Abiraterone acetate/androgen deprivation therapy combination versus docetaxel/androgen deprivation therapy combination in advanced hormone-sensitive prostate cancer: a network meta-analysis on safety and efficacy

Efficacy of Treatment for Metastatic Hormone-Sensitive Prostate Cancer: An Umbrella Review of Systematic Reviews and Meta-Analyses

PURPOSE

This umbrella review focused on evaluating the efficacy and adverse events of the metastatic hormone-sensitive prostate cancer patients receiving any treatment regimens, including ADT alone or combination treatments.

METHODS

This study conducted an umbrella review following the PRISMA 2020 checklist, aiming to summarize the available studies to evaluate the efficacy of medical treatments for metastatic hormone-sensitive prostate cancer. A literature search was performed to identify systematic reviews and meta-analyses (SRMAs) that included only randomized controlled trials (RCTs) up to September 2023. This study summarized their findings, evaluated overlapping data (i.e., the same RCTs were included in >one SRMA), tested for excessive significance (i.e., observed number of statistically significant studies > expected number by chance) and assessed the quality of the studies.

RESULTS

A total of 4191 studies were identified, but only 27 were included. Among those 27 studies, 12 were network meta-analyses and 15 were direct meta-analyses. Most studies showed no statistically significant difference in overall mortality among GnRH agonists, antagonists and bilateral orchiectomy. Combination treatment is more beneficial than ADT alone in both OS and PFS outcomes with more adverse events. Nevertheless, there is no OS advantage of any combination regimen over the others.

CONCLUSION

Combination treatments demonstrated clear benefits in OS and PFS over ADT alone with more AEs. Further studies are needed to compare among combination treatments.

Cost-Effectiveness Analysis for Therapy Sequence in Advanced Cancer: A Microsimulation Approach with Application to Metastatic Prostate Cancer

PURPOSE

Patients with advanced cancer may undergo multiple lines of treatment, switching therapies as their disease progresses. We developed a general microsimulation framework to study therapy sequence and applied it to metastatic prostate cancer.

METHODS

We constructed a discrete-time state transition model to study 2 lines of therapy. Using digitized published survival curves (progression-free survival, time to progression, and overall survival [OS]), we inferred event types (progression or death) and estimated transition probabilities using cumulative incidence functions with competing risks. We incorporated within-patient dependence over time; first-line therapy response informed subsequent event probabilities. Parameters governing within-patient dependence calibrated the model-based results to a target clinical trial. We applied these methods to 2 therapy sequences for metastatic prostate cancer, wherein both docetaxel (DCT) and abiraterone acetate (AA) are appropriate for either first- or second-line treatment. We assessed costs and quality-adjusted life-years (5-y QALYs) for 2 treatment strategies: DCT → AA versus AA → DCT.

RESULTS

Models assuming within-patient independence overestimated OS time, which corrected with the calibration approach. With generic pricing, AA → DCT dominated DCT → AA, (higher 5-y QALYs and lower costs), consistent for all values of calibration parameters (including no correction). Model calibration increased the difference in 5-y QALYs between treatment strategies (0.07 uncorrected v. 0.15 with base-case correction). Applying the correction decreased the estimated difference in cost (-$5,360 uncorrected v. -$3,066 corrected). Results were strongly affected by the cost of AA. Under a lifetime horizon, AA → DCT was no longer dominant but still cost-effective (incremental cost-effectiveness ratio: $19,463).

CONCLUSIONS

We demonstrate a microsimulation approach to study the cost-effectiveness of therapy sequences for advanced prostate cancer, taking care to account for within-patient dependence.

HIGHLIGHTS

We developed a discrete-time state transition model for studying therapy sequence in advanced cancers.Results are sensitive to dependence within patients.A calibration approach can introduce dependence across lines of therapy and closely match simulation outcomes to target trial outcomes.

Duplicated network meta-analysis in advanced prostate cancer: a case study and recommendations for change

BACKGROUND

Research overlap and duplication is a recognised problem in the context of both pairwise and network systematic reviews and meta-analyses. As a case study, we carried out a scoping review to identify and examine duplicated network meta-analyses (NMAs) in a specific disease setting where several novel therapies have recently emerged: hormone-sensitive metastatic prostate cancer (mHSPC).

