The changing natural history of metastatic prostate cancer

Men's experiences of decision-making in life-prolonging treatments of metastatic castration-resistant prostate cancer - wishing for a process adapted to personal preferences: a prospective interview study

BACKGROUND

In the fast-expanding field of life-prolonging-treatment of metastatic, castration-resistant prostate cancer, treatment decision-making is very complex - both for patients and healthcare professionals since there is no "one size that fits all" in choosing treatment in this phase. Little research has been conducted about men's experiences of treatment decision-making in this advanced, incurable, phase. Hence, this study aimed to describe men's experiences of decision-making in life-prolonging treatments of metastatic castration-resistant prostate cancer.

METHODS

Seventeen men were recruited from four oncology clinics in Sweden and interviewed at baseline. Qualitative interviews (n = 31) were conducted over two years, the timepoints for subsequent interviews (10 men were interviewed twice or more) adhered to when each man switched or terminated life-prolonging treatment. Data was analysed with qualitative content analysis.

RESULTS

Initially, the men were adamant about proceeding with treatment. As their illness continued to progress, they gradually turned their focus more towards their well-being. They wished for continuity regarding treating physicians and constantly being assigned new physicians compromised the quality of care and complicated decision-making. In their decision-making, the men adapted their own approach to the approach taken by their physician, even if it was not an approach they had originally preferred. They wished for their role preferences to be respected. Most men had made treatment decisions collaboratively with their physician, but some described having taken on a more, or less, driving role in decision-making than they really wished for. Navigating healthcare was perceived as difficult and for some it thus felt necessary to pursue and coordinate their own care by e.g. using personal connections or contacting clinics ahead of referral. A part of treatment decision-making was forming a basis for a decision, in which the need for personalized information (quality, quantity and timing) came forth as important.

CONCLUSIONS

When diagnosed with metastatic castration-resistant prostate cancer, men's preferences for their decision-making role, and perspectives on the treatment outcome need to be continuously addressed throughout their disease course. Improved continuity of care and a more personalised care approach should meet these patients' wishes and needs in this phase.

TRIAL REGISTRATION

Clinical trial number: Not applicable.

Identification of early symptoms and changes in QoL and functioning among men with primary localized prostate cancer who later develop metastases: A matched, prospective study

OBJECTIVE

To identify early symptoms and changes in QoL among men with primary localized prostate cancer (PC) who later develop metastases.

METHODS

From an ongoing prospective study of 3.885 men with localized PC, primarily treated with radiotherapy (RT), a subsample of men developing metastatic PC (mPC) following the first year after the start of RT and that had died during the follow-up (mPC group, n = 107) were matched against men who did not develop metastases (non-mPC group, n = 214). Data were collected using the EORTC QLQ-C30 and PCSS instruments. Non-parametric tests were performed for comparisons at baseline, end of RT, 3 months, and 1, 2, 3, and 5 years after RT.

RESULTS

The final sample consists of 317 men (mPC n = 106; non-mPC n = 211) who had completed at least one questionnaire. Initially, symptom levels were generally low and QoL and functioning high in both groups. An increasing difference between the groups was found, where the mPC group gradually deteriorated from the 2-year follow-up. Significant differences were found for several outcomes at 3 and 5 years. In a sensitivity analysis, where metastatic patients were removed from the time-point of verified metastases, most differences did not remain significant. Significant deterioration over time was seen within both groups for some outcomes.

SIGNIFICANCE OF RESULTS

The results indicate that unmet supportive needs occur over time among these men. Worsening QoL or functioning and symptoms may be difficult to recognize when the development is gradual over several years, and with various access to systematic follow-up in late phases. This highlights the need for continuous monitoring of PC patients to detect needs for supportive interventions early and throughout the disease course, also among those with non-metastatic disease who have undergone curatively intended treatment.

A Retrospective Comparative Study of Sodium Fluoride Na18F-PET/CT and 68Ga-PSMA-11 PET/CT in the Bone Metastases of Prostate Cancer Using a Volumetric 3-D Radiomic Analysis

Bone is the most common metastatic site in prostate cancer (PCa). 68Ga-PSMA-11 (or gozetotide) and sodium fluoride-18 (Na18F) are rather new radiopharmaceuticals for assessing PCa-associated bone metastases. Gozetotide uptake reflects cell membrane enzyme activity and the sodium fluoride uptake measures bone mineralization in advanced PCa. Here, we aim to characterize this difference and possibly provide a new method for patient selection in targeted therapies. Methods: The study consisted of 14 patients with advanced PCa (M group > 5 lesions), who had had routine PET/CT both with PSMA and NaF over consecutive days, and 12 PCa patients with no skeletal metastases (N). The bone regions in CT were used to coregister the two PET/CT scans. The whole skeleton volume(s) of interest (VOIs) were defined using the CT component of PET (HU > 150); similarly, the sclerotic/dense bone was defined as HU > 600. Additional VOIs were defined for PET, with pathological threshold values for PSMA (SUV > 3.0) and NaF (SUV > 10). Besides the pathological bone volumes measured with each technique (CT, NaF, and PSMA-PET) and their contemporaneous combinations, overlapping VOIs with the CT-based skeletal and sclerotic volumes were also recorded. Additionally, thresholds of 4.0, 6.0, and 10.0 were tested for SUVPSMA. Results: In group M, the skeletal VOI volumes were 8.77 ± 1.80 L, and the sclerotic bone volumes were 1.32 ± 0.50 L; in contrast, in group N, they were 8.73 ± 1.43 L (skeletal) and 1.23 ± 0.28 L (sclerosis). The total enzyme activity for PSMA was 2.21 ± 5.15 in the M group and 0.078 ± 0.053 in the N group (p < 0.0002). The total bone demineralization activity for NaF varied from 4.31 ± 6.17 in the M group and 0.24 ± 0.56 in group N (p < 0.0002). The pathological PSMA volume represented 0.44−132% of the sclerotic bone volume in group M and 0.55−2.3% in group N. The pathological NaF volume in those patients with multiple metastases represented 0.27−68% of the sclerotic bone volume, and in the control group, only 0.00−6.5% of the sclerotic bone volume (p < 0.0003). Conclusions: These results confirm our earlier findings that CT alone does not suit the evaluation of the extent of active skeletal metastases in PCa. PSMA and NaF images give complementary information about the extent of the active skeletal disease, which has a clinical impact and may change its management. The PSMA and NaF absolute volumes could be used for planning targeted therapies. A cut-off value 3.0 for SUVPSMA given here is the best correlation in the presentation of active metastatic skeletal disease.

