Efficacy of stem cell mobilization in patients with newly diagnosed multiple myeloma after a CTD (cyclophosphamide, thalidomide, and dexamethasone) regimen

The CTD (cyclophosphamide, thalidomide, and dexamethasone) regimen is known to be an effective primary therapy in patients with newly diagnosed multiple myeloma (MM). However, stem cell yields after CTD remain inconsistent. The aim of the present study is to identify the influence of the CTD regimen on the outcome of peripheral blood stem cell (PBSC) collection. Fifty-four patients received four cycles of CTD, and PBSCs were mobilized with cyclophosphamide and G-CSF or with G-CSF alone. Each patient from whom ≤4.0 × 10⁶ CD34⁺ cells/kg were collected received a second mobilization course. The median duration from the start of a CTD regimen to the first collection was 4.3 months. Forty-eight patients were mobilized with cyclophosphamide followed by G-CSF, and six patients were mobilized with G-CSF alone. The median day of apheresis was day 3 (range day 2–day 5). The overall response rate at mobilization was 96.3 %, including 11.1 % complete response, 22.2 % very good partial response, and 63.0 % partial response. The median number of harvested CD34⁺ cells was 12.8 × 10⁶ cells/kg. At the second mobilization, 88.9 % of patients reached the minimal stem cell collection target of ≥2.0 × 10⁶ cells/kg, and 75.9 % of patients achieved the collection target of ≥4.0 × 10⁶ cells/kg. CTD within four cycles is an effective primary therapy in patients with newly diagnosed MM and only minimally affects subsequent PBSC collection.