Bone Seeking Research Articles

In search of decoding the syntax of the bioelements in human hair – A critical overview

The principles and practice of assessing the human body nutritional status or its environmental exposure through hair bioelement analysis are presented; herein the term “bioelements” is used as a common denominator for the major elements, trace elements and ultra-trace elements that are found in the human body. The accumulation of bioelements in the hair followed the statistical Power Law and the resulting sigmoid curve can be zoned into five regions in the ascending order of abundance (Low, Marginal, Adequate, High, and Excessive). The Adequate linear region of the bioassay sigmoid curve may be further subdivided into Low adequate, Recommended, and Ample adequate sub regions in a 60:30:10 ratio. Phosphorus was the most invariant bioelement since its hair concentration varies minimally regardless of the geographical place of living, the twenty years’ time interval between the analyses, sex, race and instrumentation, i.e., atomic absorption spectrometry (AAS) atomic emission spectrometry (AES), and inductively plasma mass spectrometry (ICP MS). The osteotrophic (bone seeking) bioelements: Ca, Mg, and Sr, were 2.5 times more abundant in the hair of women than men. Two principal electrolytes of the body (Na, K) of the multi-bioelement hair profile were markedly increased in the depressed subjects diagnosed according to the American Psychiatric Association MSD-IV classification criteria. This increase in the hair Na and K of the depressed subjects was also associated with the decrease of vasopressin in the peripheral blood. The factor analysis revealed strong association of depression with sex (women > men in a 2.5:1 ratio), and with the metals from the Nieboer-Richardson series which form strong covalent bonds with proteins. We propose that the biological roots of depression are related to the non-specific impairment of the intracellular osmotic balance and ionic gradient due to the Na+K+ATPase failure from whatever cause acting either separately or in combination. We also put forward the idea of how children's autism may be related to a disproportional growth rate of various organs and tissues if children are fed up to their maximal genetic growth capacity. Finally, we have suggested the hypothesis on how the syntax or integration of the internal metabolic wiring of the bioelements in the body may occur. We have suggested the hypothetical existence of two complex distinct five-bioelement “rotors”, the P-rotor and the N-rotor, where the P-rotor integrates the mileau interior (Na, K) ions with the perception/excitability (Mg, Ca) ions. Thus, the complex five element interdependence is cross related to P which provides the energy from the phosphorus of the DNA nucleotide backbone. The hair multi-bioelement profile analysis allows us to envisage the more complex structural metabolic features that bioelements are playing in our bodies.

Theranostic radiopharmaceuticals: established agents in current use

Although use of the term "theranostic" is relatively recent, the concept goes back to the earliest days of nuclear medicine, with the use of radioiodine for diagnosis and therapy of benign and malignant thyroid disease being arguably the most successful molecular radiotherapy in history. A diagnostic scan with 123I-, 124I-, or a low activity of 131I-iodide is followed by therapy with high activity 131I-iodide. Similarly, adrenergic tumours such as phaeochromocytoma and neuroblastoma can be imaged with 123I-metaiodobenzylguanidine and treated with 131I-metaiodobenzylguanidine. Bone scintigraphy can be used to select patients with painful bone metastases from prostate cancer who may benefit from treatment with beta- or alpha-particle emitting bone seeking agents, the most recent and successful of which is 223Ra radium chloride. Anti-CD20 monoclonal antibodies can be used to image and treat non-Hodgkins lymphoma, though this has not been as commercially successful as initially predicted. More recently established theranostics include somatostatin receptor targeting peptides for diagnosis and treatment of neuroendocrine tumours with agents such as 68Ga-DOTATATE and 177Lu-DOTATATE, respectively. Finally, agents which target prostate-specific membrane antigen are becoming increasingly widely available, despite the current lack of a commercial product. With the recent licensing of the somatostatin peptides and the rapid adoption of 68Ga- and 177Lu-labelled prostate-specific membrane antigen targeting agents, we have built upon the experience of radioiodine and are already seeing a great expansion in the availability of widely accepted theranostic radiopharmaceuticals.

