Establishment and characterization of three new breast-cancer cell lines

We have established and characterized 3 new breast-cancer cell lines from pleural effusions of patients with advanced breast cancer. All 3 cell lines, designated IBEP-1, IBEP-2 and IBEP-3, showed typical ultrastructural characteristics of epithelial mammary tumor cells. Electron microscopy showed, among other characteristics, the presence of numerous microvilli, desmosomal junctions, intracytoplasmic duct-like vacuoles, well-developed endoplasmic reticulum and large nuclei. Immunohistochemical and biochemical studies revealed that the 3 cell lines expressed cytokeratin, epithelial membrane antigen, CEA and CA 15-3, but all showed negative immunoreaction for vimentin. On the other hand, other antigens (LEU-M1, GCDFP 15, c-erbB-2) were expressed by some of the cell lines, but in a variable manner. Ploidy studies confirmed the neoplastic origin of the cell lines. The doubling times were 68 hr for IBEP-1, 29 hr for IBEP-2 and 39 hr for IBEP-3. Only IBEP-2 cells expressed estrogen receptors (ER+), which were down-regulated after preincubation with E2, but they did not express progesterone receptors (PgR-). IBEP-1 and IBEP-3 cells were ER- but expressed PgR (PgR+). In these 2 cell lines, PgR were down-regulated after pre-incubation of the cells with progesterone (10(-8) M) for 24 hr. Estradiol (E2) increased the proliferation rate of IBEP-2 cells and progesterone increased the proliferation of IBEP-I and -3 cell lines. S.C. injection of the 3 IBEP cell lines into nude mice resulted in the growth of solid tumors between 11 and 16 weeks after inoculation. These cell lines could thus be new models for studying various aspects of the biology and the tumorigenicity of breast-cancer cells. A major interest of these new cell lines is that 2 of them were ER- and PgR+, which is an exceptional phenotypic feature. These 2 cell lines could be interesting models for studying the regulation of PgR and the effects of progestins and antiprogestins independently of the presence of ER.

Production and regulation of interleukin-11 by breast cancer cells

We have studied the production of interleukin-11 (Il-11) in 13 breast cancer cell (BCC) lines. Two of these cell lines (MDA-MB-231 and Hs578T) expressed the cytokine at both the protein and mRNA levels. Il-11 did not modulate the growth of five BCC lines examined, including the two cytokine-producing BCC lines. The production of Il-11 was increased by transforming growth factor-beta1 in a dose-dependent manner with a rapid (2 h) and transient (24 h) mRNA induction, but not by epidermal growth factor, insulin-like growth factor-I and -II, basic fibroblast growth factor, platelet-derived growth factor or parathyroid hormone. The cyclic AMP inducer, forskolin, and the activator of protein kinase C, phorbol 12-myristate 13-acetate, also stimulated the production of Il-11. Besides Il-11, MDA-MB-231 and Hs578T were the only BCC lines to produce interleukin-6 (Il-6) protein and mRNA. Since Il-11 and Il-6 are potent stimulators of osteoclast development and bone is a major source of TGF-beta1, our data suggest that Il-11, together with Il-6, contributes to the high bone destructive capacity of MDA-MB-231 cells and could play a role in breast cancer-induced osteolysis.

[Bone metastases: pathogenesis and treatment with diphosphonates]

Tumor-induced osteolysis is essentially mediated by the osteoclasts whose number and activity appear to be stimulated under the influence of tumor secretory products. In cases of hypercalcemia, there is also a variable inhibition of the bone formation rate leading to a characteristic "uncoupling" in bone turnover. An analog of parathyroid hormone--"parathyroid hormone-related protein (PTHrP)"--plays an essential role in the pathogenesis of neoplastic hypercalcemia. PTHrP concentrations are not regulated by calcium levels which is in marked contrast for PTH. We have also shown that osteoblasts could be essential target cells in the process of tumor-induced osteolysis leading to an increase in osteoclast function and number. From a therapeutic point of view, we have contributed to the optimalization of the therapeutic schemes for tumor-induced hypercalcemia and tumor-induced osteolysis for which the dose of 90 mg of pamidronate appears to be optimal.

