Management of bone metastases in refractory prostate cancer--role of denosumab

Precision Targets for Intercepting the Lethal Progression of Prostate Cancer: Potential Avenues for Personalized Therapy

Organ-confined prostate cancer of low-grade histopathology is managed with radiation, surgery, active surveillance, or watchful waiting and exhibits a 5-year overall survival (OS) of 95%, while metastatic prostate cancer (PCa) is incurable, holding a 5-year OS of 30%. Treatment options for advanced PCa-metastatic and non-metastatic-include hormone therapy that inactivates androgen receptor (AR) signaling, chemotherapy and genome-targeted therapy entailing synthetic lethality of tumor cells exhibiting aberrant DNA damage response, and immune checkpoint inhibition (ICI), which suppresses tumors with genomic microsatellite instability and/or deficient mismatch repair. Cancer genome sequencing uncovered novel somatic and germline mutations, while mechanistic studies are revealing their pathological consequences. A microRNA has shown biomarker potential for stratifying patients who may benefit from angiogenesis inhibition prior to ICI. A 22-gene expression signature may select high-risk localized PCa, which would not additionally benefit from post-radiation hormone therapy. We present an up-to-date review of the molecular and therapeutic aspects of PCa, highlight genomic alterations leading to AR upregulation and discuss AR-degrading molecules as promising anti-AR therapeutics. New biomarkers and druggable targets are shaping innovative intervention strategies against high-risk localized and metastatic PCa, including AR-independent small cell-neuroendocrine carcinoma, while presenting individualized treatment opportunities through improved design and precision targeting.

BRCA1 and BRCA2 associated breast cancer and the roles of current modelling systems in drug discovery

For a drug candidate to be fully developed takes years and investment of hundreds of millions of dollars. There is no doubt that drug development is difficult and risky, but vital to protecting against devastating disease. This difficulty is clearly evident in BRCA1 and BRCA2 related breast cancer, with current treatment options largely confined to invasive surgical procedures, as well as chemotherapy and radiotherapy regimes which damage healthy tissue and can leave remnant disease. Consequently, patient survival and relapse rates are far from ideal, and new candidate treatments are needed. The preclinical stages of drug discovery are crucial to get right for translation to hospital beds. Disease models must take advantage of current technologies and be accurate for rapid and translatable treatments. Careful selection of cell lines must be coupled with high throughput techniques, with promising results trialled further in highly accurate humanised patient derived xenograft models. Traditional adherent drug screening should transition to 3D culture systems amenable to high throughput techniques if the gap between in vitro and in vivo studies is to be partially bridged. The possibility of organoid, induced pluripotent stem cell, and conditionally reprogrammed in vitro models is tantalising, however protocols are yet to be fully established. This review of BRCA1 and BRCA2 cancer biology and current modelling systems will hopefully guide the design of future drug discovery endeavours and highlight areas requiring improvement.

Health economic impact of a biopsy-based cell cycle gene expression assay in localized prostate cancer

Background: Prior studies have established that broader incorporation of active surveillance, guided by additional prognostic tools, may mitigate the growing economic burden of localized prostate cancer in the USA. This study sought to further explore the potential of a particular gene expression-based prognostic tool to address this unmet need. Materials & methods: A deterministic, decision-analytic model was developed to estimate the economic impact of the Prolaris^® test on a US commercial health plan. Results & conclusion: When adopted in patients classified by the American Urological Association as low or intermediate risk, the assay was projected to reduce costs by $1894 and $2129 per patient over 3 and 10 years, respectively, largely through the increased use of active surveillance.

Economic burden of illness associated with localized prostate cancer in the United States

Aim: Prior studies have established the economic burden of prostate cancer on society. However, changes to screening, novel therapies and increased use of active surveillance (AS) create a need for an updated analysis. Methods: A deterministic, decision-analytic model was developed to estimate medical costs associated with localized prostate cancer over 10 years. Results: 10-year costs averaged $45,957, $99,445 and $188,928 for low-, intermediate- and high-risk patients, respectively. For low-risk patients, AS 10-year costs averaged $33,912/patient, whereas definitive treatment averaged $49,667/patient. Despite higher failure rates in intermediate-risk patients, AS remained less costly than definitive treatment, with 10-year costs averaging $90,614/patient and $99,394/patient, respectively. Conclusion: Broader incorporation of AS, guided by additional prognostic tools, may mitigate this growing economic burden.

