A Phase I Dose Escalation and Dose Expansion Study to Investigate the Pharmacokinetics and Safety of Subcutaneous Durvalumab

Inclusion Criteria: * An Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Life expectancy of ≥ 12 weeks at enrolment. * Adequate organ and marrow function. * Minimum body weight \> 30 kg. Part 1 only: Locally Advanced Unresectable (Stage III) NSCLC Participants - * Histological or cytological documented evidence of NSCLC (locally advanced, unresectable, Stage III). * Must have received at least 2 cycles of platinum-based chemotherapy concurrent with definitive radiation therapy. * Have not progressed following definitive concurrent chemoradiation. LS-SCLC Participants - * Histologically or cytologically documented LS-SCLC (Stage I-III). * Received 4 cycles of chemotherapy concurrent with radiotherapy, which must be completed within 1 to 42 days prior to enrolment. * Have not progressed following definitive concurrent chemoradiation. Part 1 and 2: Unresectable HCC Participants - * Unresectable HCC based on histopathological confirmation. * No prior systemic therapy for unresectable HCC. * Must not be eligible for locoregional therapy for unresectable HCC. * Child-Pugh Score class A. * Measurable disease as defined by RECIST v1.1. Exclusion Criteria: * Active or prior documented autoimmune disease requiring systemic treatment. * Uncontrolled infection (including human immunodeficiency virus \[HIV\], hepatitis B or C). * Prior exposure to immune checkpoint inhibitors. Part 1 only: Locally Advanced Unresectable (Stage III) NSCLC Participants - * Mixed SCLC and NSCLC histology. * Active pneumonitis or interstitial lung disease requiring systemic therapy. LS SCLC Participants - * Mixed SCLC and NSCLC histology. * Extensive-stage disease. * History of Grade ≥ 2 pneumonitis. Part 1 and 2: Unresectable HCC Participants - * Hepatic encephalopathy. * Uncontrolled ascites. * Active gastrointestinal (GI) bleeding.