Moving Beyond G‐CSF Mobilization—Learning From a 15‐Year Experience of Different Stem Cell Mobilization Regimens in Multiple Myeloma
Sumeet Mirgh, Bhausaheb Bagal, Sachin Punatar, Anant Gokarn, Nishant Jindal, Akanksha Chichra, Lingaraj Nayak, Sumathi Hiregoudar, Minal Poojary, Suryatapa Saha, Sarika Parab, Shashank Kumar Ojha, Prashant Tembhare, Nikhil Patkar, Sweta Rajpal, Gaurav Chatterjee, Libin Mathew, Papagudi Ganesan Subramanian, Navin Khattry
Abstract
ABSTRACT Background Stem‐cell mobilization in multiple myeloma is usually done with G‐CSF with or without Cyclophosphamide (Cy) based chemotherapy/Plerixafor. Pre‐clinical data suggest the role of proteasome inhibitors in mobilization. We previously reported that Bortezomib (Bort) when added to a Cy‐based regimen had a better stem‐cell yield. Consequent to favorable results with Bort + Cy‐G‐CSF, we used Bortezomib with G‐CSF too. Hence, four different mobilization regimens were used—Bort + G‐CSF (Group‐1); G‐CSF + Plerixafor (Group‐2); Bort – Cy‐G‐CSF (Group‐3); Cy + G‐CSF (Group‐4). We report here our 15‐year retrospective analysis of these 4 mobilization regimens. Objectives Primary objective was to determine proportion of patients with CD34 + dose ≥ 5 × 10 6 /kg in first apheresis in various groups. Secondary objectives were to determine median CD34 + dose (×10 6 /kg) in first apheresis, total median CD34 + dose (×10 6 /kg) of all harvests and frequency of mobilization failure. Mobilization failure was defined as total CD34 + dose of < 2 × 10 6 /kg or abandoned harvest attempt at physician's discretion after anticipating a poor collection. Results All consecutive patients with MM aged 18–65 years who underwent stem‐cell mobilization from September 2007–December 2022 were included. In an intention‐to‐treat analysis, a total 200 patients with 205 mobilization attempts were analysed. The median age of the cohort was 48 years. The percentage of patients who collected ≥ 5 × 10 6 CD34 + cells/kg in the first apheresis was 26%, 53%, 69%, and 63% in Groups 1–4, respectively ( p = 0.0001). The median CD34 yield in the first harvest (×10 6 /kg) was 3.62, 5.20, 6.04, and 6.05 in Groups 1–4, respectively ( p = 0.00004). The median total stem‐cell dose collected (×10 6 /kg) was 5.73, 6.17, 9.14, and 8.23 in Groups 1–4, respectively ( p < 0.00001). Mobilization failure rates were 7%, 3%, 0%, and 2%, respectively ( p = NS). Conclusion Cyclophosphamide‐based chemo‐mobilization regimens with or without Bortezomib have the advantage of higher total stem‐cell yield, while they are equivalent to G‐CSF + Plerixafor for harvest in a single apheresis. The addition of Bortezomib to Cyclophosphamide may help to increase stem cell yield.