TY - JOUR

T1 - Changes in RANKL and TRAcP 5b after discontinuation of denosumab suggest RANKL mediated formation of osteoclasts results in the increased bone resorption

AU - Solling, Anne Sophie

AU - Harslof, Torben

AU - Jorgensen, Niklas Rye

AU - Langdahl, Bente

PY - 2023

Y1 - 2023

N2 - In patients discontinuing long-term denosumab, RANKL levels are high 6 months after the last denosumab injection. Nine and 12 months after the last denosumab injection RANKL levels are lower, but TRAcP 5b levels are higher, suggesting that accumulated RANKL increases the number of active osteoclasts.Purpose: The rapid increase in bone turnover occurring when discontinuing long-term treatment with denosumab (DMAB), an antibody that neutralizes receptor activator of nuclear factor kappa-B ligand (RANKL) is not fully understood. We aimed to investigate the mechanisms underlying the rebound activation of bone resorption by measuring tartrate-resistant acid phosphatase 5b (TRAcP 5b), RANKL, osteoprotegerin (OPG), C-terminal collagen crosslinks (CTX), and procollagen type I N-propeptide (P1NP) in patients discontinuing long-term DMAB.Methods: Sixty-one patients with BMD T-score > - 2.5 at the spine and hip discontinuing long-term DMAB were randomized to treatment with zoledronate (ZOL) 6 months (6 M group, n = 20), 9 months (9 M group, n = 20) or 12 months after the last DMAB injection or when bone turnover was high (12 M group, n = 21). Bone turnover markers were measured immediately before initiation of ZOL treatment.Results: We found higher CTX and PINP in the 9 M and 12 M groups compared to the 6 M group (p < 0.001). In the 6 M group, TRAcP 5b was lower and RANKL higher than in the other two groups (p < 0.001). TRAcP 5b correlated negatively with RANKL (R = - 0.54), and time since the last DMAB injection correlated positively with CTX (R = 0.56), PINP (R = 0.72), TRAcP 5b (R = 0.51) and negatively with RANKL (R = - 0.70) (p < 0.001 for all). We found no difference in OPG between groups.Conclusion: Following discontinuation of long-term DMAB, we find high levels of RANKL, which most likely result in an increase in the number of active osteoclasts (illustrated by TRAcP5b) causing an increased bone turnover.

AB - In patients discontinuing long-term denosumab, RANKL levels are high 6 months after the last denosumab injection. Nine and 12 months after the last denosumab injection RANKL levels are lower, but TRAcP 5b levels are higher, suggesting that accumulated RANKL increases the number of active osteoclasts.Purpose: The rapid increase in bone turnover occurring when discontinuing long-term treatment with denosumab (DMAB), an antibody that neutralizes receptor activator of nuclear factor kappa-B ligand (RANKL) is not fully understood. We aimed to investigate the mechanisms underlying the rebound activation of bone resorption by measuring tartrate-resistant acid phosphatase 5b (TRAcP 5b), RANKL, osteoprotegerin (OPG), C-terminal collagen crosslinks (CTX), and procollagen type I N-propeptide (P1NP) in patients discontinuing long-term DMAB.Methods: Sixty-one patients with BMD T-score > - 2.5 at the spine and hip discontinuing long-term DMAB were randomized to treatment with zoledronate (ZOL) 6 months (6 M group, n = 20), 9 months (9 M group, n = 20) or 12 months after the last DMAB injection or when bone turnover was high (12 M group, n = 21). Bone turnover markers were measured immediately before initiation of ZOL treatment.Results: We found higher CTX and PINP in the 9 M and 12 M groups compared to the 6 M group (p < 0.001). In the 6 M group, TRAcP 5b was lower and RANKL higher than in the other two groups (p < 0.001). TRAcP 5b correlated negatively with RANKL (R = - 0.54), and time since the last DMAB injection correlated positively with CTX (R = 0.56), PINP (R = 0.72), TRAcP 5b (R = 0.51) and negatively with RANKL (R = - 0.70) (p < 0.001 for all). We found no difference in OPG between groups.Conclusion: Following discontinuation of long-term DMAB, we find high levels of RANKL, which most likely result in an increase in the number of active osteoclasts (illustrated by TRAcP5b) causing an increased bone turnover.

KW - Bone turnover markers

KW - Denosumab

KW - OPG

KW - Osteoporosis

KW - RANKL

KW - TRAcP 5b

KW - POSTMENOPAUSAL WOMEN

KW - FRACTURES

U2 - 10.1007/s00198-022-06651-0

DO - 10.1007/s00198-022-06651-0

M3 - Journal article

C2 - 36543965

VL - 34

SP - 599

EP - 605

JO - Osteoporosis International

JF - Osteoporosis International

SN - 0937-941X

ER -