Haematologic malignancies with unfavourable gene mutations benefit from donor lymphocyte infusion with/without decitabine for prophylaxis of relapse after allogeneic HSCT: A pilot study

Relapse is the main cause of treatment failure for leukaemia patients with unfavourable gene mutations who receive allogeneic haematopoietic stem cell transplantation (allo-HSCT). There is no consensus on the indication of donor lymphocyte infusion (DLI) for prophylaxis of relapse after allo-HSCT. To evaluate the tolerance and efficacy of prophylactic DLI in patients with unfavourable gene mutations such as FLT3-ITD, TP53, ASXL1, DNMT3A or TET2, we performed a prospective, single-arm study. Prophylactic use of decitabine followed by DLI was planned in patients with TP53 or epigenetic modifier gene mutations. The prophylaxis was planned in 46 recipients: it was administered in 28 patients and it was not administered in 18 patients due to contraindications. No DLI-associated pancytopenia was observed. The cumulative incidences of grade II-IV and III-IV acute graft-versus-host disease (GVHD) at 100 days post-DLI were 25.8% and 11.0%, respectively. The rates of chronic GVHD, non-relapse mortality and relapse at 3 years post-DLI were 21.6%, 25.0% and 26.1%, respectively. The 3-year relapse-free survival and overall survival (OS) rates were 48.9% and 48.2%, respectively. Acute GVHD (HR: 2.30, p = 0.016) and relapse (HR: 2.46, p = 0.003) after DLI were independently associated with inferior OS. Data in the current study showed the feasibility of prophylactic DLI with/without decitabine in the early stage after allo-HSCT in patients with unfavourable gene mutations.