Breast cancer cell response to calcitonin: modulation by growth-regulating agents

Calcitonin may induce cyclic AMP production by breast cancer cells and inhibit their growth. The molecular complex leading to cyclic AMP production in response to calcitonin is made of the calcitonin receptor coupled to the adenylate cyclase by at least one guanine nucleotide-binding protein (G-protein, of the Gs type). Our aim was to determine whether and how the responses of cells to calcitonin were modulated by growth-regulating agents not directly acting through the cyclic AMP pathway. We found that the cyclic AMP response to calcitonin was reduced after preincubation of cells with the mitogens 17beta-estradiol and epidermal growth factor (EGF), while it was enhanced after preincubation with the growth inhibitors tamoxifen and 1,25(OH)2D3, as well as with an antisense oligonucleotide to the proto-oncogene c-myc. Scatchard-plots revealed no significant change in the calcitonin receptor number or affinity. On the other hand, the cyclic AMP production of cells in response to activators unrelated to calcitonin, such as forskolin, a direct adenylate cyclase effector, and isoproterenol, a beta-adrenergic receptor agonist, was modulated only weakly or not at all by the growth-regulating agents. This suggested that the effects observed were essentially calcitonin-specific and associated with events located between the calcitonin receptor and the adenylate cyclase. Since a Go- or Gi-protein has been previously implicated in the calcitonin signal transduction, we tested the action of pertussis toxin, a specific inhibitor of these G-proteins. Pertussis toxin produced a general increase in the cyclic AMP response of cells to calcitonin; moreover, the toxin almost abolished the effect of mitogens and antimitogens on that parameter. We conclude that in breast cancer cells, the calcitonin receptor and the adenylate cyclase are coupled by at least one Go/Gi-protein sensitive to growth-regulating agents; this results in a modulation of the cyclic AMP response to calcitonin by these agents. On the other hand, the growth-inhibitory effect of calcitonin on breast cancer cells was reduced by 17beta-estradiol and enhanced by tamoxifen. We suggest that this could be a consequence of changes in cyclic AMP levels and deserves further investigation.

Clinical research update: zoledronate

The prolonged administration of bisphosphonates can reduce the frequency of morbid skeletal events in patients with metastatic breast carcinoma or multiple myeloma. The development of more potent bisphosphonates will simplify current therapeutic schemes and could improve the therapeutic effectiveness of bisphosphonate therapy. Zoledronate (CGP-42446) is the most potent of the clinically tested compounds. It is a cyclic third-generation bisphosphonate that is 100-850 times more active than pamidronate in several in vivo and in vitro pharmacological test systems. The first therapeutic trial with zoledronate has been performed in patients with tumor-induced hypercalcemia (corrected calcium [Ca] > 2.75 mmol/L after rehydration). In a Phase I multicenter trial, it was shown that a single infusion was already effective at dose levels of 0.02 and 0.04 mg of zoledronate/kg bodyweight, thus 1.2 and 2.4 mg total dose for an average 60-kg individual. Five of 5 patients became normocalcemic after a dose of 0.02 mg/kg, and 14 of 15 (93%) after a dose of 0.04 mg/kg. The median time to normalization of serum Ca was 2 days and the median duration of action was 33 days, suggesting that zoledronate has a faster onset and a longer duration of action than other clinically tested bisphosphonates. Zoledronate was well tolerated; the only side effect was an increase in body temperature in 30% of the cases, which was probably not drug-related in many patients. A Phase I trial also has been initiated in patients with lytic bone metastases. Zoledronate was given as monthly short infusions (5-30 minutes) at doses between 0.1-8.0 mg. There was an analgesic effect and even at low doses (2 mg and above), the effects on the biochemical markers of bone resorption appeared to be greater than after 90-mg pamidronate infusions. These initial human data suggest that zoledronate can be administered as convenient short intravenous infusions and lead to a more marked and a more prolonged inhibition of bone resorption than is currently possible with available compounds. Future trials will have to determine whether prolonged treatment with this extremely potent bisphosphonate also can have a greater effect on the morbidity of bone metastases.

