Aims: The optimal osteoanabolic treatment strategy in denosumab (Dmab)-users is not established. In treatment-naïve patients, teriparatide (TPTD) in combination with Dmab results in dramatic BMD gains at the spine and hip. However, BMD outcomes with combination TPTD/Dmab have not been investigated in patients already on Dmab.
Methods: We conducted retrospective review of patients in osteoporosis clinics at Royal North Shore and Westmead Hospitals between 2013-2023. Eligible patients were those managed with Dmab immediately prior to ≥12-months continuous TPTD with available pre- and post-TPTD DXA results. Patients were excluded if Dmab-to-TPTD switch occurred in setting of skeletal adverse events (AEs). Patients were grouped according to whether TPTD was added to ongoing Dmab (combination group) or Dmab was interrupted during TPTD (sequence group). Parametric outcomes are reported as mean±SD; non-parametric as median (IQR).
Results: The total cohort (N=24; 12=combination, 12=sequence) were 77±7 years and predominantly female (88%). Prior vertebral (1 (0-2)) and non-vertebral fractures (2.3±1.5) were prevalent and pre-TPTD BMD T-scores (SD) were low at lumbar spine (-2.7 (-1.5 to -3.3)), total hip (-2.2±0.6) and femoral neck (-2.4±0.7). Median Dmab exposure was 2.0 years (range 1-10) and majority (>90%) received 18-months TPTD. Groups were similar in age, sex, antiresorptive duration, number of prior fractures, BMD scan interval and pre-TPTD BMD values. The combination group had longer prior Dmab (median 3-years vs 2-years, p=0.037). Combination TPTD/Dmab was associated with greater lumbar spine BMD gains (+0.080g/cm2 vs +0.026 g/cm2, p=0.039; +9.8% vs +3.5%, p=0.060). Hip and femoral neck BMD were stable in both groups. During TPTD, one patient experienced fragility humeral fracture.
Conclusion: In this novel investigation of combination TPTD/Dmab in patients on existing Dmab, greater lumbar spine BMD gains occurred with TPTD when Dmab was not interrupted. These findings require confirmation in prospective controlled studies to inform optimal osteoanabolic strategies in Dmab-users.