• Be willing and able to provide written informed consent for the trial.

• Be aged 18 or over at the day of signing consent

• Histologic or cytologic confirmed diagnosis of neuroendocrine tumour

• Have archival tissue block available or willing to have fresh tissue biopsy if blocks not available

• Have disease that can be readily biopsied by ultrasound guidance (n=5)

• Ki67 \< 55% (only patients with well differentiated grade 1-3 NETs will be included in the study as patients with poorly differentiated grade 3 NETs have a prognosis of less than 6 months)

• Progression or intolerance to first line therapy including somatostatin analogues

• ECOG Performance status 0 - 2

• No tumoural uptake on \[68Ga\]-DOTA-TATE or uptake less than background liver

⁃ Measurable disease based on RECIST 1.1. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions

⁃ Adequate organ function as outlined in the protocol

⁃ Women of childbearing potential must be willing to use a highly effective method of contraception as outlined in the protocol for the course of the study through 6 months after the last dose of Investigational Medicinal Product (IMP).

⁃ Note: Abstinence is acceptable if this is the usual lifestyle and preferred contraception for the subjects

⁃ Sexually active males must agree to use an adequate method of contraception as outlined in the protocol starting with the first dose of IMP through 6 months after the last dose of study therapy. Note: Abstinence is acceptable if this is the usual lifestyle and preferred contraception for the subject