Can a simple pre-mobilization complete blood count predict stem cell yield? Low-cost predictors of CD34⁺ mobilization in multiple myeloma.

e19513 Background: Autologous hematopoietic stem cell transplantation (ASCT) remains a critical component of consolidation therapy in multiple myeloma. Adequate CD34⁺ stem cell yield is essential for transplant success; however, mobilization failure occurs in a substantial proportion of patients, leading to increased costs and resource utilization. While peripheral blood CD34 and mononuclear cell (MNC) monitoring guide leukapheresis, these assays are costly and not universally available. We evaluated whether routinely available pre-mobilization complete blood count (CBC) parameters could serve as affordable predictors of stem cell collection success. Methods: We performed a retrospective analysis of 94 newly diagnosed multiple myeloma patients undergoing stem cell mobilization and collection between 2018 and October 2025 at a tertiary cancer centre. All patients received G-CSF–based mobilization, with pre-emptive plerixafor administered when clinically indicated. Pre-mobilization CBC indices—including hemoglobin, total leukocyte count (TLC), absolute neutrophil count (ANC), absolute lymphocyte count (ALC), absolute monocyte count (AMC), platelet count, and platelet-to-WBC ratio—were correlated with CD34⁺ yield. Statistical analyses included chi-square testing, univariate and multivariable logistic regression, and receiver operating characteristic (ROC) curve analysis. Results: Among 94 multiple myeloma patients (median age 59 years; 57% male), most had ISS stage I–II disease (82%) and IgG myeloma (89%). Median baseline hemoglobin was 12.3 g/dL, and the majority received lenalidomide-based induction, achieving a median CD34⁺ yield of 6.6 × 10⁶/kg. Excellent CD34⁺ yield was significantly associated with MNC count (p = 0.017), total leukocyte count (p = 0.037), absolute monocyte count (AMC; p = 0.018), and plerixafor use (p = 0.003). On multivariable analysis, pre-mobilization platelet count ≥164 × 10⁹/L independently predicted excellent mobilization. ROC analysis showed modest discrimination for platelet count (AUC ≈ 0.61) with high sensitivity (~97%). In patients mobilized without plerixafor, ANC ≥2.775 × 10⁹/L and AMC ≥0.475 × 10⁹/L demonstrated the best overall discriminatory performance. Conclusions: A simple pre-mobilization platelet count is a low-cost, widely available, and independent predictor of excellent CD34⁺ stem cell yield in multiple myeloma. Integration of CBC-based markers may enable earlier risk stratification, optimize apheresis timing, guide selective plerixafor use, and reduce unnecessary costs in resource-constrained settings. Prospective validation and composite CBC-based predictive models are warranted.