Eligible participants (≥18 years, ECOG 0-1) must have advanced/metastatic solid tumors (NSCLC, SCLC, ESCC, CRPC, MEL, CRC, PDAC, HNSCC, HCC, OC, EC, TC, or SARC) refractory to standard therapies, measurable lesions per RECIST v1.1 (or PCWG3 for CRPC), and adequate organ function. Exclusions: active infections (HBV/HCV/HIV, COVID-19), uncontrolled cardiovascular/neurological conditions, recent major surgery/immunosuppressants, brain metastases (unless stable ≥1 month), prior MHB088C-targeted therapy, pregnancy/breastfeeding, or investigator-assessed ineligibility. Contraception is mandated during and for 90 days post-treatment.

This clinical trial assesses safety by monitoring adverse events (AEs) per NCI-CTCAE v5.0 and dose-limiting toxicities (DLTs) over one year to establish the maximum tolerated dose (MTD) and recommend a Phase 2 dose (RP2D) of MHB088C. Efficacy is measured via objective response rate (ORR) based on RECIST v1.1 criteria for complete (CR) or partial response (PR).

Pharmacokinetic parameters-such as Cmax, Tmax, AUC, Ctrough, t1/2, and systemic clearance (CL)-are evaluated for MHB088C, total antibody, and free toxin MH30010008 over five 28-day cycles. Immunogenicity is assessed via anti-drug antibody (ADA) testing, while efficacy outcomes include duration of response (DOR), disease control rate (DCR), progression-free survival (PFS), and RECIST v1.1-defined tumor progression over one year.