This study is exploring a new treatment for **Multiple Myeloma**, a cancer that affects white blood cells in the bone marrow. It's testing a drug called **BGB-11417** alone and with other drugs, **dexamethasone** and **carfilzomib**. Dexamethasone is a medicine that reduces inflammation, and carfilzomib helps to stop cancer cells from growing. The study is divided into two parts: the first part tests different doses of BGB-11417, and the second part looks at how well the treatment works. To join, you must have **Multiple Myeloma** with certain measurable disease markers and have tried other treatments before. Some health conditions can exclude you from participating, like serious heart issues or active infections like hepatitis or HIV. The drugs will be given through a vein, which is called intravenously. **Key Points:** - **Study Length:** The study is ongoing, with specific duration for each participant not mentioned. - **Visits Needed:** Regular visits are required for treatment and monitoring. - **Risks:** Possible side effects from the drugs; eligibility depends on health history. This study presents a potential new treatment option for people who haven't had success with other therapies.