Taxane chemotherapy vs antiandrogen agents as first-line therapy for metastatic castration-resistant prostate cancer

Novel hormonal therapy versus standard of care-A registry-based comparative effectiveness evaluation for mCRPC-patients

BACKGROUND

This paper presents results from one of the few comparative effectiveness evaluations of novel antiandrogen medications (NHT) against standard of care (SoC) for patients suffering from metastatic castrate-resistant prostate cancer (mCRPC).

METHODS

The design and the analysis are published in a protocol before accessing outcome data. Two groups of patients are balanced on hundreds of important covariates measured before the prostate cancer diagnosis and up to the date of the prescription. While the design yields balance on the observed covariates, one cannot discard the possibility that unobserved confounders are not balanced. The unconfoundedness assumption is assessed by estimating placebo regressions on two health measures, not included in the design but added together with the outcome data after protocol publication.

RESULTS

We find a substantial (64 percent) increase in mortality for patients prescribed with NHT rather than SoC. However, based on the results from one of the two placebo regressions, we cannot rule out that the difference in mortality may be due to confounding. Using a bounding strategy of the effect, we can, however, rule out that NHT reduces mortality compared to SoC. Under an empirical valid assumption that most mCRPC patients who die suffer from bone metastases, we have a strong indication of increased skeleton-related events in patients if prescribed NHT against SoC.

CONCLUSIONS

Generally, the SoC for this group of patients is docetaxel. Given the substantially higher costs of many of the NHT, the finding of no positive effects from NHT on both mortality and SRE is important. More comparative studies, including studies analysing quality of life outcomes, are thus needed.

Diethyldithiocarbamate copper nanoparticle overcomes resistance in cancer therapy without inhibiting P-glycoprotein

Copper diethyldithiocarbamate [Cu(DDC)₂] is a promising anticancer agent. However, its poor water solubility is a significant obstacle to clinical application. In previous studies, we developed a stabilized metal ion ligand complex (SMILE) method to prepare Cu(DDC)₂ nanoparticle (NP) to address the drug delivery challenge. In the current study, we investigate the use of Cu(DDC)₂ NP for treating P-glycoprotein (P-gp) mediated drug-resistant cancers. We tested its anticancer efficacy with extensive in vitro cell-based assays and in vivo xenograft tumor model. We also explored the mechanism of overcoming drug resistance by Cu(DDC)₂ NP. Our results indicate that Cu(DDC)₂ NP is not a substrate of P-gp and thus can avoid P-gp mediated drug efflux. Further, the Cu(DDC)₂ NP does not inhibit the activity or the expression of P-gp.

Predictive factors of survival outcomes in first-line therapy for metastatic castration-resistant prostate cancer

OBJECTIVES

To investigate predictive factors of survival of metastatic castration-resistant prostate cancer patients undergoing first-line treatment with androgen receptor pathway inhibitors or docetaxel.

METHODS

Japanese patients with metastatic castration-resistant prostate cancer treated with androgen receptor pathway inhibitor or docetaxel between 2008 and 2018 were included. The differential impact of various clinicopathological factors on the outcome, including progression-free survival and overall survival, was compared between treatment with androgen receptor pathway inhibitor and docetaxel.

RESULTS

Of 254 patients with metastatic castration-resistant prostate cancer, 119 (46.9%) and 135 (53.2%) were treated with androgen receptor pathway inhibitor and docetaxel, respectively. The multivariate analysis showed that androgen receptor pathway inhibitor was an independent prognostic factor for better progression-free survival (hazard ratio 0.62, 95% confidence interval 0.42-0.92, P = 0.016) and overall survival (hazard ratio 0.61, 95% confidence interval 0.41-0.93, P = 0.021), compared with docetaxel. Pretreatment prostate-specific antigen levels and time to castration-resistant prostate cancer were differentially associated with progression-free survival and overall survival between androgen receptor pathway inhibitor or docetaxel. In patients who presented <6 months to castration-resistant prostate cancer, progression-free survival was shorter in those treated with androgen receptor pathway inhibitor (median 1.1 months, 95% confidence interval 0.2-2.8 months) compared with those who received docetaxel (median 5.0 months, 95% confidence interval 1.8-6.7 months; P = 0.014).