Dietary Patterns and Prostate Cancer: CAPLIFE Study

The etiology of prostate cancer (PCa) remains uncertain, and the role of diet is unclear. We aimed to evaluate the role of diet, through dietary patterns, on PCa, considering tumor aggressiveness and extension. The CAPLIFE study is a population-based case-control study including a total of 428 incident PCa cases and 393 controls aged 40-80 years. Dietary information was collected through a validated food frequency questionnaire. Three dietary patterns were identified through principal component analysis: "Mediterranean," "Western," and "Unhealthy," which were categorized into tertiles according to the control group cutoff points. Tumor aggressiveness and extension was determined. Logistic regression models were used to assess the association between dietary patterns and PCa. High adherence to an unhealthy dietary pattern was associated with higher odds of PCa, OR_T3vsT1 = 1.52 (95% CI 1.02-2.27), especially for cases with ISUP 1-2 and localized PCa tumors. This association was not observed with a Western or Mediterranean pattern. In conclusion, adherence to an unhealthy diet appears to be associated with higher odds of PCa, especially for cases with ISUP 1-2 and localized PCa tumors.

A New Old Target: Androgen Receptor Signaling and Advanced Prostate Cancer

Owing to the development of multiple novel therapies, there has been major progress in the treatment of advanced prostate cancer over the last two decades; however, the disease remains invariably fatal. Androgens and the androgen receptor (AR) play a critical role in prostate carcinogenesis, and targeting the AR signaling axis with abiraterone, enzalutamide, darolutamide, and apalutamide has improved outcomes for men with this lethal disease. Targeting the AR and elucidating mechanisms of resistance to these agents remains central to drug development efforts. This review provides an overview of the evolution and current approaches for targeting the AR in advanced prostate cancer. It describes the biology of AR signaling, explores AR-targeting resistance mechanisms, and discusses future perspectives and promising novel therapeutic strategies. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

A Retrospective Comparative Study of Sodium Fluoride (NaF-18)-PET/CT and Fluorocholine (F-18-CH) PET/CT in the Evaluation of Skeletal Metastases in Metastatic Prostate Cancer Using a Volumetric 3-D Radiomics Analysis

Bone metastases are common in prostate cancer (PCa). Fluorocholine-18 (FCH) and sodium fluoride-18 (NaF) have been used to assess PCa associated skeletal disease in thousands of patients by demonstrating different mechanism of uptake-cell membrane (lipid) synthesis and bone mineralization. Here, this difference is characterized quantitatively in detail. Our study cohort consisted of 12 patients with advanced disease (> 5 lesions) (M) and of five PCa patients with no skeletal disease (N). They had routine PET/CT with FCH and NaF on consecutive days. Skeletal regions in CT were used to co-register the two PET/CT scans. Bone 3-D volume of interest (VOI) was defined on the CT of PET with a threshold of HU > 150, and sclerotic/dense bone as HU > 600, respectively. Additional VOIs were defined on PET uptake with the threshold values on both FCH (SUV > 3.5) and NaF (SUV > 10). The pathologic skeletal volumes for each technique (CT, HU > 600), NaF (SUV > 10) and FCH (SUV > 3.5) were developed and analyzed. The skeletal VOIs varied from 5.03 L to 7.31 L, whereas sclerotic bone VOIs were from 0.88 L to 2.99 L. Total choline kinase (cell membrane synthesis) activity for FCH (TCA) varied from 0.008 to 4.85 [kg] in M group and from 0.0006 to 0.085 [kg] in N group. Total accelerated osteoblastic (bone demineralization) activity for NaF (TBA varied from 0.25 to 13.6 [kg] in M group and varied from 0.000 to 1.09 [kg] in N group. The sclerotic bone volume represented only 1.86 ± 1.71% of the pathologic FCH volume and 4.07 ± 3.21% of the pathologic NaF volume in M group, and only 0.08 ± 0.09% and 0.18 ± 0.19% in N group, respectively. Our results suggest that CT alone cannot be used for the assessment of the extent of active metastatic skeletal disease in PCa. NaF and FCH give complementary information about the activity of the skeletal disease, improving diagnosis and disease staging.

Transient Sox9 Expression Facilitates Resistance to Androgen-Targeted Therapy in Prostate Cancer

PURPOSE

Patients with metastatic prostate cancer are increasingly presenting with treatment-resistant, androgen receptor-negative/low (AR^-/Low) tumors, with or without neuroendocrine characteristics, in processes attributed to tumor cell plasticity. This plasticity has been modeled by Rb1/p53 knockdown/knockout and is accompanied by overexpression of the pluripotency factor, Sox2. Here, we explore the role of the developmental transcription factor Sox9 in the process of prostate cancer therapy response and tumor progression.

EXPERIMENTAL DESIGN

Unique prostate cancer cell models that capture AR^-/Low stem cell-like intermediates were analyzed for features of plasticity and the functional role of Sox9. Human prostate cancer xenografts and tissue microarrays were evaluated for temporal alterations in Sox9 expression. The role of NF-κB pathway activity in Sox9 overexpression was explored.