METHODS

MEDLINE and EMBASE were systematically searched, in January 2020, for indirect or mixed treatment comparisons or network meta-analyses of the systemic treatments docetaxel and abiraterone acetate in the mHSPC setting, with a time-to-event outcome reported on the hazard-ratio scale. Eligibility decisions were made, and data extraction performed, by two independent reviewers.

RESULTS

A total of 13 eligible reviews were identified, analysing between 3 and 8 randomised comparisons, and comprising between 1773 and 7844 individual patients. Although the included trials and treatments showed a high degree of overlap, we observed considerable variation between identified reviews in terms of review aims, eligibility criteria and included data, statistical methodology, reporting and inference. Furthermore, crucial methodological details and specific source data were often unclear.

CONCLUSIONS AND RECOMMENDATIONS

Variation across duplicated NMAs, together with reporting inadequacies, may compromise identification of best-performing treatments. Particularly in fast-moving fields, review authors should be aware of all relevant studies, and of other reviews with potential for overlap or duplication. We recommend that review protocols be published in advance, with greater clarity regarding the specific aims or scope of the project, and that reports include information on how the work builds upon existing knowledge. Source data and results should be clearly and completely presented to allow unbiased interpretation.

177Lu-PSMA Radioligand Therapy Is Favorable as Third-Line Treatment of Patients with Metastatic Castration-Resistant Prostate Cancer. A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

In this systematic review and network meta-analysis (NMA), we aimed to assess the benefits and harms of third-line (L3) treatments in randomized controlled trials (RCTs) of patients with metastatic castration-resistant prostate cancer (mCRPC). Two reviewers searched for publications from 1 January 2006 to 30 June 2021. The review analyzed seven RCTs that included 3958 patients and eight treatments. Treatment with prostate-specific membrane antigen (PSMA)-based radioligand therapy (PRLT) resulted in a 1.3-times-higher rate of median PSA decline ≥50% than treatment with abiraterone, enzalutamide, mitoxantrone, or cabazitaxel (p = 0.00001). The likelihood was 97.6% for PRLT to bring about the best PSA response, out of the examined treatments. PRLT resulted in a 1.1-times-higher six-month rate of median radiographic progression-free survival. Treatment with PRLT in the VISION trial resulted in 1.05-times-higher twelve-month median overall survival than L3 treatment with cabazitaxel in other RCTs. PRLT more often resulted in severe thrombocytopenia and less often in severe leukopenia than did cabazitaxel. In conclusion, for patients with mCRPC, L3 treatment with PRLT is highly effective and safe.

Which Way to Choose for the Treatment of Metastatic Prostate Cancer: A Case Report and Literature Review

Background

Prostate cancer (PCa) is the second most common cancer among males in the world and the majority of patients will eventually progress to the metastatic phase. How to choose an effective way for the treatment of metastatic PCa, especially in the later stage of the disease is still confusing. Herein we reported the case of a patient diagnosed with metastatic PCa and conducted a literature review on this issue.

Case Presentation

A 57-year-old man with metastatic PCa had been managed by Dr. J.P. since April 2012 when the patient was admitted to the Third Affiliated Hospital of Sun Yat-sen University by aggravating frequent urination and dysuria. The prostate-specific antigen (PSA) concentration was 140 ng/ml, and the diagnosis of PCa was confirmed by prostate biopsy, with Gleason score 4 + 5 = 9. Chest CT and bone scan indicated multiple metastases in the lungs and bones. Triptorelin, bicalutamide, zoledronic acid, and docetaxel were then administered, six cycles later, the metastatic tumors in the lungs disappeared and those in the bones lessened significantly, along with a remarkable reduction in PSA level (< 2 ng/ml). Intermittent androgen deprivation was subsequently conducted until August 2018, when the serum PSA level was found to be 250 ng/ml, again docetaxel 75 mg/m² was administered immediately but the patient was intolerant this time. Instead, abiraterone was administered until March 2019 because of intolerable gastrointestinal side-effects and increasing PSA level. In October 2019, the patient came to our center, a modified approach of docetaxel (day 1 40 mg/m² + day 8 35 mg/m²) was administered. Luckily, the PSA level decreased rapidly, the bone pain was greatly relieved, and no obvious side effects occurred. However, four cycles later, docetaxel failed to work anymore, the metastatic tumor in the liver progressed. We proposed several regimens as alternatives, but they were soon denied due to the high prices or unavailability or uncertain effect of the drugs. In addition, the patient’s condition deteriorated speedily and can no longer bear any aggressive treatment. Finally, the patient died of multiple organ failure in August 2020.

