Survival Outcomes From a Cumulative Analysis of Worldwide Observational Studies on Sequential Use of New Agents in Metastatic Castration-Resistant Prostate Cancer

Targeting IL-8 and Its Receptors in Prostate Cancer: Inflammation, Stress Response, and Treatment Resistance

This review delves into the intricate roles of interleukin-8 (IL-8) and its receptors, CXCR1 and CXCR2, in prostate cancer (PCa), particularly in castration-resistant (CRPC) and metastatic CRPC (mCRPC). This review emphasizes the crucial role of the tumour microenvironment (TME) and inflammatory cytokines in promoting tumour progression and response to tumour cell targeting agents. IL-8, acting through C-X-C chemokine receptor type 1 (CXCR1) and type 2 (CXCR2), modulates multiple signalling pathways, enhancing the angiogenesis, proliferation, and migration of cancer cells. This review highlights the shift in PCa research focus from solely tumour cells to the non-cancer-cell components, including vascular endothelial cells, the extracellular matrix, immune cells, and the dynamic interactions within the TME. The immunosuppressive nature of the PCa TME significantly influences tumour progression and resistance to emerging therapies. Current treatment modalities, including androgen deprivation therapy and chemotherapeutics, encounter persistent resistance and are complicated by prostate cancer's notably "immune-cold" nature, which limits immune system response to the tumour. These challenges underscore the critical need for novel approaches that both overcome resistance and enhance immune engagement within the TME. The therapeutic potential of inhibiting IL-8 signalling is explored, with studies showing enhanced sensitivity of PCa cells to treatments, including radiation and androgen receptor inhibitors. Clinical trials, such as the ACE trial, demonstrate the efficacy of combining CXCR2 inhibitors with existing treatments, offering significant benefits, especially for patients with resistant PCa. This review also addresses the challenges in targeting cytokines and chemokines, noting the complexity of the TME and the need for precision in therapeutic targeting to avoid side effects and optimize outcomes.

Real-World Treatment Patterns in Patients With Metastatic Castration-Resistant Prostate Cancer in Greece: The PROSPECT Study

INTRODUCTION

Real-world data on management of metastatic castration resistant prostate cancer (mCRPC) with novel therapies is sparse. The aim of this study was to capture real-world management strategies in patients with mCRPC who initiated first line (1L) systemic therapy with chemotherapy or novel hormonal agents (NHAs) in Greece and describe the therapeutic sequencing strategy among patients who advanced to 2L and 3L treatment.

PATIENTS AND METHODS

In this noninterventional, multicentre, retrospective study (PROSPECT), a medical chart review of 149 patients with mCRPC who initiated 1L systemic therapy with chemotherapy or NHAs in 7 major anticancer hospital clinics, from public, academic, and private sectors in Greece was conducted. All endpoints were descriptively analysed. Kaplan-Meier was used for time-to-event outcomes.

RESULTS

At 1L (N = 149), most (78.5%) patients received NHAs; enzalutamide (52.3%), and abiraterone (26.2%). At 2L (N = 68), most (72.1%) patients received chemotherapy, most frequently docetaxel (50.0% of all patients). At 3L (N = 32), 56.3% and 31.3% of patients received chemotherapy and NHAs, respectively. Regarding treatment sequencing from 1L→2L (N = 68), most patients (55.9%) advanced from NHA→chemotherapy. Regarding treatment sequencing from 1L→2L→3L (N = 32), 34.4% advanced from NHAs→chemotherapy→chemotherapy and 31.3% from NHAs→chemotherapy→NHA. Estimated median times spent on treatment at 1L, 2L, and 3L were 9.8, 4.4, and 3.7 months, respectively.

CONCLUSION

Most patients were treated with 1L NHAs, in accordance to established guidelines (which suggest both NHA and chemo as preferred 1st line options). There appeared to be a longer time on treatment of NHAs at 1L than chemotherapy, suggesting an unmet need for treatment optimisation/recommendations for 2L and 3L treatment in mCRPC.

The prognostic value of Eastern Cooperative Oncology Group performance status on overall survival among patients with metastatic prostate cancer: a systematic review and meta-analysis

Background

There is heterogeneity in the literature regarding the strength of association between Eastern Cooperative Oncology Group performance status (ECOG PS) and mortality. We conducted a systematic review and meta-analysis of studies reporting the prognostic value of ECOG PS on overall survival (OS) in metastatic prostate cancer (mPC).

