In Part I of the study, the starting dose will be 50 mg/kg given as a 4 hour iv infusion on Day 1 only. Patients will continue to be assessed for safety, pharmacokinetics (PK) and pharmacodynamics for up to three weeks after dosing (to Day 22). The decision to escalate to the next dose in a separate cohort of patients will be based on the assessment of safety, including any DLTs, pharmacokinetic modelling (PKM) of exposure to ZMP and pharmacodynamic response data, where available, by an independent Data Monitoring Board (DMB). A DLT is defined as a Grade 3 or 4 toxicity, which may be local to the injection site or systemic, which is observed within 21 days of dosing and is considered to be related to study drug. The dose will not be escalated if PKM indicates that the exposure to ZMP has reached a plateau.