Phase 1, Open-label, single centre, non-randomised study during which, enrolled patients will undergo a number of PET scans following administration of 89Zr-CB307, in order to assess the uptake of the radiolabelled drug. A post-treatment tumour biopsy for the assessment of PSMA expression will also be taken, if medically feasible, after the last PET scan.~The sub-study consists of 2 parts: an Optimisation Phase (Part A) and an Expansion Phase (Part B).~In Part A, both 89Zr-CB307 and CB307 will be administered to patients. The timing of the scans, post-dose tumour biopsy and CB307 dose will be optimised as determined by the Optimisation Review Committee (ORC).~In Part B (Expansion Phase), 89Zr-CB307 PET scanning will be performed based on the optimal dosing and timing determined in Part A.~The sub-study will continue for 7 days after the tracer injection. Patients will then be enrolled into the main study and will receive Cycle 1 Day 1 (C1D1) CB307 treatment according to the main study protocol.
CB307 is a trispecific Humabody® targeting CD137; PSMA; and human serum albumin (HSA) undergoing Phase 1 assessment in patients with PSMA+ solid tumours. This sub study will assess the biodistribution of radiolabelled CB307 in patients with advanced and/or metastatic solid tumours that are PSMA+.