Relationship Between Metastasis-free Survival and Overall Survival in Patients With Nonmetastatic Castration-resistant Prostate Cancer

Comparative effectiveness of multiple androgen receptor signaling inhibitor medicines with androgen deprivation therapy for metastatic hormone-sensitive prostate cancer: a study in the real world

Background

The current treatment strategy for metastatic Hormone-Sensitive Prostate Cancer (mHSPC) is the combination of Androgen Receptor Signaling Inhibitors (ARSIs) medicines with androgen deprivation therapy (ADT). However, there is a lack of real-world data comparing the efficacy of different ARSI pharmaceuticals. Therefore, the objective of this study was to compare the effectiveness and safety of bicalutamide, abiraterone, enzalutamide, and apalutamide in combination with ADT for patients with mHSPC.

Methods

We retrospectively analyzed 82 patients diagnosed with mHSPC, including 18 patients treated with abiraterone acetate with prednisone, 21 patients with enzalutamide, 20 patients with apalutamide, and 23 patients with bicalutamide. We evaluated PSA progression-free survival (PSA-PFS), imaging progression-free survival (r PFS), castration resistance progression-free survival (CRPC-PFS), and overall survival (OS) using Kaplan-Meier survival analyses. Additionally, we explored relevant factors affecting prognosis through univariate and multivariate Cox risk-proportionality models. PSA response rates at 3, 6, and 12 months, nadir PSA levels (nPSA), and time to nadir (TTN) in different medication subgroups after treatment were documented, and we used one-way ANOVA to determine the effect of these measures on patient prognosis.

Results

In comparison with bicalutamide, both enzalutamide and apalutamide have shown significant advantages in delaying disease progression among mHSPC patients. Specifically, enzalutamide has been found to significantly prolong PSA-PFS (HR 2.244; 95% CI 1.366-3.685, p=0.001), rPFS (HR 2.539; 95% CI 1.181-5.461; p= 0.007), CRPC-PFS (HR 2.131; 95% CI 1.295-3.506; p= 0.003), and OS (HR 2.06; 95% CI 1.183-3.585; P=0.005). Similarly, apalutamide has significantly extended PSA-PFS (HR 5.071; 95% CI 1.711-15.032; P= 0.003) and CRPC-PFS (HR 6.724; 95% CI 1.976-22.878; P=0.002) among patients. On the other hand, the use of abiraterone in combination with ADT did not demonstrate a significant advantage in delaying diseases progression when compared with the other three agents in mHSPC patients. There were no significant differences in overall adverse event rates among the four pharmaceuticals in terms of safety. Additionally, the observation of PSA kinetics revealed that enzalutamide, apalutamide, and abiraterone acetate had a significant advantage in achieving deep PSA response (PSA ≤ 0.2 ng/ml) compared with bicalutamide (p=0.007 at 12 months). Enzalutamide and apalutamide exhibited preeminence efficacy, with no substantial difference observed between the two medications.

Conclusions

Abiraterone, enzalutamide, and apalutamide were found to significantly reduce and stabilize PSA levels in mHSPC patients more quickly and thoroughly than bicalutamide. Furthermore, enzalutamide and apalutamide were found to significantly prolong survival and delay disease progression in mHSPC patients compared with bicalutamide. It should be noted that abiraterone did not demonstrate a significant advantage in delaying disease compared with enzalutamide and apalutamide. After conducting drug toxicity analyses, it was determined that there were no significant differences among the four drugs.

Role of apalutamide in the treatment landscape for patients with advanced prostate cancer: an expert opinion statement of European clinical practice

BACKGROUND

Patients with advanced prostate cancer have a poor prognosis, and well-tolerated new treatment strategies are required to improve survival outcomes. Apalutamide is a novel androgen signalling inhibitor developed to be used in combination with continuous androgen deprivation therapy (ADT) for the treatment of patients with advanced prostate cancer. Based on evidence from two phase 3 pivotal clinical trials in non-metastatic castration-resistant (nmCRPC; SPARTAN) and metastatic hormone-sensitive prostate cancer (mHSPC; TITAN), ADT plus apalutamide significantly extends overall survival compared with the standard of care.

AIMS

To provide practical recommendations to guide optimal use in the real-world setting as the use of apalutamide in clinical practice increases.

METHODS

Expert opinion from a group of European physicians is presented here to educate on the use of apalutamide in combination with ADT in patients with mHSPC and patients with nmCRPC who are at risk of developing metastatic disease, focusing on practical considerations such as patient selection, monitoring, and management of side effects.

