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Fludarabine with intravenous busulfan (6.4 mg/kg; FB2) and fludarabine with intermediate-dose melphalan (140 mg/m2; FM140) are the most widely used reduced-intensity conditioning (RIC) regimens for allogeneic hematopoietic stem cell transplantation. FM140 generally has a lower relapse rate and higher non-relapse mortality (NRM), resulting in overall survival (OS) comparable to that seen with FB2. To evaluate the effect of reducing the melphalan dose, we retrospectively compared transplant outcomes in 156 patients who received FB2 (n = 103) or FM80 (n = 53) at our center (median age: 63 years; range 27–72 years). All patients received 4-Gy total body irradiation. Three-year OS, the cumulative incidence of relapse, and NRM were comparable between groups (FB2 vs. FM80, 58% vs. 47%, p = 0.24; 30% vs. 36%, p = 0.57; 17% vs. 21%, p = 0.44, respectively). There was no significant difference in the cumulative incidence of graft-versus-host disease (GVHD) at day 100, chronic GVHD at 3 years, or the 3-year GVHD-free/relapse-free survival rate. In the high-risk disease group, patients receiving FM80 tended to have lower 3-year OS (FB2 vs. FM80, 48% vs. 17%, p = 0.06). In summary, transplant outcomes following FB2 or FM80 were comparable except in patients with high-risk disease.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients are at high risk of developing invasive pneumococcal disease (IPD) with substantial morbidity and mortality. Pneumococcal polysaccharide vaccine (PPSV23) and pneumococcal conjugate vaccine (PCV13) are the primary prevention strategy. The difference between the Japanese and international guidelines is limited except when to start PCV13. However, Japanese data regarding the incidence of IPD after allo-HSCT that include vaccination status are limited. Therefore, we aimed to study the clinical characteristics of patients with IPD following allo-HSCT, focusing on unvaccinated patients. We retrospectively reviewed allo-HSCT recipients between April 2005 and December 2018 at Komagome Hospital. Among 1,091 recipients, 11 (1008/100,000 recipients) developed 13 episodes of IPD. The median period from the first allo-HSCT to the first IPD episode was 686 days (10-3040 days). Ten patients developed IPD before vaccination, and seven of these unvaccinated patients with late-onset IPD were ineligible for vaccination based on domestic guidelines. Although appropriate treatments resulted in a good short-term prognosis, most episodes of IPD developed in unvaccinated allo-HSCT recipients. Our data support the promotion of better adherence to the current guidelines and the importance of pneumococcal vaccination even years after allo-HSCT to protect against late-onset IPD.