Once-weekly TransCon CNP (navepegritide) in children with achondroplasia (ACcomplisH): a phase 2, multicentre, randomised, double-blind, placebo-controlled, dose-escalation trial

Background

TransCon CNP (navepegritide) is an investigational prodrug of C-type natriuretic peptide (CNP) designed to allow for continuous CNP exposure with once-weekly dosing. This 52-week phase 2 (ACcomplisH) trial assessed the safety and efficacy of TransCon CNP in children with achondroplasia.

Methods

ACcomplisH is a global, randomised, double-blind, placebo-controlled, dose-escalation trial. Study participants were recruited between June 10, 2020, and September 24, 2021. Eligible participants were prepubertal, aged 2-10 years, with genetically confirmed achondroplasia, and randomised 3:1 to once-weekly subcutaneous injections of TransCon CNP (6, 20, 50, or 100 μg CNP/kg/week) or placebo for 52 weeks. Primary objectives were safety and annualised growth velocity (AGV). ACcomplisH is registered with ClinicalTrials.gov (NCT04085523) and Eudra (CT 2019-002754-22).

Findings

Forty-two participants received TransCon CNP at doses of 6 μg (n = 10; 7 female), 20 μg (n = 11; 3 female), 50 μg (n = 10; 3 female), or 100 μg (n = 11; 6 female) CNP/kg/week, with 15 receiving placebo (5 female). Treatment-emergent adverse events (TEAEs) were mild or moderate with no grade 3/4 events reported. There were 2 serious TEAEs that were assessed as not related to TransCon CNP. Eleven injection site reactions occurred in 8 participants receiving TransCon CNP and no symptomatic hypotension occurred. TransCon CNP demonstrated a dose-dependent improvement in AGV. At 52 weeks, TransCon CNP 100 μg CNP/kg/week significantly improved AGV vs placebo (least squares mean [95% CI] 5.42 [4.74-6.11] vs 4.35 [3.75-4.94] cm/year; p = 0.0218), and improved achondroplasia-specific height SDS from baseline (least squares mean [95% CI] 0.22 [0.02-0·41] vs -0·08 [-0.25 to 0.10]; p = 0.0283). All participants completed the randomised period and continued in the ongoing open-label extension period receiving TransCon CNP 100 μg CNP/kg/week.

Interpretation

This phase 2 trial suggests that TransCon CNP is effective, safe, with low injection site reaction frequency, and may provide a novel, once-weekly treatment option for children with achondroplasia. These results support TransCon CNP at 100 μg CNP/kg/week in the ongoing pivotal trial.

Funding

Ascendis Pharma, A/S.

Post hoc longitudinal assessment of the efficacy and safety of recombinant factor IX Fc fusion protein in hemophilia B

Long-term efficacy and safety of the extended half-life recombinant factor IX Fc fusion protein (rFIXFc) has been established among previously treated patients with severe hemophilia B in 2 phase 3 trials (B-LONG [#NCT01027364] and Kids B-LONG [#NCT01440946]) and a long-term extension study (B-YOND [#NCT01425723]). In this study, we report post hoc analyses of pooled longitudinal data for up to 6.5 years for rFIXFc prophylaxis. In the B-LONG study, subjects ≥12 years received weekly dose-adjusted prophylaxis (WP; starting dose, 50 IU/kg), individualized interval-adjusted prophylaxis (IP; initially, 100 IU/kg every 10 days), or on-demand dosing. In the Kids B-LONG study, subjects <12 years received 50 to 60 IU/kg every 7 days, adjusted as needed. In the B-YOND study, subjects received WP (20-100 IU/kg every 7 days), IP (100 IU/kg every 8-16 days), modified prophylaxis, or on-demand dosing; switching between treatment groups was permitted. A total of 123 subjects from B-LONG and 30 from Kids B-LONG study were included, of whom 93 and 27, respectively, enrolled in the B-YOND study. The median cumulative duration of treatment was 3.63 years (range, 0.003-6.48 years) in B-LONG/B-YOND and 2.88 years (range, 0.30-4.80 years) in Kids B-LONG/B-YOND group. Annualized bleed rates (ABRs) remained low, annualized factor consumption remained stable, and adherence remained high throughout treatment. Low ABRs were also maintained in subjects with dosing intervals ≥14 days or with target joints at baseline. Complete resolution of evaluable target joints and no recurrence in 90.2% of baseline target joints during follow-up were observed. rFIXFc prophylaxis was associated with sustained clinical benefits, including long-term bleed prevention and target joint resolution, for severe hemophilia B.

High use of pain, depression, and anxiety drugs in hemophilia: more than 3000 people with hemophilia in an 11-year Nordic registry study

Background

Pain is a common feature of hemophilia, but prevalence of depression and anxiety is less studied. Registry data on prescription drugs can provide an objective measure of the magnitude of these complications.

Objectives

To identify treatment patterns of prescribed pain, antidepressant, and antianxiety medications compared with those of matched controls in 4 Nordic countries.