RESULTS

In clinical practice, apalutamide in combination with ADT can be used in a broad patient population including patients with high and low volume/risk mHSPC, patients with de novo metastatic disease or metastases following treatment for localised disease, as well as older patients. Apalutamide in combination with ADT is well tolerated, with manageable side effects which do not impact health-related quality of life compared to ADT alone.

CONCLUSIONS

Real-world experience with apalutamide supports the efficacy and safety findings reported by the SPARTAN and TITAN clinical trials.

Two calix[4]pyrroles as potential therapeutics for castration-resistant prostate cancer

Macrocyclic compounds meso-(p-acetamidophenyl)-calix[4]pyrrole and meso-(m-acetamidophenyl)-calix[4]pyrrole have previously been reported to exhibit cytotoxic properties towards lung cancer cells. Here, we report pre-clinical in vitro and in vivo studies showing that these calixpyrrole derivatives can inhibit cell growth in both PC3 and DU145 prostatic cancer cell lines. We explored the impact of these compounds on programmed cell death, as well as their ability to inhibit cellular invasion. In this study we have demonstrated the safety of these macrocyclic compounds by cytotoxicity tests on ex-vivo human peripheral blood mononuclear cells (PBMCs), and by in vivo subcutaneous administration. Preliminary in vivo tests demonstrated no hepato-, no nephro- and no genotoxicity in Balb/c mice compared to controls treated with cisplatin. These findings suggest these calixpyrroles might be novel therapeutic tools for the treatment of prostate cancer and of particular interest for the treatment of androgen-independent castration-resistant prostate cancer.

Matching-adjusted indirect treatment comparison of the efficacy of enzalutamide versus apalutamide for the treatment of nonmetastatic castration-resistant prostate cancer

Background

To date, the efficacy of the androgen receptor inhibitors enzalutamide and apalutamide for the treatment of nonmetastatic castration-resistant prostate cancer (nmCRPC) has not been compared directly in a clinical trial setting. Indirect comparisons can be used to assess relative efficacy and provide important information to guide treatment decisions. PROSPER and SPARTAN were double-blind, randomized, placebo-controlled, phase III trials in patients with nmCRPC with overall similar study designs and inclusion and exclusion criteria. Using an anchored matching-adjusted indirect comparison, based on the final data from the PROSPER and SPARTAN studies, we assessed the comparative efficacy of enzalutamide and apalutamide, both plus androgen deprivation therapy.

Methods

Using placebo as the common comparator, individual patient data from PROSPER were matched to the aggregate patient data from SPARTAN and efficacy endpoints from PROSPER were re-weighted accordingly. Patient baseline characteristics and endpoints were clinically and statistically tested to identify potential effect modifiers, according to National Institute for Health and Care Excellence guidelines. Hazard ratios for overall survival (OS), metastasis-free survival (MFS), and time to chemotherapy (TTCx) were re-estimated for PROSPER using weighted Cox proportional hazards models and indirectly compared with those of SPARTAN using a Bayesian network meta-analysis.

Results

Estimated hazard ratios [95% credible interval (CrI)] for enzalutamide versus apalutamide were 0.80 (95% CrI 0.58-1.10) for OS, 0.94 (95% CrI 0.69-1.29) for MFS2, and 0.90 (95% CrI 0.63-1.29) for TTCx. Similar results were seen for sensitivity analyses conducted for OS and MFS. Bayesian probability analyses showed a 91.7% favoring enzalutamide for OS, 65.1% for MFS, and 71.4% for TTCx.

Conclusions

The results of this matching-adjusted indirect comparison of final data from PROSPER and SPARTAN indicate comparable efficacy of enzalutamide and apalutamide with potentially a greater probability of longer MFS, OS, and TTCx in patients with nmCRPC treated with enzalutamide versus apalutamide.

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Enzalutamide and apalutamide relative efficacy assessed via an MAIC corrected for differences between PROSPER and SPARTAN.

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Enzalutamide and apalutamide showed similar efficacy with regards to MFS, OS, and TTCx.

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The Bayesian probability analyses were numerically in favor of enzalutamide being more effective than apalutamide.