Abstract P3-06-02: Tackling bone metastatic breast cancer growth with novel bone-seeking matrix metalloproteinase-2 inhibitors

Abstract Background. Despite medical advances, currently there is no treatment for breast to bone metastasis. The progression of bone metastatic breast cancer is critically dependent on interactions with the surrounding microenvironment. Therefore, identifying the underpinning molecular mechanisms is vital for the development of new therapies. Rationale. Gene expression analysis and validation in human and murine specimens of bone metastases revealed matrix metalloproteinases, such as MMP-2, are highly expressed in the bone metastatic microenvironment. Genetic ablation of MMP-2 demonstrated the importance of this MMP in driving the growth of the osteolytic bone metastatic breast cancer by regulating the bioavailability of transforming growth factor β (TGFβ). These data support the rationale for the development of a highly specific MMP-2 inhibitor for the eradication of active bone metastatic breast cancer. Methods. We utilized a novel chemical approach to synthesize bone seeking MMP inhibitors (BMMPIs) on a bisphosphonic backbone, with specificity for MMP-2 in the nanomolar range (IC50=140 nM). In vitro, we tested the effect of BMMPIs at varying doses (1nM-100μM) on the viability of the major cellular components of the cancer-bone microenvironment, namely breast cancer cells (PyMT, 4T1), osteoblasts (MC3T3) and osteoclasts (primary monocytes and RAW 264.7). In vivo, mice were intratibially inoculated with either luciferase expressing 4T1 or PyMT (1x105) cells. Mice (n=10/group) then received vehicle, zoledronate (1 mg/kg) or BMMPIs (1 mg/kg). Tumor growth was determined via luminescence quantitation. Cancer induced bone disease was measured ex vivo by μCT, Xray and histomorphometry. MMP activity in vivo and ex vivo was determined via specific activatable MMP probes. Pharmacokinetic and pharmacodynamic studies were performed. Plasma and bone marrow supernatants were collected from PyMT-R221A tumor bearing mice treated with ML115 (5mg/Kg) at 0.25, 0.5, 1, 2, 4, 8, 24 hours and three weeks (n=3 mice/time point). Currently, we are investigating the BMMPIs ability to impact the metastatic process through an in vivo model of intracardiac inoculation. Results. BMMPIs significantly impacted the viability of breast cancer cells and osteoclasts in vitro (p<0.05) compared to control. In vivo, BMMPIs significantly reduced the growth of bone metastatic breast cancer compared to control and the standard of care bisphosphonate, zoledronate. MMP activity was also lower in the BMMPI treated groups (using tumor burden to normalize values). μCT/Xray/Histomorphometry analysis also illustrated the significant beneficial effects of the BMMPIs in reducing the size of osteolytic lesions (up to 80% by μCT; p<0.05). ML115 is rapidly cleared from the plasma and accumulates selectively in the bone marrow microenvironment over time. Conclusions. MMP-2 specific BMMPIs prevent bone metastatic breast cancer growth by impacting cancer cell viability and cancer induced osteolysis. Given that bisphosphonates are well tolerated in the clinical setting, we predict that BMMPIs could be translated to the clinical setting for the treatment and eradication of bone metastatic breast cancer. Citation Format: Tauro M, Laghezza A, Tortorella P, Soliman HH, Lynch CC. Tackling bone metastatic breast cancer growth with novel bone-seeking matrix metalloproteinase-2 inhibitors [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-06-02.

Bone and calcium metabolism associated with malignancy. Bone management of prostate cancer in the novel anti-androgen era.

Androgen deprivation therapy(ADT)is a standard systemic therapy for prostate cancer. ADT induces bone loss(ADTIBL)and muscle loss(sarcopenia)leading to falls and farctures. There are 2 aims in bone management of prostate cancer:one is to prevent fragility fractures in patients without bone metastasis and the other is to prevent symptomatic skeletal events(SSE)which are pathologic fractures, spinal compression, radiation to bones and surgery to bones. Bone fractures and SSE are both correlated with worse overall survival(OS). Concomitant use of novel anti-androgens further increases the risk of falls and fractures. The earlier and appropiriate intervention with vitamin D and bone modifying agents(BMA)is necessary to prevent treatment related bone fractures and SSE. Bone management algorithm aids to decide the timing and doses of BMA. As for sarcopenia physical exercise and life style advices are important. Because abiraterone with glucocorticoid therapy induces stronger bone resorption, it is recommended to start denosumab simultaneously. Ra-223, bone seeking radiopharmaceuticals should not be used with abiraterone and predonisone because of high incidence of fracture and death.