RESULTS

Prostate cancer stem cell-like intermediates have reduced Rb1 and p53 protein expression and overexpress Sox2 as well as Sox9. Sox9 was required for spheroid growth, and overexpression increased invasiveness and neural features of prostate cancer cells. Sox9 was transiently upregulated in castration-induced progression of prostate cancer xenografts and was specifically overexpressed in neoadjuvant hormone therapy (NHT)-treated patient tumors. High Sox9 expression in NHT-treated patients predicts biochemical recurrence. Finally, we link Sox9 induction to NF-κB dimer activation in prostate cancer cells.

CONCLUSIONS

Developmentally reprogrammed prostate cancer cell models recapitulate features of clinically advanced prostate tumors, including downregulated Rb1/p53 and overexpression of Sox2 with Sox9. Sox9 is a marker of a transitional state that identifies prostate cancer cells under the stress of therapeutic assault and facilitates progression to therapy resistance. Its expression may index the relative activity of the NF-κB pathway.

The importance of targeting intracrinology in prostate cancer management

Accumulating evidence has shown that intracrinology in prostate cancer (PCa) has a pivotal role in survival of cancer cell. PCa cells are able to produce androgens from different androgen precursors, such as dehydroepiandrosterone, thereby maintaining androgen receptor signaling. Several drugs have been developed that target intracrinology, some of which are now being used as standard treatment for the so-called castrate-resistant prostate cancer (CRPC) patients. Recently, the US FDA approval has changed the indication of drugs targeting intracrinology, e.g., abiraterone and enzalutamide where it evolved from post-chemotherapy CRPC to hormone-naive metastatic PCa cases. This approval raises question whether those drugs can also be used as the first-line treatment in localized stage PCa cases. In addition, development of additional drugs targeting major components of intracrinology is ongoing. Application of these new drugs and administration of combinations of existing drugs will ultimately lead to an increase in the efficacy of such treatments as well as to reduce the toxicity of the therapy and to prevent the risk of resistance.

Malignant invasion of the central nervous system: the hidden face of a poorly understood outcome of prostate cancer

Malignancies of the central nervous system include primary brain tumors and brain metastases, the latter being the major cause of intracranial neoplasms in adults. Although prostate cancer (PCa) brain metastases are not the most common source, recent data show that the relevance of prostate cancer brain metastases (PCBM) cannot be neglected. In this review, we focus on the molecular repertory as well as on the phenotypical similarities between PCBM and primary PCa, such as the cellular evolution and the maintenance of androgen-receptor expression. Moreover, the simultaneous occurrence of PCBM with other PCa metastatic sites and the significance of the clinical heterogeneity of the disease are also discussed. In addition, a potential relationship between the heterogeneous behavior exhibited by PCBM and the co-occurrence of malignant cell clusters with distinct genetic profiles is also hypothesized, as well as the prominent role of astrocytes in the establishment of PCBM.

Androgen Receptor Targeted Treatments of Prostate Cancer: 35 Years of Progress with Antiandrogens

PURPOSE

Antiandrogens inhibit the androgen receptor and have an important role in the treatment of prostate cancer. This review provides a historical perspective on the development and clinical benefit of antiandrogens in the treatment of prostate cancer.

MATERIALS AND METHODS

We searched PubMed® for clinical trials with the search terms antiandrogens and prostate cancer combined with drug names for antiandrogens. This article represents a collaboration of clinical investigators who have made critical scientific contributions leading to the approval of antiandrogens for treating patients with prostate cancer.

RESULTS

Antiandrogens differ in chemical structure and exert varying efficacy and safety profiles. The unfavorable therapeutic index of steroidal antiandrogens led to replacement by safer nonsteroidal agents. Flutamide, nilutamide and bicalutamide, which were designed to target the androgen receptor, were developed primarily for use in combination with castration to provide combined androgen blockade. Modest clinical benefits were observed with the combination of first generation antiandrogens and castration vs castration alone. With increased knowledge of androgen receptor structure and its biological functions a new generation of antiandrogens without agonist activity was designed to provide more potent inhibition of the androgen receptor. Randomized clinical trials in patients with metastatic, castration resistant prostate cancer showed significant survival benefits, which led to the approval of enzalutamide in August 2012. Apalutamide was recently approved while darolutamide is not yet approved in the United States. These next generation antiandrogens are being actively tested in earlier disease states such as nonmetastatic prostate cancer. Evolving knowledge of resistance mechanisms to androgen receptor targeted treatments will stimulate research and drug discovery for additional compounds. Further testing in nonmetastatic castration resistant prostate cancer as well as castration sensitive disease states will hopefully augment our ability to treat a broader spectrum of patients with prostate cancer.

CONCLUSIONS

Antiandrogens have already provided important benefits for prostate cancer treatment. Greater knowledge about the structural and functional biology of the androgen receptor in prostate cancer will facilitate further discovery and development of further improved antiandrogens with enhanced clinical activity in patients with advanced metastatic disease. Testing these new agents earlier in the course of prostate cancer may further improve the survival and quality of life of patients with current local and/or systemic treatment modalities.

Exosomal αvβ6 integrin is required for monocyte M2 polarization in prostate cancer

Therapeutic approaches aimed at curing prostate cancer are only partially successful given the occurrence of highly metastatic resistant phenotypes that frequently develop in response to therapies. Recently, we have described αvβ6, a surface receptor of the integrin family as a novel therapeutic target for prostate cancer; this epithelial-specific molecule is an ideal target since, unlike other integrins, it is found in different types of cancer but not in normal tissues. We describe a novel αvβ6-mediated signaling pathway that has profound effects on the microenvironment. We show that αvβ6 is transferred from cancer cells to monocytes, including β6-null monocytes, by exosomes and that monocytes from prostate cancer patients, but not from healthy volunteers, express αvβ6. Cancer cell exosomes, purified via density gradients, promote M2 polarization, whereas αvβ6 down-regulation in exosomes inhibits M2 polarization in recipient monocytes. Also, as evaluated by our proteomic analysis, αvβ6 down-regulation causes a significant increase in donor cancer cells, and their exosomes, of two molecules that have a tumor suppressive role, STAT1 and MX1/2. Finally, using the Pten^pc-/- prostate cancer mouse model, which carries a prostate epithelial-specific Pten deletion, we demonstrate that αvβ6 inhibition in vivo causes up-regulation of STAT1 in cancer cells. Our results provide evidence of a novel mechanism that regulates M2 polarization and prostate cancer progression through transfer of αvβ6 from cancer cells to monocytes through exosomes.

