A Study to Investigate the Pharmacokinetics and Safety of Subcutaneous Rilvegostomig in Adult Participants With Advanced Solid Tumors Previously Treated With Standard of Care Therapy

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: this may include chemotherapy, immunotherapy, or targeted therapy as considered standard of care, where clinically appropriate. * IO monotherapy considered clinically appropriate and reasonably likely to permit study participation through at least the PK-evaluable period, in the investigator's judgment. * 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 or allogeneic stem cell 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 B or C infection or any other active or uncontrolled infection requiring systemic treatment. * Clinically significant or uncontrolled cardiovascular disease, including clinically significant arrhythmias, symptomatic heart failure, cardiomyopathy or myocarditis, recent myocardial infarction or unstable angina, or uncontrolled hypertension. * Active or ongoing interstitial lung disease (ILD)/ pneumonitis, serious chronic gastrointestinal conditions associated with diarrhea; primary immunodeficiency, or non-infectious skin disease requiring systemic treatment. * Active or prior documented autoimmune or inflammatory disorders requiring chronic systemic treatment with the use of disease-modifying agents, corticosteroids, or immunosuppressive drugs. * 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.