This study looks at two different medicines to see which works better to stop allergic reactions in patients with multiple myeloma (a type of blood cancer) who are getting ready for a stem cell transplant. The medicines are methylprednisolone and dexamethasone, both of which are corticosteroids that help reduce inflammation and allergic reactions. The trial is called the PARADE Trial. Patients who join will be given one of the two medicines before they get a drug called motixafortide, which helps collect stem cells. Some people have had allergic reactions to motixafortide, and this study wants to find the best way to prevent them.

• This trial involves comparing two steroid medications to see which one reduces reactions better when used with motixafortide.
• Participants will be divided into two groups, receiving different premedication regimens before motixafortide treatment.
• Participants will undergo several visits and tests, including stem cell collection and blood sampling.

Patients must be 18 or older, have multiple myeloma, be eligible for stem cell transplant, and follow the study schedule. Women of childbearing age need to use contraception during treatment. Those with certain medical histories are not eligible.