Conclusion

The experiences of this case provide valuable evidence and reference for the treatment choices of metastatic PCa, in some circumstances modified and advanced regimens may produce unexpected effects.

Overall Survival After Systemic Treatment in High-volume Versus Low-volume Metastatic Hormone-sensitive Prostate Cancer: Systematic Review and Network Meta-analysis

CONTEXT

Novel prospective randomized controlled observations addressing combination therapy in metastatic hormone-sensitive prostate cancer (mHSPC) have demonstrated promising overall survival (OS) outcomes.

OBJECTIVE

To compare these novel findings and systematically review and address them within formal network meta-analyses (NMAs) that include observations from other prospective randomized controlled trials (RCTs).

EVIDENCE ACQUISITION

First, we focused on abiraterone, enzalutamide, apalutamide, and docetaxel effects on OS in mHSPC using the PRISMA methodology. PubMed and abstracts identified prospective RCTs in first-line mHSPC. Second, we focused on mature studies that reached median OS and tested OS between abiraterone and docetaxel with tumor burden stratification.

EVIDENCE SYNTHESIS

The first part included seven studies (n = 6639) and the second part, five studies (n = 4462). In the first part, abiraterone ranked first for high-volume mHSPC. Conversely, enzalutamide ranked first for low-volume mHSPC. In the second part, abiraterone treatment in high-volume mHSPC resulted in median OS of 50.1 mo and exceeded that with docetaxel (45.9 mo) and ADT alone (34.0 mo). Docetaxel treatment in low volume mHSPC resulted in median OS of 69.5 mo versus 67.7 mo with ADT alone.

CONCLUSIONS

In conventional NMA that relied on conventional hazard ratios, differences were identified with respect to the relative efficacy of the combination therapies examined; abiraterone dominated the alternatives in high-volume mHSPC. In part two, which relied on trials for which median OS is available, comparison of abiraterone versus docetaxel revealed a 4-mo difference in OS in high-volume mHSPC. Conventional NMA may have overestimated the importance of treatment efficacy instead of focusing on median OS duration, which might represent a more important clinical endpoint.

PATIENT SUMMARY

We reviewed studies on hormonal treatments and chemotherapy used for prostate cancer that has spread outside the prostate gland (metastatic prostate cancer, mPC). We found that the best overall survival was with the hormone agents abiraterone in high-volume mPC and enzalutamide in low-volume mPC. In comparison to the chemotherapy drug docetaxel, median overall survival with abiraterone was 4 months longer among patients with mPC.

Management of newly diagnosed metastatic hormone-sensitive prostate cancer: A survey of UK Uro-oncologists

AIM

To explore the practice and views of uro-oncologists in the United Kingdom regarding their use of chemotherapy and androgen receptor-targeted agents (ARTAs) in patients with newly diagnosed metastatic hormone-sensitive prostate cancer (mHSPC).

METHODS

An expert-devised paper or online questionnaire was completed by members of the British Uro-oncology Group.

