The best response a patient has had during their time in the study up until RECIST progression or last valuable assessment in the absence of RECIST progression. Per Response Evaluation Criteria In Solid Tumours (RECIST version 1.1) for target lesions (TL) and assessed by MRI or CT: Partial Response (PR), >=30% decrease in the sum of the longest diameter of target lesions; Stable Disease (SD), neither sufficient shrinkage to qualify for a Partial Response nor sufficient increase to qualify for Progressive Disease (PD); Progressive Disease (PD), >=20% increase in the sum of the longest diameter of target lesions, the sum must also demonstrate an absolute increase of >=5mm; Complete Response (CR), disappearance of all target lesions, any pathological lymph nodes selected as TLs must have a reduction in short axis to <10mm