Secondary hyperparathyroidism associated with dichloromethane diphosphonate treatment of Paget's disease

Cathepsin K inhibitors prevent matrix-derived growth factor degradation by human osteoclasts

The coupling between bone formation and resorption creates a therapeutic impasse in osteoporosis: antiresorptive therapy halts bone loss, but also inhibits bone formation, and therefore does not cure the condition. Surprisingly, recent preliminary reports suggest that inhibition of resorption by cathepsin K (CathK) inhibitors augments bone formation. Uniquely amongst resorption-inhibitors, CathK-inhibitors suppress degradation of the organic matrix of bone while allowing demineralization. We hypothesized that these unique characteristics might explain a capacity of CathK inhibitors to enhance bone formation: the inhibitors might prevent degradation not only of collagen, but also other proteins, including growth factors embedded in matrix. We tested this hypothesis using osteocalcin and insulin-like growth factor I (IGF-I) as examples of matrix-embedded proteins, and found that CathK-inhibitors, unlike other resorption-inhibitors, dramatically increased the concentrations of these matrix-derived proteins in supernatants of osteoclasts on bone, most likely through protection against intracellular degradation. We found that protons are both necessary and sufficient for the release of IGF-I from bone matrix, and that recombinant CathK can degrade both marker proteins. In the presence of a CathK-inhibitor, the amount of IGF-I released from matrix substantially exceeded the amount secreted by osteoclasts. CathK-inhibition similarly augmented bone morphogenetic protein (BMP)-2 release. Lastly, MC3T3-E1 numbers were greater after co-culture with osteoclasts on bone with versus without CathK-inhibitor, showing that, in the presence of CathK-inhibitor, osteoclasts release biologically-significant quantities of biologically-active matrix-derived growth factors. These results support a model in which osteoclastic secretion of protons demineralizes bone, causing release of growth factors from bone matrix. Normally these are largely degraded, with collagen, in the resorptive hemivacuole and during transcytosis to the basal surface of the osteoclast, but in the presence of CathK inhibitor they are released intact, and so might augment bone formation.

Therapy insight: the risks and benefits of bisphosphonates for the treatment of tumor-induced bone disease

Bisphosphonates are a valuable class of drugs with potent anti-resorptive actions that make them ideal for skeletal protection in osteoporosis, cancer bone metastasis, multiple myeloma, and Paget's disease of bone. It has become apparent, however, that these drugs also have the potential to cause a number of adverse effects. While these do not limit bisphosphonate use, the incidence of these adverse events can be minimized if appropriate care is taken with their administration, and by maintaining appropriate surveillance and patient care. We review the range of adverse reactions to bisphosphonate therapy with a particular emphasis on the recently identified association between long-term bisphosphonate treatment and osteonecrosis of the jaw. This is a potentially serious side effect seen mostly in patients with multiple myeloma or breast cancer bone metastases who receive intravenous bisphosphonate treatment. While the etiology is uncertain, a strong association with dental pathology and interventions highlights the need for close attention to dental health in this patient group.

Bisphosphonate therapy for Paget's disease in a patient with hypoparathyroidism: profound hypocalcemia, rapid response, and prolonged remission

Bisphosphonate treatment for severe Paget's disease leads to hypocalcemia followed by a secondary hyperparathyroid response to restore normocalcemia. A case is presented of a 60-year-old woman with polyostotic Paget's disease and postsurgical hypoparathyroidism. In 1993 her Paget's disease--alkaline phosphatase (ALP), 1260 U/liter (35-135 U/liter), and fasting urinary hydroxyproline excretion, 13.7 micromol/liter GF (0.4-1.9 micromol/liter)--was treated with intravenous pamidronate. Symptomatic hypocalcemia followed the first 60-mg dose, requiring large doses of calcium supplementation and calcitriol. Pamidronate therapy to a total dose of 360 mg was followed by rapid and prolonged remission with indices of bone turnover in the normal range within 2 months and persisting for at least 19 months after treatment. In 1999 relapse of Paget's disease--ALP, 511 U/liter (35-135 U/liter), and fasting urinary deoxypyridinoline/creatinine 53.1 micromol/mol (5-27 micromol/mol)--was treated with alendronate, 10 mg daily. Symptomatic hypocalcemia occurred again, requiring increased calcium and calcitriol therapy. Indices of bone turnover were within the normal range 9 weeks after the start of therapy. These responses were significantly more rapid and sustained than those observed in euparathyroid subjects. This case suggests that the lack of parathyroid response may modify the response to bisphosphonates by: (a) increasing intrinsic uptake of bisphosphonate into the pagetic skeleton, allowing response to a smaller dose; (b) increasing duration and severity of hypocalcemia after bisphosphonate therapy; and (c) removing the hyperparathyroid drive to reactivation of pagetic osteoclasts, leading to a prolonged remission. These observations have implications for optimizing bisphosphonate therapy both in Paget's disease and in osteoporosis.