Impact of treatment delay in Radium-223 therapy of metastatic castration-resistant prostate cancer patients.

Radium-223-dichloride (Ra-223) is an alpha-emitting, bone seeking radionuclide therapy approved for patients with metastatic castration-resistant prostate cancer (mCRPC). In the fall of 2014, a global temporary shortage of Ra-223 occurred for 2months due to production irregularities. The aim of this study was to assess whether prolonged interval between Ra-223 cycles to non-disease related causes had a negative impact on clinical outcome of therapy. Retrospective single-center study of mCRPC patients who initiated Ra-223 therapy in the period from March 2014 to February 2015. End points were number of completed Ra-223 cycles, overall survival (OS) and radiographic progression-free survival (rPFS). Bone scintigraphy, CT of thorax and abdomen, hematological status, PSA and alkaline phosphatase were evaluated prior to first dose and after 3rd and 6th treatment, respectively. Follow-up period was 18months after first Ra-223 cycle. A total of 50 consecutive patients initiated Ra-223 therapy in the time period. Seventeen of 50 patients (34%) had prolonged interval between cycles due to delivery problems. Median delay was 4weeks (range 3-9 weeks). Patients with delayed treatment had significantly longer median rPFS [delayed patients: 7.1months (95% CI 4.9-9.3) vs. 4.5months (95% CI 2.8-6.3)]. There was no significant difference in number of completed cycles or median OS. We find no negative impact of prolonged interval between Ra-223 cycles due to non-disease related reasons on OS, rPFS or number of completed treatment cycles.

Molecular radiotheragnostics in prostate cancer

Two different molecular radio-theragnostic principles are applied in prostate cancer, providing a personalised management for those patients. Firstly, radiopharmaceuticals with the same or similar mechanism of action but different energy (gamma-γ, eg 99mTc-diphosphonates or positron-β+, eg 18F-NaF emitting isotopes) can be used to identify patients with osteoblastic metastases for a treatment with bone seeking beta (β-) or alpha (α-) emitting radionuclides to deliver targeted molecular radiotherapy. A number of such β- emitting molecules have been used for bone palliation. More recently, an alpha emitting 223Ra-dicholoride demonstrated not only symptomatic relief but also significantly improved overall survival in castration-resistant prostate cancer with predominant bone metastases. The second principle involves utilisation of the same prostatic specific membrane antigen (PSMA) or similar compound (eg PSMA-11, PSMA-617), but different label with either β+ (68Ga) or γ (99mTc) emitting radioisotope for imaging and subsequently β- (177Lu) or α (225Ac) emitting radionuclide for treatment.

Bisphosphonate-functionalized coordination polymer nanoparticles for the treatment of bone metastatic breast cancer

Bone is the most common organ affected by metastatic breast cancer. Targeting cancers within the bone remains a great challenge due to the inefficient delivery of therapeutic to bone. In this study, a polyethylene glycol (PEG) coated nanoparticles (NPs) made of a Zn2+ coordination polymer was linked with a bone seeking moiety, alendronate (ALN), to deliver cisplatin prodrug (DSP) to the bone. The particle sizes of this novel system, DSP-Zn@PEG-ALN NPs, were regulated by adjusting the volume ratio of water phase to oil phase in microemulsion. It was small enough (about 55nm) to extravasate through the clefts (80nm) of the bone's sinusoidal capillaries and localize into metastatic bones. DSP-Zn@PEG-ALN NPs showed much higher affinity for hydroxyapatite in vitro and bone in vivo than non-targeted DSP-Zn@PEG NPs and cisplatin. In addition, the in vivo biodistribution studies demonstrated that about 4-fold of platinum was delivered to the bone metastatic lesions than that in healthy bones by DSP-Zn@PEG-ALN NPs intravenously. Finally, DSP-Zn@PEG-ALN NPs not only inhibited the tumor growth efficiently but also reduced the osteocalastic bone destruction. Besides, DSP-Zn@PEG-ALN NPs showed significantly reduced toxicity of cisplatin. These results indicate that the DSP-Zn@PEG-ALN NPs have a great potential in enhancing chemotherapeutic efficacy for the treatment of bone metastatic breast cancer.