Methods

The MIND study (NCT03276130) analyzed longitudinal individual-level national data during 2007-2017. People with hemophilia (PwH) were identified from National Health Data Registers by diagnosis or factor replacement treatment and compared with population controls. Three subgroups were defined by the use of factor concentrates and sex (moderate-to-high factor consumption (factor VIII [FVIII] use of ≥40 IU/kg/week or FIX use of ≥10 IU/kg/week), low factor consumption, and women including carriers).

Results

Data of 3246 PwH, representing 30,184 person-years, were analyzed. PwH (including children and adults) used more pain, depression, and anxiety medications compared with controls. This was most accentuated in the moderate-to-high factor consumption group and notably also observed in men with low factor consumption and women including carriers, usually representing a milder phenotype. A higher opioid use was observed across all age groups: 4- to 6-fold higher in the moderate-to-high factor consumption group and 2- to 4-fold higher in the low factor consumption group.

Conclusion

The consistent higher use of pain, depression, and anxiety medications among PwH compared with population controls, regardless of age, sex, or factor consumption, in broad national data suggests a need for improved bleed protection and hemophilia care for all severities including mild hemophilia.

Efanesoctocog Alfa Prophylaxis for Patients with Severe Hemophilia A

BACKGROUND

Efanesoctocog alfa provides high sustained factor VIII activity by overcoming the von Willebrand factor-imposed half-life ceiling. The efficacy, safety, and pharmacokinetics of efanesoctocog alfa for prophylaxis and treatment of bleeding episodes in previously treated patients with severe hemophilia A are unclear.

METHODS

We conducted a phase 3 study involving patients 12 years of age or older with severe hemophilia A. In group A, patients received once-weekly prophylaxis with efanesoctocog alfa (50 IU per kilogram of body weight) for 52 weeks. In group B, patients received on-demand treatment with efanesoctocog alfa for 26 weeks, followed by once-weekly prophylaxis with efanesoctocog alfa for 26 weeks. The primary end point was the mean annualized bleeding rate in group A; the key secondary end point was an intrapatient comparison of the annualized bleeding rate during prophylaxis in group A with the rate during prestudy factor VIII prophylaxis. Additional end points included treatment of bleeding episodes, safety, pharmacokinetics, and changes in physical health, pain, and joint health.

RESULTS

In group A (133 patients), the median annualized bleeding rate was 0 (interquartile range, 0 to 1.04), and the estimated mean annualized bleeding rate was 0.71 (95% confidence interval [CI], 0.52 to 0.97). The mean annualized bleeding rate decreased from 2.96 (95% CI, 2.00 to 4.37) to 0.69 (95% CI, 0.43 to 1.11), a finding that showed superiority over prestudy factor VIII prophylaxis (P<0.001). A total of 26 patients were enrolled in group B. In the overall population, nearly all bleeding episodes (97%) resolved with one injection of efanesoctocog alfa. Weekly prophylaxis with efanesoctocog alfa provided mean factor VIII activity of more than 40 IU per deciliter for the majority of the week and of 15 IU per deciliter at day 7. Prophylaxis with efanesoctocog alfa for 52 weeks (group A) improved physical health (P<0.001), pain intensity (P = 0.03), and joint health (P = 0.01). In the overall study population, efanesoctocog alfa had an acceptable side-effect profile, and the development of inhibitors to factor VIII was not detected.

CONCLUSIONS

In patients with severe hemophilia A, once-weekly efanesoctocog alfa provided superior bleeding prevention to prestudy prophylaxis, normal to near-normal factor VIII activity, and improvements in physical health, pain, and joint health. (Funded by Sanofi and Sobi; XTEND-1 ClinicalTrials.gov number, NCT04161495.).

Pain, depression and anxiety in people with haemophilia from three Nordic countries: Cross-sectional survey data from the MIND study

Introduction

People with haemophilia (PwH) may experience symptoms of haemophilia‐related pain, depression or anxiety, which can negatively impact health‐related quality of life.

Aim

To obtain the perspective of PwH and treaters from Sweden, Finland and Denmark on the management of haemophilia‐related pain, depression and anxiety using cross‐sectional survey data from the MIND study (NCT03276130).

Methods

PwH or their caregivers completed a survey about experiences of pain, depression and anxiety related to haemophilia, and the standard EQ‑5D‐5L instrument. Five investigators at haemophilia treatment centres (HTC) were sent a complementary survey containing questions about the management of pain and depression/anxiety.

Results

There were 343 PwH (mild: 103; moderate: 53; severe: 180; seven lacking severity information) and 71 caregiver responses. Experience of pain in the last 6 months was reported by 50% of PwH respondents and 46% of caregiver respondents. Anxiety/depression was reported by 28% of PwH respondents. Reporting of pain and anxiety/depression was associated with disease severity. Whilst 62% of PwH who had experienced pain at any time point (n = 242) felt this was adequately addressed and treated at their HTC, only 24% of those who had experienced depression/anxiety (n = 127) felt this was adequately addressed. Disease severity was negatively associated with EQ‐5D‐5L utility value (p < .001). In the HTC survey, 4/5 and 2/5 agreed that pain and depression/anxiety, respectively, are adequately addressed.