Management of bone complications in patients with genitourinary malignancies

Skeletal metastases are common in genitourinary malignancies-including prostate cancer, renal cell carcinoma, and urothelial cancer-and portend significant morbidity and poor prognosis. The presence of skeletal metastases can result in decreased quality of life and increased morbidity. Strategies can be employed to prevent bone-related complications including lifestyle modifications and dietary supplementation. Additionally, pharmacologic agents exist to prevent bone loss and may be appropriate for patients at high risk of fragility-related or skeletal complications, such as pathologic fracture related to bone metastases. Finally, advancement in effective systemic treatments, particularly novel hormone-targeted agents and immunotherapies, may limit the morbidity of advanced disease and delay the onset of skeletal-related complications.

Bone Marrow Microenvironment as a Regulator and Therapeutic Target for Prostate Cancer Bone Metastasis

Bone is the most common site of prostate cancer metastasis. Once prostate cancer cells metastasize to bone, the mortality rate of prostate cancer patients increases significantly. Furthermore, bone metastases produce multiple skeletal complications, including bone pain that impairs the patients' quality of life. Effective therapies for bone metastatic disease are underdeveloped with most current therapies being primarily palliative with modest survival benefit. Although the exact mechanisms through which prostate cancer metastasizes to bone are unclear, growing evidence suggests that the bone marrow microenvironment, particularly its hematopoietic activity, is a significant mediator of prostate cancer bone tropism. Moreover, the bone microenvironment may regulate metastatic prostate cancer cells between dormant and proliferative states. In this review, we discuss (1) how prostate cancer cells interact with the bone microenvironment to establish bone metastases and (2) current and future potential treatments for prostate cancer patients with bone metastases.

Clinical and economic burden of bone metastasis and skeletal-related events in prostate cancer

PURPOSE OF REVIEW

We review the clinical trials and observational studies literature regarding the clinical and economic burden of bone metastasis and skeletal-related events (SREs) in prostate cancer, and discuss current gaps in understanding the impact of bone metastasis in this disease.

RECENT FINDINGS

Trial data indicate that SREs occur in half of prostate cancer patients with bone metastasis in the absence of treatment, and 30-45% among those who receive bone-modifying agents. In the United States, the cost of SRE ranged from $7553 per radiation episode to $88 838 per bone surgery episode. Prevalence of SRE, time to SRE occurrence, and cost of SRE varied across studies because of differences in study populations, follow-up period, and the algorithm used to measure SRE. There is limited evidence on the clinical and economic impact by SRE subtype. Information regarding patient-reported outcomes and costs from the patient's perspective is lacking.

SUMMARY

Bone metastasis and SREs in prostate cancer patients are associated with considerable morbidity, reduced survival, and substantial economic burden. Consistent study methodology, particularly the measurement of SREs, is necessary to allow comparison of estimates across studies. The inclusion of patient-centered clinical and economic outcomes in future research will provide pertinent information regarding the burden of bone metastasis and SREs.

Phase II study of single-agent orteronel (TAK-700) in patients with nonmetastatic castration-resistant prostate cancer and rising prostate-specific antigen

PURPOSE

Orteronel (TAK-700) is an investigational, nonsteroidal, oral, inhibitor of androgen synthesis with greater specificity for 17,20-lyase than for 17α-hydroxylase. We investigated orteronel without steroids in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC; M0).

EXPERIMENTAL DESIGN

Patients with nmCRPC and rising prostate-specific antigen (PSA) received orteronel 300 mg twice daily until PSA progression, metastases, or unacceptable toxicity. The primary endpoint was percentage of patients achieving PSA ≤0.2 ng/mL (undetectable levels) at 3 months. Secondary endpoints included safety, PSA response, time to metastases, and correlated endpoints.

