Bortezomib-High Dose Melphalan Conditioning for the Treatment of MM Patients Undergoing ASCT

Introduction Recent data suggests that bortezomib, a proteasome inhibitor, in combination with high-dose melphalan (Bor-HDM) provides with a synergistic effect able to improve the level of response for MM patients undergoing auto-SCT. In the present study, patients receiving induction followed by ASCT with Bor-HDM and HDM alone were evaluated. Methods All consecutive patients undergoing ASCT from 01/2004 to 03/2016 were evaluated. All patients received induction chemotherapy before undergoing auto-SCT. Patients received conditioning with either HDM at 200 mg/m² (or adjusted as per renal failure) or HDM with Bortezomib (Bor-HDM). Most of patients received Bortezomib conditioning at 1.3 mg/m2. As per physician discretion, the dose of 1 mg/m2 was also employed in 30% of cases. Definitions of response and progression were used according to the EBMT modified criteria. MRD negativity was assessed by flow cytometry at day-100 post-ASCT. Results Clinical characteristics are shown in Table 1. Among 301 cases, 129 were treated with Bor-HDM while 172 patients went onto receive HDM alone as part of the conditioning regimen. Induction regimens are shown in Table 1. At the time of analysis, 83% and 58% of patients in the Bor-HDM and HDM group are still alive and 34% and 69.1% of patients have already progressed, respectively. At day-100 post ASCT, ORR of 97%, with CR/VGPR rate of 84.2% was seen in the Bor-HDM group compared to 94.2% and 68.6% in the HDM group (p=0.001). MRD negativity was higher in the Bor-HDM group (33.3%) compared to HDM (12.2%) (p=0.001). Median OS was similar for Bor-HDM and HDM (p=0.864) (Fig 1a). In addition, median PFS did not differ among patients receiving HDM or Bor-HDM (37.7months vs 29.3 months, p=0.2) (Fig1b) In conclusion,Bor-HDMis a conditioning regimen able to provide higher rates ofnCR/CR, as well as MRD negativity compared to HDM alone. Further studies are warranted to explore this regimen, especially when other upfront therapies are employed.

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Overall Survival according to the conditioning regimen employed for patients with MM undergoing ASCT

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Overall Survival according to the conditioning regimen employed for patients with MM undergoing ASCT

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Figure 1

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Progression-Free Survival according to the conditioning regimen employed for patients with MM undergoing ASCT

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Progression-Free Survival according to the conditioning regimen employed for patients with MM undergoing ASCT

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