CONCLUSIONS

First-line therapy with androgen receptor pathway inhibitor is associated with a better prognosis when compared with docetaxel, even after adjustment for prognostic factors. However, a shorter time to castration-resistant prostate cancer is associated with better progression-free survival for patients receiving docetaxel, suggesting that docetaxel is the preferred option for patients with a shorter time to castration-resistant prostate cancer.

Prognostic significance of risk stratification in CHAARTED and LATITUDE studies among Japanese men with castration-resistant prostate cancer

Background

The CHAARTED and LATITUDE trials demonstrated a survival benefit of docetaxel and abiraterone for hormone-sensitive prostate cancer. In this study, we examined the impact of the risk stratification criteria used in the CHAARTED and LATITUDE trials on the prognosis of castration-resistant prostate cancer (CRPC). We also tested whether these risk stratification criteria could help in selecting effective initial treatment for CRPC.

Method

Japanese patients with CRPC who were treated with docetaxel or androgen receptor pathway inhibitors such as abiraterone acetate or enzalutamide between 2014 and 2018 were included in this study. Clinicopathological factors, progression-free survival, and overall survival were investigated.

Results

Of 215 patients, 110 men (51.2%) and 93 men (43.3%) were grouped as high volume by CHAARTED criteria and high risk by LATITUDE criteria, respectively. Median progression-free survival was 10.3/4.5 months (P < 0.0001) for low/high volume (CHAARTED criteria) and 9.9/4.8 months (P = 0.0032) for low/high risk (LATITUDE criteria). The median overall survival was 44.8/17.4 months (P < 0.0001) for low/high volume (CHAARTED criteria) and 37.4/17.4 months (P = 0.0011) for low/high risk (LATITUDE criteria). The prognostic impact of CHAARTED and LATITUDE criteria was comparable between androgen receptor pathway inhibitors and docetaxel as first-line treatment for CRPC.

Conclusion

The CHAARTED and LATITUDE criteria were prognostic, but not useful to discriminate the therapeutic outcome between androgen receptor pathway inhibitors and docetaxel for CRPC.

Exosomes and prostate cancer management

Exosomes (and other extracellular vesicles) are now part of the cancer research landscape, involved both as players in pathophysiological mechanisms, as biomarkers of the cancer process and as therapeutic tools. One step they have yet to take is to move into routine clinical practice and management of prostate cancer is an example of this necessary maturation. More than for many other cancers and because a possible alternative is active surveillance (neither removal nor destruction), the diagnosis of prostate cancer does not only involve the detection of cancerous cells but also the determination of its true aggressiveness. By measuring TRMPRSS2:ERG fusion and PCA3 transcripts in urine exosomes, the EPI assay seems able to help prostate biopsy decision. Results from clinical studies showed that it can reduce the proportion of unnecessary biopsies while missing only a minimal proportion of clinically significant cancers. In metastatic prostate cancer, after failure of a first step androgen deprivation therapy, when a choice has to be made between a second-generation androgen receptor (AR) signaling inhibitor and taxane-based chemotherapy, detection of the AR splicing variant AR-V7 in circulating tumor cells (CTCs) has appeared promising. Whether exosomes could be a better material (simpler to isolate from the bloodstream than CTCs?) to detect AR-V7 has been suggested by some studies and remains to be confirmed. At last, a couple of exploratory studies either targeted or used exosomes to treat prostate cancer, by respectively inhibiting their secretion (to prevent exosome-mediated transfer of biologically active oncogenic actors), or loading them with immunogenic cancer-specific proteins (to generate anticancer vaccine) or with pharmacologic agents. Overall efforts are however still needed to confirm these results and generalize exosome-based diagnostic, prognostic or therapeutic strategies in prostate cancer management.

Real-World Treatment Patterns and Overall Survival of Patients with Metastatic Castration-Resistant Prostate Cancer in the US Prior to PARP Inhibitors

Introduction

Therapeutic options for metastatic castration-resistant prostate cancer (mCRPC) patients are continuously advancing. We described mCRPC treatment patterns in the US from 2013 to 2019.

