Novel androgen axis systemic therapies for metastatic hormone-sensitive prostate cancer

[Acute spinal cord compression under systemic therapy - radiotherapy or surgery?]

Vertebral bodies are one of the most common metastasis sites found in advanced prostate cancer and have a significant impact on patients' quality of life. Spinal metastases frequently cause severe back pain and in some occasions can lead to secondary complications, with serious neurological deficits and loss of function. The main treatment goals include adequate pain management, controlling tumour growth and restoring spinal stability. Publications on the role of surgery - both conventional and stereotactic radiotherapy, and either as an individual modality or in combination - have been inconclusive. The NOMS score has proven to be useful in making treatment decisions. Existing data show better outcomes in patients with surgical therapy, both when performed in isolation and also combined with radiotherapy, in which some of the cohorts studied including patients with primary cancer other than prostate cancer. Comparative studies that specifically investigate the superiority of specific therapy modalities for metastatic prostate carcinoma are scarce. Similarly, there are limited data on microsurgical interventions for spinal metastases. Radiotherapy alone is crucial in the setting of palliation, especially for pain relief, and its effectiveness has been shown in many studies. The patient's life expectancy plays a crucial role in deciding the most appropriate treatment approach. Given the complexity of the patient population, a multimodal therapy approach is necessary. Current trends in therapy favour greater use of surgical interventions, particularly in the early detection of spinal metastases.

HER2 Mediates PSMA/mGluR1-Driven Resistance to the DS-7423 Dual PI3K/mTOR Inhibitor in PTEN Wild-type Prostate Cancer Models

Prostate cancer remains a major cause of male mortality. Genetic alteration of the PI3K/AKT/mTOR pathway is one of the key events in tumor development and progression in prostate cancer, with inactivation of the PTEN tumor suppressor being very common in this cancer type. Extensive evaluation has been performed on the therapeutic potential of PI3K/AKT/mTOR inhibitors and the resistance mechanisms arising in patients with PTEN-mutant background. However, in patients with a PTEN wild-type phenotype, PI3K/AKT/mTOR inhibitors have not demonstrated efficacy, and this remains an area of clinical unmet need. In this study, we have investigated the response of PTEN wild-type prostate cancer cell lines to the dual PI3K/mTOR inhibitor DS-7423 alone or in combination with HER2 inhibitors or mGluR1 inhibitors. Upon treatment with the dual PI3K/mTOR inhibitor DS-7423, PTEN wild-type prostate cancer CWR22/22RV1 cells upregulate expression of the proteins PSMA, mGluR1, and the tyrosine kinase receptor HER2, while PTEN-mutant LNCaP cells upregulate androgen receptor and HER3. PSMA, mGluR1, and HER2 exert control over one another in a positive feedback loop that allows cells to overcome treatment with DS-7423. Concomitant targeting of PI3K/mTOR with either HER2 or mGluR1 inhibitors results in decreased cell survival and tumor growth in xenograft studies. Our results suggest a novel therapeutic possibility for patients with PTEN wild-type PI3K/AKT-mutant prostate cancer based in the combination of PI3K/mTOR blockade with HER2 or mGluR1 inhibitors.

Metastatic Hormone-Sensitive Prostate Cancer (mHSPC): Advances and Treatment Strategies in the First-Line Setting

The treatment landscape of metastatic hormone-sensitive prostate cancer (mHSPC) has changed radically in recent years. Androgen deprivation therapy (ADT) alone was for decades the standard of care for treating mHSPC. This changed when studies showed that the addition of docetaxel chemotherapy or abiraterone acetate to ADT significantly increases overall survival of patients with mHSPC, followed by more recent evidence showing the efficacy of androgen receptor antagonists, such as enzalutamide and apalutamide, in this setting. While this rapid therapeutic evolution is welcome, it presents clinicians with a crucial challenge: the choice of treatment selection and sequencing. In the first-line setting there are no comparative data currently available to guide treatment choice between the different available regimens, and no prospective data to guide clinical decision after progression. Decisions on treatment will now need to be personalised based on indirect comparison of the available efficacy data from multiple phase 3 studies, together with considerations of disease volume, comorbidities, treatment aims, toxicity profile and cost reimbursement within the healthcare setting. Here, we provide an overview of the clinical trial data to date and propose some biological and clinical insights which may be helpful in making decisions on treatment selection and sequencing.

