Therapeutic opportunities for castration-resistant prostate cancer patients with bone metastases

Castration-resistant prostate cancer with bone metastases: toward the best therapeutic choice

The treatment landscape for metastatic castration-resistant prostate cancer has evolved extremely in recent years and several drug classes are now available. Nonetheless, the lack of validated predictive biomarkers makes therapeutic choice and the best sequential approach difficult. The location of the metastatic site could be a valid criterion for choosing among the treatment options available. Although bone remains the most frequent metastatic site and a possible target for many drugs, recent data suggest a profound shift in the disease spectrum with visceral metastases increasing incidence. This review describes the presently available and ongoing therapies for patients with CRPC and bone metastases, focusing on the role of bone metastases as a possible driver for selecting therapies in these patients.

Denosumab versus bisphosphonates for the treatment of bone metastases from solid tumors: a systematic review

BACKGROUND

Bone metastases are highly prevalent in breast, prostate, lung and colon cancers. Their symptoms negatively affect quality of life and functionality and optimal management can mitigate these problems. There are two different targeted agents to treat them: bisphosphonates (pamidronate and zoledronic acid) and the monoclonal antibody denosumab. Estimates of cost-effectiveness are still mixed.

OBJECTIVE

To conduct a systematic review of economic studies that compares these two options.

METHOD

Literature search comprised eight databases and keywords for bone metastases, bisphosphonates, denosumab, and economic studies were used. Data were extracted regarding their methodologic characteristics and cost-effectiveness analyses. All studies were evaluated regarding to its methodological quality.

RESULTS

A total of 263 unique studies were retrieved and six met inclusion criteria. All studies were based on clinical trials and other existing literature data, and they had high methodological quality. Most found unfavorable cost-effectiveness for denosumab compared with zoledronic acid, with adjusted ICERS that ranged from $4638-87,354 per SRE avoided and from US$57,274-4.81 M. per QALY gained, which varied widely according to type of tumor, time horizon, among others. Results were sensitive to drug costs, time to first skeletal-related event (SRE), time horizon, and utility.

CONCLUSIONS

Denosumab had unfavorable cost-effectiveness compared with zoledronic acid in most of the included studies. New economic studies based on real-world data and longer time horizons comparing these therapeutic options are needed.

Pain predicts overall survival in men with metastatic castration-resistant prostate cancer treated with radium-223

Background

Radium-223 dichloride is an alpha emitter approved for metastatic castration-resistant prostate cancer (mCRPC). Unfortunately, little data are available on the prognostic factors during radium-223-based therapy.

Patients and methods

Patients with histologically confirmed progressive CRPC with two or more bone metastases and symptomatic disease were eligible. Previous therapy with a novel hormonal therapy was allowed. The patients received six intravenous injections of radium-223 every 4 weeks. A visual analog scale (VAS) was adopted to evaluate patients’ basal pain.

Results

A total of 25 patients were evaluated. Of these, 6 (24%) reported VAS <4. After a median follow-up of 8 months, all patients died with a median overall survival of 8.3 months (95% CI: 5.2–11.8 months), 12.6 months in the patients with VAS <4 vs 6.6 months in the patients with VAS ≥4 (P=0.03).

Conclusion

The present study suggests that VAS could be prognostic of the survival of mCRPC treated with radium-223 irrespective of the limitations of a small number of patients and the retrospective nature of the data.

Design and Evaluation of Europium Containing Mesoporous Bioactive Glass Nanospheres: Doxorubicin Release Kinetics and Inhibitory Effect on Osteosarcoma MG 63 Cells

Functional ions and drug factors play a vital role in stimulating bone tissue regeneration as we understand it. In this work, europium-containing mesoporous bioactive glass nanospheres (Eu/MBGs), composed of 60% SiO₂-(36⁻x)%CaO-x%Eu₂O₃-4%P₂O₅ (x = 0, 0.5, 1, 2 mol%), were prepared by a facile sol-gel process. The results indicate that Eu ions play an important role to influence the microstructure of MBGs, in which a suitable concentration of Eu (1 mol%) increases their surface area (502 m²/g) as well as their pore volume (0.34 cm³/g). Proper doping of Eu ions in MBGs can observably induce apatite mineralization and improve the doxorubicin (DOX) release behavior. Furthermore, DOX-loaded Eu/MBGs could maintain a long-term inhibitory effect on the viability of osteosarcoma MG 63 cells. This work has demonstrated that it is possible to develop functional Eu/MBGs by combining excellent apatite-mineralization ability, controllable drug (DOX) release and antitumor functions for the therapy of bone tissue regeneration.