The bone isoenzyme of alkaline phosphatase in hypercalcaemic cancer patients

Alkaline phosphatase (AP) is the classic marker of bone formation, especially in cancer patients, but the interpretation of its measurement is complicated by the existence of various circulating isoenzymes, especially of liver origin. The introduction of a mass measurement of the bone isoenzyme of AP (BAP) by an immunoradiometric assay has markedly improved the sensitivity and the specificity of the determination. We measured BAP and other markers of bone turnover in 46 patients with tumour-induced hypercalcaemia (TIH), which is an interesting model for evaluating markers of bone formation because of the uncoupling between bone formation and bone resorption found by histomorphometric techniques. The extent of bone metastatic involvement was evaluated by planimetry on bone scintigraphy. Mean (+/- S.D.) BAP concentrations were slightly higher in patients with TIH than in healthy subjects, 15.5 +/- 8.5 versus 12.4 +/- 3.5 micrograms/L (P < 0.05). However, the scatter of the data in TIH patients was quite marked. Increased values (10/46 patients, 22%) occurred only in patients with bone metastases. Total AP, gamma GT and BGP levels, as well as markers of bone resorption, were not significantly different between patients with or without bone metastases. BAP levels were significantly correlated with AP (rs = 0.63; P < 0.01) but not with BGP levels nor with markers of bone resorption. BAP levels were also correlated with the extent of bone uptake at scintigraphy (rs = 0.54; P < 0.01), but this was not the case for total AP or BGP. In the 36 patients re-evaluated when normocalcemic after pamidronate therapy, BAP levels increased from 16.3 +/- 9.2 to 22.2 +/- 21.3 micrograms/L (P < 0.05) but there were no significant changes in AP or BGP concentrations. In summary, our data confirm the existence of an uncoupling in bone turnover in TIH and indicate that cancer hypercalcaemia is another pathological condition characterised by a discordance between BAP and BGP concentrations. BAP levels appear to be a better reflection of bone metastatic involvement than total AP or BGP and their short-term increase after pamidronate therapy could reflect the recently described effects of bisphosphonates on osteoblasts.

The concept of rehabilitation of cancer patients

The scope of supportive care and cancer rehabilitation is very wide and heterogeneous. In this review we focus on nutritional aspects, sexual and gonadal function, psychological rehabilitation, treatment of cancer pain, and rehabilitation of patients with bone metastases. The anorexia-cachexia syndrome is a particularly frequent manifestation of cancer that profoundly affects body image and significantly impairs quality of life of cancer patients. However, enteral feeding through nasogastric tubes, gastrostomies, or jejunostomies is an efficient method for providing long-term enteral nutrition at home and for contributing to complete rehabilitation after cancer therapy. Recent effort has focused on nutritional pharmacology and on the optimalization of the use of appetite-stimulating drugs, such as progestational agents. The psychological components of cancer, anticancer therapy, and quality of life have now been widely recognized and studied. Effective pharmacological and psychotherapeutic interventions help patients and their family to better adjust to the chronic stress of cancer, but more specific determinants of psychological morbidity should be developed. In particular, the safe and efficient use of the most recent classes of antidepressants and anxiolytics should be urgently studied. More than 90% of cancer patients present one or more pain syndromes during their illness. The adequate use of drugs is the cornerstone of treatment. The development on new molecules and new routes of administration opens interesting perspectives for cancer pain control. Bone metastases are the source of considerable morbidity. Intravenous bisphosphonates have been successfully used for the treatment of the symptoms of metastatic bone disease, especially bone pain. Moreover, monthly pamidronate infusions in addition to chemotherapy reduce the mean skeletal morbidity rate by more than one third and contribute to the rehabilitation of cancer patients with bone metastases from breast cancer or with multiple myeloma.

Regulation of c-fos and c-jun expression by calcitonin in human breast cancer cells

Breast cancer cells (BCC) have calcitonin (CT) receptors, yet the action of the hormone on these cells is largely unknown. We found that CT produced a strong and transient time- and dose-dependent increase in c-fos mRNA in BCC lines. This event was prevented by a protein kinase A (PKA) inhibitor, H89. CT alone did not influence the expression of c-jun and of the tissue inhibitors of metalloproteases (timp) -1 and -2 mRNAs; however, it reduced the induction of these mRNAs by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA), without apparent changes in the half-life of the mRNA (measured for c-jun). Along the same line, CT reduced the c-jun induction and T-47D growth stimulation by epidermal growth factor (EGF) and insulin. These effects were mimicked by forskolin and/or prevented by H89, suggesting that PKA activation was involved. These results indicate that CT modulates in BCC the mRNA levels of two important growth-related early response genes (c-fos and c-jun) and of two other genes (timp-1 and -2) involved in the control of metastatic events.