Development of bone seeker radiopharmaceuticals by Scandium-47 and estimation of human absorbed dose

In this study labeling EDTMP (ethylenediamine tetra(methylene phosphonic acid)) and HEDP (Hydroxyethylidene-1, 1-Diphosphonic Acid) as the carrier ligands with Scandium-47 were investigated. The biokinetics of the bone seeking of labeled ligands with Scandium-47 were assessed by measuring the skeletal absorbed dose and then the mice data extrapolated to human absorbed dose and compared with the 186/188Rhenium-HEDP, 153Samarium-EDTMP dosimetry data estimated by other researchers. Because the availability of 47Sc was limited we performed some preliminary studies using 46Sc.

Abstract 1981: Tissue-engineered bone for longitudinal intravital microscopy of solid tumor growth and therapy response

Abstract Bone metastases are the initial site of progression and account for many of the complications experienced by men with metastatic prostate cancer (PCa), including therapy resistance. Besides cell intrinsic mechanisms, the interaction between PCa cells and the bone microenvironment critically contributes to lesion expansion and drug sensitivity. We here developed a mouse model amenable to intravital multiphoton microscopy (iMPM) to longitudinally study PCa-stromal cell interactions and therapy response in a partially humanized neobone, established in the dermis of the mouse. Tissue engineered bone constructs, TEBCs, were generated by functionalizing polymeric polycaprolactone scaffolds with human mesenchymal stem cells (hMSCs) differentiated to osteoblasts followed by cell-derived calcification of the inter-scaffold space. 30 days after implantation of functionalized scaffolds under the skin of the mouse, bone and bone marrow maturation resulted in a 30mm3 cavity surrounded by optically transparent cortical bone of 50-60 μm thickness, as monitored by microCT and iMPM. Intra-bone tumor growth and osteolysis dynamics caused by human fluorescent PCa cells (PC3) were three-dimensionally reconstructed by multi-parameter detection through a body window, including collagen and bone matrix (SHG), calcified bone (fluorescent bisphosphonates), osteoclasts (cathepsin K), bone surface (THG), blood vessels and stromal phagocytes (fluorescent dextran), and PC3 cells (nuclear H2B/eGFP, cytoplasmatic DsRed2). As a proof of concept, the efficacy to halt bone remodeling during bisphosphonate therapy was detected, revealing the composition and kinetics of the bone-tumor interface. Combining engineered neobone with an optical window is suited to detail the 3D organization and dynamics of cancer lesions in bone and provides mechanistic insight and efficacy predictions for therapy response. Thus, this strategy will be implied to dissect the therapeutic effect of radium 223, a radioisotope with bone seeking properties, and the first agent that improves the duration and quality of life of advanced metastatic PCa patients. By using this model we will test the hypothesis that 223Ra alters stromal niches, structurally and molecularly, in a manner that accounts for the clinical observations in established macroscopic lesions. Citation Format: Eleonora Dondossola, Stephanie Alexander, Boris Holzapfel, Christopher J. Logothetis, Dietmar W. Hutmacher, Peter Friedl. Tissue-engineered bone for longitudinal intravital microscopy of solid tumor growth and therapy response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1981. doi:10.1158/1538-7445.AM2017-1981

Bone-seeking agents for the treatment of bone disorders.

