The most common means of mobilizing autologous stem cells is G-CSF alone or combined with cyclophosphamide (CY) to obtain sufficient CD34+ cells for one to two transplants. There are few prospective, randomized studies investigating mobilization regimens in multiple myeloma (MM), especially after lenalidomide-based induction. We designed this prospective, randomized study to compare low-dose CY 2 g/m2+G-CSF (arm A) and G-CSF alone (arm B) after lenalidomide-based up-front induction in MM. Of the 80 initially randomized patients, 69 patients were evaluable, 34 and 35 patients in arms A and B, respectively. The primary end point was the proportion of patients achieving a yield of ⩾3 × 106/kg CD34+ cells with 1−2 aphereses, which was achieved in 94% and 77% in arms A and B, respectively (P=0.084). The median number of aphereses needed to reach the yield of ⩾3 × 106/kg was lower in arm A than in arm B (1 vs 2, P=0.035). Two patients needed plerixafor in arm A and five patients in arm B (P=0.428). Although CY-based mobilization was more effective, G-CSF alone was successful in a great majority of patients to reach the defined collection target after three cycles of lenalidomide-based induction.

Background Autologous stem cell transplantation (auto‐SCT) is a widely used treatment option in multiple myeloma (MM) patients. The optimal graft cellular composition is not known. Study design and methods Autograft cellular composition was analyzed after freezing by flow cytometry in 127 MM patients participating in a prospective multicenter study. The impact of graft cellular composition on hematologic recovery and outcome after auto‐SCT was evaluated. Results A higher graft CD34+ cell content predicted faster platelet recovery after auto‐SCT in both the short and long term. In patients with standard‐risk cytogenetics, a higher graft CD34+ count (>2.5 × 106/kg) was linked with shorter progression‐free survival (PFS; 28 vs. 46 months, p = 0.04), but there was no difference in overall survival (OS) (p = 0.53). In a multivariate model, a higher graft CD34+CD133+CD38− (>0.065 × 106/kg, p = 0.009) and NK cell count (>2.5 × 106/kg, p = 0.026), lenalidomide maintenance and standard‐risk cytogenetics predicted better PFS. In contrast, a higher CD34+ count (>2.5 × 106/kg, p = 0.015) predicted worse PFS. A very low CD3+ cell count (≤20 × 106/kg, p = 0.001) in the infused graft and high‐risk cytogenetics remained predictive of worse OS. Conclusions Autograft cellular composition may impact outcome in MM patients after auto‐SCT. More studies are needed to define optimal graft composition.

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Autologous stem cell transplantation (ASCT) combined with novel agents is the standard treatment for transplant-eligible, newly diagnosed myeloma (NDMM) patients. Lenalidomide is approved for maintenance after ASCT until progression, although the optimal duration of maintenance is unknown. In this trial, 80 patients with NDMM received three cycles of lenalidomide, bortezomib, and dexamethasone followed by ASCT and lenalidomide maintenance until progression or toxicity. The primary endpoint was the proportion of flow-negative patients. Molecular response was assessed if patients were flow-negative or in stringent complete response (sCR). By intention to treat, the overall response rate was 89%. Neither median progression-free survival nor overall survival (OS) has been reached. The OS at 3 years was 83%. Flow-negativity was reached in 53% and PCR-negativity in 28% of the patients. With a median follow-up of 27 months, 29 (36%) patients are still on lenalidomide and 66% of them have sustained flow-negativity. Lenalidomide maintenance phase was reached in 8/16 high-risk patients but seven of them have progressed after a median of only 6 months. In low- or standard-risk patients, the outcome was promising, but high-risk patients need more effective treatment approach. Flow-negativity with the conventional flow was an independent predictor for longer PFS.Electronic supplementary materialThe online version of this article (10.1007/s00277-019-03815-7) contains supplementary material, which is available to authorized users.

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