Secretory products of breast cancer cells specifically affect human osteoblastic cells: partial characterization of active factors

The pathogenesis of tumor-induced osteolysis (TIO) following breast cancer metastases in bone remains unclear. We postulated that osteoblasts could be target cells for the secretory products of breast cancer cells. We previously showed that serum-free conditioned medium (CM) of the breast cancer cell line MCF-7 inhibits DNA synthesis by 75% of control values in osteoblast-like cells SaOS-2 and that this effect is only in a minor part due to transforming growth factor beta secretion. To establish the specificity of our observations and to look for other biologically active factors, we have tested the effects of medium conditioned by several cancer and noncancer cell lines (breast, colon, placenta, or fibrosarcoma) on the proliferation of osteoblast-like cells (SaOS-2, MG-63), normal human osteoblasts, human fibrosarcoma cells, and normal human fibroblasts. Culture medium (1:2) of the breast cancer cell lines MCF-7, T-47D, MDA-MB-231, and SK-BR-3 inhibited by 25-50% the proliferation of osteoblast-like cells SaOS-2, MG-63, and normal osteoblasts as evaluated by the MTT survival test or [3H]thymidine incorporation. MCF-7 cells completely inhibited the proliferation of normal human osteoblasts in coculture. This inhibitory effect was reversible and not due to cytotoxicity. Moreover, the cyclic adenosine monophosphate (cAMP) response to parathyroid hormone (PTH) of osteoblast-like cells SaOS-2 was also increased by 100-240% by the same CM. Such activities were, however, not detected in medium from the breast noncancer cell line HBL-100 or in the medium conditioned by non-breast cancer cell lines (COLO 320DM, HT-29, JAR, or HT-1080). Medium from the breast cancer cells had no effect on normal human fibroblasts or fibrosarcoma cells (HT-1080), suggesting the specificity of their action on human osteoblasts. After partial purification by ultrafiltration and size-exclusion chromatography, we found that medium of T-47D cells contained at least three nonprostanoid factors of low molecular weights (apparent MW of 700, 1500, and 4000 D) which affected human osteoblast-like cells. These factors were heat stable and could be peptides without disulfide bonds. In summary, our data show that human breast cancer cells release soluble factors that inhibit osteoblast proliferation and increase their cAMP response to PTH, indicating that osteoblasts could be important target cells for breast cancer cells and could be involved in the process of TIO.

Comparative evaluation of markers of bone resorption in patients with breast cancer-induced osteolysis before and after bisphosphonate therapy

The understanding of the pathophysiology and the monitoring of metastatic bone disease remains unsatisfactory. We compared several new markers of bone turnover in normocalcaemic patients with breast cancer-induced osteolysis before and after a single infusion of the bisphosphonate pamidronate. We studied 19 ambulatory patients with advanced breast cancer and extensive bone metastases who did not receive any systemic antineoplastic therapy. Pamidronate was administered at doses of 30, 60, 90 or 120 mg and the patients were followed weekly during a mean of 8 (range 4-10) weeks. Compared with healthy premenopausal women, the percentage of elevated values at baseline was 47% for fasting urinary calcium (uCa), 74% for hydroxyproline, 83% for CrossLaps (a new marker of type I collagen degradation) and 100% for the collagen cross-links (measured by high performance liquid chromatography), namely pyridinoline (Pyr) and deoxyPyr (D-Pyr). Pretreatment levels of uCa did not correlate significantly with any of the four markers of bone matrix resorption, whereas the correlations between these four markers were generally significant (r(s)=0.43-0.71). Alkaline phosphatase correlated significantly with markers of bone matrix resorption (r(s)=0.54-0.74). All parameters, except phosphaturia (uPi) and the bone formation markers (osteocalcin and alkaline phosphatase), fell significantly after pamidronate therapy, up to day 42 for hydroxyproline, D-Pyr and CrossLaps and day 56 for uCa. This longer lasting effect was probably due to the parathyroid hormone (PTH) surge following the decrease in serum calcium, implying that the decrease in uCa can overestimate the effects of bisphophonates on bone resorption. The decrease in bone turnover parameters was most marked for CrossLaps, indicating the potential of this new marker for monitoring therapy. Sequential determinations of markers of bone matrix resorption should be useful in delineating the optimal therapeutic schemes of bisphosphonates and for evaluating treatment effects on bone in cancer patients.