RESULTS

Thirty-nine patients with a median baseline PSA doubling time of 2.4 months (range, 0.9-9.2) received a median of fourteen 28-day treatment cycles. PSA decreased >30% in 35 patients and 6 (16%) achieved PSA ≤ 0.2 ng/mL at 3 months. Median times to PSA progression and metastasis were 13.8 and 25.4 months, respectively. Kaplan-Meier estimates of freedom from PSA progression were 57% and 42% at 12 and 24 months, and of freedom from metastasis were 94% and 62% at 12 and 24 months, respectively. At 3 months, median testosterone declined by 89% from baseline. Adverse events led to therapy discontinuation in 12 patients and grade ≥3/4 adverse events occurred in 22 patients. Most frequent all-cause adverse events included fatigue (64%), hypertension (44%), diarrhea (38%), and nausea (33%), which were primarily grade 1/2.

CONCLUSIONS

Single-agent orteronel produced marked and durable declines in PSA in patients with nmCRPC. Orteronel has moderate but manageable toxicities and its chronic administration without steroids appears feasible.

Time Course of Calcium Concentrations and Risk Factors for Hypocalcemia in Patients Receiving Denosumab for the Treatment of Bone Metastases From Cancer

BACKGROUND

Severe hypocalcemia sometimes develops during denosumab treatment for bone metastases from cancer and is, therefore, an important issue. However, limited information is available on the risk factors for hypocalcemia and the appropriate interval for monitoring serum calcium concentration.

OBJECTIVE

The present study aimed to identify the risk factors for grade ≥2 hypocalcemia and to investigate the time course of serum calcium concentrations in patients receiving denosumab for bone metastases from cancer.

METHOD

The medical records of 66 cancer patients treated with denosumab between April 2012 and August 2013 were retrospectively reviewed.

RESULT

Of the 66 enrolled patients, 11, 5, and 1 developed grade 1, 2, and 3 hypocalcemia, respectively. All 4 patients with a baseline estimated glomerular filtration rate (eGFR) of <30 mL/min developed hypocalcemia. Hypocalcemia occurred in only 20%, 24%, and 15% of patients with an eGFR of 30 to 59, 60 to 89, and ≥90 mL/min, respectively. Multivariate logistic regression analysis revealed that lower eGFR values (odds ratio, 1.72 per 10 mL/min decrease, P = 0.02) were significantly associated with grade ≥2 hypocalcemia. In 11 patients who developed hypocalcemia during the first treatment course, the mean calcium concentrations decreased from 9.8 mg/dL at baseline to 8.4 mg/dL during the first week and reached a nadir of 8.1 mg/dL during the second week.

CONCLUSION

Our results support more frequent monitoring of serum calcium concentrations at baseline and during the first 2 weeks of treatment in patients receiving denosumab, especially those with an eGFR <30 mL/min.

Andrographolide prevents human breast cancer-induced osteoclastic bone loss via attenuated RANKL signaling

Bone metastasis is a common and serious complication in advanced cancers such as breast cancer, prostate cancer, and multiple myeloma. Agents that prevent bone loss could be used to develop an alternative therapy for bone metastasis. RANKL, a member of the tumor necrosis factor superfamily, has been shown to play a significant role in cancer-associated bone loss. In this study, we examined the efficacy of the natural compound andrographolide (AP), a diterpenoid lactone isolated from the traditional Chinese and Indian medicinal plant Andrographis paniculata, in reducing breast cancer-induced osteolysis. AP prevented human breast cancer-induced bone loss by suppressing RANKL-mediated and human breast cancer cell-induced osteoclast differentiation. Molecular analysis revealed that AP prevented osteoclast function by inhibiting RANKL-induced NF-κB and ERK signaling pathway in lower dose (20 μM), as well as inducing apoptosis at higher dose (40 μM). Thus, AP is a potent inhibitor of breast cancer-induced bone metastasis.

Molecular signaling pathways mediating osteoclastogenesis induced by prostate cancer cells

Background

Advanced prostate cancer commonly metastasizes to bone leading to osteoblastic and osteolytic lesions. Although an osteolytic component governed by activation of bone resorbing osteoclasts is prominent in prostate cancer metastasis, the molecular mechanisms of prostate cancer-induced osteoclastogenesis are not well-understood.

