Treatment with Daratumumab in Combination with Glucocorticosteroids as First-Line Treatment Achieves a Complete Remission for a Patient with Multiple Myeloma and Resolves Neutropenia: A Case Report.

Introduction: Multiple myeloma (MM) is a bone marrow malignancy of plasma cells that can be treated with monoclonal antibodies (mAbs) including daratumumab. This mAb binds to CD38 proteins expressed on MM cells, allowing the immune system to recognize and kill these tumor cells. Neutropenia is a common complication in MM, often attributed to the disease itself or treatment with agents such as immunomodulatory drugs. However, its resolution with first-line mAb therapy has not previously been reported. Case Presentation: We report a case of a 32-year-old Filipino female with smoldering MM. She developed neutropenia and as a result was treated with a combination of daratumumab and glucocorticosteroids. She achieved a complete remission (CR), and her absolute neutrophil count normalized. The treatment was well tolerated with no adverse effects reported, and the patient remains in CR after more than 3 years of therapy. Discussion: This case highlights the potential for daratumumab combined with glucocorticosteroids alone to effectively manage a patient's MM and severe neutropenia, suggesting a dual therapeutic benefit without treatment-related toxicity. Our findings support the consideration of daratumumab and glucocorticosteroids as a viable first-line therapeutic option for patients with MM who develop neutropenia.