The targeting and delivery of therapeutic and diagnostic agents to bone tissue presents both a challenge and opportunity. Osteoporosis, Paget's disease, cancer, and bone metastases are all skeletal diseases whose treatment would benefit from new targeted therapeutic strategies. Osteoporosis, in particular, is a very prevalent disease, affecting over one in three women and one in five men in Canada alone with the cost to the healthcare system estimated at over $2.3billion in 2010. Bone tissue is often considered a rigid structure when in reality there is a process of continuous remodeling that takes place via complex endocrine-regulated cell signaling pathways in addition to the signaling pathways unique to bone tissue. It is these specific boneremodeling processes that provide unique targeting opportunities but also present a number of challenges.

Radiopharmaceuticals in the elderly cancer patient: Practical considerations, with a focus on prostate cancer therapy: A position paper from the International Society of Geriatric Oncology Task Force

Molecular imaging using radiopharmaceuticals has a clear role in visualising the presence and extent of tumour at diagnosis and monitoring response to therapy. Such imaging provides prognostic and predictive information relevant to management, e.g. by quantifying active tumour mass using positron emission tomography/computed tomography (PET/CT). As these techniques require only pharmacologically inactive doses, age and potential frailty are generally not important. However, this may be different for therapy involving radionuclides because the radiation can impact normal bodily function (e.g. myelosuppression). Since the introduction of Iodine-131 as a targeted therapy in thyroid cancer, several radiopharmaceuticals have been widely used. These include antibodies and peptides targeting specific epitopes on cancer cells. Among therapeutic bone seeking agents, radium-223 (223Ra) stands out as it results in survival gains in patients with castration-resistant prostate cancer and symptomatic bone metastases. The therapeutic use of radiopharmaceuticals in elderly cancer patients specifically has received little attention. In elderly prostate cancer patients, there may be advantages in radionuclides' ease of use and relative lack of toxicity compared with cytotoxic and cytostatic drugs. When using radionuclide therapies, close coordination between oncology and nuclear medicine is needed to ensure safe and effective use. Bone marrow reserve has to be considered. As most radiopharmaceuticals are cleared renally, dose adjustment may be required in the elderly. However, compared with younger patients there is less, if any, concern about adverse long-term radiation effects such as radiation-induced second cancers. Issues regarding the safety of medical staff, care givers and the wider environment can be managed by current precautions.

Korean Treatment Guidelines for Metastatic Prostate Cancer Developed by the Korean Association for Clinical Oncology

The management of advanced prostate cancer has evolved rapidly. Androgen deprivation therapy, via surgical or medical castration, is the first-line therapy for hormone-naive metastatic prostate cancer. For approximately a decade, docetaxel-based chemotherapy was the only approved agent to show a survival benefit for castration-resistant prostate cancer. However, over the last 5 years, significant advances in the field have led to the approval of several new agents with different mechanisms of action, such as the new androgen pathway inhibitors abiraterone and enzalutamide, a new cytotoxic agent, cabazitaxel, and new bone-seeking agents such as radium-223, which have all been associated with improved quality of life and pain palliation and an increase in survival. However, there has been no Korean treatment guideline for metastatic prostate cancer which is developed based on thorough search for relevant articles, including recently developed agents, and adequate review and assessment of evidences, and thus, a guideline adequate for domestic circumstance is eagerly needed. Experts from the Genitourinary Oncology Committee of the Korea Cancer Study Group developed clinical recommendations for the treatment of metastatic prostate cancer based on 19 key questions. The Korean Association for Clinical Oncology, the Korean Prostate Society, the Korean Urological Oncology Society, and the Korean Society of Pathologists reviewed and endorsed the guidelines. These are the first Korean treatment guidelines developed specifically for metastatic prostate cancer. (Korean J Med 2017;92:124-141)