Dose-response study of ibandronate in the treatment of cancer-associated hypercalcaemia

Hypercalcaemia is an important cause of morbidity in malignant disease. We studied the efficacy and safety of intravenous ibandronate (a new, potent bisphosphonate) in a multicentre study of 147 patients with severe cancer-associated hypercalcaemia which had been resistant to treatment with rehydration alone. Of 131 randomized patients who were eligible for evaluation, 45 were allocated to receive 2 mg ibandronate, 44 patients to receive 4 mg and 42 patients to receive 6 mg. Serum calcium values fell progressively in each group from day 2, reaching a nadir at day 5, and in some patients normocalcaemia was maintained for up to 36 days after treatment. The 2-mg dose was significantly less effective than the 4-mg or 6-mg dose in correcting hypercalcaemia, as the number of patients who achieved serum calcium values below 2.7 mM after treatment was 50% in the 2-mg group compared with 75.6% in the 4-mg group and 77.4% in the 6-mg group (P < 0.05; 2 mg vs others). In a logistic regression analysis, three factors were found to predict response; ibandronate dose (higher doses were more effective), severity of presenting hypercalcaemia (severe hypercalcaemia was associated with less complete response) and tumour type (patients with breast carcinoma and haematological tumours responded better than those with other tumours). Ibandronate was generally well tolerated and no serious drug-related adverse events were observed. We conclude that ibandronate is a safe, well tolerated and effective treatment for cancer-associated hypercalcaemia, which should prove a useful addition to the current range of therapies available to treat this condition.

Retrobulbar optic neuritis after pamidronate administration in a patient with a history of cutaneous porphyria

We describe the case of a patient who developed reversible retrobulbar optic neuritis after intravenous pamidronate therapy for established osteoporosis. This possible complication has never been previously reported and, since our patient had a history of porphyria, it suggests that bisphosphonates should be administered cautiously in patients with this disease.

Tumor-induced hypercalcemia in a patient with extensive soft tissue sarcoma: effects of bisphosphonate therapy and surgery

Tumor-induced hypercalcemia (TIH) is a frequent complication of advanced cancer, but it has been rarely reported in patients with sarcoma. We describe the case of a young female patient with TIH and with an extensive synoviosarcoma of the left lower limb destroying the bony structures. Hypercalcemia was severe (18.3 mg/dl) and accompanied by low serum Pi and suppressed parathyroid hormone (PTH) and 1,25(OH)2 vit D3 serum concentrations. Hypercalcemia was successfully treated with ibandronate, a new third-generation bisphosphonate, and radical surgery was performed when the patient was normocalcemic. Circulating levels of PTH-related protein (PTHrP) were elevated at 22.5 pmol/L (NI < 9). PTHrP levels did not change after successful therapy of TIH, in contrast with PTH, which increased sharply. PTHrP levels were normalized after radical surgery. Moreover, low serum Pi with reduced threshold for phosphate excretion and increased tubular calcium reabsorption supported the notion that PTHrP was indeed the essential mediator of paraneoplastic hypercalcemia in this case despite the extensive bone destruction.

Cyclical pamidronate infusions in postmenopausal osteoporosis

OBJECTIVES

Until recently, two bisphosphonates, pamidronate (APD) and etidronate were available for clinical purposes. Contrary to etidronate, pamidronate was not extensively studied in osteoporosis. Therefore, we investigated the effect of cyclic intravenous APD treatment in postmenopausal osteoporosis.

