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ASCT Produces Deeper Responses Following Salvage Therapy in Relapsed WM
According to a retrospective cohort analysis, autologous stem cell transplantation (ASCT) is a feasible treatment option for patients with relapsed Waldenström macroglobulinemia (WM). These data were presented at the 2021 American Society of Hematology (ASH) Annual Meeting.
“The role of ASCT in WM is not well established, largely due to the paucity of evidence. It remains unclear where ASCT should be placed in the sequence of treatment lines. The debate is stronger in the era of targeted therapies that can achieve prolonged progression free survival (PFS) intervals and expected treatment-free intervals of approximately 4 to 8 years,” explained Suzanne O. Arulogun, MBBS, FRACP, FRCPA, University College London Hospitals NHS Foundation Trust, London, United Kingdom, and co-investigators.
Thus, Dr Arulogun and the study investigators reviewed response and survival outcomes, as well as relapse risk factors, in WM patients who underwent ASCT at a single WM referral center between 2003 and 2020. The primary end point was depth of response, overall survival (OS), PFS, transplant-related mortality (TRM), and relapsed-associated mortality.
In all, 32 patients received an ASCT, with the median age at time of ASCT of 57 years, and the median interval from diagnosis to ASCT of 2.3 years. Conditioning therapies included LEAM or lomustine, etoposide, cytarabine, and melphalan (18 patients, 56.2%); BEAM or carmustine, etoposide, cytarabine, and melphalan (12 patients, 37.5%); or melphalan only (2 patients, 6.2%). Every patient had a successful engraftment
Prior to ASCT, 11 patients (34%) had 1 prior therapy, 11 patients had 2 prior lines, and 10 patients had 3 or more. The disease status pre-ASCT was complete remission (CR)/very good partial response (VGPR) in 14 patients (43.7%) and partial response (PR) in 18 patients (56.2%).
The median time from stem cell reinfusion to hiatal discharge was 15.5 days in the 24 patients who were evaluable. Out of them, 5 patients (21%) were discharged >25 days after the reinfusion. Restaging at day 100 post-ASCT showed a deepening of response by ASCT in 17 patients (53.1%). CR/VGPR was met by 26 patients (81.2%) and PR by 4 patients (12.5%). Disease progression before day 100 post-ASCT happened in 2 patients (6.2%, both receiving ASCT in second remission).
At the median follow-up of 8.9 years, the estimated median PFS was 4.5 years (95% CI, 3.2-5.7), with estimated 2- and 5-year PFS rates of 75 percent and 35.9 percent, respectively. At the time of the analysis, 14 patients (43.7%) died. The TRM rate was 6.2 percent, 4 patients died of Parkinson disease (PD), and 1 patient died of unknown reasons. Another 7 patients died of infections after the immediate post-ASCT period. The median time from ASCT to death among these patients was 5.5 years. The estimated median OS was 10.8 years (95% CI, 7.3-14.3), with estimated 2- and 5-year OS rates of 87.5 percent and 77.5 percent, respectively. One patient (3.1%) underwent ASCT after BTK inhibitor therapy, which achieved a deep response (PR to VGPR) with ASCT and PFS of 11 months.
“ASCT is a feasible treatment option for patients with relapsed WM, producing deeper responses following salvage therapy and resulting in PFS intervals comparable to other currently available therapeutic options. With the benefit of a long follow up period, performing ASCT at later stages in the treatment course did not appear to result in inferior survival outcomes; timing of ASCT should therefore be considered on an individual patient basis and in light of other available therapy options for relapsed disease,” concluded Dr Arulogun et al.—Emily Bader
Arulogun S, Kyriakou C, Horder J, et al. Autologous Haematopoietic Stem Cell Transplantation in Waldenström Macroglobulinemia: A Single-Centre 18-Year Experience. Presented at: the 2021 ASH Annual Meeting; Dec. 11-14; 2021; Abstract 3548.
