• 18 years and older patients.

• Signed informed consent prior to initiation of any study-specific procedures or treatment, as confirmation of the patient's awareness and willingness to comply with the study requirements.

• Documented histological or cytological diagnosis of well differentiated Lung and GEP-NENs (NET G1, NET G2, NET G3 in WHO 2017 classification) progressing after a first line of therapy with SSAs, sunitinib, everolimus, chemotherapy and/or PRRT or documented histological or cytological diagnosis of Large cells neuroendocrine carcinoma patients with Ki67\< 55% progressed after platinum-based first line chemotherapy.

• Subjects must have evidence of progressed disease, radiologically documented in the 12 months previous study entry.

• Subjects must have evidence of measurable disease as determined by the investigator. Target lesions must have shown evidence of disease progression by Response Evaluation Criteria in Solid Tumors (RECIST) version (v)1.1 criteria in the 12 months prior to study entry. Patients must have measurable disease per RECIST 1.1 by computer tomography (CT) scan or magnetic resonance imaging (MRI). Gallium 68 PET Scan can be considered useful before and during the treatment.

• Subject must have adequate swallowing capacity.

• Subjects with functional (associated with a clinical hormone syndrome) and non functional tumors are eligible for the study.

• The concurrent use of somatostatin analogues is allowed provided that the patient has been on a stable dose for at least two months.

• At least 4 weeks of wash-out from previous targeted therapies.

⁃ At least 6 months of wash-out from previous PRRT treatment.

⁃ Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0-2.

⁃ Subjects must have adequate organ function, including the following:

⁃ Bone marrow reserve consistent with: absolute neutrophil count (ANC) ≥1.5 x109/L; platelet count ≥ 100 x 109/L; haemoglobin ≥ 9 g/dL;

⁃ Hepatic: total bilirubin ≤ 1.5 x upper limit of normal (ULN), transaminases (aspartate aminotransferase/serum glutamic oxaloacetic transaminase \[AST/SGOT\] and alanine aminotransferase/serum glutamic pyruvic transaminase \[ALT/SGPT\]) ≤ 2.5 x ULN (\< 5 x ULN if liver metastases are present);

⁃ Renal: normal serum creatinine or calculated creatinine clearance ≥ 60 mL/min (Cockroft-Gault formula);

⁃ Recovery from toxicities related to any prior treatments, unless AE(s) are clinically nonsignificant and/or stable on supportive therapy.

⁃ Estimated life expectancy of ≥12 weeks

⁃ Sexually active fertile female subjects must agree to use effective contraceptive methods during the course of the study and for 4 months after the last dose of study treatment. While sexually active fertile male subjects must agree to use effective contraceptive methods during the course of the study and up to 6 months after the last dose of study treatment;

⁃ For women of child-bearing potential, negative serum pregnancy test within 14 days prior to the first study drug administration;

⁃ Ability to understand and willingness to sign informed consent form prior to initiation of any study procedures and willingness to comply with the study requirements.