Outcomes and risk factors of second allogeneic haematopoietic stem cell transplantation in patients with relapsed haematological malignancy after first transplantation

Summary The therapeutic utility of a second allogeneic haematopoietic stem cell transplantation (allo‐HSCT) remains uncertain in patients with relapsed haematological malignancies following initial allo‐HSCT. This retrospective cohort study analysed 58 consecutive patients undergoing second allo‐HSCT, predominantly haploidentical, to determine indications and identify predictive factors. All evaluable patients achieved successful and sustained haematopoietic reconstitution, with confirmed complete donor chimerism. As of the data cut‐off, two patients died at 1.3 and 2 months post second transplantation with persistent non‐response (NR). Twelve of the remaining 56 patients relapsed after the second transplantation, with a median relapse time of 5.5 (3.0–13.5) months. One‐year overall survival (OS), disease‐free survival and cumulative incidence of relapse rates after the second transplant were 52.1%, 46.5% and 21.8% respectively. Treatment‐related mortality (TRM) following the second transplant was 5.3% and 31.9% at 3 months and 1 year respectively. Age >55 and/or HCT‐CI ≥3 and short initial remission duration (≤8 months) contributed to significantly inferior OS and higher TRM. This study implemented a strategy combining donor switching and post‐transplant maintenance therapy for second transplantation in haematological malignancy patients with post‐transplant relapse. Prospective studies are warranted to validate prognostic factors affecting outcomes after second transplantation.