Improving Treatment for Advanced Prostate Cancer

Systematic review of the efficacy of stereotactic ablative radiotherapy for oligoprogressive disease in metastatic cancer

BACKGROUND

Stereotactic Ablative Radiotherapy (SABR) for the treatment of oligometastatic disease can improve survival and delay the requirement for systemic therapy. The benefits of SABR in oligoprogressive disease are less well-defined. Here, we evaluate the available evidence investigating the efficacy of SABR in the treatment of oligoprogressive disease.

METHODS

A systematic review was carried out following PRISMA guidelines. Medline and Embase databases were searched using the terms "stereotactic radiotherapy" OR "SABR" OR "Stereotactic Ablative Body Radiotherapy" OR "SBRT" OR "SRT" AND "oligoprogression" in May 2022, June 2023, and February 2024. Studies were excluded where: SABR was used as a radical treatment, a specific oligoprogressive cohort could not be identified, publication was as a conference abstract or where fewer than 10 patients were recruited. Studies treating only brain metastases were also excluded. The site of primary tumour, oligoprogressive sites, rates of overall survival (OS), progression free survival (PFS), local control (LC) and time to next systemic therapy were collected.

RESULTS

Thirty-three full text studies were included. These consisted of single centre and multi-institutional observational studies, case series and phase II trials. Twenty-two studies were related to a specific tumour type: 12 urological cancer (9 prostate, 3 renal cancer), 6 non-small cell lung cancer, 2 colorectal cancer, 2 breast cancer and 11 were studies covering multiple tumour sites (5 studies involving SABR to a single organ and 6 studies involving SABR to multi-organ). Median PFS was >6 months in patients with oligoprogressive prostate, non-small cell lung cancer and renal cancer patients.

CONCLUSIONS

SABR appears to have clinical benefit in oligoprogresssive prostate, lung, and renal patients. However, the optimal management of patients with oligoprogressive disease is still somewhat uncertain due to lack of prospective data. This will hopefully become clearer in the near future with the publication of further randomised trials.

The Plant Derived 3-3'-Diindolylmethane (DIM) Behaves as CB2 Receptor Agonist in Prostate Cancer Cellular Models

3-3'-Diindolylmethane (DIM) is a biologically active dimer derived from the endogenous conversion of indole-3-carbinol (I3C), a naturally occurring glucosinolate found in many cruciferous vegetables (i.e., Brassicaceae). DIM was the first pure androgen receptor antagonist isolated from the Brassicaceae family and has been recently investigated for its potential pharmacological use in prostate cancer prevention and treatment. Interestingly, there is evidence that DIM can also interact with cannabinoid receptors. In this context, by considering the well-known involvement of the endocannabinoid system in prostate cancer, we have pharmacologically characterized the properties of DIM on both CB₁ and CB₂ cannabinoid receptors in two human prostate cancer cell lines: PC3 (androgen-independent/androgen receptor negative) and LNCaP (androgen-dependent). In the PC3 cell line, DIM was able to activate CB₂ receptors and potentially associated apoptotic pathways. On the other hand, although DIM was also able to activate CB₂ receptors in the LNCaP cell line, no apoptotic effects were observed. Our evidence confirms that DIM is a CB₂ receptor ligand and, moreover, it has a potential anti-proliferative effect on androgen-independent/androgen receptor-negative prostate cancer cells.

Health Disparities in Prostate Cancer and Approaches to Advance Equitable Care

The American Cancer Society estimates approximately 268,490 new cases of prostate cancer and approximately 34,500 deaths caused by prostate cancer in the United States for 2022. Globally, a total of 1,414,259 new cases of prostate cancer and 375,304 related deaths were reported in 2020. Well-documented health disparities and inequities exist along the continuum of care for prostate cancer management-from screening to diagnostic and staging work-up, surveillance, and treatment-ultimately impacting clinical outcomes. This session-based article discusses innovative patient-centered approaches to advance equitable prostate cancer care. It begins with a review of domestic health disparities in diagnostic imaging and radiotherapy for prostate cancer, and it summarizes barriers and solutions to achieving health equity, such as equity metrics and practice quality improvement projects. Next, a global perspective is provided that describes approaches to address financial and geographic barriers to prostate cancer care, including specific examples of strategies that emphasize the use of the cheapest method of care delivery while maintaining outcomes for drug delivery and radiotherapy.

Metronomic Chemotherapy for Advanced Prostate Cancer: A Literature Review

Metastatic castration-resistant prostate cancer (mCRPC) is the ultimately lethal form of prostate cancer. Docetaxel chemotherapy was the first life-prolonging treatment for mCRPC; however, the standard maximally tolerated dose (MTD) docetaxel regimen is often not considered for patients with mCRPC who are older and/or frail due to its toxicity. Low-dose metronomic chemotherapy (LDMC) is the frequent administration of typically oral and off-patent chemotherapeutics at low doses, which is associated with a superior safety profile and higher tolerability than MTD chemotherapy. We conducted a systematic literature review using the PUBMED, EMBASE, and MEDLINE electronic databases to identify clinical studies that examined the impact of LDMC on patients with advanced prostate cancer. The search identified 30 reports that retrospectively or prospectively investigated LDMC, 29 of which focused on mCRPC. Cyclophosphamide was the most commonly used agent integrated into 27/30 (90%) of LDMC regimens. LDMC resulted in a clinical benefit rate of 56.8 ± 24.5% across all studies. Overall, there were only a few non-hematological grade 3 or 4 adverse events reported. As such, LDMC is a well-tolerated treatment option for patients with mCRPC, including those who are older and frail. Furthermore, LDMC is considered more affordable than conventional mCRPC therapies. However, prospective phase III trials are needed to further characterize the efficacy and safety of LDMC in mCRPC before its use in practice.