Conclusions

Pain and depression/anxiety occur more frequently with increasing haemophilia severity, with negative impacts on health‐related quality of life. PwH with depression/anxiety or unaddressed pain could benefit from improved management strategies.

Long-term safety and sustained efficacy for up to 5 years of treatment with recombinant factor IX Fc fusion protein in subjects with haemophilia B: Results from the B-YOND extension study

INTRODUCTION

Recombinant factor IX Fc fusion protein (rFIXFc) has demonstrated efficacy for treatment of haemophilia B in the Phase 3 B-LONG and Kids B-LONG studies. However, long-term rFIXFc safety and efficacy data have not yet been reported.

AIM

To report long-term rFIXFc safety and efficacy in subjects with haemophilia B.

METHODS

B-YOND (NCT01425723) was an open-label extension for eligibl previously treated subjects who completed B-LONG or Kids B-LONG. Subjects received ≥1 treatment regimen: weekly prophylaxis (WP), individualized interval prophylaxis (IP), modified prophylaxis or episodic treatment. Subjects could switch regimens at any time. The primary endpoint was inhibitor development.

RESULTS

Ninety-three subjects from B-LONG and 27 from Kids B-LONG (aged 3-63 years) were enrolled. Most subjects received WP (B-LONG: n = 51; Kids B-LONG: n = 23). For subjects from B-LONG, median (range) treatment duration was 4.0 (0.3-5.4) years and median (range) number of exposure days (EDs) was 146 (8-462) EDs. Corresponding values for paediatric subjects were 2.6 (0.2-3.9) years and 132 (50-256) EDs. No inhibitors were observed (0 per 1000 subject-years; 95% confidence interval, 0-8.9) and the overall rFIXFc safety profile was consistent with prior studies. Annualized bleed rates remained low and extended-dosing intervals were maintained for most subjects. Median dosing interval for the IP group was approximately 14 days for adults and adolescents (n = 31) and 10 days for paediatric subjects (n = 5).

CONCLUSIONS

B-YOND results confirm the long-term (up to 5 years, with cumulative duration up to 6.5 years) well-characterized safety and efficacy of rFIXFc treatment for haemophilia B.

Recombinant factor VIII Fc fusion protein for the treatment of severe haemophilia A: Final results from the ASPIRE extension study

Introduction

The efficacy and safety of recombinant factor VIII Fc fusion protein (rFVIIIFc) as an extended half‐life treatment for severe haemophilia A were demonstrated in the Phase 3 A‐LONG and Kids A‐LONG studies. Eligible subjects who completed A‐LONG and Kids A‐LONG could enrol in ASPIRE (NCT01454739), an open‐label extension study.

Aim

To report the long‐term safety and efficacy of rFVIIIFc in subjects with severe haemophilia A who enrolled in ASPIRE.

Methods

Previously treated subjects received one or more of the following regimens: individualized prophylaxis (IP), weekly prophylaxis, modified prophylaxis or episodic treatment. Subjects could switch treatment regimen at any time. The primary endpoint was inhibitor development.

Results

A total of 150 subjects from A‐LONG and 61 subjects from Kids A‐LONG enrolled in ASPIRE. Most subjects received the IP regimen (A‐LONG: n = 110; Kids A‐LONG: n = 59). Median (range) treatment duration in ASPIRE for subjects from A‐LONG and Kids A‐LONG was 3.9 (0.1‐5.3) years and 3.2 (0.3‐3.9) years, respectively. No inhibitors were observed (0 per 1000 subject‐years; 95% confidence interval, 0‐5.2) and the overall rFVIIIFc safety profile was consistent with prior studies. For subjects on the IP regimen, annualized bleed rates (ABR) remained low (median overall ABR for adults and adolescents was <1.0) and extended‐dosing intervals were maintained (median of 3.5 days) for the majority of subjects in ASPIRE.

Conclusion

ASPIRE results, which include up to 5 years of follow‐up data, confirm earlier reports on the consistent and well‐characterized safety and efficacy of rFVIIIFc treatment for severe haemophilia A.

Design of a prospective observational study on the effectiveness and real-world usage of recombinant factor VIII Fc (rFVIIIFc) compared with conventional products in haemophilia A: the A-SURE study

INTRODUCTION

Haemophilia A is a rare bleeding disorder caused by coagulation factor VIII (FVIII) deficiency. This is treated with factor VIII, conventionally using products with a half-life of 8-12 hours typically administered every 2-3 days. Recombinant FVIII Fc (rFVIIIFc) represents a new generation of products with an extended half-life allowing higher FVIII levels and longer dosing interval. The efficacy and safety of rFVIIIFc have been established in clinical studies and several years of postmarketing use. However, there remains a need to compare treatment outcome with conventional products in routine clinical use.

