Characteristics of oral mucositis in patients undergoing haploidentical stem cell transplantation with posttransplant cyclophosphamide: marked difference between busulfan and melphalan regimens

Purpose This study was performed to examine the effects of conditioning regimens on oral mucositis in haploidentical (haplo) donor hematopoietic stem cell transplantation (HSCT) with posttransplant cyclophosphamide (PTCy).
Methods Thirty consecutive patients (male, 23; female, 7; 18–68 years, median, 59 years) undergoing haplo-HSCT with PTCy using one of three conditioning regimens—reduced intensity conditioning (RIC)-melphalan (Mel); RIC-Busulfan (Bu); and myeloablative conditioning (MAC)-Bu—were enrolled in this study. Data on the WHO grade of oral mucositis (day − 7 to + 20) were collected retrospectively. The incidences of ulcerative and severe mucositis (Grade 2–4 and Grade 3–4, respectively) were compared between the three groups.
Results Ulcerative mucositis occurred in 0% (0/10) of patients in the RIC-Mel group, 57.1% (4/7) in the RIC-Bu group, and 100% (13/13) in the MAC-Bu group. The differences between the RIC-Mel and RIC-Bu groups and between the RIC-Bu and MAC-Bu groups were significant (all P < 0.05). Severe mucositis occurred in 57.1% (4/7) of patients in the RIC-Bu group and 100% (13/13) of patients in the MAC-Bu group, and the difference was significant (P < 0.05). The rates of ulcerative mucositis (≥ grade 2) and of severe mucositis (≥ grade 3) were significantly higher in the MAC-Bu group than the RIC-Bu group on days 10, 13, 15, and 16 and on days 10, 14, 15, and 16, respectively (all P < 0.05).
Conclusion The risk of oral mucositis in patients undergoing haplo-HSCT with PTCy is highest with the MAC-Bu conditioning regimen, followed by RIC-Bu, and lowest with RIC-Mel.