Prostate cancer as a paradigm of multidisciplinary approach? Highlights from the Italian young radiation oncologist meeting

Aims and background

The diagnostic and therapeutic approach to prostate cancer has evolved rapidly in last decades. Young professionals need an update about these recent developments in order to improve the care of patients treated in their daily clinical practice.

Methods

On May 18, 2013, AIRO Giovani (the young section of the Italian Association of Radiation Oncology) organized a multidisciplinary meeting involving, as speakers, several young physicians from many parts of Italy actively involved in the diagnostic and therapeutic approach to prostate cancer. The meeting was specifically addressed to young physicians (radio-oncologists, urologists, medical oncologists) and presented the state-of-the-art of the diagnostic/therapeutic approach based on the latest evidence on the issue. Highlights of the congress are summarized and presented in this report.

Results

The large participation in the meeting (more than 120 participants were present) confirmed the interest of young radiation oncologists in improving their skills in prostate cancer management. The contributions of the speakers confirmed the need for regular updates, considering the promising results of recently published studies and the many new ongoing trials, on the diagnostic and therapeutic approaches to prostate cancer.

Conclusions

Multidisciplinary meetings are helpful to improve the skills of young professionals.

Therapy-induced developmental reprogramming of prostate cancer cells and acquired therapy resistance

Treatment-induced neuroendocrine transdifferentiation (NEtD) complicates therapies for metastatic prostate cancer (PCa). Based on evidence that PCa cells can transdifferentiate to other neuroectodermally-derived cell lineages in vitro, we proposed that NEtD requires first an intermediary reprogramming to metastable cancer stem-like cells (CSCs) of a neural class and we demonstrate that several different AR+/PSA+ PCa cell lines were efficiently reprogrammed to, maintained and propagated as CSCs by growth in androgen-free neural/neural crest (N/NC) stem medium. Such reprogrammed cells lost features of prostate differentiation; gained features of N/NC stem cells and tumor-initiating potential; were resistant to androgen signaling inhibition; and acquired an invasive phenotype in vitro and in vivo. When placed back into serum-containing mediums, reprogrammed cells could be re-differentiated to N-/NC-derived cell lineages or return back to an AR+ prostate-like state. Once returned, the AR+ cells were resistant to androgen signaling inhibition. Acute androgen deprivation or anti-androgen treatment in serum-containing medium led to the transient appearance of a sub-population of cells with similar characteristics. Finally, a 132 gene signature derived from reprogrammed PCa cell lines distinguished tumors from PCa patients with adverse outcomes. This model may explain neural manifestations of PCa associated with lethal disease. The metastable nature of the reprogrammed stem-like PCa cells suggests that cycles of PCa cell reprogramming followed by re-differentiation may support disease progression and therapeutic resistance. The ability of a gene signature from reprogrammed PCa cells to identify tumors from patients with metastasis or PCa-specific mortality implies that developmental reprogramming is linked to aggressive tumor behaviors.

A new model of multi-visceral and bone metastatic prostate cancer with perivascular niche targeting by a novel endothelial specific adenoviral vector

While modern therapies for metastatic prostate cancer (PCa) have improved survival they are associated with an increasingly prevalent entity, aggressive variant PCa (AVPCa), lacking androgen receptor (AR) expression, enriched for cancer stem cells (CSCs), and evidencing epithelial-mesenchymal plasticity with a varying extent of neuroendocrine transdifferentiation. Parallel work revealed that endothelial cells (ECs) create a perivascular CSC niche mediated by juxtacrine and membrane tethered signaling. There is increasing interest in pharmacological metastatic niche targeting, however, targeted access has been impossible. Here, we discovered that the Gleason 7 derived, androgen receptor negative, IGR-CaP1 cell line possessed some but not all of the molecular features of AVPCa. Intracardiac injection into NOD/SCID/IL2Rg -/- (NSG) mice produced a completely penetrant bone, liver, adrenal, and brain metastatic phenotype; noninvasively and histologically detectable at 2 weeks, and necessitating sacrifice 4-5 weeks post injection. Bone metastases were osteoblastic, and osteolytic. IGR-CaP1 cells expressed the neuroendocrine marker synaptophysin, near equivalent levels of vimentin and e-cadherin, all of the EMT transcription factors, and activation of NOTCH and WNT pathways. In parallel, we created a new triple-targeted adenoviral vector containing a fiber knob RGD peptide, a hexon mutation, and an EC specific ROBO4 promoter (Ad.RGD.H5/3.ROBO4). This vector was expressed in metastatic microvessels tightly juxtaposed to IGR-CaP1 cells in bone and visceral niches. Thus, the combination of IGR-CaP1 cells and NSG mice produces a completely penetrant metastatic PCa model emulating end-stage human disease. In addition, the metastatic niche access provided by our novel Ad vector could be therapeutically leveraged for future disease control or cure.