Methods

Patients with a confirmed mCRPC diagnosis and adenocarcinoma histology were included in the US Flatiron Health Electronic Health Record-derived de-identified database. Treatment patterns [including treatment per lines of therapies (LOTs), LOT sequences, and time on treatment] and overall survival (OS) have been described in mCRPC settings.

Results

Of 5213 patients (mean age: 72.6 years), 4374 (83.9%) were treated with ≥ 1 LOT post-mCRPC diagnosis (among those with ≥ 1 LOT, 55.3%, 29.5%, 14.7%, and 6.7% had ≥ 2, 3, 4, and 5 LOTs, respectively). In first line (1L), the main treatment class was next-generation hormonal agents (NHA; 62.5% of patients with ≥ 1 LOT), while the shortest and longest time on 1L were observed for chemotherapy (median 2.8 months) and NHA (median 5.1 months), respectively. The most common LOT sequences were NHA → NHA (29.4% of patients with ≥ 2 LOTs) and NHA → NHA → chemotherapy (16.7% of patients with ≥ 3 LOTs). In Kaplan–Meier analyses, the median OS was 19.4, 14.6, and 11.1 months post-1L, 2L, and 3L start, respectively. Patients who moved rapidly through LOTs had an increased risk of death.

Conclusions

NHA were widely used as 1L therapy in mCRPC patients from 2013 to 2019, but time on 1L NHA treatment was on average < 6 months. While NHA → NHA was the most observed 1L → 2L LOT sequence, a plethora of other LOT sequences were observed. OS was poor, highlighting an unmet need for life-prolonging treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01823-6.

Identification of patients with metastatic castration-sensitive or metastatic castration-resistant prostate cancer using administrative health claims and laboratory data

OBJECTIVE

To develop algorithms to identify metastatic castration-sensitive prostate cancer (mCSPC) patients and castration-resistant prostate cancer (mCRPC) patients, using health claims data and laboratory test results.

METHODS

A targeted literature review summarized mCSPC and mCRPC patient selection criteria previously used in real-world retrospective studies. Novel algorithms to identify mCSPC and mCRPC were developed based on diagnosis codes indicating hormone sensitivity/resistance, prostate-specific antigen (PSA) test results, and claims for castration and mCRPC-specific treatments. These algorithms were applied to claims data from Optum Clinformatics Extended DataMart (Date of Death) Databases (commercial insurance/Medicare Advantage [COM/MA]; 01 January 2014-31 July 2019) and Medicare Fee-for-Service (Medicare-FFS; 01 January 2014-31 December 2017).

RESULTS

Previous real-world studies identified mCSPC primarily based on metastasis diagnosis codes, and mCRPC based on mCRPC-specific drugs. Using the current study's algorithms, 7034 COM/MA and 19,981 Medicare-FFS patients were identified as having mCSPC, and 2578 COM/MA and 11,554 Medicare-FFS as having mCRPC. Most mCSPC patients were identified based on evidence of being hormone/castration-naive. Patients were identified as having mCRPC most commonly based on rising PSA (COM/MA), or at the metastasis diagnosis date if it occurred after castration (Medicare-FFS). Among patients with mCSPC, 14-17% had evidence of progression to castration resistance during a median 1-year follow-up period, mostly based on use of mCRPC-specific drugs.

CONCLUSIONS

Comprehensive algorithms based on claims and laboratory data were developed to identify and distinguish patients with mCSPC and mCRPC. This will facilitate appropriate identification of mCSPC and mCRPC patients based on health claims data and better understanding of patient unmet needs in real-world settings.

