A Study to Investigate Efficacy and Safety of Ceralasertib Plus Durvalumab in Participants Aged ≥ 18 Years With Advanced or Metastatic Non-small Cell Lung Cancer Whose Disease Progressed on or After Prior Anti-PD-(L)1 Therapy and Platinum-based Chemotherapy

Inclusion Criteria: * Histologically or cytologically documented NSCLC that is locally advanced or metastatic according to Version 8 of the IASLC Staging Manual in Thoracic Oncology. * Documented epidermal growth receptor factor (EGFR) and anaplastic lymphoma kinase (ALK) wild-type status. * Documented radiological PD whilst on or after receiving the most recent treatment regimen. * Eligible for second- or third-line therapy and must have received an anti-PD-(L)1 therapy and a platinum doublet containing therapy for locally advanced or metastatic NSCLC. * Eastern Cooperative Oncology Group (ECOG)/World Health Organization (WHO) performance status of 0 or 1. * Adequate organ function and marrow reserve. * Body weight \> 30 kg and no cancer-associated cachexia. Exclusion Criteria: * Participant with mixed SCLC and NSCLC histology. * Brain metastases or spinal cord compression unless the participant is stable and off steroids. * Persistent toxicities (CTCAE Grade \> 2) caused by previous anticancer therapy. * Active or prior documented autoimmune or inflammatory disorders. * History of leptomeningeal carcinomatosis. * Participants who have received more than one line of prior anti-PD-(L)1. * Participants must not have experienced a toxicity that led to discontinuation of the prior anti-PD(L)1 therapy. * Participants must not have experienced a Grade ≥ 3 immune-mediated adverse event (imAE) or an immune-related neurologic or ocular AE of any grade while receiving prior anti-PD(L)1 therapy. * Participants must not have required the use of additional immunosuppression other than corticosteroids for the management of an AE, not have experienced recurrence of an AE if re-challenged. * Participants who have received more than one prior line of platinum-based chemotherapy in metastatic setting. * As judged by the investigator, any evidence of medical condition, which, in the investigator's opinion, makes it undesirable for the participant to participate in the study. * Participants who have received a prior ATR inhibitor. * Diagnosis of ataxia telangiectasia.