Prevention of Delayed CINV After Autologous Transplant: Olanzapine-Containing Regimen vs. Dexamethasone-Containing Regimen

This study compares two anti-nausea medication regimens for patients with multiple myeloma who are receiving high-dose chemotherapy (melphalan) before a stem cell transplant, to see which better controls delayed nausea and vomiting that can occur several days after chemotherapy. **You may be eligible if...** - You have multiple myeloma and are scheduled for an autologous stem cell transplant (using your own stem cells) - Your preparatory chemotherapy regimen includes high-dose melphalan (200 mg/m²) - You are between 18 and 65 years old - Your overall health is adequate (ECOG 0-2) and expected survival is more than 3 months - You do not have increased pressure in the skull or gastrointestinal obstruction **You may NOT be eligible if...** - You have nausea or vomiting within 48 hours before enrollment, with prior antiemetic use - You are currently taking certain medications that interact with the study drugs (CYP3A4 inducers or inhibitors) - You have a known allergy to fosaprepitant or olanzapine - Your kidney function is significantly reduced (creatinine clearance below 60 mL/min) - You are unable to complete treatment and follow-up at the study site Talk to your doctor to see if this trial is right for you.