Highlights of This Issue

Since the failure of matrix metalloproteinase (MMP) inhibitor in clinical trials, highly selective reagents that target individual MMPs have been the new focus. MMP-2 is highly expressed in bone metastatic breast cancer and drives the progression of the disease. Here, Tauro and colleagues have generated MMP-2 highly selective bone seeking MMP inhibitors (BMMPIs) based on bisphosphonates. In vivo studies reveal BMMPIs are effective in promoting the apoptosis of bone metastatic breast cancer cells and protecting against cancer induced bone disease. Given the well-tolerated nature of bisphosphonates, BMMPIs could be rapidly translated to the clinic for the treatment of skeletal malignancies such as bone metastatic breast cancer.Immune checkpoint blockade has shown promise in melanoma, with a subset of patients experiencing complete durable responses. However, the majority of patients still do not receive long-term benefit. Farren and colleagues combined immune checkpoint blockade with selinexor, a small molecule inhibitor of exportin-1 that has anti-melanoma activity of its own. This treatment combination skewed immune responses toward a Th1 type, and proved more effective in controlling tumor growth when administered at multiple schedules in a murine model. These results support further development of this novel combination of immune checkpoint blockade and small molecule nuclear export inhibitors.Selinexor (KPT-330) is a first in class nuclear transport inhibitor currently in clinical trials as an anti-cancer agent. Tyler, Servos and colleagues analyzed immune homeostasis in mice treated with selinexor and found disruptions in T cell development, a progressive loss of CD8 T cells and increases in inflammatory monocytes. Altering the frequency of drug dosing preserved normal immune function better than decreasing the dose. Overall, selinexor treatment leads to transient inhibition of T cell activation but clinically relevant once and twice weekly dosing schedules that incorporate sufficient drug holidays allow for normal CD8 T cell functioning and development of anti-tumor immunity.Stage III/IV head-and-neck squamous cell carcinomas (HNSCCs) are often treated with cisplatin-containing chemoradiation protocols. However, not all tumors respond well and biomarkers to personalize chemoradiotherapy are not available. Martens-de Kemp and colleagues performed an unbiased genome-wide functional genetic screen to identify genes that influence cisplatin response. Pathway analysis on cisplatin-sensitizing genes identified the FA/BRCA pathway as the predominant cisplatin response pathway in HNSCC cells. Expression of genes involved in this pathway predicted prognosis of (chemo-) radiation treated HNSCC patients. Biomarkers that indicate FA/BRCA pathway activity in tumors are prime candidates to predict cisplatin response in HNSCC.

Preparation and evaluation of rhenium-188-pamidronate as a palliative treatment in bone metastasis

ObjectiveRhenium-188-hydroxyethylidene diphosphonate (188Re-HEDP) as a first generation bisphosphonate has been widely used for bone seeking radiopharmaceutical in cases of metastatic bone disease. No study has been yet reported on preparing a complex of 188Re with pamidronate (3-aminohydroxypropylidene-1,1-bisphosphonic acid) (PMA) as a second generation bisphosphonate. Based on this fact, it was hypothesized that a bone-seeking 188Re-PMA radiopharmaceutical could be developed as an agent for palliative radiotherapy of bone pain due to skeletal metastases. MethodsPamidronate was labeled with 188ReO4− eluted from the alumina based 188W/188Re generator. Labeling was optimized, and radiochemical analysis was performed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Biodistribution of this radioconjugate was evaluated and verified further in mice. Results188Re-PMA was prepared successfully in a high labeling yield (˃95%) corresponding to a specific activity of 124MBq/μmol and good in vitro stability, but it is likely to consist of multiple species. In biodistribution studies selective uptake and retention of activity in the skeletal system (0.81±0.25% ID/g and 0.57±0.16 at 4 and 48h in bone post injection respectively) followed by clearance in the soft tissues were observed. ConclusionThese results show that due to its biological capabilities it would be advantageous to use 188Re-PMA for bone pain palliation therapy.

Abstract P6-12-10: Bone seeking matrix metalloproteinase-2 inhibitors prevent bone metastatic breast cancer growth