Inhibition of Janus Kinase 1 synergizes docetaxel sensitivity in prostate cancer cells

Prostate cancer (PCa) is the second most common malignancy and is the fifth leading cause of cancer mortality among men globally. Docetaxel-based therapy remains the first-line treatment for metastatic castration-resistant prostate cancer. However, dose-limiting toxicity including neutropenia, myelosuppression and neurotoxicity is the major reason for docetaxel dose reductions and fewer cycles administered, despite a recent study showing a clear survival benefit with increased total number of docetaxel cycles in PCa patients. Although previous studies have attempted to improve the efficacy and reduce docetaxel toxicity through drug combination, no drug has yet demonstrated improved overall survival in clinical trial, highlighting the challenges of improving the activity of docetaxel monotherapy in PCa. Herein, we identified 15 lethality hits for which inhibition could enhance docetaxel sensitivity in PCa cells via a high-throughput kinome-wide loss-of-function screen. Further drug-gene interactions analyses identified Janus kinase 1 (JAK1) as a viable druggable target with existing experimental inhibitors and FDA-approved drugs. We demonstrated that depletion of endogenous JAK1 enhanced docetaxel-induced apoptosis in PCa cells. Furthermore, inhibition of JAK1/2 by baricitinib and ruxolitinib synergizes docetaxel sensitivity in both androgen receptor (AR)-negative DU145 and PC3 cells, but not in the AR-positive LNCaP cells. In contrast, no synergistic effects were observed in cells treated with JAK2-specific inhibitor, fedratinib, suggesting that the synergistic effects are mainly mediated through JAK1 inhibition. In conclusion, the combination therapy with JAK1 inhibitors and docetaxel could be a useful therapeutic strategy in the treatment of prostate cancers.

Clinicopathological and prognostic significance of osteopontin expression in patients with prostate cancer: a systematic review and meta-analysis

Background: Evaluation of the feasibility for osteopontin (OPN) to serve as a biomarker in the prognosis and clinical-pathological features of prostate cancer (PCA) patients.

Methods: The original publications related to OPN and PCA were comprehensively searched in the online databases, including PubMed, Embase, Cochrane Library, Web of Science, Medline, Wanfang and China National Knowledge Infrastructure up to August 2019. Results were analyzed by Revman 5.3 and Stata 12.0.

Results: A total of 21 studies were included in the analysis and the result showed that the positive OPN expression group had a lower overall survival than the negative expression group (univariate: hazards ratio (HR) = 2.32, 95% confidence interval (95% CI) [1.74, 3.10], multivariate: HR = 2.41, 95% CI [1.63, 3.57]) and a lower biochemical relapse-free survival than the negative group (univariate: HR = 1.42, 95% CI [0.92, 2.17], multivariate: HR = 1.61, 95% CI [1.39, 1.87]). In addition, there was a higher expression level of OPN in PCA tissues than in normal prostate tissues (OR = 46.55, 95% CI [12.85, 168.59], P<0.00001) and benign prostatic hyperplasia (BPH) tissues (OR = 11.07, 95% CI [3.43, 35.75], P<0.0001). Moreover, OPN positive expression was also related to high Gleason score (OR = 2.64, 95% CI [1.49, 4.70], P=0.0009), high TNM stage (OR = 3.15, 95% CI [1.60, 6.20, P=0.0009), high Whitmore–Jewett stage (OR = 2.53, 95% CI [1.06, 6.03], P=0.04), high lymph node (OR = 3.69, 95% CI [1.88, 7.23], P=0.0001), and distant metastasis (OR = 8.10, 95% CI [2.94, 22.35], P=0.01). There was no difference observed in the differentiation of PCA (OR = 1.79, 95% CI [0.39, 8.33], P=0.46).

Conclusion: OPN could be recognized as a promising diagnostic and prognostic biomarker for PCA patients.

Development of human prostate cancer stem cells involves epigenomic alteration and PI3K/AKT pathway activation

Background

Human prostate cancer spheres endowed with stem cell properties have been obtained from androgen-dependent cell line LNCaP after exposure to an epigenomic modulator phenethyl isothiocynate (PEITC). Sphere cells can self-renew and grow with androgen, and also without androgen. Little is known about the signaling pathway and mechanism in the development of the stem cells in the spheres.

Methods

Expression of phosphoinositol-3 kinase (PI3K) pathway members and histone acetylation were quantified in the tumor spheres and LNCaP cells by western immunoblotting.

Results

The level of phosphorylated AKT was significantly increased in the sphere stem cells than the LNCaP cells at an average of 7.4 folds (range 5.8–10.7 folds), whereas the P27 level was elevated 5.4 folds (range 4.8–6.3 folds) (P < 0.05). The acetylation level on histone H3 lysine 9 was decreased.

Conclusions

PEITC appears to regulate the epigenome through histone acetylation and activate the PI3K/AKT pathway in the LNCaP cells. This mechanism may be responsible in part for the development of the prostate cancer stem cells.