METHODS AND ANALYSIS

A-SURE is an ongoing, non-interventional European study with the primary objective to compare the clinical effectiveness of rFVIIIFc with conventional factor products used for haemophilia A prophylaxis. Data covering a 24-month prospective period and a 12-month retrospective period will be collected. Three primary endpoints: bleeding rate, injection frequency and factor consumption will be used to evaluate treatment outcomes. Enrolment of 175 patients on rFVIIIFc and 175 on conventional products is planned. All eligible patients from participating centres will be invited to participate. Visits and treatments follow routine clinical practice. Bias will be reduced by patient matching for age at baseline and the last weekly prophylaxis dose of a conventional product prior to baseline. Propensity scores will be calculated based on prognostic factors and potential confounders assessed at baseline and adjusted for in the estimation of the treatment effect.

ETHICS AND DISSEMINATION

Study approval was obtained by local independent ethics committees and/or authorities, and informed consent from patients or their legal representative is a requirement for participation. Names of ethical committees and approval numbers are provided as supplementary information. The study results will be submitted for publication in a peer-reviewed scientific journal and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

NCT02976753, Pre-results.

Extending recombinant factor IX Fc fusion protein dosing interval to 14 or more days in patients with hemophilia B

BACKGROUND

In the phase 3 B-LONG study (NCT01027364), prophylaxis with recombinant factor IX Fc fusion protein (rFIXFc) every 7 to >14 days was associated with low annualized bleed rates (ABRs) in males aged ≥12 years with severe hemophilia B. The long-term safety and efficacy of rFIXFc prophylaxis was confirmed in the B-YOND study (NCT01425723), an extension of the B-LONG clinical trial.

OBJECTIVE

The aim of this post-hoc analysis was to evaluate the efficacy of a ≥14-day rFIXFc dosing interval in patients treated prophylactically during B-LONG or B-YOND.

METHODS

The analysis included 22 patients aged ≥12 years who received prophylactic rFIXFc with a ≥14-day dosing interval at any time during B-LONG or B-YOND up until the second interim analysis of B-YOND (September 2015).

RESULTS

The median (interquartile range [IQR]) rFIXFc exposure on the ≥14-day dosing interval was 3.4 (1.8-4) years. Patients treated with a ≥14-day dosing interval were well controlled with a median (IQR) overall ABR of 1.6 (0.6-2.7) and a median (IQR) spontaneous ABR of 0.7 (0.3-1.1) in 18 evaluable patients. A rFIXFc dosing interval of ≥14 days was well tolerated, with no new safety concerns identified.

CONCLUSION

Most patients on rFIXFc prophylaxis, with a dosing interval of ≥14 days, remained well controlled; ABRs were consistent with those reported in the overall study population. A ≥14-day dosing interval can be utilized in some well controlled individuals and reduces the burden imposed by frequent prophylactic injections while maintaining adequate bleed suppression.

Improved joint health in subjects with severe haemophilia A treated prophylactically with recombinant factor VIII Fc fusion protein

INTRODUCTION

Joint arthropathy is the long-term consequence of joint bleeding in people with severe haemophilia.

AIM

This study assessed change in joint health over time in subjects receiving recombinant factor VIII Fc fusion protein (rFVIIIFc) prophylaxis.

METHODS

ALONG is the phase 3 pivotal study in which the benefit of rFVIIIFc as a prophylactic treatment for bleeding control was shown in previously treated severe haemophilia patients ≥12 years of age (arm 1: 25-65 IU/kg every 3-5 days, arm 2: 65 IU/kg weekly and arm 3: episodic). After completing ALONG, subjects had the option to enrol into the extension study (ASPIRE). This interim, post hoc analysis assessed changes in joint health over ~2.8 years in these patients.

RESULTS

Forty-seven subjects had modified Haemophilia Joint Health Score (mHJHS) data at A-LONG baseline, ASPIRE baseline and ASPIRE Year 1 and Year 2. Compared with A-LONG baseline (23.4), mean improvement at ASPIRE Year 2 was -4.1 (95% confidence interval [CI], -6.5, -1.8; P = .001). Regardless of prestudy treatment regimen, subjects showed continuous improvement in mHJHS from A-LONG baseline through ASPIRE Year 2 (prestudy prophylaxis: -2.4, P = .09; prestudy episodic treatment: -7.2, P = .003). Benefits were seen in subjects with target joints (-5.6, P = .005) as well as those with severe arthropathy (-8.8, P = .02). The mHJHS components with the greatest improvement at ASPIRE Year 2 were swelling (-1.4, P = .008), range of motion (-1.1, P = .03) and strength (-0.8, P = .04).

CONCLUSIONS

Prophylaxis with rFVIIIFc may improve joint health over time regardless of prestudy prophylaxis or episodic treatment regimens.