Overall Survival Among Chemotherapy-Naive Patients With Castration-Resistant Prostate Cancer Under Abiraterone Versus Enzalutamide: A Direct Comparison Based on a 2014-2018 French Population Study (the SPEAR Cohort)

Abiraterone acetate (ABI) and enzalutamide (ENZ) are considered to be clinically relevant comparators among chemotherapy-naive patients with castration-resistant prostate cancer. No clinical trials comparing overall survival with ABI versus ENZ in a head-to-head approach have been published so far. A few observational studies with low power suggested a potential benefit of ENZ. We used the French National Health Data System to compare overall survival of new users of ABI and ENZ among chemotherapy-naive patients with castration-resistant prostate cancer in 2014-2017, followed through 2018 (the SPEAR cohort, a 2014-2018 cohort study). With an intent-to-treat approach, a survival analysis was performed, estimating hazard ratios for overall survival with the inverse probability weighted Cox model method. Among 10,308 new users, 64% were treated with ABI and 36% with ENZ. The crude mortality rate was 25.2 per 100 person-years (95% confidence interval (CI): 24.4, 26.0) for ABI and 23.7 per 100 person-years (95% CI: 22.6, 24.9) for ENZ. In the weighted analysis, ENZ was associated with better overall survival compared with ABI (hazard ratio = 0.90 (95% CI: 0.85, 0.96) with a median overall survival of 31.7 months for ABI and 34.2 months for ENZ). When restricting to 2015-2017 new users, the effect estimate shifted up to a hazard ratio of 0.93 (95% CI: 0.86, 1.01).

Risk stratification for the prediction of overall survival could assist treatment decision-making at diagnosis of castration-resistant prostate cancer: a multicentre collaborative study in Japan

OBJECTIVES

To assess whether a new risk stratification system according to predictors for overall survival (OS) at the diagnosis of metastatic castration-resistant prostate cancer (mCRPC) could determine treatment outcomes and assist in treatment decision-making.

PATIENTS AND METHODS

Two independent clinical cohorts of patients, treated with androgen signalling inhibitors (ASIs: abiraterone and enzalutamide) or docetaxel as a first-line treatment for mCRPC, were used in this study: a derivation cohort (196 patients with mCRPC) and an external validation cohort (211 patients with mCRPC).

RESULTS

Three independent predictors for OS, including duration of initial androgen deprivation therapy <12 months before mCRPC diagnosis, alkaline phosphatase level >350 U/dL and haemoglobin level <11 g/dL at the diagnosis of mCRPC, were defined as risk factors. Patients with zero, one and multiple risk factors were assigned to a favourable-, intermediate- and poor-risk group, respectively. The median OS values in each risk group were well separated in the derivation cohort (P < 0.001) as well as in the validation cohort (P < 0.001). Of a total of 407 patients with mCRPC, 84 were assigned to the poor-risk group with the median OS of 12 months. In this group, a trend towards longer OS favouring docetaxel compared to ASIs as the first-line treatment (medians of 17 and 12 months, respectively) was observed.

CONCLUSION

The new risk group stratification system could predict patient survival at the diagnosis of mCRPC. Given the convenience of these risk definitions, physicians may be encouraged to consider these risk groups in daily practice.

Association of Body Composition With Survival and Treatment Efficacy in Castration-Resistant Prostate Cancer

Objectives: The association of body composition with survival and the efficacy of first-line treatment was investigated in patients with castration-resistant prostate cancer (CRPC).

Methods: The records of CRPC patients treated with docetaxel or androgen receptor signaling inhibitors (ARSi) between 2005 and 2018 were reviewed. Skeletal muscle index (SMI), visceral fat index, and subcutaneous fat index were evaluated using pretreatment computed tomography images.

Results: Of 230 eligible patients, 144 received docetaxel, and 86 received ARSi as the first-line treatment for CRPC. The SMI^hi (based on median values) group had higher prostate-specific antigen (PSA) progression-free survival (median 13.5 vs. 8.3 months, p = 0.030), radiologic progression-free survival (14.9 vs. 9.1 months, p < 0.001), and overall survival (24.1 vs. 16.9 months, p = 0.015) than the SMI^lo group. In docetaxel-treated patients, the SMI^hi group had higher PSA progression-free survival (13.5 vs. 5.9 months, p = 0.016) and radiologic progression-free survival (14.6 vs. 6.7 months, p < 0.001) than the SMI^lo group. However, PSA progression-free survival and radiologic progression-free survival were comparable between the two groups in ARSi-treated patients. SMI was independently associated with the risk of radiologic progression in patients treated with docetaxel but not in those treated with ARSi.