Methods

We studied the effect of soluble mediators released from human prostate carcinoma cells on osteoclast formation from mouse bone marrow and RAW 264.7 monocytes.

Results

Soluble factors released from human prostate carcinoma cells significantly increased viability of naïve bone marrow monocytes, as well as osteoclastogenesis from precursors primed with receptor activator of nuclear factor κ-B ligand (RANKL). The prostate cancer-induced osteoclastogenesis was not mediated by RANKL as it was not inhibited by osteoprotegerin (OPG). However inhibition of TGFβ receptor I (TβRI), or macrophage-colony stimulating factor (MCSF) resulted in attenuation of prostate cancer-induced osteoclastogenesis. We characterized the signaling pathways induced in osteoclast precursors by soluble mediators released from human prostate carcinoma cells. Prostate cancer factors increased basal calcium levels and calcium fluctuations, induced nuclear localization of nuclear factor of activated t-cells (NFAT)c1, and activated prolonged phosphorylation of ERK1/2 in RANKL-primed osteoclast precursors. Inhibition of calcium signaling, NFATc1 activation, and ERK1/2 phosphorylation significantly reduced the ability of prostate cancer mediators to stimulate osteoclastogenesis.

Conclusions

This study reveals the molecular mechanisms underlying the direct osteoclastogenic effect of prostate cancer derived factors, which may be beneficial in developing novel osteoclast-targeting therapeutic approaches.

The osteoblastic and osteoclastic interactions in spinal metastases secondary to prostate cancer

Prostate cancer (PC) is one of the most common cancers arising in men and has a high propensity for bone metastasis, particularly to the spine. At this stage, it often causes severe morbidity due to pathological fracture and/or metastatic epidural spinal cord compression which, if untreated, inevitably leads to intractable pain, neurological deficit, and paralysis. Unfortunately, the underlying molecular mechanisms driving growth of secondary PC in the bony vertebral column remain largely unknown. Further investigation is warranted in order to identify therapeutic targets in the future. This review summarizes the current understanding of PC bone metastasis in the spine, highlighting interactions between key tumor and bone-derived factors which influence tumor progression, especially the functional roles of osteoblasts and osteoclasts in the bone microenvironment through their interactions with metastatic PC cells and the critical pathway RANK/RANKL/OPG in bone destruction.

Multifunctional properties of RANKL/RANK in cell differentiation, proliferation and metastasis

It is known that there are close relationships between bone destruction and tumor growth in bone metastasis. RANKL is a central factor in bone metastasis, inducing osteoclastogenesis mediated by its receptor RANK. Recent reports demonstrate that RANKL has important roles in organogenesis stimulating proliferation and differentiation of epithelial and stroma cells. RANKL is induced not only by cytokines and hormones but also by UV-irradiation, inflammation and carcinogens. Expression of RANK and RANKL is found in several human cancer cell lines, and RANK signaling stimulates proliferation, migration and epithelial–mesenchymal transition of cancer cells, which may be involved in metastasis via an autocrine/paracrine mechanism. RANKL regulates the number of Tregs that produce RANKL, which may affect cancer metastasis. In this review we discuss the multifunctional roles of RANKL/RANK in osteoclastogenesis, organogenesis, and the metastasis and tumorigenesis of cancer cells.

Clinical features and treatment strategies for older prostate cancer patients with bone metastasis

To identify the clinical features and independent predictors of survival in older patients with bone metastasis from prostate cancer (PCa). We retrospectively analysed 205 older patients with bone metastases from PCa between 1997 and 2012. The Kaplan-Meier method was used with the log-rank test for survival rate calculations and to evaluate each variable. Multivariate analysis was performed with the Cox regression model. The chi-squared test was used to compare survival rates between older and younger (n=197) patients. All patients were followed up. The 1-, 2-, 3- and 5-year survival rates were 95.5%, 77.5%, 68.5% and 33.7%, respectively. Gleason score, radiotherapy of the primary tumour, the number of bone metastases, the alkaline phosphatase alkaline phosphatase (ALP) level, organ metastasis and regional lymph node metastasis were associated with the survival rates. Multivariate Cox regression analysis showed that Gleason score at diagnosis of the primary tumour was a significant predictor of overall survival following the diagnosis of bone metastases. In addition, the overall survival rates of older patients were higher compared with younger patients, but older patients who underwent radiotherapy had higher mortality. These data may serve as a guide for creating clinical prediction models in further studies.

