The goal of the phase 1 study is to evaluate the safety, efficacy, pharmacokinetics, and pharmacodynamics activity of FP008 in subjects with advanced solid tumors.

This is a first-in-human (FIH), multicenter, open-label, dose escalation and dose expansion Phase 1 study of FP008 injection in subjects with advanced solid tumors. This study will evaluate the safety, tolerability, PK, PD, immunogenicity, and preliminary antitumor activity of FP008.

The study consists two parts: Part 1 (dose escalation phase) will evaluate the safety, tolerability, PK, PD, immunogenicity, and preliminary antitumor activity of FP008 treatment, and to estimate the DRDE(s) of FP008. Part 2 (Dose expansion phase) will evaluate the safety, tolerability, PK, PD, immunogenicity, and efficacy at the different DRDE(s)/schedule(s) of FP008 in subjects with selected advanced solid tumors.

Inclusion Criteria:

1. Signed written ICF and be able to comply with the protocol.
2. Male and female subjects ≥18 years of age.
3. Life expectancy of >3 months.
4. Laboratory values for sufficient organ function at screening.
5. Toxicity from prior antitumor treatment has resolved to ≤Grade 1 as defined by NCI CTCAE v5.0.
6. Women of childbearing potential must have a negative serum or urine pregnancy test within 7 days prior to the start of FP008.
7. Male or women of childbearing potential, if sexually active, must agree to use contraception considered adequate and appropriate by the investigator during the period of study drug administration and for at least 5 months after the last dose of FP008.
8. ECOG performance status of 0 to 1.
9. Histologically or cytologically confirmed malignancy diagnosis and at least one measurable documented advanced/unresectable or metastatic solid tumor as assessed by RECIST v1.1.
10. Documented progressive disease, refractory/resistance/intolerant to standard therapy (documented the reason(s) why they are intolerant to standard therapy by the investigator), or there is no standard therapy.

Exclusion Criteria:

1. Subjects who have received other IL-10 agents.
2. A history of other malignancies other than basal cell carcinoma of skin, squamous cell carcinoma of skin, non-muscle invasive bladder cancer, thyroid papillary carcinoma or carcinoma in situ of the cervix that have been cured for 2 years after effective treatment.
3. Received live vaccine within 30 days prior to the first dose of FP008.
4. Not completely recovered from the effects of major surgery or significant traumatic injury at least 14 days before the first dose of FP008.
5. Known hypersensitivity to either the drug substances or inactive ingredient of FP008.
6. Subjects with diagnosis of immunodeficiency, organ transplant requiring immunosuppressive therapy, or allogeneic bone marrow or hematopoietic stem cell transplant.
7. Daily requirement for corticosteroids within 2 weeks prior to first dose of FP008.
8. Any other medical disorder, physical exam finding, laboratory finding, altered mental status, or psychiatric condition that the investigator considers unsuitable for participation in the study.
9. Cardiovascular dysfunction or clinically significant cardiac disease.