Effects of Teriparatide or Denosumab on Bone in Postmenopausal Women With Osteoporosis

MS /BS is a measure of the proportion of BS on which new mineralized bone is deposited at the time of DEM or TET labeling and is calculated as the sum of the total extent of DL plus half the extent of SL divided by BS. At baseline (18 days prior to randomization / study drug administration), DEM was administered (3 days on, 12 days off, 3 days on). 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered (same dosing schedule as DEM). Both DEM and TET temporarily bind to new bone and fluoresce under UV light. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicated active bone formation and a SL or NL suggested varying degrees of suppression of bone formation.

MS /BS is a measure of the proportion of BS on which new mineralized bone is deposited at the time of DEM or TET labeling and is calculated as the sum of the total extent of DL plus half the extent of SL divided by BS. At baseline (18 days prior to randomization / study drug administration), DEM was administered (3 days on, 12 days off, 3 days on). 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered (same dosing schedule as DEM). Both DEM and TET temporarily bind to new bone and fluoresce under UV light. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicated active bone formation and a SL or NL suggested varying degrees of suppression of bone formation.

In this study, post-treatment DLs in the CC, EC, and PC were classified as remodeling-based or modeling-based bone formations which was determined by whether the underlying reversal line was scalloped or smooth and by the collagen fiber orientation. Percentage = (remodeling-based formation units or modeling-based formation units/ total bone formation units) \* 100.

The percentage of mineralizing surface where post-treatment DLs in the CC, EC, and PC were classified as remodeling-based or modeling based bone formation based on collagen fiber orientation and whether the underlying reversal line was scalloped or smooth. Percentage = percentage remodeling- or modeling-based formation units \* MS/BS

The percentage of overfilled remodeling sites in the CC, EC, and PC were defined as the percentage of observed remodeling units in which the second DL (TET) extended beyond the limits of the scalloped reversal line and into the adjacent, previously unresorbed surface of the bone. Percentage = (overfilled remodeling bone formation unit / total bone formation unit) \* 100.

BMUs are local groups of osteoblasts and osteoclasts that act in concert to complete a single remodeling cycle. The label length is a measure of the extent of the mineralization front within each BMU in the CC, EC, IC and PC. At baseline (18 days prior to randomization / study drug administration), DEM was administered. 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicated active bone formation, and a SL or NL suggested suppression of bone formation.

MAR is a measure of the linear rate of production of mineralized bone matrix by osteoblasts and is measured by the mean distance between 2 consecutive labels divided by the time interval. At baseline (18 days prior to randomization / study drug administration), DEM was administered. 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicated active bone formation, and a SL or NL suggested suppression of bone formation. SL cases were imputed to a value of 0.3 micrometers per day (µm/day) or counted as missing. NL cases were reported as missing.

BFR/BS is the volume of mineralized bone formed per unit surface of bone per unit of time \[mm cubed per mm squared per year (mm³/mm²/year)\]. At baseline (18 days prior to randomization / study drug administration), DEM was administered. 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicates active bone formation, a SL or NL suggests suppression of bone formation. BFR = MAR \* (MS/BS). SL cases were imputed to a value of 0.3 mcm/day or counted as missing. NL cases were assigned a value of zero.

At baseline (18 days prior to randomization / study drug administration), DEM was administered. 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicated active bone formation and a SL or NL suggested suppression of bone formation. Percentage = (Single or double TET labels / BS) \*100.

PTH regulates calcium and phosphate metabolism in bone and kidney, and is typically measured in serum using the intact PTH assay. Percentage = (PTH value at specified time points - PTH value at baseline) / PTH value at baseline \* 100.

P1NP is a marker of bone turnover and is a measure of bone formation. Percentage = (P1NP value at specified time points - P1NP value at baseline) / P1NP value at baseline \* 100.

Osteocalcin is a marker of bone turnover and a measure of osteoblast function. Percentage = (osteocalcin value at specified time points - osteocalcin value at baseline) / (osteocalcin value at baseline) \* 100.

CTX is a marker of bone turnover and is a measure of bone resorption. Percentage = (CTX value at specified time points - CTX value at baseline) / (CTX value at baseline) \* 100.

Ac.f is the probability of new remodeling cycles initiated on the BS per year. Ac.f = (BFR/BS) / wall thickness. At baseline (18 days prior to randomization / study drug administration), DEM was administered. 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicated active bone formation and a SL or NL suggests suppression of bone formation. SL cases were imputed to a value of 0.3 µm/day or counted as missing. NL cases were assigned a value of zero.

Aj.AR is MAR averaged over the entire osteoid surface and in a steady state is an estimate of the mean rate of matrix apposition. At baseline (18 days prior to randomization / study drug administration), DEM was administered. 22 days prior to the biopsy procedure (biopsy obtained 3 months post first dose of study drug), TET was administered. New bone in the biopsy was seen as the amount of bone between the 2 fluorescently DEM- or TET-labeled lines under a microscope. A DL indicated active bone formation and a SL or NL suggested suppression of bone formation. BFR = MAR \* (MS/BS). SL cases were imputed to a value of 0.3 µm/day or counted as missing. NL cases were counted as missing.

OV is the percentage of a given volume of bone tissue that consists of new unmineralized bone matrix (osteoid). Percentage = (OV/BV) \*100.

OS is the percentage of the entire trabecular BS that is covered by osteoid. Percentage = (OS / BS) \*100.

O.Th is a measure of the average thickness of osteoid seams.

W.Th is the distance from the cement line to the marrow space of completed trabecular bone packets.