Non-metastatic castrate-resistant prostate cancer: a call for improved guidance on clinical management

Prognostic Outcomes and Predictive Factors in Non-Metastatic Castration-Resistant Prostate Cancer Patients Not Treated with Second-Generation Antiandrogens

Background/Objectives: Patients with non-metastatic castration-resistant prostate cancer (nmCRPC) and high-risk features frequently have progression to life-threatening metastasis without second-generation antiandrogens. This study investigated nmCRPC patients for the survival and prognostic factors from a cohort before the approved use of second-generation antiandrogens. Methods: From March 2016 to January 2021, 326 patients treated with second-generation antiandrogens for metastatic castration-resistant prostate cancer (mCRPC) or metastatic castration-sensitive prostate cancer were retrieved. Forty-four patients experiencing nmCRPC with no use of second-generation antiandrogens were reviewed. The prognostic factors, at initial diagnosis or at nmCRPC, associated with metastasis-free survival (MFS) and overall survival (OS) were analyzed. Results: The median follow-up time after nmCRPC was 46 months. The median PSA level at nmCRPC was 2.7 ng/mL. Thirty-eight of forty-four patients with nmCRPC had a PSA doubling time (PSADT) of 10 months or shorter, and the median PSADT was 4 months. The median OS from nmCRPC was 53 months, and the median interval for nmCRPC patients progressing to mCRPC was 20 months. Upon univariate analysis, PSADT < 10 months (p = 0.049) and the very-high-risk group at the initial diagnosis (p = 0.043) were associated with significantly shorter post-nmCRPC MFS. The very-high-risk group (p = 0.031) was associated with significantly worse post-nmCRPC OS. In terms of survivals from the initial diagnosis of prostate cancer, Gleason grade ≥ 8 was the only independent factor with MFS and OS. Conclusions: Without second-generation antiandrogens, nmCRPC patients with PSADT <10 months and in the initial very-high-risk group developed subsequent mCRPC in a significantly faster fashion. Patients of the very-high-risk group had shorter survival rates after nmCRPC.

Impact of darolutamide on local symptoms: pre-planned and post hoc analyses of the ARAMIS trial

OBJECTIVE

To assess, the effect of darolutamide (a structurally distinct androgen receptor inhibitor) on urinary and bowel symptoms, using data from the phase III ARAMIS trial (NCT02200614) that showed darolutamide significantly reduced the risk of metastasis and death versus placebo.

PATIENTS AND METHODS

Patients with non-metastatic castration-resistant prostate cancer (nmCRPC) were randomised 2:1 to darolutamide (n = 955) or placebo (n = 554). Local symptom control was assessed by first prostate cancer-related invasive procedures and post hoc analyses of time to deterioration in quality of life (QoL) using total urinary and bowel symptoms, and individual questions for these symptoms from the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Prostate Cancer Module subscales and Functional Assessment of Cancer Therapy-Prostate prostate cancer subscale. Prostate-specific antigen (PSA) responses were correlated with urinary and bowel adverse events (AEs).

RESULTS

Fewer patients receiving darolutamide (4.7%) versus placebo (9.6%) underwent invasive procedures, and time to first procedure was prolonged with darolutamide (hazard ratio 0.42, 95% confidence interval 0.28-0.62). Darolutamide significantly (P < 0.01) delayed worsening of QoL for total urinary and bowel symptoms versus placebo, mostly attributed by individual symptoms of urinary frequency, associated pain, and interference with daily activities. AEs of urinary retention and dysuria were less frequent with darolutamide, and greater PSA response (≥90%, ≥50% and <90%, <50%) among darolutamide-treated patients was associated with lower incidences of urinary retention (2.2%, 4.2%, 5.1%) and dysuria (0.5%, 3.2%, 5.1%), respectively.

CONCLUSIONS

Darolutamide demonstrated a positive impact on local disease recurrence and symptom control in patients with nmCRPC, delayed time to deterioration in QoL related to urinary and bowel symptoms, and a favourable safety profile showing similar incidence of urinary- and bowel-related AEs compared with placebo.

