A Phase I, Multicenter, Dose Finding and Dose Confirmation Study to Investigate the Pharmacokinetics, and Safety of Subcutaneous Rilvegostomig in Adult Participants With Advanced Solid Tumors Previously Treated With Standard of Care Therapy (ARTEMIDE-subQ)

Inclusion Criteria: * Histologically or cytologically documented advanced (metastatic and/or unresectable) solid tumor. * Participants must have received prior anticancer treatment for the disease under study. * IO monotherapy deemed appropriate by the investigator. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 at enrollment with no deterioration. * Minimum life expectancy of ≥ 12 weeks at enrollment. * Adequate organ and marrow function. * Body weight ≥ 30 kg. Exclusion Criteria: * Any severe or uncontrolled systemic diseases, which makes it undesirable for the participant to participate in the study or that would jeopardize compliance with the protocol. * History of organ transplant. * History of another primary malignancy that was active within past 2 years. * Persistent toxicities caused by previous anticancer treatment(s) excluding alopecia, not yet improved to Grade ≤ 1 or baseline. * Unstable, symptomatic brain metastasis or spinal cord compression. * History of leptomeningeal carcinomatosis. * Active primary immunodeficiency/active infectious disease including tuberculosis (TB), human immunodeficiency virus (HIV) infection or hepatitis A, B or C infection. * History of clinically significant arrhythmia, cardiomyopathy of any etiology; symptomatic congestive heart failure, history of myocardial infarction within the past 6 months. * Uncontrolled intercurrent illness including but not limited to ongoing or active known infection; interstitial lung disease (ILD), serious chronic gastrointestinal conditions associated with diarrhea; active non-infectious skin disease requiring systemic treatment. * Active or prior documented autoimmune or inflammatory disorders requiring chronic treatment with steroids or other immunosuppressive treatment. * Known allergy or hypersensitivity to rilvegostomig, hyaluronidase, or any excipients of the investigational products. * Participants experienced a toxicity to prior immunotherapy that led to permanent discontinuation of prior immunotherapy. * Prior anticancer treatment, including immunotherapy, up to 28 days prior to the first dose of study treatment.