Measurement of tumor load and distribution in a model of cancer-induced osteolysis: A necessary precaution when testing novel anti-resorptive therapies

The Arguello model of cancer metastasis to bone has been used extensively to study breast cancer-induced osteolytic disease. The effects of therapy on skeletal disease and on tumour burden in soft organs are traditionally measured using radiography and/or time-consuming histomorphometry, respectively. The purpose of this study was to develop a sensitive and efficient method for evaluating tumour burden in vivo using MDA-231 cells transduced with the E. coli lacZ gene (MDA-231BAG). Osteolysis was measured by radiography and tumour burden was measured histomorphometrically or biochemically. In untreated mice, measurements of tumour burden in bone extracts using human cytokeratin-associated tissue polypeptide antigen (TPA) ELISA or E. coli beta-galactosidase (beta-gal) activity immunoassay reflected the extent of osteolytic disease as measured by radiography; however, tumour load could be detected before onset of osteolysis. When monitoring the effect of therapy (0.2 mg/kg ibandronate/day), radiography alone proved to be insufficient. Mice treated with the bisphosphonate ibandronate from time of inoculation with cancer cells had no radiologically visible signs of osteolysis but significant tumour load was measured in the bone extracts using these assays. Furthermore, beta-gal activity could be used as a measurement of tumour load in soft organs, and unlike other human breast cancer markers expressed by the MDA-231 cells in vitro, beta-gal activity was detected in the serum of mice with progressive disease. In conclusion, we describe an efficient model of breast cancer-induced osteolysis to quantify the effect of therapy on disease load and distribution, which could be beneficial in evaluating novel therapies for the treatment of the disease.

Estradiol enhances osteolytic lesions in mice inoculated with human estrogen receptor-negative MDA-231 breast cancer cells in vivo

The effect of 17-beta-estradiol (E2) on the induction of osteolytic lesions by estrogen receptor (ER)-negative breast cancer cells was investigated in 4-week-old female nude mice. Exposure to exogenous E2 was found to increase osteolytic areas on radiographs up to 5.3 times in mice inoculated intracardially with MDA-231 human breast cancer cells. The MDA-231 cells were ER-negative, both before inoculation, and after isolation from osteolytic lesions, and the corresponding cell cultures were insensitive to E2. The induction of skeletal lesions by E2 in this mouse model was mainly effectuated at the early development of bone metastases, since exposure to E2 for 8 days around MDA-231 inoculation increased osteolysis to the same level, as did E2 given throughout the entire 31-day experimental period, and because E2-exposure for just the final 14 days had no effect. Independently of exposure to E2, histology revealed cancer cells in hind limp long bones of approximately 80% of the mice, and tumors were absent in non-skeletal organs. In vitro studies showed that the number and activity of osteoclasts generated from mouse bone marrow cells were increased 5-6 times when co-cultured with MDA-231 cells. Addition of 0.1-10 nM E2 further dose-dependently increased the osteoclastogenesis and associated bone resorption in these co-cultures. In conclusion, E2 was found to increase the morbidity in mice inoculated with ER-negative MDA-231 cells, and to stimulate osteoclast formation and bone resorption in co-cultures of bone marrow cells and MDA-231, suggesting that the progression of osteolytic metastases by ER-negative breast cancer cells can be induced by E2 due to stimulation of osteoclastogenesis.

Synthetic matrix metalloproteinase inhibitors inhibit growth of established breast cancer osteolytic lesions and prolong survival in mice

PURPOSE

Breast cancer frequently leads to incurable bone metastasis. Essential requirements for the development of bone metastasis are cell-cell and cell-matrix interactions, release of bioactive growth factors and cytokines, and removal of large amounts of bone matrix. Matrix metalloproteinases (MMPs) play an important role in all of these processes, but the possibility of using synthetic MMP inhibitors to decrease bone metastasis has received little attention.

EXPERIMENTAL DESIGN

In the present study, we tested two general MMP inhibitors, BB-94 and GM6001, in a mouse model of breast cancer-induced bone metastasis.

RESULTS

In a simulation of intervention therapy, mice were inoculated with breast cancer cells, and at the time of diagnosis of osteolytic lesions, the mice were treated for 10 or 15 consecutive days with BB-94 or GM6001, respectively. Both inhibitors reduced the growth of osteolytic lesions by >55% compared with control mice. Next, we simulated prevention therapy by initiating treatment with GM6001 at time of inoculation with cancer cells or 3 days earlier. Assessment of osteolytic lesions 28 days after inoculation showed that, in both cases, the treatment reduced the size of the osteolytic lesions by 60%, compared with that of control mice. Importantly, MMP inhibition also resulted in extension of symptom-free survival in the mice, whether the treatment was initiated at the time of diagnosis of osteolytic lesions or of cancer cell inoculation.

CONCLUSIONS

The present study suggests the potential of synthetic MMP inhibitors as intervention or prevention treatments of breast cancer-induced osteolysis.