Clodronate is effective in preventing corticosteroid-induced bone loss among asthmatic patients

Clodronate is a novel drug used for inhibiting osteoclastic activity. The aim of the present double-blind study was to evaluate the efficacy and tolerability of clodronate (Leiras, Finland) in corticosteroid-induced bone loss among asthmatic patients. Seventy-four adult patients (41 women and 33 men, mean age 57.3 years) having a long history (mean 8.1 years) of oral and inhaled corticosteroid therapy were randomized to four parallel treatment groups: clodronate 800, 1600, or 2400 mg/day, or an identical placebo. The bone mineral density (BMD) of the lumbar spine (L2-4), femoral neck, and trochanter were assessed using dual-energy X-ray absortiometry at entry, 6 months, and 12 months. The baseline BMDs did not differ significantly between the study groups. In the lumbar spine, the mean BMD increased significantly between the baseline and 12-month visit in the clodronate groups of 1600 and 2400 mg/day, 2.6% (0.02 g/cm2, p < 0.02) and 3.0% (0.03 g/cm2, p < 0.01), respectively, but not in the placebo and clodronate 800 mg/day groups. The test for a linear trend (BMD percent change for L2-4) at 12 months was significant (p < 0.02), indicating a dose response to clodronate. The mean BMD values of the femoral neck increased significantly in the 2400 mg/day group, 4.3% (0.03 g/cm2, p < 0.0001), as well as in the trochanter region 2.8% (0.02 g/cm2, p < 0.02). Gastric irritation was the most common adverse effect noted on a clodronate dose of 2400 mg/day. We conclude that oral clodronate is effective in preventing bone loss or increasing bone mass in asthmatic patients having a long history of continuous peroral and inhaled corticosteroid administration.

Treatment of hypercalcaemia of malignancy with clodronate

The bisphosphonate clodronate has been widely used in the treatment of hypercalcaemia and osteolytic bone metastases. It can normalize plasma calcium in most hypercalcaemic, rehydrated cancer patients when increased bone resorption is the prevailing disturbance of calcium metabolism. When given intravenously either as a single infusion or as repeated daily administrations, serum calcium levels fall to normal 3-5 days after the onset of therapy. Long-term maintenance treatment must be adjusted individually since relapse appears to depend upon the tumour type, the degree of malignancy and any anticancer therapy. In patients in whom increased tubular calcium reabsorption is the prevailing disturbance of calcium metabolism, the effect of clodronate on plasma calcium is incomplete, despite the normalization of bone resorption. This type of therapeutic response can be reproduced experimentally in bisphosphonate-treated animals receiving a constant infusion of parathyroid hormone-related peptide, a peptide isolated from various tumour types including lung, kidney, breast and neuroendocrine tumour of the pancreas. In patients having a good response to clodronate, the fall in plasma calcium is accompanied by an increase in the calcium-regulating hormones, parathyroid hormone and 1,25-dihydroxyvitamin D3. This homeostatic response probably explains why hypocalcaemia occurs rarely in clodronate-treated patients. No serious side-effects of treatment have been reported. Clodronate appears to be a safe and effective treatment for the hypercalcaemia of malignancy, where increased bone resorption is the major mechanism disturbing the homeostasis of extracellular calcium.