Methods

PubMed was searched from inception to March 21, 2022. A meta-analysis pooling the effect of ECOG PS categories (≥2 vs. <2, 2 vs. <2, and ≥1 vs. <1) on OS was performed separately for studies including patients with metastatic castration-resistant prostate cancer (mCRPC) and metastatic castration-sensitive prostate cancer (mCSPC) using a random-effects model. Analyses were stratified by prior chemotherapy and study type.

Results

Overall, 75 studies, comprising 32,298 patients, were included. Most studies (72/75) included patients with mCRPC. Higher ECOG PS was associated with a significant increase in mortality risk, with the highest estimate observed among patients with mCRPC with an ECOG PS of ≥2 versus <2 (hazard ratio [HR]: 2.10, 95% confidence interval [CI]: 1.87-2.37). When stratifying by study type, there was a higher risk estimate of mortality among patients with mCRPC with an ECOG PS of ≥1 versus <1 in real-world data studies (HR: 1.98, 95% CI: 1.72-2.26) compared with clinical trials (HR: 1.32, 95% CI: 1.13-1.54; p < 0.001). There were no significant differences in the HR of OS stratified by previous chemotherapy.

Conclusion

ECOG PS was a significant predictor of OS regardless of category, previous chemotherapy, and mPC population. Additional studies are needed to better characterize the effect of ECOG PS on OS in mCSPC.

Real-world effectiveness, long-term safety and treatment pathway integration of radium-223 therapy in patients with metastatic castration-resistant prostate cancer

Radium-223 dichloride (223Ra) is an α-emitter approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC) with bone metastases, but without visceral involvement. Despite being a life-prolonging therapy (LPT), 223Ra remains underutilized. A large body of real-world evidence (RWE) for 223Ra has been published in the decade since the pivotal phase 3 ALSYMPCA study, a period during which the treatment landscape has continued to evolve. How to optimize 223Ra use, including how to integrate it into the mCRPC management pathway amongst other current LPTs (i.e., with respect to timing and concurrent, layered, or sequential use), is therefore of considerable interest. RWE studies lack the conventional restraints of clinical trials and can therefore help to build an understanding of how treatments may be best used in routine practice. Here we review RWE studies investigating the efficacy and safety of 223Ra in mCRPC [including in sequence with the recently approved 177-Lutetium conjugated to the ligand prostate-specific membrane antigen (177Lu-PSMA)], as well as response marker development, imaging techniques, and current clinical practice recommendations.

A European, prospective, observational study of enzalutamide in patients with metastatic castration-resistant prostate cancer: PREMISE

In randomized clinical trials, the androgen‐receptor inhibitor enzalutamide has demonstrated efficacy and safety in metastatic castration‐resistant prostate cancer (mCRPC). This study captured efficacy, safety and patient‐reported outcomes (PROs) of enzalutamide in mCRPC patients in a real‐world European setting. PREMISE (NCT0249574) was a European, long‐term, prospective, observational study in mCRPC patients prescribed enzalutamide as part of standard clinical practice. Patients were categorized based on prior docetaxel and/or abiraterone use. The primary endpoint was time to treatment failure (TTF), defined as time from enzalutamide initiation to permanent treatment discontinuation for any reason. Secondary endpoints included prostate‐specific antigen (PSA) response, time to PSA progression, time to disease progression and safety. PROs included EuroQol 5‐Dimension, 5‐Level questionnaire, Functional Assessment of Cancer Therapy—Prostate and Brief Pain Inventory—Short Form. Overall, 1732 men were enrolled. Median TTF with enzalutamide was 12.9 months in the chemotherapy‐ and abiraterone‐naïve cohort (Cohort 1) and 8.4 months in the postchemotherapy and abiraterone‐naïve cohort (Cohort 2). Clinical outcomes based on secondary endpoints also varied between cohorts. Cohorts 1 and 2 showed small improvements in health‐related quality of life and pain status. The proportions of patients reporting treatment‐emergent adverse events (TEAEs) were 51.0% and 62.2% in Cohorts 1 and 2, respectively; enzalutamide‐related TEAEs were similar in both cohorts. The most frequent TEAE across cohorts was fatigue. These data from unselected mCRPC patients in European, real‐world, clinical‐practice settings confirmed the benefits of enzalutamide previously shown in clinical trial outcomes, with safety results consistent with enzalutamide's known safety profile.

What's new?