Early detection of bone metastases in a murine model using fluorescent human breast cancer cells: application to the use of the bisphosphonate zoledronic acid in the treatment of osteolytic lesions

A very common metastatic site for human breast cancer is bone. The traditional bone metastasis model requires human MDA-MB-231 breast carcinoma cell inoculation into the left heart ventricle of nude mice. MDA-MB-231 cells usually develop osteolytic lesions 3-4 weeks after intracardiac inoculation in these animals. Here, we report a new approach to study the formation of bone metastasis in animals using breast carcinoma cells expressing the bioluminescent jellyfish protein (green fluorescent protein [GFP]). We first established a subclone of MDA-MB-231 cells by repeated in vivo passages in bone using the heart injection model. On stable transfection of this subclone with an expression vector for GFP and subsequent inoculation of GFP-expressing tumor cells (B02/GFP.2) in the mouse tail vein, B02/GFP.2 cells displayed a unique predilection for dissemination to bone. Externally fluorescence imaging of live animals allowed the detection of fluorescent bone metastases approximately 1 week before the occurrence of radiologically distinctive osteolytic lesions. The number, size, and intensity of fluorescent bone metastases increased progressively with time and was indicative of breast cancer cell progression within bone. Histological examination of fluorescent long bones from B02/GFP.2-bearing mice revealed the occurrence of profound bone destruction. Treatment of B02/GFP.2-bearing mice with the bisphosphonate zoledronic acid markedly inhibited the progression of established osteolytic lesions and the expansion of breast cancer cells within bone. Overall, this new bone metastasis model of breast cancer combining both fluorescence imaging and radiography should provide an invaluable tool to study the effectiveness of pharmaceutical agents that could suppress cancer colonization in bone.

Human breast cancer cells induced angiogenesis, recruitment, and activation of osteoclasts in osteolytic metastasis

PURPOSE

The purpose of this study was to elucidate the potential of human breast cancer cells (BCC) to induce matrix degradation and neo-vascularization, essential for continued tumor growth, in osteolytic lesions.

METHODS

BCC were inoculated into the left cardiac ventricle of female athymic mice and osteolytic lesions were radiologically visualized within 4 weeks from inoculation.

RESULTS

Histomorphometric analysis of bone sections revealed a significant increase in the number and maturity of osteoclasts (OCl) lining the bone surfaces next to tumor tissue when compared to corresponding bone surfaces in healthy mice. In addition, a large number of newly formed blood vessels could be visualized by immunohistochemistry at the periphery of and within tumor tissue. When bone marrow (BM) cells were cultured in the presence of BCC the OCl formation was increased threefold. These OCl were also found to be more mature and to have greater resorptive activity. Moreover, BCC were found to stimulate proliferation, migration, and differentiation of BM-derived endothelial cells.

CONCLUSIONS

Matrix destruction and neo-vascularization are accomplished by BCC arrested in the BM cavity by increasing recruitment and activity of OCl and by induction of angiogenesis within or in proximity to the tumor tissue.

Proteinases in bone resorption: obvious and less obvious roles

Bone resorption is critical for the development and the maintenance of the skeleton, and improper regulation of bone resorption leads to pathological situations. Proteinases are necessary for this process. In this review, we show that this need of proteinases is not only because they are required for the solubilization of bone matrix, but also because they are key components of the mechanism that determines where and when bone resorption will be initiated. Moreover, there are indications that proteinases may also determine whether resorption will be followed by bone formation. Some of the proteinases involved in these different steps of the resorption processes were recently identified, as for instance cathepsin K, MMP-9 (gelatinase B), and interstitial collagenase. However, there is also increasing evidence showing that the critical proteinase(s) may vary depending on the bone type or on other factors.

Identification of breast cancer cell line-derived paracrine factors that stimulate osteoclast activity

Metastatic breast cancer causes destruction of significant amounts of bone, and, although bone is the most likely site of breast cancer metastasis, little is understood about interactions between tumor cells and bone-resorbing osteoclasts. We have investigated the paracrine factors produced by breast cancer cells that are involved in increasing osteoclast activity. We have determined by immunoassay that the human breast cancer cell line MDA MB 231 (231) cultured in serum-free medium secretes transforming growth factors type beta(TGF-beta) 1 and 2, macrophage colony-stimulating factor (M-CSF), granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin (IL) -1 and -6, tumor necrosis factor alpha (TNF-alpha), insulin-like growth factor II (IGF II), and parathyroid hormone-related peptide. To determine which of these are involved in increased bone destruction, we have fractionated serum-free 231-conditioned media and measured these fractions for effects on osteoclast resorption activity using multiple activity assays. The pattern of responses was complex. Several fractions stimulated osteoclast resorption either by increasing the number of osteoclasts binding to the bone or by elevating the resorption activity of the individual osteoclasts. Other fractions inhibited osteoclast activity. Analysis of active fractions for the factors identified in the 231-conditioned medium revealed that the presence of TNF-alpha and IGF-II was restricted to separate fractions that stimulated osteoclast resorption activity. The fractions that inhibited osteoclast resorption activity contained M-CSF, IL-6, TGF-beta2, and GM-CSF. No TGF-beta1 or IL-1 was detected in any of the active fractions. Our data support the hypothesis that breast cancer cells modulate osteoclast activity using multiple regulatory factors that increase both the number of mature osteoclasts attached to the bone and the bone resorption activity of these individual osteoclasts. Once it is understood how metastatic breast cancer elevates osteoclast-mediated bone loss, effective therapies to slow the progression and/or prevent this bone loss will become possible.

