 1.1, with investigator-assessed tumor responses.