Clodronate in hypercalcemia of malignancy

Of the many compounds belonging to the diphosphonate family, clodronate has been widely used in hypercalcemia and osteolysis of malignancy. All published reports indicate that clodronate can normalize plasma calcium in the majority of hypercalcemic, rehydrated cancer patients in whom increased bone resorption is the prevailing disturbed calcium flux. In these patients, clodronate, given intravenously either as a single infusion or as repeated daily administrations, can normalize serum calcium, usually 3-5 days after the onset of therapy. In these good responders, long-term maintenance treatment should be individually adjusted since relapse appears to depend upon the type of tumor, the extent of malignancy and the administration of anticancer therapy. In a subset of well-rehydrated hypercalcemic patients in whom increased tubular calcium reabsorption represents the prevailing disturbed calcium flux, the acute effect of clodronate on plasma calcium is incomplete, despite the normalization of bone resorption. This type of therapeutic response can be experimentally reproduced in diphosphonate-treated animals receiving a constant infusion of parathyroid hormone-related peptide, a peptide isolated from lung, kidney and breast carcinomas. This indicates that, in addition to antiosteolytic drugs, such as clodronate, patients with hypercalcemia of malignancy would benefit from the development of agents that can selectively reduce the renal tubular reabsorption of calcium. In patients displaying a good response to clodronate, the fall in plasma calcium is accompanied by an increase in the calcium-regulating hormones, parathyroid hormone and 1,25-dihydroxyvitamin D3. This homeostatic reaction probably explains why hypocalcemia rarely occurs in clodronate-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of Paget's disease of bone with (4-chloro-phenyl) thiomethylene bisphosphonate

Introduction of antiosteoclastic drugs, calcitonin and etidronate, has profoundly changed the treatment of active Paget's disease of bone. Nevertheless, the use of these drugs is limited in some patients by the occurrence of side-effects or by a resistance to therapy. We report the results of an open, nonrandomized study with a new bisphosphonate, (chloro-4 phenyl) thiomethylene bisphosphonate (Cl-TMBP), given orally to 35 patients with active Paget's disease of bone. At two different dosages this new bisphosphonate induced a significant decrease in disease activity. Patients receiving a mean dosage of 5 mg/kg/d (n = 14) showed a significant reduction of serum alkaline phosphatase levels to 43% of pretherapeutic values (from 499 +/- 91 to 214 +/- 41 IU/l) while hydroxyproline/creatinine ratio decreased to 43% of baseline (from 93 +/- 21 to 40 +/- 11). A second group of patients (n = 21) receiving a mean dosage of 11 mg/kg/d exhibited a similar response: serum alkaline phosphatase activity was reduced to 42% of initial values (from 1384 +/- 209 to 584 +/- 111 IU/l) while hydroxyproline/creatinine ratio fell to 48% of baseline (from 144 +/- 27 to 69 +/- 15). This was accompanied by a reduction in radionuclide uptake in pagetic areas. A prolonged beneficial effect was observed in most patients. In patients receiving the highest dosage significant reduction in serum calcium and rise in parathyroid hormone were observed. Otherwise no clinical or biological side-effect occurred throughout the study.

Treatment of tumor hypercalcemia with clodronate

In an open, controlled study 34 patients with tumor hypercalcemia of different origin were treated with clodronate. The initial dosage was 300 mg intravenously daily. After achieving normocalcemia, treatment was continued orally using 400-3200 mg/day depending on serum calcium concentration. Most patients showed normocalcemia within 1 week of treatment - only few of them needed a longer time. Fifteen of 34 patients died within the observation time of up to 24 weeks, some being normocalcemic. However, a reincrease in plasma calcium during treatment was an indicator of deterioration. Measurements of plasma parathyroid hormone (PTH) using an intact molecule radioimmunometric assay showed depressed levels before clodronate treatment started, but PTH rose after achieving normal and especially low normal calcium levels. Starting 1,25-dihydroxycholecalciferol [1,25(OH)2D3] values were decreased or in the lower normal range in the majority of patients, but in 6/21 patients plasma 1,25(OH)2D3 was in the upper normal range or elevated despite hypercalcemia. After lowering plasma calcium the 1,25(OH)2D3 levels increased. However, there was no significant correlation between PTH and 1,25(OH)2D3. Therefore we assume that in some patients additional stimulation of renal 1 alpha-hydroxylase by tumor products is present.