RESULTS

All respondents stated that they would offer patients with newly diagnosed mHSPC docetaxel and androgen deprivation therapy (ADT) if they were sufficiently fit to receive chemotherapy (this was the only option available at the time of the survey); 64% would strongly recommend docetaxel for those with high-volume metastatic disease and 31% for those with low-volume disease. Hypothetically, if both docetaxel and ARTAs were available in the United Kingdom for mHSPC, almost 65% of respondents would recommend an ARTA with ADT to these patients in at least one-half of all cases, with the strongest recommendations to patients with high-risk disease. Imaging for the response was conducted according to suspicion of disease progression, regardless of treatment, with the minority of clinicians recommending routine imaging. If a choice of therapy was available, docetaxel would be more likely to be offered to patients with liver or lung metastases, and ARTAs to patients with bone or lymph node only metastases. Almost all respondents would offer local radiotherapy to the primary tumour in patients with low-volume disease.

CONCLUSION

All the UK uro-oncologists surveyed stated that they would offer docetaxel in combination with ADT to all newly diagnosed patients with mHSPC if fit enough for chemotherapy. ARTAs would be offered to many patients if available, especially those with high-risk disease or those unfit to receive chemotherapy. Scanning was typically conducted following treatment only at the suspicion of disease progression.

Gonadotropin-Releasing Hormone Receptors in Prostate Cancer: Molecular Aspects and Biological Functions

Pituitary Gonadotropin-Releasing Hormone receptors (GnRH-R) mediate the activity of the hypothalamic decapeptide GnRH, thus playing a key role in the regulation of the reproductive axis. Early-stage prostate cancer (PCa) is dependent on serum androgen levels, and androgen-deprivation therapy (ADT), based on GnRH agonists and antagonists, represents the standard therapeutic approach for PCa patients. Unfortunately, the tumor often progresses towards the more aggressive castration-resistant prostate cancer (CRPC) stage. GnRH receptors are also expressed in CRPC tissues, where their binding to both GnRH agonists and antagonists is associated with significant antiproliferative/proapoptotic, antimetastatic and antiangiogenic effects, mediated by the Gαi/cAMP signaling cascade. GnRH agonists and antagonists are now considered as an effective therapeutic strategy for CRPC patients with many clinical trials demonstrating that the combined use of these drugs with standard therapies (i.e., docetaxel, enzalutamide, abiraterone) significantly improves disease-free survival. In this context, GnRH-based bioconjugates (cytotoxic drugs covalently linked to a GnRH-based decapeptide) have been recently developed. The rationale of this treatment is that the GnRH peptide selectively binds to its receptors, delivering the cytotoxic drug to CRPC cells while sparing nontumor cells. Some of these compounds have already entered clinical trials.

Genistein Combined Polysaccharide (GCP) Can Inhibit Intracrine Androgen Synthesis in Prostate Cancer Cells

Our group and others have previously shown that genistein combined polysaccharide (GCP), an aglycone isoflavone-rich extract with high bioavailability and low toxicity, can inhibit prostate cancer (CaP) cell growth and survival as well as androgen receptor (AR) activity. We now elucidate the mechanism by which this may occur using LNCaP and PC-346C CaP cell lines; GCP can inhibit intracrine androgen synthesis in CaP cells. UPLC-MS/MS and qPCR analyses demonstrated that GCP can mediate a ~3-fold decrease in testosterone levels (p < 0.001) and cause decreased expression of intracrine androgen synthesis pathway enzymes (~2.5-fold decrease of 3βHSD (p < 0.001), 17βHSD (p < 0.001), CYP17A (p < 0.01), SRB1 (p < 0.0001), and StAR (p < 0.01)), respectively. Reverse-phase HPLC fractionation and bioassay identified three active GCP fractions. Subsequent NMR and LC-MS analysis of the fraction with the highest level of activity, fraction 40, identified genistein as the primary active component of GCP responsible for its anti-proliferative, pro-apoptotic, and anti-AR activity. GCP, fraction 40, and genistein all mediated at least a ~2-fold change in these biological activities relative to vehicle control (p < 0.001). Genistein caused similar decreases in the expression of 17βHSD and CYP17A (2.5-fold (p < 0.001) and 1.5-fold decrease (p < 0.01), respectively) compared to GCP, however it did not cause altered expression of the other intracrine androgen synthesis pathway enzymes; 3βHSD, SRB1, and StAR. Our combined data indicate that GCP and/or genistein may have clinical utility and that further pre-clinical studies are warranted.