Pituitary adenylyl cyclase-activating polypeptides and vasoactive intestinal peptide inhibit bone resorption by isolated rabbit osteoclasts

Nerve fibres present in the periosteum, cortical bone and bone marrow are proposed to be involved in the regulation of bone metabolism by the release of neuropeptides acting locally on bone cells. The present study describes the effects of vasoactive intestinal polypeptide (VIP), shown to be present in the vicinity of bone, and the two related neuropeptides pituitary adenylyl cyclase-activating polypeptide(1-38) (PACAP-38) and PACAP-27 on bone resorption in vitro induced by osteoclasts isolated from 10-day-old rabbits. Bone resorption was measured as the number and total area of pits formed by tartrate-resistant acid phosphatase-positive multinucleated cells (TRAP + MNCs) cultured for 3 days on devitalized slices of bovine cortical bone. All three neuropeptides had significant inhibitory effects on both the number and area of pits formed. At a high concentration (10(-7) M) the mean +/- S.E.M. reductions in the total area resorbed compared with controls were 70.3 +/- 8.2, 45.2 +/- 7.3 and 63.4 +/- 7.2% for PACAP-38, PACAP-27 and VIP, respectively. The corresponding values for the apparent dissociation constants were 0.93 +/- 0.30, 3.2 +/- 1.6 and 0.35 +/- 0.14 nM, respectively. The number of TRAP + MNCs was unaffected by application of neuropeptides. Autoradiography showed the presence of 125I-VIP binding sites on some stromal cells, whereas osteoclasts had no binding sites for 125I-VIP. A high number of 125I-calcitonin binding sites was demonstrated on osteoclasts in the same preparation. The signal transduction pathway remains to be fully elucidated but seems to be partly dependent on changes in intracellular calcium concentrations, since a number of stromal cells responded to application of 10(-8) M PACAP-38 or VIP, and at least partly independent of cAMP accumulation. Trifluoperazine and mellitin, two selective calmodulin inhibitors, failed to block the VIP-induced inhibition of bone resorption. Our results demonstrate a non-toxic and probably stromal cell-derived effect of PACAP-38, PACAP-27 and VIP on isolated rabbit osteoclasts, resulting in a potent inhibition of bone resorption in vitro. The signal transduction pathway for inhibition induced by PACAP-38, PACAP-27 and VIP may be mediated partly by changes in intracellular Ca2+ in stromal cells.

Evidence of a correlation of estrogen receptor level and avian osteoclast estrogen responsiveness

Isolated osteoclasts from 5-week-old chickens respond to estradiol treatment in vitro with decreased resorption activity, increased nuclear proto-oncogene expression, and decreased lysosomal enzyme secretion. This study examines osteoclasts from embryonic chickens and egg-laying hens for evidence of estrogen responsiveness. Although osteoclasts from both of these sources express estrogen receptor mRNA and protein, estradiol treatment had no effect on resorption activity. In contrast to the lack of effect on resorption, estradiol treatment for 30 minutes resulted in steady-state mRNA levels of c-fos and c-jun increasing in osteoclasts from embryonic chickens and decreasing in osteoclasts from egg-laying hens. These data suggest that a nuclear proto-oncogene response may not be involved in estradiol-mediated decreased osteoclast resorption activity. To examine the influence of circulating estrogen on osteoclast estrogen responsiveness, 5-week-old chickens were injected with estrogen for 4 days prior to sacrifice. Estradiol treatment of osteoclasts from these chickens did not decrease resorption activity in vitro. Transfection of an estrogen receptor expression vector into osteoclasts from the estradiol-injected chickens and egg-laying hens restored estrogen responsiveness. Osteoclasts from 5-week-old chickens and estradiol treated 5-week-old chickens transfected with the estrogen receptor expression vector contained significantly higher levels of estrogen receptor protein and responded to estradiol treatment by decreasing secretion of cathepsins B and L and tartrate-resistant acid phosphatase. In contrast, osteoclasts from embryonic chickens, egg-laying hens, and estradiol-treated 5-week-old chickens either untransfected or transfected with an empty expression vector did not respond similarly. These data suggest that modulation of osteoclast estrogen responsiveness may be controlled by changes in the osteoclast estrogen receptor levels.