In clinical trials, the androgen‐receptor inhibitor enzalutamide has demonstrated efficacy and safety in metastatic castration‐resistant prostate cancer (mCRPC). However, results in the real world may differ from those in controlled studies. This large, prospective study thus assessed unselected mCRPC patients with different prior treatment histories, who were then treated with enzalutamide. The results confirm and validate the benefits of enzalutamide in real‐world, clinical‐practice settings that were previously seen in clinical‐trial outcomes. These include improved health‐related quality of life (HRQoL).

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.

Sequencing Life-Prolonging Agents in Castration-Resistant Prostate Cancer Patients: Comparison of Sequences With and Without 223Ra

Background: The retrospective studies that have so far described the outcomes of the sequential use of life-prolonging agents (LPAs) did not include metastatic castration-resistant prostate cancer (mCRPC) patients who received radium-223 (²²³Ra) as part of their treatment. Consequently, it is not known whether including ²²³Ra in the therapeutic sequence has an impact on cumulative survival. The aim of this study was to evaluate this impact by comparing the cumulative overall survival (OS) in two series of mCRPC patients sequentially treated with two or three LPAs after first-line docetaxel (DOC), including ²²³Ra and not. Materials and Methods: The authors retrospectively reviewed the records of mCRPC patients with bone involvement alone who received two or three LPAs (including ²²³Ra) after first-line DOC. The control group was a contemporary series of mCRPC patients with bone involvement alone treated with sequences of two or three LPAs other than ²²³Ra after first-line DOC. Results: Median cumulative OS was 40.6 months in the ²²³Ra group of 78 patients and 36.2 months in the non-²²³Ra group of 186 patients (p = 0.08). OS outcomes were significantly influenced by the number of treatment lines, and baseline Eastern Cooperative Oncology Group performance status (PS) and prostate-specific antigen levels. Conclusions: To the best of the authors' knowledge, this is the first study designed to evaluate the impact of introducing ²²³Ra in the treatment sequences for mCRPC patients, and the results show that its use does not negatively affect cumulative OS.

Novel Combinatorial Approaches to Tackle the Immunosuppressive Microenvironment of Prostate Cancer

Prostate cancer (PCa) is the second-most common cancer in men worldwide and treatment options for patients with advanced or aggressive prostate cancer or recurrent disease continue to be of limited success and are rarely curative. Despite immune checkpoint blockade (ICB) efficacy in some melanoma, lung, kidney and breast cancers, immunotherapy efforts have been remarkably unsuccessful in PCa. One hypothesis behind this lack of efficacy is the generation of a distinctly immunosuppressive prostate tumor microenvironment (TME) by regulatory T cells, MDSCs, and type 2 macrophages which have been implicated in a variety of pathological conditions including solid cancers. In PCa, Tregs and MDSCs are attracted to TME by low-grade chronic inflammatory signals, while tissue-resident type 2 macrophages are induced by cytokines such as IL4, IL10, IL13, transforming growth factor beta (TGFβ) or prostaglandin E2 (PGE2) produced by Th2 cells. These then drive tumor progression, therapy resistance and the generation of castration resistance, ultimately conferring a poor prognosis. The biology of MDSC and Treg is highly complex and the development, proliferation, maturation or function can each be pharmacologically mediated to counteract the immunosuppressive effects of these cells. Herein, we present a critical review of Treg, MDSC and M2 involvement in PCa progression but also investigate a newly recognized type of immune suppression induced by the chronic stimulation of the sympathetic adrenergic signaling pathway and propose targeted strategies to be used in a combinatorial modality with immunotherapy interventions such as ICB, Sipuleucel-T or antitumor vaccines for an enhanced anti-PCa tumor immune response. We conclude that a strategic sequence of therapeutic interventions in combination with additional holistic measures will be necessary to achieve maximum benefit for PCa patients.