Treatment of nonmetastatic castration-resistant prostate cancer: focus on second-generation androgen receptor inhibitors

BACKGROUND

Nonmetastatic castration-resistant prostate cancer (nmCRPC) is defined as a rising prostate-specific antigen concentration, despite castrate levels of testosterone with ongoing androgen-deprivation therapy or orchiectomy, and no detectable metastases by conventional imaging. Patients with nmCRPC progress to metastatic disease and are at risk of developing cancer-related symptoms and morbidity, eventually dying of their disease. While patients with nmCRPC are generally asymptomatic from their disease, they are often older and have chronic comorbidities that require long-term concomitant medication. Therefore, careful consideration of the benefit-risk profile of potential treatments is required.

METHODS

In this review, we will discuss the rationale for early treatment of patients with nmCRPC to delay metastatic progression and prolong survival, as well as the factors influencing this treatment decision. We will focus on oral pharmacotherapy with the second-generation androgen receptor inhibitors, apalutamide, enzalutamide, and darolutamide, and the importance of balancing the clinical benefit they offer with potential adverse events and the consequential impact on quality of life, physical capacity, and cognitive function.

RESULTS AND CONCLUSIONS

While the definition of nmCRPC is well established, the advent of next-generation imaging techniques capable of detecting hitherto undetectable oligometastatic disease in patients with nmCRPC has fostered debate on the criteria that inform the management of these patients. However, despite these developments, published consensus statements have maintained that the absence of metastases on conventional imaging suffices to guide such therapeutic decisions. In addition, the prolonged metastasis-free survival and recently reported positive overall survival outcomes of the three second-generation androgen receptor inhibitors have provided further evidence for the early use of these agents in patients with nmCRPC in order to delay metastases and prolong survival. Here, we discuss the benefit-risk profiles of apalutamide, enzalutamide, and darolutamide based on the data available from their pivotal clinical trials in patients with nmCRPC.

Prostate Cancer in Latin America: Challenges and Recommendations

Prostate cancer (PCa) is the most frequent tumor among Latin American (LATAM) men. The incidence of de novo metastatic PCa is higher in LATAM than other parts of the world, and demographic changes in the region have increased disease burden. However, region-specific information regarding prevalence, progression, and treatment effectiveness is not currently available for nonmetastatic, castration-resistant PCa (nmCRPC). Nonmetastatic, castration-resistant PCa is a heterogeneous disease with varying potential to develop metastasis with limited treatments available, until recently. New clinical trials with promising results have allowed second-generation antiandrogen drugs to be used as first-line treatments, rendering guidelines outdated. As a result, this panel of experts reviewed the current status and challenges and developed recommendations for nmCRPC diagnosis and management in LATAM. The Americas Health Foundation (AHF) conducted a literature review and identified LATAM scientists and clinicians who have published in the field of PCa since 2012. The AHF convened a panel of 7 chosen experts urologists and medical oncologists from the region. The AHF developed specific questions relating to nmCRPC, which were answered by the experts prior to the multiday meeting. Each narrative was discussed and edited by the panel, through numerous rounds of discussion until a consensus was reached in a final manuscript. The panel proposes specific and realistic recommendations for improving access to diagnosis and management of PCa in LATAM. No treatment has yet shown improvement in overall survival; however, when including metastasis-free survival as an end point, second-generation antiandrogen drugs have emerged as effective treatment options and are currently included as first-line treatment. Although nmCRPC is a specific disease that represents a small percentage of patients with PCa, effective diagnostic and treatment strategies can contribute toward increasing quality of life and survival rates of patients with PCa in LATAM.

Predictors of survival, healthcare resource utilization, and healthcare costs in veterans with non-metastatic castration-resistant prostate cancer

OBJECTIVES

The objective of this study was to evaluate the association of prostate-specific antigen doubling time (PSADT) with metastasis-free survival (MFS) and overall survival (OS), and to describe healthcare resource utilization (HRU) and costs among patients with non-metastatic castrate-resistant prostate cancer (nmCRPC) in the Veterans Health Administration setting.

