Treatment of Paget's disease with the calcitonins

Immunogenicity of xenopeptide hormone therapies

Peptides are a growing class of agents whose therapeutic use originated with non-human treatments such as animal insulins. Xenopeptides continue to be explored for biotherapeutic development using genetic engineering, and through the rich resource of animal and plant polypeptides. One of the major concerns of therapeutic administration of xenopeptides is the potential for untoward immune responses that may lead to loss of drug efficacy or adverse events in recipients. An increased risk of immunogenicity is perceived with xenopeptides, however, human-derived therapies also induce antibody formation that in some cases has been associated with severe clinical sequelae. In this review, antibody responses to xenopeptides are highlighted looking at current hormone therapies used to treat endocrine disorders. Similar to clinical experiences with peptide-based agents in general, antibody responses against xenopeptide hormone therapies in majority of cases have been benign in nature with minimal clinical impact.

Bone density changes in Paget's disease 2 years after iv pamidronate: profound, sustained increases in pagetic bone with severity-related loss in forearm nonpagetic cortical bone

Bone mineral density (BMD) was measured at three sites (forearm, spine, and hip) using dual X-ray and single-photon absorptiometry in 68 patients with Paget's disease before and after treatment with iv pamidronate. Patients were treated according to the severity of their disease; the mild category (Group I, hydroxyproline excretion (Hyp(E)) <5.0 micromol/L GF) received 120 mg, the moderate category (Group II, Hyp(E) 5.0-9.99 micromol/GF) 180 mg, and the severe category (Group III, > or = 10.0 micromol/GF) 240 mg. Group I was followed for 1 year, and both Groups II and III for 2 years. At the lumbar spine in pagetic bone there were no differences between groups in early responses, with a profound increase 6 months after treatment 20.5 +/- 2.0% above baseline values to 1.403 +/- 0.063 g/cm(2) (mean +/- SEM)(P < 0.001). This increase in BMD was sustained to 2 years (1.355 +/- 0.078 g/cm(2), P < 0.001) and was 15.0 +/- 2.2% above baseline values. The pagetic total hip BMD increased after treatment in all groups, with a mean rise of 10.4 +/- 1.4% at 1 year to 1.505 +/- 0.083 g/cm(2) (P < 0.01). At the pagetic femoral neck the response was similar, with a peak significant rise at 1 year of 10.7 +/- 1.7% to 1.403 +/- 0.097 g/cm(2) (P < 0.01). In nonpagetic spinal bone there were no differences between the group responses, with a combined mean increase of 4.3 +/- 0.7% at 1 year to 0.999 +/- 0.027 g/cm(2) (P < 0.01). In both Groups II and III the increase in BMD was significantly higher than baseline values at 1 and 2 years (P < 0.01). In the nonpagetic total hip BMD remained unchanged over the 2-year period and likewise, there were no significant changes from baseline at the nonpagetic femoral neck site. In the nonpagetic forearm we found a significant loss in BMD at the ultradistal (mainly trabecular), midregion (80% cortical), and proximal shaft (95% cortical) sites in Group III, persisting to 2 years at the latter two sites. The increase in bone density in pagetic bone, persisting at least 2 years, provides a new modality of assessment of the response of pagetic bone to treatment and suggests a mechanism for the reduction in fracture risk in such bone after effective bisphosphonate treatment. Severity-dependent nonpagetic forearm bone loss, persisting to 2 years at cortical sites, suggests a potential drug-induced fracture risk at the forearm and possibly elsewhere in the absence of appropriate preventive cotreatment.

A double-blind, placebo-controlled, dose-finding trial of intermittent nasal salmon calcitonin for prevention of postmenopausal lumbar spine bone loss

PURPOSE

Nasal administration of salmon calcitonin (SCT) has been suggested for preventing trabecular bone loss during the first years following the menopause, but no conclusive evidence has appeared about the minimal effective dose. Since nasal calcitonin is highly expensive, it makes sense to define this dose.

PATIENTS AND METHODS

We performed a double-blind, placebo-controlled, randomized, single-center study with a 3-arm parallel-group design. The subjects were 251 healthy women who had experienced natural menopause within the past 6 to 72 months and were not affected by any diseases or treatments that interfere with calcium metabolism. They were randomly allocated in groups of 6 to receive intranasal SCT 50 IU (n = 84), SCT 200 IU (n = 84), or placebo (n = 83). All treatments were given on 5 consecutive days per week. Statistical analysis was based on two populations: intention-to-treat (IT) and valid completers (VC). The main assessments performed were bone mineral density of the lumbar spine (LSBMD) and biochemical parameters reflecting bone turnover (serum alkaline phosphatase, urinary calcium/creatinine, and hydroxyproline/creatinine ratios).