METHODS

Parameters of bone remodelling and lumbar spine bone mineral density (BMDL) were assessed in 36 postmenopausal women with osteoporosis (BMDL t-score < -2.5). They received five courses of APD. Intervals between courses were defined according to the fasting urinary calcium excretion (UCa/Cr, mg/mg creatinine) which was measured before each APD course and every 2 weeks after the first treatment. The patients were retreated when UCa/Cr had reached baseline levels. Serum biochemical parameters and urinary hydroxyproline (UOHPro/Cr, mg/mg) were measured before each APD.

RESULTS

UCa/Cr decreased during 21-28 days after each course but UCa/Cr measured before APD infusion remained unchanged. UOHPro/Cr significantly fell after the third APD (P = 0.02). Serum calcium was however not modified. Parameters of bone remodelling decreased with time: bone-GLA protein (BGP) started to fall after the first APD (P = 0.0001) and continued to decrease until the fourth APD course, alkaline phosphatase (ALP) significantly decreased after the first APD (P = 0.005); intact PTH significantly increased at the fifth APD (P = 0.02). BMDL significantly increased after 1 year treatment: +2.9% of baseline value.

CONCLUSIONS

Cyclical pamidronate treatment of postmenopausal osteoprosis appeared to be effective in reducing bone turnover assessed by BGP, ALP and OHPro/Cr. This effect is followed by an increase in vertebral BMD.

Technical and clinical validation of a new immunoradiometric assay for human osteocalcin

The measurement of circulating osteocalcin or bone GLA protein (BGP) constitutes a well established and non-invasive means for evaluating preferentially the bone formation rate, but most available commercial assays suffer from several technical constraints, notably a rapid degradation of BGP at room temperature or after thawing and the inability to measure subnormal values. We evaluated, from a technical and a clinical viewpoint, a newly available two-site sandwich immunoradiometric assay (IRMA) using standard of human origin and two different monoclonal antibodies. The theoretical and functional assay detection limit was 0.3 ng/ml. Concentrations of BGP progressively decreased when the serum was left at 4 degrees C or at room temperature (mean apparent loss of 15% after 24 h). Two cycles of freezing-thawing only lightly reduced the BGP concentrations. The mean (+/- SD) BGP concentration was 19.6 +/- 7.9 ng/ml in healthy subjects (NI, N = 61); the normal range was 8.1-35.6 ng/ml. There was a marked difference between pre- and postmenopausal women: 15.1 +/- 4.4 vs 22.3 +/- 8.4 ng/ml, respectively (p < 0.05). The mean BGP concentration in patients with tumor-induced hypercalcemia (N = 29) was not significantly different from NI, but nine patients (31%) had subnormal levels and five (17%) had elevated BGP levels. Concentrations of BGP were significantly increased in patients with hyperparathyroidism (N = 14) (45.1 +/- 21.0 ng/ml) and significantly lower than NI in patients with hypoparathyroidism (N = 18) (7.3 +/- 4.6 ng/ml). Concentrations of BGP were also measured by a classical radioimmunoassay using bovine standards and tracer; the correlations between both sets of measurements were significant in all groups, except in patients with hypoparathyroidism. In summary, this newly available IRMA for measuring circulating human BGP appears to be quite sensitive, reproducible and robust. It should be especially useful for investigating clinical conditions characterized by a low bone formation rate.