Comparative assessment of docetaxel for safety and efficacy between hormone-sensitive and castration-resistant metastatic prostate cancer

OBJECTIVE

To compare toxicity and response of docetaxel chemotherapy between metastatic hormone-sensitive prostate cancer (mHSPC) and castration-resistant metastatic prostate cancer (mCRPC) patients of the same therapeutic era for assessing of upfront docetaxel against the benchmark of docetaxel in the castrate resistant stage in the setting outside of clinical trials.

METHODS

A prospectively collected database of real-world prostate cancer patients receiving docetaxel was divided in mHSPC and mCRPC cases and retrospectively analyzed. Principal objectives were toxicity measured by the common criteria of adverse events terminology and response characterized by Prostate specific antigen decline and radiographic progression-free disease at restaging. The prognostic value of suspected variables for grade 3 to 5 toxicity and response was investigated by logistic regression analysis.

RESULTS

Of 72 patients 34 (47%) were treated for mHSPC and 38 (53%) for mCRPC. Patients with mCRPC were older and had worse performance status (P< 0.01). In mHSPC total number of grade 3 to 5 adverse events (24, median 0, interquartile range 0-1) was significantly less than in mCRPC (46, median 1, interquartile range 1-2) (P = 0.01). Multivariable analysis revealed age as independent predictive variable for grade 3 to 5 toxicity (P = 0.03) but not disease stage, Prostate specific antigen predocetaxel, volume of disease, and Eastern Cooperative Oncology Group performance status (P > 0.05). Objective response was significantly higher in mHSPC compared to mCRPC patients (P < 0.01). Multivariable analysis confirmed mHSPC stage as independent prognostic factor for radiographic progression free disease at restaging (P < 0.01).

CONCLUSIONS

The association of age with toxicity and of mHSPC stage with response resulted in significantly fewer grade 3 to 5 adverse events but higher response rates for upfront docetaxel in mHSPC compared with docetaxel in the later mCRPC stage.

Apalutamide for Metastatic, Castration-Sensitive Prostate Cancer

BACKGROUND

Apalutamide is an inhibitor of the ligand-binding domain of the androgen receptor. Whether the addition of apalutamide to androgen-deprivation therapy (ADT) would prolong radiographic progression-free survival and overall survival as compared with placebo plus ADT among patients with metastatic, castration-sensitive prostate cancer has not been determined.

METHODS

In this double-blind, phase 3 trial, we randomly assigned patients with metastatic, castration-sensitive prostate cancer to receive apalutamide (240 mg per day) or placebo, added to ADT. Previous treatment for localized disease and previous docetaxel therapy were allowed. The primary end points were radiographic progression-free survival and overall survival.

RESULTS

A total of 525 patients were assigned to receive apalutamide plus ADT and 527 to receive placebo plus ADT. The median age was 68 years. A total of 16.4% of the patients had undergone prostatectomy or received radiotherapy for localized disease, and 10.7% had received previous docetaxel therapy; 62.7% had high-volume disease, and 37.3% had low-volume disease. At the first interim analysis, with a median of 22.7 months of follow-up, the percentage of patients with radiographic progression-free survival at 24 months was 68.2% in the apalutamide group and 47.5% in the placebo group (hazard ratio for radiographic progression or death, 0.48; 95% confidence interval [CI], 0.39 to 0.60; P<0.001). Overall survival at 24 months was also greater with apalutamide than with placebo (82.4% in the apalutamide group vs. 73.5% in the placebo group; hazard ratio for death, 0.67; 95% CI, 0.51 to 0.89; P = 0.005). The frequency of grade 3 or 4 adverse events was 42.2% in the apalutamide group and 40.8% in the placebo group; rash was more common in the apalutamide group.

CONCLUSIONS

In this trial involving patients with metastatic, castration-sensitive prostate cancer, overall survival and radiographic progression-free survival were significantly longer with the addition of apalutamide to ADT than with placebo plus ADT, and the side-effect profile did not differ substantially between the two groups. (Funded by Janssen Research and Development; TITAN ClinicalTrials.gov number, NCT02489318.).

