This Study is a Phase II Study of AZD6738 in Combination With Durvalumab in Patients With Solid Tumor (Cohort A (N=30): GC Who Have Failed Secondary Chemotherapy Treatments Regimen; Cohort B (B=30): Melanoma Patients Who Have Failed to IO)

This study is a phase II study of AZD6738 in combination with durvalumab in patients with solid tumor (cohort A (N=30): GC who have failed secondary chemotherapy treatments regimen; cohort B (B=30): melanoma patients who have failed to IO). Patients will receive AZD6738 plus durvalumab combination regimen. AZD6738 will be administered at 240 mg twice daily on days 1 to 7 in Cycle 0 (lead-in period) and therafter at 240 mg BD on days 22 to 28 in a 28-day cycle. Durvalumab will be administered at 1500 mg every 4 weeks from cycle 1 day 1. Tumour evaluation using modified RECIST 1.1 will be conducted at screening (within 28 days prior to first dose) and every 8 weeks relative to the date of first dose, up to week 40, then every 12 weeks until objective disease progression (within a window of +/- 7 days of the scheduled date). Patients will continue to receive treatment with AZD6738 and durvalumab provided that the treatment is tolerable and there is evidence of clinical benefit (as judged by the investigator) and secure supply of medication. Upon confirmation of objective disease progression, or treatment disconiutation criteria are met, both durvalumab and AZD6738 must be discontinued. Patients may continue with AZD6738/durvalumab beyond objective disease progression (determined by modified RECIST 1.1) at the discretion of the investigator if they are clinically benefiting from the treatment and they do not meet any other discontinuation criteria. If either durvalumab and/or AZD6738 are deemed intolerable (as judged by the investigator) so that discontinuation of either agent is deemed in the patient's best interest despite dose interruptions, dose modification and initiation of supportive treatments, both durvalumab and AZD6738 must be discontinued and the patient withdrawn from the study. Patients are not permitted to continue either AZD6738 or durvalumab as monotherapy. There is no maximum duration of treatment with AZD6738 and durvalumab. The imaging modalitie