Effects of secretory products of breast cancer cells on osteoblast-like cells

The pathogenesis of breast cancer-induced osteolysis remains largely unknown. To evaluate the potential role of osteoblasts as target cells during this process, we incubated SaOS-2 human osteoblast-like cells (OBL) with culture media conditioned by proliferative (PM, 'Proliferation Media') or confluent (CfM, 'Confluence Media') MCF-7 human breast cancer cells. CfM decreased the growth of OBL by 26% (P < 0.01) while PM was without significant effect on this parameter. In contrast, both PM and CfM obtained from MCF-7 cultures increased the cyclic AMP (cAMP) response of OBL to the osteolytic agents PTH (10(-8) M) and PTH-related peptide (PTHrP, 10(-8) M) by a factor of about 3 (P < 0.001), and to prostaglandin E(2) (PGE(2),10(-6) M) by a factor of about 2 (P < 0.01). No significant modulation of OBL growth or sensitivity to PTH, PTHrP, or PGE2 was induced by media obtained from HBL-100 non-malignant immortalized breast epithelial cell cultures. 17betaestradiol (E(2), 10(-8) M) and the antiestrogen tamoxifen (Tam, 10(-7) M) added for 48 h to MCF-7 cultures before collecting conditioned media attenuated and potentiated, respectively, the PM- but not the CfM-induced increase in the response of OBL to PTH or PTHrP Along the same line, the addition to MCF-7 conditioned media of a polyclonal anti-transforming growth factor-beta (TGF-beta) antibody attenuated by about 25% (P < 0.01) the PM-induced increase in OBL response to PTH and PTHrP while abrogating the modulatory effects of E(2) and Tam on that response. Together, our results indicate that MCF-7 breast cancer cells secrete factors which inhibit the growth of OBL and increase their sensitivity to various osteolytic agents. TGF-beta was only partly responsible for these effects, and accounts for their modulation by E(2) and Tam. The identification of other osteoblast-modulatory factor(s) should contribute to a better understanding and treatment of breast cancer-induced osteolysis.

Administration of the bisphosphonate ibandronate (BM 21.0955) by intravenous bolus injection

Bisphosphonates (BPs) are used for the treatment of both benign and malignant diseases characterized by increased bone resorption. Because of their potential nephrotoxicity, currently available BPs have to be administered by slow intravenous infusion, with conventional doses requiring an infusion time of at least 2 h. In the present investigation, we evaluated the safety and efficacy of the new BP ibandronate as administered by intravenous bolus injection. On day 0, 15 normocalcemic breast cancer patients with bone metastases were treated with 3 mg of ibandronate injected intravenously over 60-120 s. Ibandronate treatment led to significant decreases in serum levels of calcium (p < 0.0001) and phosphate (p < 0.0001) and to subsequent increases in serum concentrations of parathyroid hormone (p <0.0001) and calcitriol (p <0.0001). Moreover, there was a significant reduction in the urinary excretion of calcium (p <0.0001), pyridinoline (p <0.001), and deoxypyridinoline (p < 0.0001). Three serious adverse events were observed: vomiting (WHO grade 3), pulmonary infection (WHO grade 2), and deterioration of a pre-existing impaired glucose tolerance (WHO grade 3). Only vomiting appeared to be related to administration of the drug. The most frequent nonserious adverse events were 10 cases of transient clinically asymptomatic hypocalcemia and 8 cases of asymptomatic hypophosphatemia. Serum levels of creatinine and urea nitrogen did not increase, nor did creatinine clearance deteriorate. When tested with the dipstick method, proteinuria was present in five (33%) patients prior to ibandronate treatment (median protein concentration, 30 mg/dl). Following the BP injection, seven (47%) patients showed slight (highest protein concentration, 30 mg/dl) transient proteinuria at at least one time point, of which six cases appeared in conjunction with leucocyturia and three with microhematuria. Side effects specific to aminosubstituted BPs (fever, reduction in white blood cell counts, and lymphocyte counts) were not seen in these 15 patients. In conclusion, a single intravenous injection of 3 mg of ibandronate significantly inhibited osteoclast activity as reflected by the decrease in serum calcium and in urinary parameters of bone resorption. Serum creatinine levels and estimates of creatinine clearance were not affected by therapy. However, before repeated bolus injections of ibandronate at this dosage can be recommended for further clinical trials, whether a relationship exists between the transient pathological urinary findings and injected ibandronate needs to be determined.

Randomized phase II trial comparing different doses of the bisphosphonate ibandronate in the treatment of hypercalcemia of malignancy

PURPOSE

To evaluate the hypocalcemic effect and safety of three different doses of the bisphosphonate ibandronate in tumor-associated hypercalcemia, and to identify factors predicting response.

PATIENTS AND METHODS

One hundred seventy-four cancer patients with a serum calcium level greater than 2.7 mmol/L (10.8 mg/dL) were enrolled onto the trial. If hypercalcemia persisted after fluid repletion, patients were randomly assigned to treatment with 0.6 mg, 1.1 mg, and 2.0 mg of ibandronate. Response, defined as restoration of normocalcemia, was evaluated by an intent-to-treat analysis.