Abstract Bone metastasis is a common event during breast cancer progression. The resultant lesions are painful and currently, despite medical advances, are incurable. The progression of bone metastatic breast cancer is critically dependent on interactions with the surrounding microenvironment. Therefore, identifying the underpinning molecular mechanisms is vital for the development of new therapies. Rationale: Gene expression analysis and validation in human and murine specimens of bone metastases revealed that matrix metalloproteinases, such as MMP-2, are highly expressed in the bone metastatic microenvironment and significantly associated with aggressive breast cancer and poorer overall survival. In bone, tumor or host derived MMP-2 contributes to breast cancer growth and does so by processing substrates including type I collagen and transforming growth factor beta (TGFβ) latency proteins. These data provide strong rationale for the application of MMP-2 inhibitors to treat the disease. However, in vivo, MMP-2 is systemically expressed. Therefore, to overcome potential toxicities noted with previous broad-spectrum MMP inhibitors (MMPIs), we used highly selective bisphosphonic based MMP-2 inhibitors (BMMPIs) that allowed for specific bone targeting. Methods: We utilized a novel chemical approach to synthesize bone seeking MMP inhibitors (BMMPIs) on a bisphosphonic backbone, with specificity for MMP-2 in the nanomolar range (IC50=140 nM). Results: In vitro, we tested the effect of BMMPIs at varying doses (1nM-100μM) on the viability of the major cellular components of the cancer-bone microenvironment, namely breast cancer cells, (PyMT, 4T1, MDA-MB-231, MCF-7), osteoblasts (MC3T3) and osteoclasts (primary monocytes and RAW 264.7). In vivo, we demonstrated using two bone metastatic models (PyMT-R221A-Luc and 4T1-Luc) that BMMPI treatment significantly reduced tumor growth and tumor associated bone destruction. Additionally, BMMPIs are superior in promoting tumor apoptosis compared to the standard of care bisphosphonate, zoledronate. MMP activity was also lower in the BMMPI treated groups (using tumor burden to normalize values). μCT/Xray/Histomorphometry analysis also illustrated the significant beneficial effects of the BMMPIs in reducing the size of osteolytic lesions (up to 80% by μCT; p<0.05). We demonstrated MMP-2 selective inhibition in the bone microenvironment using specific and broad spectrum MMP probes. Further, compared to zoledronate, BMMPI treated mice had significantly lower levels of TGFβ signaling and MMP generated type I collagen carboxy-terminal (ICTP) fragments. Taken together, our data show the feasibility of selective inhibition of MMPs in the bone metastatic breast cancer microenvironment. Conclusions. MMP-2 specific inhibition was achieved in the bone microenvironment. BMMPIs significantly inhibit breast cancer growth in bone, they are able to induce breast cancer cell apoptosis and prevent cancer induced bone destruction. Given that bisphosphonates are well tolerated in the clinical setting, we predict that BMMPIs could be translated to the clinical setting for the treatment and eradication of bone metastatic breast cancer. Citation Format: Tauro M, Laghezza A, Tortorella P, Lynch CC. Bone seeking matrix metalloproteinase-2 inhibitors prevent bone metastatic breast cancer growth [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-12-10.

Bone seeking bisphosphonate therapy

Bone seeking bisphosphonate therapy

Engineered Nanomedicine with Alendronic Acid Corona Improves Targeting to Osteosarcoma.

We engineered nanomedicine with the stealth corona made up of densely packed bone seeking ligand, alendronic acid. In a typical nanoconstruct, alendronic acid is conjugated with hydrophilic head moiety of phospholipid that has an ability to self-assemble with hydrophobic polymeric core through its hydrophobic long carbon-chain. Proposed nanomedicine has three distinct compartments namely; poly(l-lactic-co-glycolic acid) polymeric core acting as a drug reservoir and skeleton of the nanoconstruct, phospholipid monolayer covers the core acting as a diffusion barrier, and a densely packed alendronic acid corona acting as a stabilizer and targeting moiety. Thus engineered nanomedicine attain spherical entity with ~90 ± 6 nm having negative zeta potential, −37.7 ± 2 mV, and has an ability to load 7 ± 0.3 wt% of doxorubicin. In-vitro bone targeting efficiency of nanomedicine was studied using hydroxyapatite crystals as a bone model, and found significant accumulation of nanoparticle in the crystals. Moreover, cellular internalization studies with mouse osteosarcoma confirm the selectivity of nanomedicine when compared to its internalization in non-targeted mouse melanoma. This nanomedicine shows prolong stability in serum and deliver the drug into the cell exhibiting an IC50 of 3.7 μM. Given the strong interacting property of alendronic acid with bone, the proposed nanomedicine hold promises in delivering drug to bone microenvironment.

