- For the Phase Ib dose-expansion portion: patients must have measurable disease per RECIST v1.1 and irRECIST criteria, must have at least 1 tumour lesion amenable to biopsy, and must be medically fit and willing to undergo a biopsy before first treatment and, unless clinically contraindicated, after 6 weeks on therapy. Patients in the Phase Ia portion may agree to have optional paired biopsies.