Cancer stem cell and mesenchymal cell cooperative actions in metastasis progression and hormone resistance in prostate cancer: Potential role of androgen and gonadotropin‑releasing hormone receptors (Review)

Prostate cancer (PCa) is the leading cause of male cancer‑associated mortality worldwide. Mortality is associated with metastasis and hormone resistance. Cellular, genetic and molecular mechanisms underlying metastatic progression and hormone resistance are poorly understood. Studies have investigated the local effects of gonadotropin‑releasing hormone (GnRH) analogs (used for androgen deprivation treatments) and the presence of the GnRH receptor (GnRH‑R) on PCa cells. Furthermore, cell subpopulations with stem‑like properties, or cancer stem cells, have been isolated and characterized using a cell culture system derived from explants of human prostate tumors. In addition, the development of preclinical orthotopic models of human PCa in a nonobese diabetic/severe combined immunodeficiency mouse model of compromised immunity has enabled the establishment of a reproducible system of metastatic progression in vivo. There is increasing evidence that metastasis is a complex process involving the cooperative actions of different cancer cell subpopulations, in which cancer stem‑like cells would be responsible for the final step of colonizing premetastatic niches. It has been hypothesized that PCa cells with stemness and mesenchymal signatures act cooperatively in metastatic progression and the inhibition of stemness genes, and that overexpression of androgen receptor (AR) and GnRH‑R decreases the rate the metastasis and sensitizes tumors to hormone therapy. The aim of the present review is to analyze the evidence regarding this cooperative process and the possible influence of stem‑like cell phenotypes, AR and GnRH‑R in metastatic progression and hormone resistance. These aspects may represent an important contribution in the understanding of the mechanisms underlying metastasis and hormone resistance in PCa, and potential routes to blocking these processes, enabling the development of novel therapies that would be particularly relevant for patients with metastatic and castration‑resistant PCa.

Metastatic Castration-Sensitive Prostate Cancer: Optimizing Patient Selection and Treatment

The treatment landscape for metastatic castration-sensitive prostate cancer (mCSPC) has rapidly evolved over the past 5 years. Although androgen-deprivation therapy (ADT) is still the backbone of treatment, the addition of docetaxel or abiraterone acetate has improved outcomes for patients with mCSPC and become standard of care. With multiple treatment options available for patients with mCSPC, treatment selection to optimize patient outcomes has become increasingly difficult. Here, we review the clinical trials involving ADT plus docetaxel or abiraterone and provide clinicians with guidelines for treatment. Although surgery and/or radiation are standard of care for localized, intermediate- and high-risk prostate cancer, these treatments are not routinely used as part of initial treatment plans for patients with de novo mCSPC. Recent clinical data are challenging that dogma, and we review the literature on the addition of surgery and radiation to systemic therapy for mCSPC. Finally, the standard of care for oligometastatic prostate cancer (a subset of mCSPC with limited metastases) has not been established compared with that for some other cancers. We discuss the recent studies on metastasis-directed therapy for treatment of oligometastatic prostate cancer.

Germline Variant in HSD3B1 (1245 A > C) and Response to Abiraterone Acetate Plus Prednisone in Men With New-Onset Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

The HSD3B1 gene encodes the enzyme 3β-hydroxysteroid dehydrogenase-1 (3βHSD1), which catalyzes adrenal androgen precursors into dihydrotestosterone, the most potent androgen. Recently, the HSD3B1 (1245C) variant was shown to predict shorter duration of response to androgen deprivation therapy with medical or surgical castration in the setting of castration-sensitive prostate cancer (CSPC). The HSD3B1 (1245C) variant also predicts longer duration of response to ketoconazole in men with castration-resistant prostate cancer (CRPC). We hypothesized that the HSD3B1 (1245C) variant predicts response to treatment with abiraterone acetate (AA) and can help personalize treatment in men with advanced prostate cancer.

METHODS

Clinical data and samples were from a prospectively maintained prostate cancer registry at the University of Utah. Genotyping was performed. The primary study end point was progression-free survival in first-line AA in men with metastatic CRPC. We performed prespecified multivariate analyses to assess the independent predictive value of HSD3B1 genotype on progression-free survival on AA.

RESULTS

Seventy-six men with metastatic CRPC treated with first-line AA were included. In multivariate analysis, the HSD3B1 (1245C) variant did not predict response to first-line AA.

CONCLUSION

The HSD3B1 (1245C) variant does not predict response to first-line AA in metastatic CRPC. This finding could be due to the ability of AA metabolites to act as both agonist (3-keto-5α-abiraterone) and antagonist (Δ4-abiraterone) on androgen signaling.

Recent advances in the management of metastatic prostate cancer: optimizing use of existing therapies, while searching for novel interventions

PURPOSE OF REVIEW

Summarizes recent advances in the treatment of metastatic castration-sensitive and castration-resistant prostate cancer.

RECENT FINDINGS

New randomized data suggest a survival advantage to early abiraterone in castration-sensitive metastatic prostate cancer. Prospective and retrospective studies are examining sequencing of existing cytotoxic and androgen-receptor-targeted therapies in both castration-sensitive and castration-resistant disease. Genomic analysis of both circulating tumor cells and circulating tumor nucleic acids is being examined as a potential method for selecting existing therapies and identifying novel therapeutic targets. Finally, immunotherapy combinations are being evaluated in the setting of advanced prostate cancer.

SUMMARY

In this review, we hope to summarize the recent data supporting the use of early abiraterone in castration-sensitive metastatic prostate cancer and discuss how this data might be incorporated with previous trials showing a survival advantage to early docetaxel. We present recent series examining sequencing of approved therapies as well as trials evaluating novel biomarkers and genomic analyses designed to help choose from among approved therapies or evaluate drugs in development. Lastly, we review ongoing trials examining novel immunotherapy combinations in advanced prostate cancer.