NAC1 promotes the migration of prostate cancer cells and participates in osteoclastogenesis by negatively regulating IFNβ

Nucleus accumbens-associated protein 1 (NAC1), a transcriptional co-regulator, is overexpressed in advanced prostate cancer. However, the NAC1-regulated transcriptome has not been completely explored. In the present study, the functional silencing of NAC1 blocked the migration of prostate cancer cells and suppress osteoclastogenesis. The present study also determined that NAC1 was overexpressed in the highly aggressive prostate cancer cell lines PC-3, DU-145 and LNCaP. NAC1 small interfering RNA treatment of DU-145 cells decreased cell migration, but interestingly had no significant effects on cell proliferation. Furthermore, microarray analysis showed that a group of genes may be associated with the development of prostate cancer after NAC1 knockdown, including interferon-β (IFNβ), which is reported to be involved in osteoclastogenesis, an important factor affecting bone metastasis. The mechanisms of NAC1 function were further explored by co-culture studies using PC-3 and RAW264.7 osteoclast precursor cells, which demonstrated that silencing NAC1 downregulated the genes associated with the activation of osteoclasts. Furthermore, it was revealed that NAC1 had the ability to affect the release of IFNβ into the extracellular environment. Together, these findings indicated that NAC1 promoted cell migration, and that NAC1 may have a key role in osteoclastogenesis.

Overcoming immunosuppression in bone metastases

Bone metastases are present in up to 70% of advanced prostate and breast cancers and occur at significant rates in a variety of other cancers. Bone metastases can be associated with significant morbidity. The establishment of bone metastasis activates several immunosuppressive mechanisms. Hence, understanding the tumor-bone microenvironment is crucial to inform the development of novel therapies. This review describes the current standard of care for patients with bone metastatic disease and novel treatment options targeting the microenvironment. Treatments reviewed include immunotherapies, cryoablation, and targeted therapies. Combinatorial treatment strategies including targeted therapies and immunotherapies show promise in pre-clinical and clinical studies to overcome the suppressive environment and improve treatment of bone metastases.

Opioid Use Among Metastatic Prostate Cancer Patients With Skeletal-related Events

PURPOSE

The development of skeletal-related events (SREs) (pathologic fracture, need for surgery and/or radiation to bone, spinal cord compression, and hypercalcemia of malignancy) in metastatic prostate cancer (MPC) is associated with worsened pain and compromised quality of life. Opioids are frequently used throughout the course of SRE treatment. This study describes the treatment patterns and incremental use of opioids in MPC patients diagnosed with SREs.

METHODS

PC patients with bone metastases newly diagnosed with an SRE between January 1, 2005, and September 30, 2014, were identified using MarketScan Commercial and Medicare databases. Included patients were aged ≥40 years, had medical/pharmacy benefits for ≥12 months before (preindex) and ≥6 months after (postindex) diagnosis, and were without evidence of other primary cancers. Patients were categorized as nonusers of opioids (<10 days), short-term users (≥10 and <60 days), or long-term users (≥60 days) and further by SRE type. Opioid type, proportion of time on opioids, morphine-equivalent dose, adjuvant medications, and radiation use before and after SRE diagnosis were evaluated.

FINDINGS

A total of 1071 eligible patients were identified (mean age, 71 years; 10.8% had chronic pain at baseline). The most common SRE types present were radiation (60.2%), radiation and bone surgery (15.0%), pathologic fracture (7.2%), and bone surgery (6.5%). Opioid use increased from 49.9% preindex to 53.3% postindex (P < 0.0001). The proportion of time on opioids doubled after SRE (pre, 0.3 vs post, 0.6; P < 0.0001). A greater percentage of patients used only opioids after an SRE (pre, 11.0%; post, 46.1% [P < 0.0001]), while a lesser percentage of patients used only radiation after an SRE (pre, 36.0%; post, 4.7% [P < 0.0001]). An increase was observed in patients using neither radiation nor opioids (pre, 14.5%; post, 42.0% [P < 0.0001]). An increase of ~50% was noted in long-term opioid users (from 22.1% to 32.1%). The use of monotherapy with a short-acting opioid decreased (pre, 35.1%; post, 32.5% [P < 0.0001]), while use of mixed opioids increased (pre, 13.7%; post, 19.1% [P < 0.0001]). Mean morphine-equivalent dose increased from pre- to post-SRE (9.1 vs 13.1 mg). Bisphosphonate and NSAID users decreased from before to after an SRE diagnosis (bisphosphonates, 40.2% vs 8.6%; NSAIDs, 26.7% vs 17.5% [both, P < 0.0001]).

IMPLICATIONS

Long-term opioid use and dose were significantly increased after SRE development in MPC. The high percentage of patients not treated with an opioid or radiation potentially supports the need for additional treatment options for controlling pain if medically necessary and/or to prevent SREs.

Evaluation of Bone Metastases by 18F-Choline PET/CT in a Patient with Castration-Resistant Prostate Cancer Treated with Radium-223

Background

To date, bone metastases remain the main cause of morbidity and mortality in patients with metastatic castration-resistant prostate cancer (mCRPC). Therefore, the combination of accurate early detection of bony disease and effective treatment of these lesions is crucial in the management of mCRPC patients, but clinical trials specifically designed to test novel approaches are currently lacking.