Paget's disease of bone treated in five days with AHPrBP (APD) per Os

Amino-hydroxypropylidene bisphosphonic acid (AHPrBP, previously APD) is a potent inhibitor of bone resorption. Since it remains in bone for a long time, and since it was not found to impair bone mineralization, it could be administered at high dose over a short period of time. Therefore, 11 patients with symptomatic Paget's disease received AHPrBP orally at 1200 mg/day over 5 consecutive days. Controls were performed after 1 month in all patients, 6 months in 8 patients, and one year in 4 patients. Clinical improvement and biochemical remission was observed in all patients, except one with severe disease. Side effects were negligible. Disease activity at bone scintigram decreased over 6 months. Plasma alkaline phosphatase activity fell progressively and significantly from 210 +/- 26 U/l (means +/- SEM) to 103 +/- 10 U/l after 6 months (nl less than 120 U/l). Urinary excretion of hydroxyproline decreased immediately and became normal (nl less than 2.3 mumol/lGF) as a mean at day 5 (from 4.6 +/- 0.4 mumol/lGF to 2.1 +/- 0.3 mumol/lGF). Thereafter it remained within the normal range (2.0 +/- 0.2 mumol/l at day 180). Plasma calcium and phosphate concentrations fell transiently between day 4 and 15, whereas plasma PTH levels increased over this period of time. In conclusion, a short course of AHPrBP given per os at high dose induces a rapid decline in activity and remission of moderate Paget's disease, without significant side effects.

A single-day treatment of tumor-induced hypercalcemia by intravenous amino-hydroxypropylidene bisphosphonate

Twenty patients with malignant hypercalcemia were treated with amino-hydroxypropylidene bisphosphonate (AHPrBP, previously APD), a potent inhibitor of osteoclast-mediated bone resorption. To assess the efficacy of a single-day treatment and determine the optimal dose of this compound, all patients received AHPrBP intravenously over 24 h, but they were divided into two subsequent groups of 10 patients: Group A received a single dose of 60 mg AHPrBP and group B received a single dose of 30 mg. In both groups all patients responded to AHPrBP with a decrease in plasma calcium concentration after a mean time lag of 1 day. Within 6 days, plasma calcium (corrected for serum proteins) fell from 3.24 +/- 0.14 to 2.24 +/- 0.06 mmol/liter in group A (p less than .001), but only from 3.22 +/- 0.15 to 2.49 +/- 0.10 mmol/liter in group B (p less than .005). Whereas in all patients from group A plasma calcium was within the normal range at days 9 and 14, in 4 patients of group B it was still above the normal range at day 9, and in 5 patients at day 14. There was a significant difference in plasma calcium between group A and group B from days 5 to 14 (p less than .005). In both groups, urinary calcium excretion fell dramatically and similarly, and plasma phosphate concentration decreased significantly (p less than .01) to values slightly below the normal range from days 4 to 6.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of the bisphosphonate APD in the control of Paget's bone disease

Fifty-four patients with Paget's bone disease have been treated with the bisphosphonate APD. Twenty-six patients had not previously received treatment for Paget's disease; and 28 had been treated before with EHDP alone or in combination with calcitonin. APD was given orally in a mean dose of 500 mg daily (congruent to 6.8 mg/kg of body weight) for 4 to 12 months. Bone pain diminished or disappeared in 34 of 39 patients with symptoms. A very significant diminution of the biochemical indices of bone turnover was observed in all patients, but the responses were faster in patients who had not previously received treatment for Paget's disease. After 4 months of treatment the serum levels of alkaline phosphatase of previously untreated patients diminished from 58.8 +/- 8.0 to 20.0 +/- 3.9 KA units (P less than 0.001) and urinary excretion of hydroxyproline diminished from 108.6 +/- 16.9 to 42.4 +/- 8.3 mg/24 h (P less than 0.001). In 23 of 26 previously untreated patients the biochemical indices decreased to the normal range (complete response). A reduction of 50% or more without reaching the normal range was observed in the other 3 patients (partial response). Actuarial analysis of the duration of the effect 12 months after stopping APD disclosed that 63% of patients who had achieved a complete response but only 23% of those with a partial response were in biochemical remission. A second course of APD was administered to 11 patients. The results were as effective during the second as the first course in 9 patients, whereas 2 patients had no response to retreatment.(ABSTRACT TRUNCATED AT 250 WORDS)