Post‐relapse survival in Waldenstrom macroglobulinemia patients experiencing therapy failure following autologous transplantation. Issue 1 (20th November 2021) - Ahmed, Sairah
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]: 17.5 months‐NR). Among patients who relapsed <1 year versus ≥1 year from auto‐HCT, the median PR‐OS was 18.4 months (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.