Post-relapse survival in Waldenstrom macroglobulinemia patients experiencing therapy failure following autologous transplantation.

Abstract

Waldenström macroglobulinemia (WM) is a rare B-cell lymphoproliferative malignancy. Autologous hematopoietic cell transplantation (auto-HCT) is considered in a subset of WM patients with relapsed disease. While registry data has shown a benefit for auto-HCT in relapsed WM, there is a paucity of data on outcomes of patients relapsing after auto-HCT. Eligibility criteria included adult patients with relapsed/refractory WM who underwent auto-HCT between 2007 and 2017. The primary endpoint was post-relapse overall survival (PR-OS). Secondary endpoints were to identify factors prognostic of PR-OS. Of the 48 patients with WM who underwent auto-HCT, 22 (46%) experienced relapse following auto-HCT. Median PR-OS of relapsed WM patients after auto-HCT (n=22) was not reached (NR) (95% confidence interval [CI]: 17.5months-NR). Among patients who relapsed <1year versus ≥1year from auto-HCT, the median PR-OS was 18.4months (95%CI: 0.8-NR) months and NR (95%CI: 17.5-NR), respectively (p=0.06). Of note, disease status at the time of transplant, CR/VGPR versus partial remission did not appear to impact PR-OS. The median PR-OS was significantly longer in patients who received ibrutinib in the post-transplant setting compared to those who did not (NR vs. 18.4 months, 95%CI: 9.1-NR, p=0.02). On univariable analysis, the presence of complex karyotype (RR=4.87, 95% CI=1.22-19.53) and a higher number of prior lines of therapy (RR=1.81, 95% CI=1.23-2.67) were associated with a significantly higher risk of relapse. This is the only study to date that evaluated outcomes of WM patients who relapsed following auto-HCT and provides a benchmark for future trials evaluating survival following auto-HCT relapse.