Pituitary tumor-transforming gene 1 regulates invasion of prostate cancer cells through MMP13

It is critical to understand the molecular mechanisms underlying the migration and invasiveness of prostate cancer (PC) for improving the outcome of therapy. A relationship of pituitary tumor-transforming gene 1 (Pttg1) and matrix metalloproteinase 13 (MMP13) in PC as well as their roles in the metastases of PC has not been studied. Here, we reported significantly higher levels of Pttg1 and MMP13 in the resected PC specimens, compared to the adjacent normal prostate tissue from the same patient. Interestingly, Pttg1 and MMP13 levels strongly correlated with each other. In vitro, Pttg1 activated MMP13, which determined PC cell invasiveness. However, Pttg1 levels were not significantly affected by MMP13. Furthermore, the Pttg1-activated MMP13 in PC cells was significantly suppressed by inhibition of PI3k/Akt, but not ERK/MAPK or JNK pathways. Together, our data suggest that Pttg1 may increase PC cell metastasis by MMP13, and highlight Pttg1/MMP13 axis as a promising therapeutic target for PC treatment.

VEGF-activated miR-144 regulates autophagic survival of prostate cancer cells against Cisplatin

Cisplatin is a commonly used chemotherapy drug for prostate cancer (PC). However, some PCs are resistant to cisplatin treatment, while the molecular mechanisms underlying the resistance of PCs to cisplatin are not completely understood. In this study, we found that cisplatin dose-dependently activated Beclin-1 in two PC cell lines, PC3 and LNCap. Autophagy suppression significantly increased the cisplatin-induced cell death of these PC cells in a CCK-8 assay. Moreover, microRNA (miR)-144 levels were significantly downregulated in cisplatin-treated PC cells, in a VEGF-dependent manner. Bioinformatics analysis showed that miR-144 targeted the 3'-UTR of Beclin-1 mRNA to inhibit its translation, which was confirmed by luciferase reporter assay. In PC patients after cisplatin treatment, low miR-144 levels appeared to predict poor outcome of patients' survival. Together, these data suggest that cisplatin may induce VEGF to suppress miR-144 levels in PC cells, which subsequently upregulates Beclin-1 to increase autophagic cell survival against cisplatin-induced cell death. Upregulation of miR-144 or suppression of cell autophagy may improve the outcome of cisplatin therapy in PC.

Molecular Markers and Targeted Therapeutics in Metastatic Tumors of the Spine: Changing the Treatment Paradigms

STUDY TYPE

A review of the literature.

OBJECTIVE

The aim of this study was to discuss the evolution of molecular signatures and the history and development of targeted therapeutics in metastatic tumor types affecting the spinal column.

SUMMARY OF BACKGROUND DATA

Molecular characterization of metastatic spine tumors is expected to usher in a revolution in diagnostic and treatment paradigms. Molecular characterization will provide critical information that can be used for initial diagnosis, prognosticating the ideal treatment strategy, assessment of treatment efficacy, surveillance and monitoring recurrence, and predicting complications, clinical outcome, and overall survival in patients diagnosed with metastatic cancers to the spinal column.

METHODS

A review of the literature was performed focusing on illustrative examples of the role that molecular-based therapeutics have played in clinical outcomes for patients diagnosed with metastatic tumor types affecting the spinal column.

RESULTS

The impact of molecular therapeutics including receptor tyrosine kinases and immune checkpoint inhibitors and the ability of molecular signatures to provide prognostic information are discussed in metastatic breast cancer, lung cancer, prostate cancer, melanoma, and renal cell cancer affecting the spinal column.

CONCLUSION

For the providers who will ultimately counsel patients diagnosed with metastases to the spinal column, molecular advancements will radically alter the management/surgical paradigms utilized. Ultimately, the translation of these molecular advancements into routine clinical care will greatly improve the quality and quantity of life for patients diagnosed with spinal malignancies and provide better overall outcomes and counseling for treating physicians.

LEVEL OF EVIDENCE

N/A.

c-Src, Insulin-Like Growth Factor I Receptor, G-Protein-Coupled Receptor Kinases and Focal Adhesion Kinase are Enriched Into Prostate Cancer Cell Exosomes

It is well known that Src tyrosine kinase, insulin-like growth factor 1 receptor (IGF-IR), and focal adhesion kinase (FAK) play important roles in prostate cancer (PrCa) development and progression. Src, which signals through FAK in response to integrin activation, has been implicated in many aspects of tumor biology, such as cell proliferation, metastasis, and angiogenesis. Furthermore, Src signaling is known to crosstalk with IGF-IR, which also promotes angiogenesis. In this study, we demonstrate that c-Src, IGF-IR, and FAK are packaged into exosomes (Exo), c-Src in particular being highly enriched in Exo from the androgen receptor (AR)-positive cell line C4-2B and AR-negative cell lines PC3 and DU145. Furthermore, we show that the active phosphorylated form of Src (Src^pY416 ) is co-expressed in Exo with phosphorylated FAK (FAK^pY861 ), a known target site of Src, which enhances proliferation and migration. We further demonstrate for the first time exosomal enrichment of G-protein-coupled receptor kinase (GRK) 5 and GRK6, both of which regulate Src and IGF-IR signaling and have been implicated in cancer. Finally, Src^pY416 and c-Src are both expressed in Exo isolated from the plasma of prostate tumor-bearing TRAMP mice, and those same mice have higher levels of exosomal c-Src than their wild-type counterparts. In summary, we provide new evidence that active signaling molecules relevant to PrCa are enriched in Exo, and this suggests that the Src signaling network may provide useful biomarkers detectable by liquid biopsy, and may contribute to PrCa progression via Exo. J. Cell. Biochem. 118: 66-73, 2017. © 2016 Wiley Periodicals, Inc.

Atg7 cooperates with Pten loss to drive prostate cancer tumor growth

To assess the importance of autophagy in prostate cancer, Santanam et al. generated a new autochthonous genetically engineered mouse model with inducible prostate-specific deficiency in the Pten tumor suppressor and autophagy-related-7 (Atg7) gene. Atg7 deficiency produced an autophagy-deficient phenotype and delayed Pten-deficient prostate tumor progression in both castrate-naïve and castrate-resistant cancers.