Cost-effectiveness analysis of Abiraterone Acetate versus Docetaxel in the management of metastatic castration-sensitive prostate cancer: Hong Kong's perspective

BACKGROUND

Several randomized control trials (RCTs) have showed that adding either abiraterone acetate (AA) or docetaxel (D) to androgen-deprivation therapy (ADT) improves survival of metastatic castration-sensitive prostate cancer patients (mCSPC). Yet, the cost-effectiveness of these treatment options has not been fully compared under Hong Kong's setting. This cost-effectiveness analysis (CEA) serves as the first study in Hong Kong to compare the economic value of these two combinations ADT + AA vs. ADT + D.

METHODS

A deterministic Markov model is used to project cost-effectiveness of each treatment until death. Survival curves for progression/death were extracted and digitized from the five RCTs (CHAARTED, LATITUDE, two STAMPEDE (2016/2017), and GETUG-AFU15). Clinically significant adverse events (AEs) were modeled; utility values were obtained from the literature. Primary outcomes were the quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio (ICER). We used the societal perspective from Hong Kong and considered three times of local gross domestic product per capita (GDPpc) as the willingness-to-pay (WTP) threshold (i.e., US$138,649). We estimated the break-even cost of AA in case ADT + AA is not a cost-effective strategy under this WTP threshold. While considering the standard AA dosage (1000 mg) as the main analysis, we also examined the potential impact of the low-dose AA (250 mg) strategy.

RESULTS

Integrating simulations with probabilistic sensitivity analysis, ADT + D returns 0.79 (median; 95% credible interval 0.56-0.97) QALY with an ICER of US$14,397/QALY ($7824-22,632) compared to ADT-alone. A head-to-head comparison indicates that ADT + AA further gains 0.79 (0.45-1.17) QALY but with an ICER of $361,439/QALY ($260,615-599,683) when compared to ADT + D. Considering three times of GDPpc as WTP threshold, ADT + D is more cost-effective in all simulations; while ADT + AA is more cost-effective than ADT + D only if the cost of AA is reduced by at least 63%. The low-dose AA (250 mg) strategy is potentially cost-effective when it generates equivalent efficacy as the standard dosage (1000 mg).

CONCLUSIONS

ADT + D is therefore shown to be a more cost-effective strategy than ADT + AA in metastatic castration-sensitive prostate cancer patients in developed economies. Addition of AA substantially improved QALY compared to D but at a significant cost.

Timing of androgen deprivation monotherapy and combined treatments in castration-sensitive and castration-resistant prostate cancer: a narrative review

PURPOSE

Standard androgen deprivation therapy (ADT) can be initiated early at the time of diagnosis in asymptomatic castration-sensitive advanced prostate cancer. This definition has recently been expanded to also include an early combined treatment with standard ADT and new antihormonal drugs. We aimed to present the best available evidence for the timing of initiation of ADT monotherapy and combined treatments in castration-sensitive/-resistant prostate cancer.

METHODS

For this narrative review, we searched Cochrane reviews in the Cochrane Library, systematic reviews and randomized controlled trials in MEDLINE, phase III and ongoing trials in ClinicalTrials.gov and screened the reference lists to extract articles of interest. One author screened the references which were finally included after assessing their relevance through discussion with other experts in the field.

RESULTS

The identified references were grouped by medication (standard ADT, androgen biosynthesis inhibitor, androgen receptor antagonists or combined therapies) and tumor stage (castration sensitive or resistant). The evidence was narratively summarized and discussed in the context of the current therapeutic landscape.

CONCLUSIONS

Early standard ADT can reduce symptoms of disease progression and may extend progression-free and overall survival. The patient should be well informed about the higher rates of treatment-related side effects. Deferring standard ADT might be indicated only for well-informed or unfit patients. Early standard ADT is increasingly combined with new antihormonal drugs in castration-sensitive metastatic prostate cancer to gain additional survival and quality of life benefits. Combined treatment at the time of development of castration-resistant disease is well established.