Conclusions: High skeletal muscle mass may be associated with reduced risk of disease progression and mortality in patients with CRPC. However, the significance of these relationships is limited in patients treated with docetaxel. These results suggest that assessing skeletal muscle mass may be worthwhile when selecting treatments for CRPC; however, further prospective validation and large-scale studies are needed.

Expression profile-based screening for critical genes reveals S100A4, ACKR3 and CDH1 in docetaxel-resistant prostate cancer cells

Docetaxel is a first-line anticancer drug widely used in the treatment of advanced prostate cancer. However, its therapeutic efficacy is limited by its side effects and the development of chemoresistance by the tumor. Using a gene differential expression microarray, we identified 449 genes differentially expressed in docetaxel-resistant DU145 and PC3 cell lines as compared to docetaxel-sensitive controls. Moreover, western blotting and immunohistochemistry revealed altered expression of S100A4, ACKR3 and CDH1in clinical tumor samples. Cytoscape software was used to investigate the relationship between critical proteins and their signaling transduction networks. Functional and pathway enrichment analyses revealed that these signaling pathways were closely related to cellular proliferation, cell adhesion, cell migration and metastasis. In addition, ACKR3 knockout using the crispr/cas9 method andS100A4knockdownusing targeted shRNA exerted additive effects suppressing cancer cell proliferation and migration. This exploratory analysis provides information about potential candidate genes. It also provides new insight into the molecular mechanism underlying docetaxel-resistance in androgen-independent prostate cancer and highlights potential targets to improve therapeutic outcomes.

The Evolving Systemic Treatment Landscape for Patients with Advanced Prostate Cancer

Prostate cancer (PC) is a major health issue in developed countries, with, on the one hand, men suffering from sequelae related to unnecessary treatment of non-lethal PC, and, on the other hand, still dying because of advanced PC that progresses to castration-resistant disease. Systemic treatment is the mainstay of therapy of castration-resistant PC (CRPC). To date, a multitude of systemic agents have been tested and many of these have failed to provide a clinically meaningful benefit in CRPC, while others have been approved by the US Food and Drug Administration and/or the European Medicines Agency, including antiandrogen hormonal drugs (abiraterone, enzalutamide, apalutamide), chemotherapy (docetaxel and cabazitaxel), immunotherapy (Sipuleucel-T), and radiopharmaceutical (Radium-223) agents. In this review, systemic treatments regarded as most likely to have an impact in clinical practice are presented and discussed. In addition to the pivotal clinical studies, selected retrospective and non-randomized clinical trials are also discussed if deemed to have an impact on clinical practice or future research. A comprehensive appraisal of the expanding landscape of systemic therapies for advanced PC is provided from an expert perspective, with a focus on novel classification and diagnostic tools that have been paving the way for the development of precision medicine in PC.

Androgen Receptor Splice Variant, AR-V7, as a Biomarker of Resistance to Androgen Axis-Targeted Therapies in Advanced Prostate Cancer

Many therapeutic options are now available for men with metastatic castration-resistant prostate cancer (mCRPC), including next-generation androgen receptor axis-targeted therapies (AATTs), immunotherapy, chemotherapy, and radioisotope therapies. No clear consensus has been reached for the optimal sequencing of treatments for patients with mCRPC, and few well-validated molecular markers exist to guide the treatment decisions for individual patients. The androgen receptor splice variant 7 (AR-V7), a splice variant of the androgen receptor mRNA resulting in the truncation of the ligand-binding domain, has emerged as a biomarker for resistance to AATT. AR-V7 expression in circulating tumor cells has been associated with poor outcomes in patients treated with second- and third-line AATTs. Clinically validated assays are now commercially available for the AR-V7 biomarker. In the present review of the current literature, we have summarized the biology of resistance to AATT, with a focus on the AR-V7; and the clinical studies that have validated AR-V7 expression as a strong independent predictor of a lack of clinical benefit from AATTs. Existing evidence has indicated that patients with AR-V7-positive mCRPC will have better outcomes if treated with taxane chemotherapy regimens rather than additional AATTs.