Understanding new therapeutic paradigms for both castrate-sensitive and more aggressive castrate-resistant prostate cancer is essential to improve clinical outcomes. As a critically important cellular process, autophagy promotes stress tolerance by recycling intracellular components to sustain metabolism important for tumor survival. To assess the importance of autophagy in prostate cancer, we generated a new autochthonous genetically engineered mouse model (GEMM) with inducible prostate-specific deficiency in the Pten tumor suppressor and autophagy-related-7 (Atg7) genes. Atg7 deficiency produced an autophagy-deficient phenotype and delayed Pten-deficient prostate tumor progression in both castrate-naïve and castrate-resistant cancers. Atg7-deficient tumors display evidence of endoplasmic reticulum (ER) stress, suggesting that autophagy may promote prostate tumorigenesis through management of protein homeostasis. Taken together, these data support the importance of autophagy for both castrate-naïve and castrate-resistant growth in a newly developed GEMM, suggesting a new paradigm and model to study approaches to inhibit autophagy in combination with known and new therapies for advanced prostate cancer.

Clinical research in metastatic prostate cancer: a focus on impact and value

KEY POINTS

Several therapies targeting the androgen receptor and other pathways have improved survival and quality of life for patients with metastatic prostate cancer.

Many costly therapeutic clinical trial efforts have failed to improve outcomes.

Prostate cancer is a complex disease. Its biologic heterogeneity warrants that future clinical trials be carefully designed to achieve higher levels of clinical impact by attention to targeting more critical pathways; integrating improved diagnostics; well-designed and powered clinical trials using multi-targeted strategies; and optimized timing of therapy.

A randomised non-comparative phase II trial of cixutumumab (IMC-A12) or ramucirumab (IMC-1121B) plus mitoxantrone and prednisone in men with metastatic docetaxel-pretreated castration-resistant prostate cancer

BACKGROUND

Cixutumumab, a human monoclonal antibody (HuMAb), targets the insulin-like growth factor receptor. Ramucirumab is a recombinant HuMAb that binds to vascular endothelial growth factor receptor-2. A non-comparative randomised phase II study evaluated cixutumumab or ramucirumab plus mitoxantrone and prednisone (MP) in metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

Men with progressive mCRPC during or after docetaxel therapy received mitoxantrone 12 mg/m(2) on day 1 and prednisone 5mg twice daily and were randomised 1:1 to receive either cixutumumab or ramucirumab 6 mg/kg intravenously weekly in a 21-day cycle. Primary end-point was composite progression-free survival (cPFS). Secondary end-points included safety, response, radiographic progression-free survival (PFS) and overall survival (OS). Sample size was based on a 50% increase in median cPFS from 2.6 (MP) to 3.9 months (either combination).

RESULTS

132 men were treated (66 per arm). Median cPFS was 4.1 months (95% confidence interval (CI), 2.2-5.6) for cixutumumab and 6.7 months (95% CI, 4.5-8.3) for ramucirumab. Median time to radiographic progression was 7.5 months for cixutumumab and 10.2 months for ramucirumab, with a median OS of 10.8 and 13.0 months, respectively. Fatigue was the most frequent adverse event (AE). Incidence of most non-haematologic grade 3-4 AEs was <10% on both arms. Grade 3 cardiac dysfunction occurred in 7.6% of patients on ramucirumab.

CONCLUSION

Combinations of cixutumumab or ramucirumab plus MP were feasible and associated with moderate toxicities in docetaxel-pretreated men with mCRPC. Of the two regimens, the ramucirumab regimen is worthy of further testing based on the observed cPFS relative to the historical control.

Radium-223 dichloride: a review of its use in patients with castration-resistant prostate cancer with symptomatic bone metastases

Radium-223 dichloride (Xofigo®; formerly Alpharadin™) [hereafter referred to as radium-223] is a first-in-class alpha particle-emitting radiopharmaceutical that has recently been approved for the treatment of patients with castration-resistant prostate cancer (CRPC) with symptomatic bone metastases and no known visceral metastatic disease. Radium-223 is a calcium mimetic, which targets bone, delivering cytotoxic radiation to the sites of bone metastases. In the recently reported Alpharadin™ in Symptomatic Prostate Cancer (ALSYMPCA) phase III study, radium-223 was associated with significantly improved overall survival compared with placebo, making it the first bone-targeted CRPC therapy for which an overall survival benefit has been demonstrated. The ALSYMPCA study also demonstrated the beneficial effects of radium-223 on disease-related symptomatic skeletal events, pain and health-related quality of life. Radium-223 was generally well tolerated, being associated with low rates of myelosuppression and generally mild gastrointestinal adverse events. Thus, radium-223 is a valuable addition to the treatment options for this poor-prognosis population.

Efficacy studies of an antibody-drug conjugate PSMA-ADC in patient-derived prostate cancer xenografts

BACKGROUND

It is timely and important to develop new treatment modalities for advanced prostate cancer, because even the newly FDA approved treatments, despite providing significant survival benefits, do not constitute cure of this disease. Antibody drug conjugates (ADCs) represent a promising approach to cancer therapy. Prostate-specific membrane antigen (PSMA) is expressed in advanced prostate cancer and targeting this protein is used for imaging of advanced prostate cancer as well as development of targeting strategies. The objective of our studies was to evaluate the efficacy of PSMA ADC against a series of patient-derived prostate cancer xenografts (LuCaP 58, LuCaP 77, LuCaP 96CR, and LuCaP 105) with different characteristics, including varying levels of PSMA expression and responses to androgen suppression.

METHODS

Mice bearing subcutaneous LuCaP prostate cancer-derived xenografts received PSMA antibody monomethyl auristatin E (MMAE) drug conjugate (PSMA ADC) in which the antibody and MMAE are linked via a protease-cleavable linker. PSMA ADC dose ranged from 1 to 6 mg/kg. Unmodified PSMA mAb + free MMAE at the amount equivalent to those contained in 6 mg/kg PSMA ADC was used as control. All treatments were administered once a week via tail-vein injections and repeated four times once a week and tumor responses were monitored for 10 weeks. IHC analyses were performed to determine PSMA and AR expression and effects on proliferation.