Quantification of the collagenolytic activity of isolated osteoclasts by enzyme-linked immunosorbent assay

Difficulties in the geometrical definition and measurement of resorption pits is a major problem for the quantitative analysis of bone resorption by isolated osteoclasts cultured on bone or dentin substrates. In this study we developed an enzyme-linked immunosorbent assay (ELISA) for quantification of bone resorption in vitro, which specifically quantifies type I collagen fragments released into the culture medium by the resorptive action of bone cells cultured on slices of bone or dentin. A consistently high correlation between the formation of resorption pits and the release of antigenic collagen fragments was observed for isolated rabbit osteoclasts seeded at various densities and cultured for various periods on bovine, elephant, and human substrates. In a further support of the osteoclastic nature of the collagenolytic effects, a high consistency between pit formation and collagenolysis was also observed when the rabbit bone cells were cultured in the presence of very differently acting but typical inhibitors of pit formation, i.e., the carbonic anhydrase inhibitor acetazolamide, the cysteine proteinase inhibitor epoxysuccinyl-L-leucylamido-(4-guanodino)butane (E-64), the phosphatidyl-inositol 3-kinase inhibitor wortmannin, and the bisphosphonate ibandronate (BM 21.0955). In conclusion, the ELISA represents a simple, precise, and objective way to dynamically monitor bone resorption in vitro through quantification of the collagenolytic activity of isolated osteoclasts.

Desensitization and reactivation of ACh-regulated exocrine secretion in hen tracheal epithelium

We have studied acetylcholine (ACh) desensitization of Cl- secretion and its reactivation by atropine in the hen tracheal epithelium employing voltage-clamp technique. Adding 4 microM ACh to the serosal side induces a maximal bumetanide-sensitive Cl- secretion. The ACh-induced Cl- secretion is desensitized nearly 100% at 512 microM ACh. The desensitization of Cl- secretion may be reduced 30-40% by 0.32 microM atropine (reactivation). From a kinetic model for desensitization and reactivation with two muscarinic receptors (mAChR), we have estimated the maximal secretory response, the apparent dissociation coefficients, and the apparent Hill coefficients for ACh and atropine at the two receptors. Based on the kinetic model we can predict an optimal fixed concentration ratio (Ofcor) between ACh and atropine that will maintain Cl- secretion above 40% of maximum over a wide concentration range, ACh 1-4,100 microM, and we have confirmed the predicted Ofcor experimentally. A cellular model is proposed with two mAChR, one stimulatory and another inhibitory, that accounts for an observed dissociation between desensitization in short-circuit current and conductance.

Second messengers and ion channels in acetylcholine-induced chloride secretion in hen trachea

1. Hen tracheal epithelium can be stimulated by serosal application of acetylcholine (ACh) to secrete Cl- equal to approximately 60-90 microA/cm2. 2. Radio-ligand-displacement for IP3, cAMP and cGMP and ion channel selective drugs in voltage clamp set-ups were employed to characterize second messengers and Cl-, K+ and Ca2+ channels involved in the ACh response. 3. ACh induced a significant rise in IP3 in isolated tracheocytes, while ACh did not influence the production of cAMP in whole tissue, isolated tracheocytes or basolateral cell membrane vesicles. Further ACh desensitization did not effect cAMP level in tracheocytes. In addition neither ACh stimulation nor desensitization interfered with cAMP production in presence of 4.5 microM forskolin in tracheocytes, a level of forskolin rising base level cAMP by around five fold. 4. Around 35% of ACh Cl- secretion depends on Ca2+ mobilization from internal stores and about 65% on Ca2+ influx over basolateral membrane. The activated Ca2+ channel is insensitive to class I, II, III and IV Ca2+ antagonists. 5. A 23187 can mimic the ACh effect although 30% is indomethacin-sensitive demonstrating a prostaglandin activated adenylyl cyclase. 6. Two K+ channels are involved in ACh secretion, one sensitive to Ba2+ and quinine and both insensitive to 4-aminopyridine, apamin, charybdotoxin and TEA. 7. Flufenamate and triaminopyrimidine block a non-selective ion channel likely involved in the ACh response. An ACh activated apical Cl- channel is NPPB-sensitive.

Characterization of a muscarinic receptor controlling Cl- secretion in hen trachea

We have attempted to characterize a muscarinic receptor subtype involved in Cl- secretion in isolated epithelium of hen trachea, taking advantage of drugs developed in the last 15 yr. Hen trachea can be stimulated to secrete Cl- equal to approximately 80-90 microA/cm2 by application of acetylcholine (ACh) to the serosal side. The process has an apparent dissociation constant (Kd) for ACh of 740 nM. The Cl- secretion is completely inhibited by 20 microM bumetanide at the serosal side. Of five selective antagonists for muscarinic receptors, pirenzepine, hexahydrosiladifenidol, dicyclomine, 11-([2-[(diethylamino)-methyl]-1-piperidinyl]acetyl)-5,11- dihydro-6H-pyrido(2,3-b)(1,4)benzodiazepine-6-one, and 4 diphenyl acetoxy-N-methylpiperidine methobromide, only the latter had a high affinity for the functional receptor with an apparent Kd of 3 nM. The receptor may be classified as an M4-muscarinic receptor subtype and probably belongs to a group of muscarinic receptors on exocrine glands and mucosal cells involved in ion transport. All the functional responses caused by muscarinic agonists and antagonists tested exhibited exponents (apparent Hill coefficients) in the range from 1.3 to 2.4, indicating a gain in the stimulus secretion coupling mechanism, an aspect of muscarinic receptor function that is not revealed in radioligand binding studies.