METHODS AND MATERIALS

Patients with nmCRPC were identified from the Veterans Health Administration electronic health record database (1/2007-8/2017). PSADT was categorized as <3 months, 3 to 9 months, 9 to 15 months, ≥15 months, and unknown. MFS and OS were assessed using multivariable Cox proportional hazards regression, including PSADT as a predictor. HRU and costs were described per-patient-per-year (PPPY).

RESULTS

Among 12,083 patients in the study, shorter PSADT was associated with shorter MFS and OS (PSADT <3 months vs. PSADT ≥15 months hazard ratio [HR] [95% confidence interval (CI)] = 0.307 [0.281, 0.335] and 0.371 [0.335, 0.410], respectively). Patients who developed metastasis had a 3-fold higher risk of death compared to those without metastasis (HR [95% CI] = 2.933 [2.763, 3.113]). Mean HRU increased following the onset of nmCRPC and metastatic castrate-resistant prostate cancer (mCRPC); mean inpatient stays more than doubled (0.2 vs. 0.5 and 0.6 vs. 2.8 PPPY, respectively). Similar increases in healthcare costs were observed; pharmacy costs more than tripled following nmCRPC ($2,074 vs. $6,839 PPPY). From nmCRPC to mCRPC, large increases were observed for inpatient costs ($7,257-$61,691), emergency room costs ($844-$1,958), and pharmacy costs ($4,115-$26,279) PPPY.

CONCLUSIONS

In Veterans with nmCRPC, shorter PSADT was significantly associated with shorter MFS and OS. Onset of nmCRPC and mCRPC was associated with substantial HRU and cost increases.

Matching-Adjusted Indirect Comparison of the Efficacy of Apalutamide and Enzalutamide with ADT in the Treatment of Non-Metastatic Castration-Resistant Prostate Cancer

INTRODUCTION

Apalutamide and enzalutamide are next-generation androgen receptor inhibitors that demonstrated efficacy in placebo-controlled studies (SPARTAN for apalutamide; PROSPER for enzalutamide) when used in combination with androgen deprivation therapy (ADT) for treatment of non-metastatic castration-resistant prostate cancer (nmCRPC). In the absence of comparative studies between these agents, the present study sought to indirectly compare metastasis-free survival (MFS) and overall survival (OS) in patients with nmCRPC who received these therapies.

METHODS

Individual patient-level data from SPARTAN (apalutamide plus ADT) and published data from PROSPER (enzalutamide plus ADT) were utilized. An anchored matching-adjusted indirect comparison (MAIC) was conducted by weighting the patients from the SPARTAN study to match baseline characteristics reported for PROSPER. Hazard ratios (HRs) for MFS and OS were re-estimated for SPARTAN using weighted Cox proportional hazards models and indirectly compared with those of PROSPER using a Bayesian network meta-analysis.

RESULTS

From the SPARTAN population (N = 1207), a total of 1171 patients were matched to the PROSPER population (N = 1401). The recalculated HRs (95% confidence interval) for apalutamide versus ADT based on the reweighted SPARTAN data to mimic the PROSPER patient population were 0.26 (0.21; 0.33) for MFS and 0.62 (0.41; 0.94) for OS. MAIC-based HRs (95% credible interval) for apalutamide versus enzalutamide were 0.91 (0.68; 1.22) for MFS and 0.77 (0.46; 1.30) for OS. The Bayesian probabilities of apalutamide being more effective than enzalutamide were 73.6% for MFS and 83.5% for OS.

CONCLUSIONS

MAIC results suggest that nmCRPC patients treated with apalutamide have a higher probability of a more favorable MFS and OS compared with those treated with enzalutamide.

The LACOG-0415 phase II trial: abiraterone acetate and ADT versus apalutamide versus abiraterone acetate and apalutamide in patients with advanced prostate cancer with non-castration testosterone levels

BACKGROUND

Testosterone suppression is the standard treatment for advanced prostate cancer, and it is associated with side-effects that impair patients' quality of life, like sexual dysfunction, osteoporosis, weight gain, and increased cardiovascular risk. We hypothesized that abiraterone acetate with prednisone (AAP) and apalutamide, alone or in combination, can be an effective hormonal therapy also possibly decreasing castration-associated side effects.