RESULTS

Treatment responses varied widely across the tumor models, from complete tumor regressions in LuCaP 96CR to largely unimpeded tumor progression of LuCaP 58, which had the lowest baseline level of PSMA expression. Intermediate antitumor effects were seen for LuCaP 77 and LuCaP 105 tumors, despite their having similar basal expression of PSMA as LuCaP 96CR. Interestingly, we detected substantial differences in responses even within the same model, indicating that PSMA expression is not the only factor involved in treatment outcomes.

CONCLUSIONS

Our results show high efficacy of PSMA ADC in advanced prostate cancer but also considerable variability in effects despite PSMA expression. Further studies to identify tumor characteristics that are predictive of treatment response are ongoing.

Adiponectin inhibits VEGF-A in prostate cancer cells

A role of adiponectin in tumorigenesis has recently been appreciated. Although plasma adiponectin levels in subjects with prostate cancer have been found to be significantly lower than in subjects with benign prostatic hyperplasia or in normal healthy controls, the underlying molecular mechanisms remain unknown. Here, we not only detected significant decreases in plasma adiponectin levels in prostate cancer patients, but also showed significant decreases in adiponectin receptor I (AdipoR1) levels in the resected prostate cancer specimen. Prostate cancer cell lines examined in the current study had all lower levels of adiponectin and AdipoR1, compared to normal healthy prostate tissue. Moreover, overexpression of adiponectin in prostate cancer cells decreased production of vascular endothelial growth factor A (VEGF-A), while adiponectin depletion increased VEGF-A. Furthermore, adiponectin seemed to activate AMPK/TSC2 to inhibit mTor-mediated activation of VEGF-A. Taken together, our data suggest that adiponectin may play an essential role in suppressing growth of prostate cancer cells through inhibition of VEGF-A-mediated cancer neovascularization.

Prognostic impact of synchronous second primary malignancies on the overall survival of patients with metastatic prostate cancer

PURPOSE

We determined the prognostic impact of a synchronous second primary malignancy on overall survival in patients with metastatic prostate cancer. Identifying features that stratify the risk of overall survival is critical for judiciously applying definitive therapy.

MATERIALS AND METHODS

We retrospectively analyzed the records of 582 consecutive patients with prostate cancer diagnosed with metastasis between May 7, 1998 and August 27, 2011. Patient age, body mass index, ECOG performance status, Charlson comorbidity index, prostate specific antigen, T and N stages, Gleason and ASA® scores, progression to castration resistant prostate cancer, prior local treatments and synchronous second primary malignancies at metastasis were assessed. A synchronous second primary malignancy was defined as a cytologically or histologically proven solid malignancy. Cox proportional hazards regression analysis was done to estimate overall survival by second primary type and evaluate predictive variables.

RESULTS

A total of 164 patients (28.1%) had a synchronous second primary malignancy, of which colorectal (9.1%), stomach (7.3%) and lung (7.1%) cancers were the most prevalent types. During a median followup of 34.1 months patients without a synchronous second primary malignancy had a significantly higher overall survival rate than those with lung or stomach cancer. However, men without a second malignancy had outcomes comparable to those in men with colorectal cancer. Clinical stage T4 or greater, ASA score 1 or greater and lung or stomach cancer were independent predictors of overall mortality.

CONCLUSIONS

A substantial proportion of patients with metastatic prostate cancer present with a synchronous second primary malignancy. Definitive therapy targeting prostate cancer may confer a limited survival benefit in patients with synchronous lung or stomach cancer.

Canine prostate cancer cell line (Probasco) produces osteoblastic metastases in vivo

BACKGROUND

In 2012, over 240,000 men were diagnosed with prostate cancer and over 28,000 died from the disease. Animal models of prostate cancer are vital to understanding its pathogenesis and developing therapeutics. Canine models in particular are useful due to their similarities to late-stage, castration-resistant human disease with osteoblastic bone metastases. This study established and characterized a novel canine prostate cancer cell line that will contribute to the understanding of prostate cancer pathogenesis.

METHODS

A novel cell line (Probasco) was derived from a mixed breed dog that had spontaneous prostate cancer. Cell proliferation and motility were analyzed in vitro. Tumor growth in vivo was studied by subcutaneous, intratibial, and intracardiac injection of Probasco cells into nude mice. Tumors were evaluated by bioluminescent imaging, Faxitron radiography, µCT, and histology. RT-PCR and genome-wide DNA copy number profiling were used to characterize the cell line.

RESULTS

The Probasco cells grew in vitro (over 75 passages) and were tumorigenic in nude mice. Probasco cells expressed high levels of BMP2, CDH1, MYOF, FOLH1, RUNX2, and SMAD5 modest CXCL12, SLUG, and BMP, and no PTHrP mRNA. Following intracardiac injection, Probasco cells metastasized primarily to the appendicular skeleton, and both intratibial and intracardiac injections produced osteoblastic tumors in bone. Comparative genomic hybridization demonstrated numerous DNA copy number aberrations throughout the genome, including large losses and gains in multiple chromosomes.

CONCLUSIONS

The Probasco prostate cancer cell line will be a valuable model to investigate the mechanisms of prostate cancer pathogenesis and osteoblastic bone metastases.

Evolution of androgen receptor targeted therapy for advanced prostate cancer

The discovery of androgen dependence in prostate cancer in 1941 by Huggins and colleagues has remained the backbone for the treatment of this disease. However, although many patients initially respond to androgen depletion therapy, they almost invariably relapse and develop resistance with transition of the disease to a castration-resistant state. Over the past decade, the better understanding of the mechanisms that drive resistance to castration has led to the development of next-generation androgen receptor targeting agents such as abiraterone acetate and enzalutamide. This Review aims to revisit the discovery and evolution of androgen receptor targeting therapeutics for the treatment of advanced-stage prostate cancer over the years and to discuss the upcoming future and challenges in the treatment of this common cancer.

