This is a multi-center, Phase 2, open-label, single dose level study of PRL3-zumab monotherapy in patients with unresectable or metastatic solid tumor.

The study consists of a Screening Period (Day - 14 to Day -1), a Treatment Period during which visits will occur every 2 weeks, an End of Treatment visit within 14 days of the decision to discontinue treatment for any reason, and a Safety Follow-up visit at 14 ± 4 days after the last dose of study treatment. PRL3-zumab will be administered by intravenous (IV) infusion till patient meets any of the discontinuation criteria (progressive disease, clinically or per RECIST v1.1 and iRECIST, intolerable toxicity or withdrawal of consent). One cycle of treatment will be 4 weeks (2 infusions, 12 days ±2 days apart).

Inclusion Criteria:

• Patients with unresectable or metastatic solid tumors willing to provide signed informed consent.
• Histopathological diagnosis and metastatic status cancer at study entry.
• Must have received at least 1 prior line of systemic therapy for metastatic disease but no more than 3 prior lines of treatment for metastatic disease.
• Life expectancy of more than 6 months.
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) score or less than 2.
• Adequate organ and hematological function.
• Measurable disease by RECIST v1.1 and iRECIST.

Exclusion Criteria:

• Patient has known untreated or symptomatic central nervous system metastasis.
• Patient is receiving systemic glucocorticoids or other immunosuppressive treatments for autoimmune disease or any other medical condition.
• Patient has experienced a severe hypersensitivity reaction to another monoclonal antibody.
• Patient has received treatment with any systemic anti-cancer therapies within 3 weeks prior to starting study treatment.
• Patient has undergone radiotherapy ≤ 4 weeks prior to starting study treatment.
• Patient has received > 3 lines of prior systemic chemotherapy for metastatic disease