Case Description

This report describes the case of a 74-year-old male with bone mCRPC and symptomatic and biochemical progression, who underwent radium-223 therapy, following previous treatment failure. 18F-choline positron emission tomography (PET)/computed tomography (CT) was used to assess changes in skeletal tumor activity before and after radium-223. Changes in prostate-specific antigen and alkaline phosphatase were also determined. 18F-choline PET/CT showed that treatment with radium-223 was able to effectively reduce bone metastatic disease, and this was accompanied by an excellent metabolic response.

Conclusions

In clinical practice, metabolic assessment of lesions by 18F-choline PET/CT following radium-223 seems a valid approach to monitor treatment response. Until results from clinical trials become available, reporting of single cases relating to data on the use of this technique remains paramount.

Virus encoded circulatory miRNAs for early detection of prostate cancer

BACKGROUND

Prostate cancer (PCa) is the most commonly diagnosed cancer and kills about 28,000 American men annually. Although progress has been made in understanding the molecular features of different forms of the disease, PCa is considered incurable when it becomes resistant to standard therapies. Prostate specific antigen (PSA) test has been a gold standard of diagnosis for PCa, however, it can result in lead to the unnecessary biopsies and treatment of indolent cancers due to the low specificity. Thus, the limitations of PSA screening for PCa have prompted much focus on strategies how to enhance the accuracy of PSA for distinction between aggressive and indolent cancers.

DISCUSSION

Studies of miRNAs in PCa patients have suggested differentially expressed miRNAs between healthy controls and those with PCa, providing potential biomarker candidates using body fluids including urine and blood. Virus infection has been considered to associate with PCa incidence. Virus infected PCa cells may shed extracellular vesicles and communicate with neighboring cells, which were not infected yet, however, no mechanistic approaches were performed to understand the biology. The miRNAs composition in the shedding extracellular vesicles, and its role in PCa are completely undefined. In the near future, new insights to connect between the viral derived miRNAs and PCa progression might provide an opportunity to diagnose, risk prediction and therapeutic strategies. The goal of this debate article is to provide a short review on miRNAs, virus infection and viral encoded miRNAs in PCa, with a primary focus on circulating miRNAs as potential non-invasive biomarkers for PCa patients.

Hypernociceptive responses following the intratibial inoculation of RM1 prostate cancer cells in mice

BACKGROUND

Pain due to bone metastases of prostatic origin is a relevant clinical issue. We study here the nociceptive responses obtained in mice receiving the intratibial inoculation of RM1 prostate cancer cells.

METHODS

10(2) -10(5) RM1 cells were inoculated to C57BL/6 mice and tumor development was analysed histologically and with luciferase-expressing RM1 cells. Spinal astroglial (GFAP) or microglial (Iba-1) expression was assessed with immunohistochemical methods and hypernociception was measured by the unilateral hot plate, the paw pressure and the von Frey tests. The analgesic effect of morphine, zoledronic acid or the CCR2 antagonist RS504393 was measured. Levels of the chemokines CCL2, CCL3, and CCL5 were determined by ELISA.

RESULTS

The inoculation of 10(3) RM1 cells induced tumoral growth in bone with a mixed osteoclastic/osteoblastic pattern and evoked astroglial, but not microglial, activation in the spinal cord. Hyperalgesia and allodynia were already established four days after inoculation and dose-dependently inhibited by the s.c. administration of morphine (1-5 mg/kg) or zoledronic acid (1-3 mg/kg). CCL2 and CCL5, but not CCL3, were released by RM1 cells in culture whereas only an increased presence of CCL2 was found in bone tumor homogenates. The administration of the CCR2 antagonist RS504393 (0.3-3 mg/kg) inhibited RM1 induced thermal hyperalgesia without modifying mechanical allodynia.

CONCLUSION

The intratibial inoculation of RM1 cells in immunocompetent mice induces hypernociceptive responses and can be useful to perform studies of bone cancer induced pain related to androgen-independent prostate cancer. The antinociceptive role derived from the blockade of the CCR2 chemokine receptors is further envisaged.

Radium 223 dichloride: a multidisciplinary approach to metastatic castration-resistant prostate cancer

ABSTRACT 

The role of nuclear medicine physicians in the multidisciplinary team for the management of patients with prostate cancer has been restricted because of a lack of available tools. The only drugs approved to relieve pain related to bone metastases were β-emitting radiopharmaceuticals. These drugs did not prove to prolong survival when used as single agent and resulted associated with important adverse events. This situation has changed with the introduction of radium 223 because of evidence of improved survival in patients, the good safety profile and the opportunity to avoid clonal selection of tumor cells. Cooperation among physicians involved in cancer management will lead to improvements in the treatment of bone metastases due to prostate cancer and is thought to extend to other tumor types.