Quality of Life and Sexual Health in the Aging of PCa Survivors

Prostate cancer (PCa) is the most common malignancy in elderly men. The progressive ageing of the world male population will further increase the need for tailored assessment and treatment of PCa patients. The determinant role of androgens and sexual hormones for PCa growth and progression has been established. However, several trials on androgens and PCa are recently focused on urinary continence, quality of life, and sexual function, suggesting a new point of view on the whole endocrinological aspect of PCa. During aging, metabolic syndrome, including diabetes, hypertension, dyslipidemia, and central obesity, can be associated with a chronic, low-grade inflammation of the prostate and with changes in the sex steroid pathways. These factors may affect both the carcinogenesis processes and treatment outcomes of PCa. Any treatment for PCa can have a long-lasting negative impact on quality of life and sexual health, which should be assessed by validated self-reported questionnaires. In particular, sexual health, urinary continence, and bowel function can be worsened after prostatectomy, radiotherapy, or hormone treatment, mostly in the elderly population. In the present review we summarized the current knowledge on the role of hormones, metabolic features, and primary treatments for PCa on the quality of life and sexual health of elderly Pca survivors.

Diffuse osteosclerosis in a patient with prostate cancer

A 61-year-old man was referred to our outpatient clinic because of severe bilateral upper leg pain for 1 year. On admission, the patient had anemia and a high serum alkaline phosphatase level. Lumbar and femoral neck T-scores were +10.5 and +9.6, respectively. His radius 33 % T-score was -2.8. Plain radiographs of the patient's pelvis, spine, and long bones revealed osteosclerosis. The patient had previously undergone a prostate biopsy, which showed prostate adenocarcinoma (Gleason score 3 + 4). The patient's total and free prostate-specific antigen were very high. According to previous records, the patient did not have anemia, and his serum alkaline phosphatase (ALP) level was normal. An abdominal radiograph taken 2 years earlier revealed a normal spine and pelvic bone. Bone scintigraphy yielded nontypical findings for prostate cancer metastasis. Computed tomography of the patient's thorax and abdomen showed heterogeneous sclerotic areas in all bones consistent with prostate cancer metastasis. A bone marrow biopsy disclosed disseminated carcinomatosis of bone marrow in association with prostate cancer. Clinicians should be aware of the possibility of prostate malignancy as a cause of high bone mineral density (BMD), even in the absence of typical localized findings on plain radiographs.

FOXM1 and androgen receptor co-regulate CDC6 gene transcription and DNA replication in prostate cancer cells

CDC6 is a key component of the DNA replication initiation machinery, and its transcription is regulated by E2F or androgen receptor (AR) alone or in combination in prostate cancer (PCa) cells. Through both overexpression and knockdown approaches, we found that in addition to its effects on the E2F pathway, the cell proliferation specific transcription factor FOXM1 stimulated CDC6 transcription in cooperation with AR. We have identified a forkhead box motif in the CDC6 proximal promoter that is occupied by FOXM1 and is sufficient to drive FOXM1-regulated transcription. Indirectly, FOXM1 elevated AR protein levels and AR dependent transcription. Furthermore, FOXM1 and AR proteins physically interact. Using synchronized cultures, we observed that CDC6 expression is elevated near S phase of the cell cycle, at a time coinciding with elevated FOXM1 and AR expression and CDC6 promoter occupancy by both AR and FOXM1 proteins. Androgen increased the binding of AR protein to CDC6 promoter, and AR and FOXM1 knockdown decreased AR binding. These results provided new evidence for the regulatory mechanism of aberrant CDC6 oncogene transcription by FOXM1 and AR, two highly expressed transcription factors in PCa cells. Functionally, the cooperation of FOXM1 and AR accelerated DNA synthesis and cell proliferation by affecting CDC6 gene expression. Furthermore, siomycin A, a proteasome inhibitor known to inhibit FOXM1 expression and activity, inhibited PCa cell proliferation and its effect was additive to that of bicalutamide, an antiandrogen commonly used to treat PCa patients.

The biology and natural history of prostate cancer: a short introduction

This chapter aims to serve as a quick glance outlining an overall picture of mainstream thoughts, and to serve as a point of departure for more thorough discussions. The introduction of PSA testing has immensely complicated research in prostate cancer epidemiology and biology and added new clinical and biological domains. As for many cancers, age and ethnic origin are the strongest known risk factors. While migrant studies imply that environment and/or personal life style is important, epidemiological studies have failed to establish any strong leads. Despite the known androgen dependence of prostate cancer, there is little to support that circulating levels of androgens, estrogens or 5-alpha-reductase are associated with risk of developing the disease. However, a consistent finding is a positive association with levels of Insulin-like Growth Factor-1 (IGF-1). Prostate cancer is one of the cancers most strongly related to inherited susceptibility, even when taking into account that family history of prostate cancer triggers PSA testing among relatives. A number of somatic genetic alterations (amplifications, deletions, point mutations, translocations) are associated with prostate cancer risk. Findings for alterations in FASN, HPN, AMACR and MYC have been fairly consistent. Recent research shows that the notion of "hormone-independent prostate cancer" has to be revised: most prostate cancers remain dependent on androgen receptor signalling also after progression despite traditional androgen deprivation therapy. Traditional markers of stage and type of disease still play a major role for prognostication and treatment decisions. Prostate cancer is one of the few cancers where patients have been recommended watchful waiting or active surveillance. This provides opportunities for studies of natural history of the disease. The understanding of prostate cancer aetiology and natural history has progressed slowly. However, the current situation is positively challenging and opens up possibilities for fruitful research.