RESULTS

Changes over the treatment period were comparable in the IT and VC populations. In the group receiving the placebo, LSBMD decreased from baseline to end point by a mean of 6.28% (95% confidence interval [CI] -7.69 to -4.89) in the IT population and 6.98% (95% CI -8.86 to -5.11) in the VC population (P = 0.0001, end LSBMD versus baseline LSBMD). LSBMD increased slightly with the 50-IU/d dose of SCT, by 0.82% (95% CI -0.26 to 1.89) in the IT population, and 0.51% (95% CI -0.69 to 1.72) in the VC (P = NS, versus baseline). Subjects who received SCT 200 IU/d experienced significant increases of 2.03% (95% CI 0.92 to 3.15) in the IT population and 2.26% (95% CI 1.01 to 3.51) in the VC (both P = 0.001). The difference between the evolution of the combined groups receiving nasal SCT and the group treated with the placebo was highly significant (P = 0.0001). No significant changes were recorded in biochemical parameters reflecting bone turnover.

CONCLUSIONS

SCT 50 IU/d administered nasally and intermittently appears to prevent lumbar bone loss in nonobese early postmenopausal women.

Prevention of osteoporosis with nasal salmon calcitonin: effect of anti-salmon calcitonin antibody formation

The amino acid sequence of salmon calcitonin (SCT) differs considerably from that of the human hormone and specific antibodies (Ab) develop in a significant proportion of patients after parenteral or nasal administration of SCT. Controversy remains regarding the functional importance of these Ab. We report on the development of specific anti-SCT Ab in a population of postmenopausal women receiving nasal SCT for prevention of postmenopausal bone loss, and compare the effects of nasal SCT in women with or without Ab. Thirty-nine per cent of women developed Ab after 6 months of treatment with SCT, 52% after 12 months, and 61% after 18 and 24 months. After 24 months the AB titre was 3.47-17.7 x 10(-9) M/l (mean +/- SD: 13.3 +/- 3.1 x 10(-9) M/l). No significant differences appeared between the changes in lumbar bone mineral density (BMD) measured in the whole population (n = 44) (mean +/- SD: +1.06 +/- 3.9%), the patients without Ab (n = 17) (+0.05 +/- 3.7%) or in those with Ab (n = 27) (+1.7 +/- 4.6%). During the same period, a control population randomly assigned to a 500 mg/day calcium intake showed a significant loss of lumbar BMD (-4.57 +/- 4.9%) (p < 0.01). In conclusion, in healthy postmenopausal women nasal SCT seems to maintain the same preventive effect against bone loss whether or not Ab are present.

Hypocalcemic actions of amylin amide in humans

Amylin (also known as islet amyloid polypeptide and diabetes-associated peptide) has recently been shown by us to have a potent hypocalcemic effect in rat and rabbit owing to inhibition of osteoclast-mediated bone resorption. The hypocalcemic potency of amylin was found to be second only to that of calcitonin (CT) and is 100-fold more potent than calcitonin gene-related peptide. Here we demonstrate that amylin has a hypocalcemic effect in patients with Paget's disease of bone. Both human CT (hCT) and amylin induced a maximum hypocalcemic effect 2 h following intravenous administration of the peptides (p less than 0.001). Although on a molar basis amylin is less potent than CT, it exhibits a significantly prolonged hypocalcemic effect compared to hCT. Here we demonstrate for the first time a profound hypocalcemic effect of amylin in the human, despite sharing only 15% amino acid sequence identity with hCT.

Biochemical response to combination of disodium etidronate with calcitonin in Paget's disease

The biochemical responses to salmon calcitonin (SCT: 100 MRC units thrice weekly) and disodium etidronate (EHDP: 400 mg daily) alone and in combination for 6 months were compared in 72 patients with symptomatic Paget's disease of bone unresponsive to simple analgesic agents. SCT produced a 53% reduction in alkaline phosphatase (AP) and a 38% reduction in 24 h urinary hydroxyproline excretion (HYPRO). The response to EHDP was not significantly different--56% reduction in AP and 48% reduction in HYPRO. Their use in combination produced a significantly greater reduction of 71% in AP (P less than 0.002) and 69% reduction in HYPRO (P less than 0.0001). In those that remained symptomatic with increased disease activity treatment for longer than 6 months had a unpredictable effect and normal bone turnover was rarely achieved. Once therapy was withdrawn AP and HYPRO increased rapidly in those given SCT alone, returning to initial levels within 6 months. More sustained control of disease activity was achieved in those given EHDP either alone or with SCT but the combination retained the advantage obtained during treatment. Combinations of SCT + EHDP may find a place in the treatment of very active Paget's disease.

