Intermittent zoledronic Acid prevents bone loss in adults after allogeneic hematopoietic cell transplantation

Bone mineral density (BMD) loss is common in survivors of allogeneic hematopoietic cell transplantation (alloHCT). We performed a multicenter, phase II, randomized open-label trial of intravenous zoledronic acid (ZA) to prevent BMD loss in adult recipients of alloHCT with osteopenia before HCT. The treatment group received ZA 4 mg intravenously within 28 days pre-HCT and at 3 and 6 months after HCT. Both treatment and control groups received calcium carbonate and vitamin D supplements. Of 61 patients, 32 were randomized to the ZA cohort and 29 to the control cohorts. More patients in the ZA group had an HCT comorbidity index high-risk score of ≥3 (50% versus 21%, P < .01). Baseline BMD, T-scores, serum osteocalcin, bone alkaline phosphatase, and urine N-telopeptide (UNTX) levels were similar in both cohorts. Thirty patients were evaluable for outcomes (11 from the treatment and 19 from the control group). At 12 months, subjects in the treatment group had an improvement in BMD at the femoral neck (mean change, .018 for ZA group versus -.054 for controls; P = .04) and a significant decline in levels of UNTX (-56 for ZA group versus -9 for control; P = .04) compared with baseline. ZA was well tolerated and not associated with any cases of osteonecrosis of jaw or renal impairment. Lower survival observed in the ZA cohort was likely related to baseline imbalance in HCT-CI scores. Intermittent ZA is effective in preserving long-term bone health in adult alloHCT recipients at risk for osteoporosis.