[Advanced prostate cancer: sequence of androgen receptor-targeted substances and chemotherapy determines long-term survival]

The treatment of advanced prostate cancer is changing. New study data and the resulting new therapeutic options have led to increasingly differentiated treatment decisions. Despite the changing therapy landscape, taxane-based chemotherapy-being a life-prolonging treatment-remains an indispensable therapeutic component for chemotherapy-fit patients in the metastatic setting. The current results of the randomized study CARD show that cabazitaxel has a higher oncological effectiveness, including a significant survival benefit and no negative impact on quality of life parameters, compared to a second androgen receptor targeted agent (ARTA) in patients with metastatic castration-resistant prostate cancer (mCRPC) who progressed after treatment with docetaxel and an androgen receptor-targeted agent (ARTA). In mCNPC the combination therapies of ADT (androgen deprivation therapy) plus docetaxel or of ADT plus ARTA have been established. In addition, three ARTAs tested in recent phase III studies in a clinical setting for patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) showed that their use significantly prolongs metastasis-free survival and overall survival. The potential early use of ARTAs also has implications for the treatment of mCNPC. The aim of this publication is to provide guidance for clinical routine and to develop criteria for individual therapy decisions with a special focus on the use of chemotherapy.

The role of taxane-based chemotherapy in the treatment of prostate cancer

PURPOSE OF REVIEW

Indications for chemotherapy have increased in prostate cancer (PCA), many of which are shared with new hormonal agents (NHA). With no head to head comparison available, defining the optimal sequence and identifying biomarkers to predict response, has been a focus of intense research in PCA. We aim to summarize the best currently available evidence in all stages of disease to help guide therapy.

RECENT FINDINGS

In metastatic castration-resistant prostate cancer, Cabazitaxel has shown improved radiographic progression-free survival over another NHA after Docetaxel and one NHA. For hormone sensitive PCA (mHSPC) multiple meta-analyses have shown combination therapy with Docetaxel or an NHA to be superior to androgen deprivation therapy alone, yet no clear benefit over each other. For peri-interventional chemotherapy with local therapy, there is currently only one positive prospective trial, for very high-risk disease.

SUMMARY

Cabazitaxel is underutilized and should be used earlier. NHAs should not be used in succession as there is significant cross resistance. Combination therapy should be used in mHSPC, yet there is no clear benefit for any combination. Peri-interventional chemotherapy might have a benefit for a small group of patients with very high-risk disease, yet this must be carefully evaluated, and side effects must be taken into account.

To treat or not to treat: is it acceptable to avoid active therapies in advanced prostate cancer today?

Introduction: Recently, there has been a paradigm shift in the treatment of advanced prostate cancer (PCa) because the approval of a number of new agents has significantly improved overall survival. However, as PCa is a heterogeneous disease that may be more or less aggressive and patients may be more or less responsive to treatment, it is often debated whether or not it is acceptable to avoid active therapies.Areas covered: This review discusses different settings of advanced PCa.Expert opinion: In metastatic castration-resistant PCa, it is unethical not to use active treatments but the use of both androgen receptor targeting agents (ARTA) in sequence should be avoided in most patients and the use of the available agents for fourth-line treatment or beyond should only be considered for highly selected patients. In metastatic hormone-sensitive PCa, patients with de novo disease should receive one additional agent in combination with androgen deprivation therapy (ADT), whereas patients in relapse should be managed with ADT alone. In non-metastatic castration-resistant prostate cancer (PCa), all patients with a PSA doubling time of ≤6 months should receive one ARTA, whereas the others might wait until there is an acceleration in the kinetics of their PSA levels.

Abiraterone acetate in combination with prednisone in the treatment of prostate cancer: safety and efficacy

INTRODUCTION

Metastatic prostate cancer is a life-threatening disease and an important public health concern with prevalence rates varying drastically between high- and low-income countries. Androgen-deprivation therapy alone has been the first-line treatment option for decades, temporarily controlling disease until invariable tumor regression. At the castration-resistant stage, metastatic disease becomes lethal. In recent years several new treatments, including second-generation hormone therapies, have proven to be life-prolonging in metastatic castration-resistant prostate cancer, and at an earlier hormone-sensitive stage. Abiraterone acetate in combination with prednisone was the first approved hormone therapy demonstrating survival benefit, and represents, to date, an alternative, or a second-line treatment after taxane-based chemotherapy, in addition to androgen-deprivation therapy, in hormone sensitive, and metastatic castration-resistant prostate cancer.

AREA COVERED

We performed a literature review of papers from 2012 to 2020 using PubMed, Web of Science, and Embase searching for the safety and efficacy of abiraterone acetate in prostate cancer management. Search results were limited to phase III-IV trials and post hoc analysis of Phase III trials evaluated Abiraterone acetate in the English language.

EXPERT OPINION

This literature review confirms the role of abiraterone acetate in the therapeutic landscape with well-proven safety and efficacy, demonstrated in trials and post-approval studies.