One vs two busulfan TDM sets show similar outcomes in myeloablative alloHCT

Outcomes of allogeneic hematopoietic cell transplant (alloHCT) do not differ in patients who underwent either one or two sets of busulfan therapeutic drug monitoring (TDM) sampling, reports a study.

This suggests that a single-time TDM and dose adjustment is enough to take full advantage of the outcomes following myeloablative conditioning (MAC) alloHCT, according to the researchers.

The study examined the effect of busulfan TDM frequency and dose adjustments on relapse-free survival (RFS), the primary outcome. Other outcomes measured were the incidence of acute and chronic graft versus host disease (GVHD), oral mucositis, pulmonary toxicity, sinusoidal obstruction syndrome (SOS), the cumulative incidence of relapse (CIR), and overall survival (OS).

Of the patients, 22 underwent one set of sampling and 53 underwent two sets. Participants in the two groups shared similar baseline characteristics.

No significant differences were seen in RFS by day 180 (77.3 percent vs 79.2 percent; p=1.0), CIR by day 180 (18.2 percent vs 17.8 percent; p=0.74), or OS (p=0.73). Similar incidences of acute GVHD, chronic GVHD, SOS, and severe mucositis were also observed between groups.

Notably, 63 percent of patients in each group received busulfan dose adjustments following the first set, and 52.8 percent received further dose adjustments after the second set.

“Busulfan is a common component of alloHCT conditioning, [but] interpatient pharmacokinetic variability can result in enhanced toxicity or increased relapse risk,” the researchers said. “TDM can minimize [such] variability.”