Abstract 4618: Response post first autologous stem cell transplantation (ASCT) for multiple myeloma identify patients who may benefit from tandem transplants: A single center prospective phase II study

Abstract

Abstract The role of tandem transplants as well as a later salvage second transplant has been in the center of interest for many myeloma investigators. Also, the need for tandem ASCT in patients (pts) achieving very good partial remission (VGPR) or complete remission has not been studied prospectively. We conducted a prospective phase II clinical trial in which enrolled myeloma pts are assessed after the first ASCT and offered either 2nd tandem ASCT if they achieve ≤ PR or maintenance if they achieve ≤ VGPR. These latter pts received 2nd salvage transplant after relapse. The conditioning regimens used were different for the two ASCT: Busulfan 0.75 mg/kg PO q 6 hr days –8 through –5, Cyclophosphamide (CP) 60 mg/kg IV days –3 and –2, and Etoposide 10 mg/kg IV days –4 to –2 for the first ASCT, and 96 hr (days –6 to –3) continuous IV CP 6 gr/m2 and total body irradiation (TBI) 600 cGy (days –2 and –1) for the second ASCT. Etoposide was omitted if pts were ≤ 65 year old, and TBI was substituted by melphalan 140 mg/m2 if prior radiation did not allow TBI. Between the years 2001-2009, 76 pts were enrolled. Of the 31 pts planned to have tandem ASCT, 20 received tandem ASCT, 2 additional pts had tandem auto-allo transplants and one patient had progressive disease. The primary reasons for not receiving the planned tandem ASCT were lack of socioeconomic resources and physical co-morbidities. Maintenance treatment was offered to both groups of pts. There were no treatment related mortalities in the ASCT pts. We compared the progression-free (PFS) and overall (OS) survival following the first ASCT between pts who received tandem ASCT (n=20) and pts who received single ASCT (n=54). The median PFS for tandem pts was 27 mo (range, 10-93) versus 28 mo for single ASCT (range, 4-99) (P=0.889); the OS was 38 mo (range, 11-120) versus 72 mo (range, 5-136), respectively (P=0.293). At the present time, a total of 7 (35%) and 30 (55%) pts are still alive in the tandem and single ASCT groups, respectively. Among the tandem pts, 2 underwent salvage ASCT and one non-myeloablative allogeneic transplant (allo-SCT); while in the single ASCT group 6 had salvage ASCT and 6 had allo-SCT. All salvage transplants were done at a median of 37 mo (range, 8-91) from 1st ASCT. In conclusion, pts who achieve ≤ VGPR after 1st ASCT have similar PFS and may be better OS than pts who had tandem ASCT. Thus, the use of such response criteria may identify a group of lower risk pts that will do well without the upfront tandem ASCT. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4618. doi:1538-7445.AM2012-4618