METHODS

Phase II, open-label, randomized, efficacy trial of abiraterone acetate plus prednisone (AAP) and Androgen Deprivation Therapy (ADT) versus apalutamide versus the combination of AAP (without ADT) and apalutamide. Key eligibility criteria are confirmed prostate adenocarcinoma; biochemical relapse after definitive treatment (PSA ≥ 4 ng/ml and doubling time less than 10 months, or PSA ≥ 20 ng/ml); newly diagnosed locally advanced or metastatic prostate cancer; asymptomatic to moderately symptomatic regarding bone symptoms. Patients with other histology besides adenocarcinoma or previous use of hormonal therapy or chemotherapy were excluded.

DISCUSSION

There is an urgent need to study and validate regimens such as new hormonal agents that may add benefit to castration with an acceptable safety profile. We aim to evaluate if apalutamide in monotherapy or in combination with AAP is an effective and safety hormonal treatment that can spare patients of androgen deprivation therapy.

TRIAL REGISTRATION

This trial was registered in ClinicalTrials.gov on October 16, 2017, under Identifier: NCT02867020.

Comparative assessment of prognostic outcomes between first-generation antiandrogens and novel androgen-receptor-axis-targeted agents in patients with non-metastatic castration-resistant prostate cancer

BACKGROUND

To compare the prognostic outcomes between first-generation antiandrogen (FGA) and novel androgen-receptor-axis-targeted agent (ARATA) as first-line therapy in patients with non-metastatic castration-resistant prostate cancer (nmCRPC).

METHODS

This study retrospectively included a total of 103 consecutive nmCRPC patients consisting of 47 (45.6%) and 56 (54.4%) who received FGA (bicalutamide or flutamide) and ARATA (abiraterone acetate or enzalutamide), respectively, as the first-line agent after the failure of primary androgen deprivation therapy (ADT).

RESULTS

There were no significant differences in the major clinicopathological parameters and previous therapeutic histories between the FGA and ARATA groups. During the observation period, 31 (66.0%) and 29 (51.8%) discontinued first-line therapy in the FGA and ARATA groups, respectively, and of these, 27 (87.1%) and 23 (79.3%) in the FGA and ARATA groups, respectively, were subsequently treated with approved agents as second-line therapy. The prostate-specific antigen (PSA) response rate in the FGA group was significantly lower than that in the ARATA group. Although no significant difference in overall survival was noted between the FGA and ARATA groups, there were significant differences in the PSA progression-free survival on first-line therapy and metastasis-free survival between the two groups, favoring the ARATA group compared with FGA group.

CONCLUSIONS

Collectively, these findings suggest that among nmCRPC patients who progressed following treatment with the primary ADT, the introduction of ARATA may result in the delay of disease progression compared with FGA.

Apalutamide and its use in the treatment of prostate cancer

High-risk nonmetastatic castration-resistant prostate cancer is a lethal disease that previously lacked clear treatment options. Progression to bone metastases is associated with significant morbidity and high cost. Apalutamide, an androgen receptor inhibitor, has substantial clinical response in nonmetastatic castration-resistant prostate cancer. Apalutamide + androgen deprivation therapy is well tolerated and improves metastasis-free survival, progression-free survival and time to symptomatic progression, and is associated with a favorable trend of improved overall survival. Future research is needed to elucidate mechanisms of resistance to treatment with androgen signaling inhibitors.

Impact of age, comorbidity, and PSA doubling time on long-term competing risks for mortality among men with non-metastatic castration-resistant prostate cancer

BACKGROUND

Understanding competing risks for mortality is critical in determining prognosis among men with non-metastatic castration-resistant prostate cancer (nmCRPC), a disease state that often affects older men and has substantial heterogeneity in risk of cancer mortality. We sought to determine the impact of age, comorbidity, and PSA doubling time (PSADT) on competing risks for mortality in men with nmCRPC.