Risk of osteonecrosis of the jaw in cancer patients receiving denosumab: a meta-analysis of seven randomized controlled trials

AIMS

The aim of this study is to gain a better understanding of the overall incidence and risk of osteonecrosis of the jaw (ONJ) in cancer patients receiving denosumab.

METHODS

We performed a meta-analysis of relevant randomized controlled trials identified in Pubmed, Embase, and Cochrane databases. Abstracts presented at the conferences were also searched. Overall incidence rates, relative risk (RR), and 95 % confidence intervals (CI) were calculated employing fixed- or random-effects models depending on the heterogeneity of the included trials.

RESULTS

A total of 8963 patients with a variety of solid tumors from 7 randomized controlled trials (RCTs) were included for the meta-analysis. The overall incidence of ONJ in cancer patients receiving denosumab was 1.7 % [95 % CI: 0.9-3.1 %]. Also, the use of denosumab was associated with significantly increased risk of ONJ in comparison with bisphosphonates (BPs)/placebo treatment (RR 1.61, 95 % CI: 1.05-2.48, P = 0.029). Subgroup analysis based on controlled therapies demonstrated an increased risk of ONJ in denosumab therapy, when compared with BPs (RR 1.48, 95 % CI: 0.96-2.29, P = 0.078) or placebo (RR 16.28, 95 % CI: 1.68-158.05, P = 0.017). Similar results were observed in prostate cancer (RR 3.358, 95 % CI: 1.573-7.166, P = 0.002) while there was a non-significantly increased risk of denosumab-related osteonecrosis of the jaw (DONJ) in non-prostate cancers (RR 1.142, 95 % CI: 0.678-1.921, P = 0.618).

CONCLUSIONS

The use of denosumab is associated with an increased risk of developing ONJ when compared with BP treatment or placebo, although the increased risk was not statistically significant between denosumab and BP treatment. Further studies are still needed to establish guidelines for the prevention and effective treatment of ONJ.

[Four new drugs on the market: abiraterone, belatacept, vandetanib and fidaxomycine]

Among the 35 new molecular entities approved by the FDA in 2011, 17 were particularly notable for their significant contributions to the health of patients, including abiraterone acetate, vandetanib, belatacept and fidaxomicin. Thus, abiraterone acetate, namely Zytiga®, was included as the first in a new class of drugs to treat late-stage prostate cancer. The ability of Zytiga® to prolong survival in these patients was considered as significant because they have few other treatments options and the benefits of Zytiga® outweighed the risks of reported side-effects. Vandetanib, namely Caprelsa®, was also considered as a relevant drug since it represents the first drug approved to treat particularly aggressive medullary thyroid cancer, an orphan disease. Despite huge progress in transplantation, renal transplantation remains a serious problem since patients treated with the calcineurin inhibitors cyclosporine and tacrolimus are at high risk of developing renal injury. With longer follow-up, the novel immunosuppressant belatacept continued to show better renal function compared with a cyclosporine-based regimen, as well as a consistent safety profile and comparable efficacy. It was approved by the Food and Drug Administration in June 2011 for the prophylaxis of organ rejection in adult recipients of a kidney transplant acting by a selective T-cell costimulation blocker given as an infusion. Clostridium difficile is currently the most important cause of infectious diarrhea in the United States. Fidaxomicin, a macrolide antibiotic, was recently approved for treatment of these infections (CDIs). It could be an alternative treatment for infection with C. difficile, with similar efficacy and safety to vancomycin. Fidaxomicin has minimal activity against Bacteroides species, which may be advantageous in maintaining colonization resistance and protecting the gastrointestinal tract from colonization by C. difficile.