The Prognosis of PR Patients after Induction Therapy Was Not Inferior to CR in ASCT-Eligible NDMM Patient.

Introduction:

Autologous stem cell transplantation (ASCT) is standard therapy for newly diagnosed multiple myeloma (NDMM) patients who are younger than 70 years old. In the IFM 90 trial, 5-year OS was 52% in the ASCT group compared to 12% in the initial chemotherapy group (p=0.03). 5-year EFS was 28% in the ASCT group compared to 10% in the chemotherapy only group (p=0.01). MRC Ⅳ trial also showed a higher rate of OS (p=0.04) and PFS (p<0.001) in the ASCT group. However, there was no result about the differences of the prognosis between CR and PR before ASCT. In this study, we studied the response level before ASCT to understand if it is related to the prognosis after ASCT.

Methods:

We studied 25 NDMM patients who received ASCT in our hospital from 2005 to 2015. Induction therapies were VRD, VCD, VAD, VD, Rd or VTD-PACE. Stem cells were collected using G-CSF or cyclophosphamide plus G-CSF. After stem cell harvest, all patients underwent high dose melpharan (200mg/m2) before ASCT. The responses according to the IMWG guidelines were performed at the point of 4-6 weeks after ASCT. Statistical analyses were performed using a software, EZR version 1.

Results:

The total number of NDMM patients was 25. The median age was 55 years (range 33-62), the median follow-up period was 1,375 days (range 340-3,763). Male were 16 (64%), 11 patients (44%) were ISS Ⅱor more and 20 (80%) were D&S stageⅡor more. ECOG PS 2 was 4 patients (8%) and one (4%) is ECOG PS 3. Before ASCT, 21 patients (84%) received 1 regimen and 4 (16%) received 2 regimens. In the 1 regimen group, 9 patients (43%) were treated by VCD with 2-4 cycles, 9 received VD with 4-5 cycles and 5 (24%) were received VAD with 3 cycles before ASCT. In the 2 regimens group, details of induction therapy were VD with BCD, VCD with Rd, VCD with VRD and VCD with VTD-PACE. In all patients, 3-year OS was 91.6% (95% CI, 70-98%) and 3-year PFS was 56% (95% CI, 34-74%). After induction therapy, CR was achieved in 11 (44%), VGPR was 2 (8%), PR was 11 (44%) and MR was 1 (4%). After ASCT, CR was achieved in 18 (72%), VGPR was 2 (8%), PR was 4 (16%) and PD was 1 (4%). 4 patients (16%) died for progression of multiple myeloma.

There were no statistical differences in 3-year OS and PFS between CR group and VGPR + PR group after induction therapy (3-year OS; 100% vs 92%, p=0.11, 3-year PFS; 70% vs 50%, p=0.26). There were also no differences between the two groups CR group and PR without VGPR group (3-year OS; 100% vs 90%, p=0.18a, 3-year PFS; 70% vs 60%, p=0.4). As sub-analysis, the achievement time until normalization of FLC and disappearance of serum or urine M-protein in IFE did not affect 3-year OS and PFS.

Discussion and Conclusions:

When MM patients having residual disease did the stem-cell harvest, it has been possible to contaminate of myeloma cells in their collected stem cells. Several literatures described the contamination of myeloma cells in the stem cells induced inferior prognosis after ASCT. However our limited data suggested that the prognosis of patients who had residual disease after induction therapy, if they had achieved better than PR, were not inferior to CR group. This is reasonable data for recommendation of ASCT to MM patients getting PR after induction therapy.