RESULTS

One hundred seventy-three (99%) patients were assessable for toxicity and 151 (87%) for efficacy. The administration of 0.6 mg (group A), 1.1 mg (group B), or 2.0 mg (group C) of ibandronate led to response rates of 44%, 52%, and 67%, respectively. Significantly more patients in group C responded than in group A (P = .0276). Of the various parameters examined, only the initial serum calcium level (P < .0001; odds ratio, 0.083) and the dose of ibandronate (P = .0162; odds ratio, 2.094) correlated with response. One hundred ninety-five adverse events (AEs) were reported, 99 classified as serious and 96 as nonserious. Three serious and sixteen nonserious AEs were considered related to ibandronate treatment. The three serious AEs were one case with thrombocytopenia, one with nausea, and one with fever.

CONCLUSION

Ibandronate therapy led to a dose-dependent reduction in serum calcium levels. The response to ibandronate treatment correlated negatively with the initial serum calcium level and positively with the dose administered. A dose of 2 mg was necessary to achieve a response rate comparable to that in previous studies with the bisphosphonates pamidronate and clodronate. Because the incidence of drug-associated AEs was low, a dose escalation of ibandronate can be recommended for further clinical trials.

Clinical trials in metastatic breast cancer to bone: past--present--future

The skeleton is the most common site of metastatic disease in breast cancer and the site of first distant relapse in almost one half of the cases. Bone metastases are the source of a considerable morbidity, including pain, long bone fractures in 10-20%, and hypercalcemia in 10-15% of the cases. The median survival after first relapse in bone is close to two years compared to three months after first relapse in liver. A review of endocrine and chemotherapy trials indicates that patients with metastatic bone disease have a lower response rate to antineoplastic therapy than patients with soft tissue or visceral metastases, but this probably reflects selection bias and the insensitivity of our current methods for evaluating bone response. Classical UICC criteria require radiological recalcification, implying not only tumor regression but also bone healing, which can take many months. Symptom evaluation, measurement of tumor markers and of biochemical parameters of bone turnover should be further investigated for early assessment of bone response. Pain relief could occur in more than half of the patients after radiotherapy, but uncertainty remains as to the relationship between radiotherapy dose or fractionation and the incidence duration of pain relief. Radioactive isotopes have been used successfully in patients with blastic bone metastases from prostate cancer, but controlled studies are lacking in breast cancer. The pathophysiology of metastatic bone destruction makes it logical to use osteoclast inhibitors. Bisphosphonates are potent inhibitors of bone resorption that have opened the way for a noncytotoxic medical treatment of bone metastases. Two large-scale studies in patients with breast cancer metastatic to the skeleton, one with clodronate and one with pamidronate, indicate that the prolonged administration of oral bisphosphonates, in addition to systemic antineoplastic therapy, can reduce the frequency of morbid skeletal events, including the incidence of hypercalcemic episodes and the need for radiotherapy, and probably the incidence of severe pain and of fractures. On the other hand, in patients with established tumor-induced osteolysis, intravenous pamidronate infusions can induce bone pain relief and an objective sclerosis of lytic lesions maybe in one-third and in one-fourth of the cases, respectively. These figures must, however, be taken with caution, and prospective placebo-controlled trials in large series of patients are needed.

Calcitonin for prevention and treatment of postmenopausal osteoporosis

Prolonged calcitonin administration (intramuscular, subcutaneous, or intranasal) can prevent postmenopausal trabecular bone loss. Nasal administration constitutes a particularly attractive option for women who cannot tolerate or benefit from estrogen replacement therapy. The optimal schedule of administration still has to be precised, but 100 U/day of nasal calcitonin, combined with calcium supplements, can currently be recommended. Interrupted regimens are maybe favourable. Calcitonin can also prevent further bone loss in established osteoporosis particularly if bone turnover is increased. The anti-fracture efficacy of calcitonin is suggested by different types of studies but has not been formally demonstrated. Lastly, its analgesic efficacy in cases of painful vertebral compression fractures has been demonstrated in controlled studies.