S1622 TANDEM AUTOLOGOUS‐REDUCED INTENSITY ALLOGENEIC STEM CELL TRANSPLANTATION IN HIGH‐RISK RELAPSED HODGKIN LYMPHOMA: A RETROSPECTIVE STUDY OF THE LWP‐EBMT

Background: Autologous stem cell transplantation (auto‐SCT) is considered the standard treatment for patients with relapsed or refractory (R/R) Hodgkin lymphoma (HL). For those with high‐risk disease, such as those with a short interval from diagnosis to auto‐SCT or those who have received multiple lines of therapy, an alternative consolidation strategy with allogeneic SCT (allo‐SCT) could be a potential option to improve the outcome. However, allo‐SCT with a reduced‐intensity conditioning (RIC) needs around 3 months for the graft‐versus‐lymphoma effect (GVL) to develop, thus in patients with an aggressive HL the disease might progress before this happens. In this setting, a tandem auto‐RIC‐SCT approach has the potential of combining cytoreduction to keep the lymphoma under control and the potential benefit of a GVL effect. Aims: We conducted a retrospective analysis of patients treated with this strategy between January 2004 and December 2015 and reported to the EBMT registry to analyze its efficacy in high‐risk patients. Methods: Patients were included if they had received an auto‐SCT followed by a planned RIC‐SCT in <6 months with no disease relapse between the procedures. The primary endpoint was progression‐free survival (PFS) after the tandem procedure. Results: One‐hundred and thirty patients [58% male, median age at auto‐SCT, 30 years (range: 18–65)] fulfilled the inclusion criteria. The median time between diagnosis (Dx) and auto‐SCT was 16 months (range: 2–174); with 21% of the patients having an interval Dx‐autoSCT of ≤12 months; the median number of lines prior to auto‐SCT 2 (2–4) and one third of the patients received ≥3 lines of therapy prior to auto‐SCT. Disease status at auto‐SCT was complete response in 32%, partial response in 27% and the remaining 41% were transplanted with active disease. The median time from auto to allo‐SCT was 3 months (1–6). Forty percent underwent an identical sibling allo‐SCT, 39% unrelated and 21% haplo. TBI was used in 35% of the patients as a part of RIC. GVHD prophylaxis was cyclosporine‐methotrexate in 36% of the patients, cyclosporine‐micofenolate mofetil in 16% and post‐transplant cyclophosphamide in the remaining 17%. 91% of the patients engrafted after RIC‐SCT. After a median follow‐up of 44 months (6–130), 33% of the patients have relapsed and 34% died. The main causes of death were SCT‐related in 53% and disease in 35%. 3y‐PFS, OS, IR and NRM were 53% (44–63), 72% (64–80), 34% (25–43) and 13% (8–20), respectively. 3y‐PFS and OS were 49% and 69%, respectively, for patients who received an auto‐SCT ≤12 months from diagnosis, whereas it was 54% and 72%, respectively, for those with an interval >12 months (p = NS for PFS and OS). There were no significant differences in PFS or OS according to the number of prior treatment lines: 3y‐PFS and OS of were 45% and 62% for patients with ≥3 lines in comparison with 57% and 77% (p = NS) for patients who had received <3 lines. Summary/Conclusion: This is the largest series analysing the efficacy and safety of a tandem auto‐RIC‐SCT approach in R/R HL. The low NRM and IR with promising PFS and OS suggest that this might be an effective procedure. Around half the patients with a time from diagnosis to auto‐SCT <12 months or ≥3 lines of treatment before auto‐SCT remain free of disease at 3 years, suggesting that this high risk population could benefit from this approach.