Collection of Stem Cell Early In the Disease Course of Multiple Myeloma Is Associated with Early Engraftment.
Authors: Buadi Francis , Dispenzieri Angela , Kumar Shaji , Lacy Martha , Dingli David , Hayman Suzanne R. , Hogan William J , Leung Nelson , Gastineau Dennis , Gertz Morie Abraham A 
Published: October 2019

Abstract
Abstract 4518

Introduction:
Autologous stem cell transplant (PBSCT) is an integral part of the management of Multiple Myeloma (MM). Available data suggest that the timing of PBSCT has no effect on overall outcome. Some patients currently opt to delay their transplant, especially in this era of proteosome inhibitors and iMIDs. In such patients the best time for stem cell collection is unknown. We conducted a retrospective study looking at early stem collection and storage compared to stem cell collection at the time of transplant in patients who opt to be transplanted at a later date.

Method:
All patients who had PBSCT performed more than one year from the time of diagnosis were reviewed. Two groups of interest were then evaluated. Early collection (ET): those who had stem cells collected within 6 months of diagnosis, and Late collection (LT): those who had stem cells collected more than 1 year from diagnosis and within 3 months of PBSCT.

Results:
Table 1 shows some patient characteristics. 334 patients were identified, ET (85) and LT (249). Gender distribution, Durie Salmon stage, immunoglobulin subtype and cytogenetic abnormalities were similar in both groups. The LT group was older 60 yrs compared to ET 56.6 yrs, P=0.02. More patients in the ET (77%) group were mobilized with cyclophosphamide compared to LT (51%) p<0.0001. Stem cell yield was similar in both groups 9.26 × 10(6) CD34/kg in ET and 8.19 × 10(6) in LT, P=0.16. Median number of collections was 3 in both. More patients in the LT (67%) received Melphalan 200 mg/m2 conditioning compared to ET (59%) p=0.03. Neutrophil engraftment occurred at day + 11 ET and +12 (LT) p<0.0001. ET patients achieved platelet engraftment on day + 13 compared to + 15 (LT) p=0.002. Complete response rates were similar 30% (ET) and 34% (LT). Duration of response after PBSCT was not different 12.6 months (ET) and 11.6 months (LT). Median overall survival from diagnosis was 70.5 months (ET) and 74.5 months (LT) p=0.5. Similarly there was no difference in overall survival post PBSCT 33.5 month (ET) and 32.2 months (LT).

Conclusion:
Stem cell collection and storage early in the disease course of multiple myeloma results in early engraftment compared to stem cell collection at the time of transplant in patients who opt for a delayed transplant. More studies looking at cost analysis will however be need to determine the cost effectiveness of early versus late stem cell collection.

Disclosures:
Dispenzieri: Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Kumar:Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding. Gertz:Celgene: Honoraria; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees.