The main purpose of the study is to determine the Maximum Tolerated Dose (MTD), the Recommended Expansion Dose and the safety and tolerability of ADCE-B05 when given as a single therapy over a range of different dose levels.

Safety and tolerability will be evaluated by incidence of DLTs. Efficacy will be evaluated by antitumor activity: ORR, DOR, PFR, and TTR per RECIST v 1.1

Inclusion Criteria:

• Histologically or cytologically confirmed diagnosis of solid tumor
• Advanced disease (i.e., unresectable locally advanced or metastatic) and refractory to, intolerant of, or ineligible for approved therapies
• Radiologically or clinically determined progressive disease during or after most recent line of therapy
• Measurable disease per RECIST 1.1
• ECOG performance status of 0 or 1
• Adequate hematological and biochemical parameters
• A male patient must agree to use barrier contraception during the treatment period and for at least 4 months after the last infusion of study treatment, and refrain from donating sperm during this period. Male patients with a pregnant partner must practice sexual abstinence or use a barrier method of contraception (e.g., condom) to prevent exposure of the fetus or neonate
• A female patient who is not pregnant, not breast feeding, and either not a woman of childbearing potential (WOCBP) or agrees to follow the contraceptive guidance during the treatment period and for at least 7 months after last infusion of study treatment

Exclusion Criteria

• Treatment with systemic anticancer therapy, including any investigational agent within 3 weeks or 5 half-lives (whichever is shorter) prior to study treatment administration
• Prior treatment with an ADC containing a topoisomerase I inhibitor payload
• Primary brain malignancy or known, untreated central nervous system (CNS) or leptomeningeal metastases, or symptoms suggesting CNS involvement for which treatment is required
• Other malignancy
• Major surgical procedure or significant traumatic injury within 28 days prior to study drug administration
• Ongoing systemic infection requiring treatment with antibiotics, antivirals, or antimycotics, other than prophylactic treatment
• Persistent toxicities from previous systemic anti-neoplastic treatments of Grade >1
• Clinically significant cardiovascular disease
• Acute infection with human immunodeficiency virus (HIV)-1 or HIV-2
• Current active liver disease due to hepatitis B or hepatitis C
• History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis or pulmonary lymphangitic carcinomatosis