Le traitement des métastases osseuses par radiopharmaceutiques à tropisme osseux

Bone seeking radiopharmaceutics are often used in patients with skeletal lesions during the diagnostic and, less frequently, the therapeutic setting. The aim of the radionuclide therapy in patients with bone metastases is to release the maximum of the energy on neoplastic cells, with the minimum of toxicity for the remnant bone cells and extracellular environment. The radionuclides used in nuclear medicine therapy could be β-emitters, such as 131iodine, 90ytrium, 188rhenium, 186rhenium, 177lutetium, 89strontium and 153samarium, α emitters, such as 223radium, 211actinium, 212bismuth or Auger electron emitters, such as 125iodine and 111indium. To date, 89strontium chloride and 153samarium ethylene diamine tetramethylene bisphosphonate are successfully used for palliative treatment in patients with bone metastases from prostate cancer; moreover, 153samarium can be used also in osteoblastic metastases derived from other neoplasms. Recently, 223RaCl2 a “new” agent has been shown to be useful not only to prolong overall survival of patients with bone metastases from prostate cancer, but also to extend the delay of symptomatic skeletal events, to reduce bone pain and to reduce need for external beam radiation therapy in order to treat bone pain. Therefore, to date 223RaCl2 is recommended in the treatment of castrate resistant prostate cancer by international clinical guidelines. Potential benefits of 223RaCl2 in patients with metastases from other neoplasms are currently under investigation and results will be available very soon.

Monomethyl Auristatin E Phosphate Inhibits Human Prostate Cancer Growth.

Bone metastasis from primary prostate cancer leads to markedly diminished quality of life with poor long-term survival. Bone seeking treatment options are limited with adverse consequences on rapidly proliferating tissues such as bone marrow. In the present study, we seek to determine the bone-enriching capabilities of monomethyl auristatin E phosphate (MMAEp), a derivative of the potent antimitotic monomethyl auristatin E (MMAE). The in vitro actions and mechanisms of cytotoxicity were assessed using cell viability, immunofluorescence, flow cytometry, and Western blot analysis. In vivo efficacy was determined using an intratibial xenograft mouse model of human prostate cancer and live animal imaging. The half maximal inhibitory concentration (IC50) of MMAE and MMAEp was determined to be approximately 2 and 48 nM, respectively, in PC-3 and C4-2B cell lines. MMAEp retained the mechanism of action of MMAE in reducing microtubule polymerization and stalling cell cycle progression at the G2/M transition. MMAEp was able to bind hydroxyapatite in in vitro assays. MMAEp significantly reduced intratibial tumor growth compared to the vehicle control treatment. MMAEp is an antimitotic compound that binds to calcium ions in the bone and inhibits prostate tumor growth in the bone. Prostate 76:1420-1430, 2016. © 2016 Wiley Periodicals, Inc.

Development and biological evaluation of 90Y-BPAMD as a novel bone seeking therapeutic Agent

Abstract Nowadays, the bone-seeking radiopharmaceuticals play an important role in the treatment of the bone-related pathologies. Whereas various phosphonate ligands have already been identified, a DOTA-based bisphosphonate, 4-{[(bis(phosphonomethyl))carbamoyl]methyl}- 7,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododec- 1-yl (BPAMD) with better characteristics has recently been synthesized. In this study, 90Y-BPAMD was developed with radiochemical purity >98% and the specific activity of 3.52 TBq/mmol in the optimized conditions as a new bone-seeking therapeutic agent. The complex demonstrated significant stability at room temperature and in human serum even after 48 h. At even low amount of hydroxyapatite (5 mg), more than 90% binding to hydroxyapatite was observed. Biodistribution studies after injection of the complex into the Syrian rats showed major accumulation of the labelled compound in the bone tissue and an insignificant uptake in the other organs all the times after injection. Generally, 90Y-BPAMD demonstrated interesting characteristics compared to the other 90Y bone-seeking agents and even 166Ho-BPAMD, and can be considered as a new bone-seeking candidate for therapeutic applications.