METHODS

We conducted a retrospective analysis of 1238 patients diagnosed with nmCRPC in 2000-2015 in the SEARCH database. Multivariable Cox proportional hazards and competing risks regression were used to determine the hazards of overall, prostate cancer-specific (PCSM), and other-cause mortality (OCM) across age, Charlson comorbidity index (CCI), and PSADT subgroups.

RESULTS

Men with nmCRPC were elderly (median age 77) and had substantial comorbidity burdens (CCI > 1 n = 701, 57%). Multivariable Cox analysis showed higher CCI was associated with higher hazard of OCM, while slower PSADT was associated with lower hazard of PCSM across all age subgroups. Among those with CCI ≥ 3 (vs. CCI0), the hazard ratio of OCM was 2.7 (95% CI 1.1-6.3), 2.0 (95% CI 1.1-3.6), and 2.5 (95% CI 1.5-4.0) for those aged <70, 70-79, and ≥80, respectively. Among those with PSADT ≥ 9 months (vs. < 9 months), the hazard ratios for PCSM were 0.5 (95% CI 0.3-0.9), 0.6 (95% CI 0.4-0.9), and 0.6 (95% CI 0.4-0.9) for those aged <70, 70-79, and ≥80. Competing risks curves revealed PCSM was the predominant cause of death for those with PSADT < 9 months across all age and comorbidity groups. PCSM and OCM were relatively equal competitors for mortality among those with PSADT≥9 months except those aged > 80 with CCI ≥ 3, in whom OCM was the predominant cause of death.

CONCLUSIONS

Among men with nmCRPC, age, comorbidity, and PSADT are associated with risk and cause of death and may assist clinicians in counseling patients regarding cancer prognosis.

Management of Patients with Advanced Prostate Cancer: The Report of the Advanced Prostate Cancer Consensus Conference APCCC 2017

BACKGROUND

In advanced prostate cancer (APC), successful drug development as well as advances in imaging and molecular characterisation have resulted in multiple areas where there is lack of evidence or low level of evidence. The Advanced Prostate Cancer Consensus Conference (APCCC) 2017 addressed some of these topics.

OBJECTIVE

To present the report of APCCC 2017.

DESIGN, SETTING, AND PARTICIPANTS

Ten important areas of controversy in APC management were identified: high-risk localised and locally advanced prostate cancer; "oligometastatic" prostate cancer; castration-naïve and castration-resistant prostate cancer; the role of imaging in APC; osteoclast-targeted therapy; molecular characterisation of blood and tissue; genetic counselling/testing; side effects of systemic treatment(s); global access to prostate cancer drugs. A panel of 60 international prostate cancer experts developed the program and the consensus questions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The panel voted publicly but anonymously on 150 predefined questions, which have been developed following a modified Delphi process.

RESULTS AND LIMITATIONS

Voting is based on panellist opinion, and thus is not based on a standard literature review or meta-analysis. The outcomes of the voting had varying degrees of support, as reflected in the wording of this article, as well as in the detailed voting results recorded in Supplementary data.

CONCLUSIONS

The presented expert voting results can be used for support in areas of management of men with APC where there is no high-level evidence, but individualised treatment decisions should as always be based on all of the data available, including disease extent and location, prior therapies regardless of type, host factors including comorbidities, as well as patient preferences, current and emerging evidence, and logistical and economic constraints. Inclusion of men with APC in clinical trials should be strongly encouraged. Importantly, APCCC 2017 again identified important areas in need of trials specifically designed to address them.

PATIENT SUMMARY

The second Advanced Prostate Cancer Consensus Conference APCCC 2017 did provide a forum for discussion and debates on current treatment options for men with advanced prostate cancer. The aim of the conference is to bring the expertise of world experts to care givers around the world who see less patients with prostate cancer. The conference concluded with a discussion and voting of the expert panel on predefined consensus questions, targeting areas of primary clinical relevance. The results of these expert opinion votes are embedded in the clinical context of current treatment of men with advanced prostate cancer and provide a practical guide to clinicians to assist in the discussions with men with prostate cancer as part of a shared and multidisciplinary decision-making process.