Radiotherapy plus androgen-deprivation therapy for PSA persistence in lymph node-positive prostate cancer

The treatment for lymph node involvement (LNI) after radical prostatectomy (RP) has not been established. This study aimed to reveal the outcomes of various management strategies among patients with LNI after RP. Retrospectively, 561 patients with LNI after pelvic lymph node dissection (PLND) with RP treated between 2006 and 2019 at 33 institutions participating in the Japanese Urological Oncology Group were investigated. Metastasis-free survival (MFS) was the primary outcome. Patients were stratified by PSA persistence after RP. Cox regression models were used to analyze the relationships between clinicopathological characteristics and survival. Survival analyses were conducted using the Kaplan-Meier method and log-rank test with or without propensity score matching. Prognoses, including MFS and overall survival, were prominently inferior among patients with persistent PSA than among those without persistent PSA. In multivariate analysis, androgen-deprivation therapy (ADT) plus radiotherapy (RT) was associated with better MFS than ADT alone among patients with persistent PSA (hazard ratio = 0.37; 95% confidence interval = 0.15-0.93; P = 0.034). Similarly, MFS and overall survival were significantly better for ADT plus RT than for ADT alone among patients with persistent PSA after propensity score matching. This study indicated that PSA persistence in LNI prostate cancer increased the risk of poor prognoses, and intensive treatment featuring the addition of RT to ADT might improve survival.

Receptor-interacting protein kinase 2 (RIPK2) stabilizes c-Myc and is a therapeutic target in prostate cancer metastasis

Despite progress in prostate cancer (PC) therapeutics, distant metastasis remains a major cause of morbidity and mortality from PC. Thus, there is growing recognition that preventing or delaying PC metastasis holds great potential for substantially improving patient outcomes. Here we show receptor-interacting protein kinase 2 (RIPK2) is a clinically actionable target for inhibiting PC metastasis. RIPK2 is amplified/gained in ~65% of lethal metastatic castration-resistant PC. Its overexpression is associated with disease progression and poor prognosis, and its genetic knockout substantially reduces PC metastasis. Multi-level proteomics analyses reveal that RIPK2 strongly regulates the stability and activity of c-Myc (a driver of metastasis), largely via binding to and activating mitogen-activated protein kinase kinase 7 (MKK7), which we identify as a direct c-Myc-S62 kinase. RIPK2 inhibition by preclinical and clinical drugs inactivates the noncanonical RIPK2/MKK7/c-Myc pathway and effectively impairs PC metastatic outgrowth. These results support targeting RIPK2 signaling to extend metastasis-free and overall survival.

Correlation Between Imaging-Based Intermediate Endpoints and Overall Survival in Men With Metastatic Castration-Resistant Prostate Cancer: Analysis of 28 Randomized Trials Using the Prostate Cancer Clinical Trials Working Group (PCWG2) Criteria in 16,511 Patients

INTRODUCTION/BACKGROUND

Radiographic progression-free survival (rPFS) based on Prostate Cancer Working Group 2 (PCWG2) has been increasingly used as a meaningful imaging-based intermediate endpoint (IBIE) for overall survival (OS) in patients with metastatic castration-resistant prostate cancer (mCRPC). In randomized phase III trials, rPFS showed good correlation with OS at the individual trial level. We aimed to assess the correlation between the hazard ratios (HR) of IBIE and OS among PCWG2-based randomized trials.

MATERIALS AND METHODS

PubMed and EMBASE databases were systematically searched for randomized trials evaluating systemic treatments on mCRPC using PCWG2 up to April 15, 2020. Hazard ratios for OS and IBIEs were extracted and their correlation was assessed using weighted linear regression. Subgroup analyses were performed according to various clinical settings: prior chemotherapy, drug category, type of IBIE (rPFS vs. composite IBIE, latter defined as progression by imaging and one or a combination of PSA, pain, skeletal-related events, and performance status), and publication year.

RESULTS

Twenty-eight phase II-III randomized trials (16,511 patients) were included. Correlation between OS and IBIE was good (R² = 0.57, 95% confidence interval [CI], 0.35-0.78). Trials using rPFS showed substantially higher correlation than those using a composite IBIE (R² = 0.58, 95% CI, 0.32-0.82 vs. 0.00, 95% CI, -0.01 to 0.01). Correlations between OS and IBIE in other subgroups were at least moderate in nearly all subgroups (R² = 0.32-0.91).

CONCLUSION

IBIEs in the era of PCWG2 correlate well with OS in randomized trials for systemic drugs in patients with mCRPC. PCWG2-based rPFS should be used instead of a composite IBIE that includes PSA and other clinical variables.

