PBMC-based Leukocyte Immunotherapy

Inclusion Criteria: 1. Patients of 18 years or older (all genders) 2. Patients with histologically or cytologically confirmed locally advanced or metastatic solid tumors and who have failed standard treatment, have no standard treatment, or are not suitable for standard treatment at this stage as determined by the investigator 3. Progressed on or refractory to at least two prior lines of systemic therapy 4. At least one measurable lesion according to RECIST 1.1 5. An Eastern Cooperative Oncology Group (ECOG) Performance Status of ≤ 2 6. Life expectancy of at least 3 months 7. Adequate organ and bone marrow function, in the absence of growth factors, defined by specific laboratory parameters. 8. Negative serology for human immunodeficiency virus, syphilis, hepatitis B and hepatitis C 9. No prior chemotherapy, radiation therapy (except for palliative purpose), endocrine therapy, immunotherapy or investigational agent within 3 weeks (or five half-lives) prior to Day 0 (6 weeks for nitrosoureas and mitomycin C) before treatment 10. Toxicities from previous anti-cancer therapies or surgical procedures to grade ≤1 that have not resolved (except alopecia) 11. Previous exposure to a checkpoint inhibitor is allowed (except exposure of Cbl-b inhibition) 12. Women of childbearing potential must have a negative pregnancy test, should not be breastfeeding, and must be willing to use highly effective methods of contraception for at least 1 month before, while participating in this study and until 1 month after the end of the treatment 13. Patient voluntarily agrees to participate in this study and signs an Ethics Committee approved informed consent prior to performing any of the screening visit procedures, indicating that the patient understands the purpose and procedures required for the study 14. Patient is not participating in any other interventional clinical study within the past 30 days Exclusion Criteria: 1. Active untreated brain metastases 2. Use of systemic corticosteroids (\> 10 mg prednisone or equivalent) within 15 days (except for prophylaxis for radiodiagnostic contrast reactions), or other immunosuppressive drugs within 30 days, prior to the first dose of APN401. Replacement therapy (e.g., physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency) is not considered a form of systemic treatment and is allowed 3. Active, known, or suspected autoimmune disease except type I diabetes, vitiligo and thyroid disorders (thyroxine or insulin replacement therapy is allowed) 4. Patients at high medical risk because of non-malignant systemic disease, active or unstable cardiac or cerebro-vascular disease, or active uncontrolled infection 5. Any other severe acute or chronic medical or psychiatric condition, or laboratory abnormality that may increase the risk associated with study participation or APN401 administration, or may interfere with the interpretation of study results and, in the judgement of the investigator, would make the patient unsuitable for the study 6. Any vaccination prior and/or after 7 days while on APN401 treatment