The Analgesic Effect of Calcitonin in Active Paget's Disease of Bone and in Metastatic Bone Disease

In a clinical study of 25 pagetic patients, it was found that calcitonin has analgesic activity independent of its metabolic efficacy on bone turnover. A separate study in 21 patients demonstrates greater analgesia from doses of salmon calcitonin than from human calcitonin or placebo.

Response of Paget's disease to human calcitonin in patients resistant to porcine calcitonin

Eleven patients with Paget's disease of bone, treated intermittently for 2-4 years with porcine calcitonin (pCT) and clinically resistant to pCT [no modifications of serum alkaline phosphatase (ALP) and urinary hydroxyproline ( uHOP ) during pCT administration] were treated with 0.5-0.25 mg/day of human calcitonin (hCT) for 3-6 months. Nine of our patients showed biochemical improvement during the first 2 months of treatment, with reduction in ALP and uHOP . In one patient with slightly increased ALP and uHOP , and in another one during the second treatment course, hCT treatment did not modify the biochemical indices of bone disease. However all patients, including those with biochemical resistance, experienced a remarkable diminution of bone pain, which had not been observed during previous pCT treatment courses. Therefore, hCT appears to be indicated for therapeutic use in patients who are resistant to foreign calcitonins.

A double-blind controlled trial of salmon calcitonin in pain due to malignancy

Thirty-two patients with established malignancy and associated pain participated in a randomised double-blind controlled trial. They received salmon calcitonin SC 200 UI or matching placebo 6-hourly for 48 h and were assessed by using a combination of a 20-point visual analogue scale (VAS), a 4-point physician's global pain scale, and ranking of the co-administered analgesics into 20 grades of potency. Twenty-five patients (13 calcitonin, 12 placebo) were evaluated. Seven patients (4 calcitonin, 3 placebo) were excluded either because the initial pain score was less than or equal to 5 on the VAS, or because there were insufficient data (due to death occurring within the first week of the study or, in one patient, blindness preventing completion of the VAS). One week after commencing therapy there was improvement or marked improvement of pain in significantly more patients in the calcitonin group (5/13) than in the placebo group (0/12) (Fisher's exact two-tailed probability test, P = 0.0484). At the end of the second week three patients in the calcitonin group were still showing marked improvement.

Calcitonin and diphosphonate in the treatment of Paget's disease of bone

The ideal treatment for Paget's disease of bone should control turnover irrespective of its initial activity and produce a sustained remission once treatment is withdrawn. Unfortunately, neither the calcitonins nor the diphosphonates currently available entirely fulfil these requirements. Preliminary studies suggest that combinations of calcitonin and EHDP produce significantly better responses than those of the individual agents alone. This proposition is examined critically in terms of the optimum effects achieved with calcitonin and EHDP alone paying particular attention to variables such as disease activity, dose and duration of treatment.

Salmon calcitonin therapy for Paget's disease of bone. The problem of acquired clinical resistance

During the initial months of long-term treatment of Paget's disease of bone with salmon calcitonin, circulating alkaline phosphatase activity and urinary hydroxyproproline excretion usually decrease by about 50%. In 22 of 85 patients these parameters returned to pretreatment levels despite continuous therapy. Nineteen patients who were resistant to salmon calcitonin had salmon calcitonin antibodies in high titer. Human calcitonin has been effective in suppressing disease activity in these patients. The pathogenesis of calcitonin resistance in patients without antibodies is unknown.

Spinal-cord syndrome due to non-compressive Paget's disease of bone: a spinal-artery steal phenomenon reversible with calcitonin

A 76-year-old man had progressive low back pain, leg weakness, and sensory loss. Radiology showed changes consistent with wide-spread Paget's disease, but no cord compression or involvement of nerve roots was detected by myelography or computerised axial tomography. His symptoms were relieved within 12 days of starting 100 MRC units of subcutaneous salmon calcitonin and recurred when calcitonin was discontinued for 5 days. The improvement continued on calcitonin treatment for 1 year, with falls in serum alkaline phosphatase and urinary hydroxyproline excretion. It is suggested that calcitonin treatment, in reducing the abnormally high metabolic activity of the diseased bone, and hence its vascular perfusion, allows more blood to reach the spinal cord.