A meta-analysis on overall survival and safety outcomes in patients with nonmetastatic castration-resistant prostate cancer treated with novel hormonal agents

Several novel androgen receptor (AR)-inhibitors have been introduced for nonmetastatic castration-resistant prostate cancer (nmCRPC) treatment, with the improvement of survival outcomes which need to be balanced against the risk of adverse events. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating enzalutamide, apalutamide and darolutamide in nmCRPC patients, to assess overall survival (OS), incidence and risk of adverse drug events, adverse-events-related death and adverse-events-related treatment discontinuation. We selected three RCTs (SPARTAN, PROSPER and ARAMIS). New hormonal agents administration resulted in better OS, despite the increased risk of several any grade and grade 3-4 adverse events. In the decision-making process, careful evaluation of expected adverse events, patients' comorbidities and maintenance of quality of life are mandatory.

Implications of prognosis-associated genes in pancreatic tumor metastasis: lessons from global studies in bioinformatics

Pancreatic cancer (PC) is a highly lethal malignancy with a 5-year survival rate of 10%. The occurrence of metastasis, among other hallmarks, is the main contributor to its poor prognosis. Consequently, the elucidation of metastatic genes involved in the aggressive nature of the disease and its poor prognosis will result in the development of new treatment modalities for improved management of PC. There is a deep interest in understanding underlying disease pathology, identifying key prognostic genes, and genes associated with metastasis. Computational approaches, which have become increasingly relevant over the last decade, are commonly used to explore such interests. This review aims to address global studies that have employed global approaches to identify prognostic and metastatic genes, while highlighting their methods and limitations. A panel of 48 prognostic genes were identified across these studies, but only five, including ANLN, ARNTL2, PLAU, TOP2A, and VCAN, were validated in multiple studies and associated with metastasis. Their association with metastasis has been further explored here, and the implications of these genes in the metastatic cascade have been interpreted.

A real-world comparison of docetaxel versus abiraterone acetate for metastatic hormone-sensitive prostate cancer

Background

Docetaxel (D) or secondary hormonal therapy (SHT) each combined with androgen deprivation therapy (ADT) represent possible treatment options in males with metastasized hormone‐sensitive prostate cancer (mHSPC). Real‐world data comparing different protocols are lacking yet. Thus, our objective was to compare the efficacy and safety of abiraterone acetate (AA)+ADT versus D+ADT in mHSPC.

Methods

In a retrospective multicenter analysis including males with mHSPC treated with either of the aforementioned protocols, overall survival (OS), progression‐free survival 1 (PFS1), and progression‐free survival 2 (PFS2) were assessed for both cohorts. Median time to event was tested by Kaplan–Meier method and log‐rank test. The Cox‐proportional hazards model was used for univariate and multivariate regression analyses.

Results

Overall, 196 patients were included. The AA+ADT cohort had a longer PFS1 in the log‐rank testing (23 vs. 13 mos., p < 0.001), a longer PFS2 (48 vs. 33 mos., p = 0.006), and longer OS (80 vs. 61 mos., p = 0.040). In the multivariate analyses AA+ADT outperformed D+ADT in terms of PFS1 (HR = 0.34, 95% CI = 0.183–0.623; p = 0.001) and PFS2 (HR = 0.33 95% CI = 0.128–0.827; p = 0.018), respectively, while OS and toxicity rate were similar between both groups.

Conclusions

AA+ADT is mainly associated with a similar efficacy and overall toxicity rate as D+ADT. Further prospective research is required for validation of the clinical value of the observed benefit of AA+ADT for progression‐free end‐points.

Hormonal Therapy for Prostate Cancer

Huggins and Hodges demonstrated the therapeutic effect of gonadal testosterone deprivation in the 1940s and therefore firmly established the concept that prostate cancer is a highly androgen-dependent disease. Since that time, hormonal therapy has undergone iterative advancement, from the types of gonadal testosterone deprivation to modalities that block the generation of adrenal and other extragonadal androgens, to those that directly bind and inhibit the androgen receptor (AR). The clinical states of prostate cancer are the product of a superimposition of these therapies with nonmetastatic advanced prostate cancer, as well as frankly metastatic disease. Today's standard of care for advanced prostate cancer includes gonadotropin-releasing hormone agonists (e.g., leuprolide), second-generation nonsteroidal AR antagonists (enzalutamide, apalutamide, and darolutamide) and the androgen biosynthesis inhibitor abiraterone. The purpose of this review is to provide an assessment of hormonal therapies for the various clinical states of prostate cancer. The advancement of today's standard of care will require an accounting of an individual's androgen physiology that also has recently recognized germline determinants of peripheral androgen metabolism, which include HSD3B1 inheritance.

