This Phase 1 study in healthy adults looks at whether sevabertinib changes how the body handles metformin. The study is based on the idea that sevabertinib may block kidney transporters (proteins that move medicines) called MATE1 and MATE2-K, which help remove metformin from the body. Each participant receives a single dose of metformin alone, and later receives sevabertinib for several days and then takes metformin again while still taking sevabertinib. The study aims to learn how metformin, gets into, moves through, and out of the body when it is administered with sevabertinib. This is called "Pharmacokinetics". Furthermore, the study will help us learn about the safety and tolerability of sevabertinib and metformin when given alone or in combination.