Trends in Autologous Transplantation for Myeloma in EBMT Centres between 1993 and 2017

Introduction

The use of autologous haematopoietic cell transplantation (auto-HCT) in the treatment of myeloma (MM) has greatly increased over the last twenty-five years. There are, however, few large datasets detailing the overall trends in transplant use, patient selection, induction regimen, choice of mobilisation regimen, stem cell yield, response to transplant and survival. We performed a retrospective analysis of all patients who underwent first auto-HCT for MM in EBMT centres between 1993 and 2017 and analysed these trends over consecutive five-year cohorts: (1) 1993-1997, (2) 1998-2002, (3) 2003-2007, (4) 2008-2012 and (5) 2013-2017.

Methods

Data on patients with MM who underwent a first auto-HCT at EBMT centres between 1993 and 2017 were obtained from the EBMT registry. Med-A forms consist of registration and follow-up forms. More detailed information in captured in Med-B forms.

Results

A total of 103,032 patients in 568 centres in 54 countries were included in this analysis. The number of transplants increased seven-fold between the first and fifth cohorts: (1) 5,246, (2) 12,554, (3) 21,153, (4) 28,390 and (5) 35,689. The gender breakdown has been consistent over time: 58% Male, 42% Female. Over these years, the median patient age at transplant has increased significantly, as follows: (1) 54, (2) 57, (3) 58, (4) 59, and (5) 61 years. The percentage of patients >65 years at transplant has also increased: (1) 3%, (2) 9%, (3) 14%, (4) 14%, and (5) 22%. Between 1993 and 1997, IgG, IgA and Light Chain (LC) MM constituted 58%, 22% and 16%, respectively. The corresponding percentages between 2013 and 2017 were 52%, 18% and 27%, respectively.

Data on the choice of first induction regimen was available in 19,882 (21%) cases (Med-B forms) though only cohorts 4 (2008-2012) and 5 (2013-2017) had specific data in more than 80% of cases. The trends in the percentage use of these regimens in the two cohorts since 2008 are as follows: VTD: 11% to 32%; VCD: 5% to 20%; CTD 15% to 10%; VD: 19% to 7%; PAD 5% to 4%; VRD 2% to 3%; VAD: 8% to 3%. The CR rates pre-ASCT have improved: (1) 16% (2) 14% (3) 13% (4) 20% and (5) 21%; >PR rates pre-ASCT also reveal deeper responses over time: (1) 65%, (2) 68%, (3) 70%, (4) 72%, and (5) 73%.

Stem cell mobilisation regimen data was available in 19,882 (19%) cases. In these centres, the use of cyclophosphamide has steadily increased: (1) 31%, (2) 54%, (3) 63%, (4) 64%, and (5) 65%. Conversely, the use of single agent G-CSF has declined: (1) 69%, (2) 45%, (3) 36%, (4) 31%, and (5) 28%. G-CSF + Plerixafor was used in 3.5% of cases from 2008-2012 and 5% in 2013-2017. The median number of stem cells collected (CD34+cells x 10^6/kg) has gradually increased: (1) 5.1, (2) 5.2, (3) 6.3, (4) 6.6, and (5) 6.5, though the median cell dose infused has remained relatively constant: (1) 3.6, (2) 4.1, (3) 4.0, (4) 3.8, and (5) 3.8. Almost all (99%) patients received peripheral blood (PB) stem cells. The number of months from diagnosis to auto-HCT has been stable since 1998: (1) 8.9, (2) 7.7, (3) 7.4, (4) 7.4, and (5) 7.3. Finally, three-year overall survival (OS) post-transplant has risen from 65% to 81% and Progression-Free Survival (PFS) from 41% to 46% (Figure 1).

Conclusions

This very large dataset shows consistently increasing numbers of auto-HCT for MM in Europe over the last 25 years. Although it is still sometimes stated that 65 years is the upper age limit for auto-HCT in Europe, 22% of auto-HCT recipients in the most recent cohort were older. Analysis of MM subtypes shows an increasing rate of auto-HCT for patients with LC MM, possibly facilitated by the deeper responses which are now being achieved, overall CR rates having risen from 16% to 21% and >PR rates from 65% to 73%. Most patients (59%) in the most recent cohort (2013-2017) received bortezomib-based triplet induction regimens: VTD: 32%; VCD: 20%; PAD 4%; VRD 3%. Data from a subset of centres confirm the use of cyclophosphamide-based stem cell mobilisation in two-thirds; only 5% used G-CSF + Plerixafor. The median stem cell yield has increased by a quarter. As the median cell dose infused remains unchanged, this most likely reflects increasing rates of storage for subsequent transplants. Finally, serial cohort analysis reveals rising rates of OS and PFS over the 25 years, reflecting the deeper responses achieved pre-transplant and the increasing availability of novel agents, whether in the setting of consolidation or maintenance.

Figure 1

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Figure 1

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