Current Status and Future Perspectives of Androgen Receptor Inhibition Therapy for Prostate Cancer: A Comprehensive Review

The androgen receptor (AR) is one of the main components in the development and progression of prostate cancer (PCa), and treatment strategies are mostly directed toward manipulation of the AR pathway. In the metastatic setting, androgen deprivation therapy (ADT) is the foundation of treatment in patients with hormone-sensitive prostate cancer (HSPC). However, treatment response is short-lived, and the majority of patients ultimately progress to castration-resistant prostate cancer (CRPC). Surmountable data from clinical trials have shown that the maintenance of AR signaling in the castration environment is accountable for disease progression. Study results indicate multiple factors and survival pathways involved in PCa. Based on these findings, the alternative molecular pathways involved in PCa progression can be manipulated to improve current regimens and develop novel treatment modalities in the management of CRPC. In this review, the interaction between AR signaling and other molecular pathways involved in tumor pathogenesis and its clinical implications in metastasis and advanced disease will be discussed, along with a thorough overview of current and ongoing novel treatments for AR signaling inhibition.

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.

Novel therapies are changing treatment paradigms in metastatic prostate cancer

Metastatic castration-resistant prostate cancer (mCRPC) remains a terminal diagnosis with an aggressive disease course despite currently approved therapeutics. The recent successful development of poly ADP-ribose polymerase (PARP) inhibitors for patients with mCRPC and mutations in DNA damage repair genes has added to the treatment armamentarium and improved personalized treatments for prostate cancer. Other promising therapeutic agents currently in clinical development include the radiotherapeutic 177-lutetium-prostate-specific membrane antigen (PSMA)-617 targeting PSMA-expressing prostate cancer and combinations of immunotherapy with currently effective treatment options for prostate cancer. Herein, we have highlighted the progress in systemic treatments for mCRPC and the promising agents currently in ongoing clinical trials.

Apalutamide and Overall Survival in Prostate Cancer

BACKGROUND

The phase 3 SPARTAN study evaluated apalutamide versus placebo in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) and prostate-specific antigen doubling time of ≤10 mo. At primary analysis, apalutamide improved median metastasis-free survival (MFS) by 2 yr and overall survival (OS) data were immature.

OBJECTIVE

We report the prespecified event-driven final analysis for OS.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1207 patients with nmCRPC (diagnosed by conventional imaging) were randomised 2:1 to apalutamide (240mg/d) or placebo, plus on-going androgen deprivation therapy. After MFS was met and the study was unblinded, 76 (19%) patients still receiving placebo crossed over to apalutamide.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

OS and time to cytotoxic chemotherapy (TTChemo) were analysed by group-sequential testing with O'Brien-Fleming-type alpha spending function.

RESULTS AND LIMITATIONS

At median 52-mo follow-up, 428 deaths had occurred. The median treatment duration was 32.9 mo for apalutamide group and 11.5 mo for placebo group. Median OS was markedly longer with apalutamide versus placebo, reaching prespecified statistical significance (73.9 vs 59.9 mo, hazard ratio [HR]: 0.78 [95% confidence interval {CI}, 0.64-0.96]; p=0.016). Apalutamide also lengthened TTChemo versus placebo (HR: 0.63 [95% CI, 0.49-0.81]; p=0.0002). Discontinuation rates in apalutamide and placebo groups due to progressive disease were 43% and 74%, and due to adverse events 15% and 8.4%, respectively. Subsequent life-prolonging therapy was received by 371 (46%) patients in the apalutamide arm and by 338 (84%) patients in the placebo arm including 59 patients who received apalutamide after crossover. Safety was consistent with previous reports; when adverse events were adjusted for treatment exposure, rash had the greatest difference of incidence between the apalutamide and placebo groups.

CONCLUSIONS

Extension of OS with apalutamide compared with placebo conferred impactful benefit in patients with nmCRPC. There was a 22% reduction in the hazard of death in the apalutamide group despite 19% crossover (placebo to apalutamide) and higher rates of subsequent therapy in the placebo group.

PATIENT SUMMARY

With data presented herein, all primary and secondary study end points of SPARTAN were met; findings demonstrate the value of apalutamide as a treatment option for nonmetastatic castration-resistant prostate cancer.