Enzalutamide versus flutamide for castration-resistant prostate cancer after combined androgen blockade therapy with bicalutamide: the OCUU-CRPC study

Risk of Fractures and Falls in Men with Advanced or Metastatic Prostate Cancer Receiving Androgen Deprivation Therapy and Treated with Novel Androgen Receptor Signalling Inhibitors: A Systematic Review and Meta-analysis of Randomised Controlled Trials

CONTEXT

The addition of androgen receptor signalling inhibitors (ARSIs) to standard androgen deprivation therapy (ADT) has improved survival outcomes in patients with advanced prostate cancer (PCa). Advanced PCa patients have a higher incidence of osteoporosis, compounded by rapid bone density loss upon commencement of ADT resulting in an increased fracture risk. The effect of treatment intensification with ARSIs on fall and fracture risk is unclear.

OBJECTIVE

To assess the risk of falls and fractures in men with PCa treated with ARSIs.

EVIDENCE ACQUISITION

A systematic review of EMBASE, MEDLINE, The Cochrane Library, and The Health Technology Assessment Database for randomised control trials between 1990 and June 2023 was conducted in accordance with Preferred Reporting Items for Systematic Review and Meta-analyses guidance. Risk ratios were estimated for the incidence of fracture and fall events. Subgroup analyses by grade of event and disease state were conducted.

EVIDENCE SYNTHESIS

Twenty-three studies were eligible for inclusion. Fracture outcomes were reported in 17 studies (N = 18 811) and fall outcomes in 16 studies (N = 16 537). A pooled analysis demonstrated that ARSIs increased the risk of fractures (relative risk [RR] 2.32, 95% confidence interval [CI] 2.00-2.71; p < 0.01) and falls (RR 2.22, 95% CI 1.81-2.72; p < 0.01) compared with control. A subgroup analysis demonstrated an increased risk of both fractures (RR 2.13, 95% CI 1.70-2.67; p < 0.01) and falls (RR 2.19, 95% CI 1.53-3.12; p < 0.0001) in metastatic hormone-sensitive PCa patients, and an increased risk of fractures in the nonmetastatic (RR 2.27, 95% CI 1.60-3.20; p < 0.00001) and metastatic castrate-resistant (RR 2.85, 95% CI 2.16-3.76; p < 0.00001) settings. The key limitations include an inability to distinguish fragility from pathological fractures and potential for a competing risk bias.

CONCLUSIONS

Addition of an ARSI to standard ADT significantly increases the risk of fractures and falls in men with prostate cancer.

PATIENT SUMMARY

We found a significantly increased risk of both fractures and falls with a combination of novel androgen signalling inhibitors and traditional forms of hormone therapy.

Systemic Therapies for Metastatic Castration-Resistant Prostate Cancer: An Updated Review

The introduction of novel therapeutic agents for advanced prostate cancer has led to a wide range of treatment options for patients with metastatic castration-resistant prostate cancer (mCRPC). In the past decade, new treatment options for mCRPC, including abiraterone, enzalutamide, docetaxel, cabazitaxel, sipuleucel-T, radium-223, 177Lu-PSMA-617, and Olaparib, have demonstrated a survival benefit in phase 3 trials. Bone-modifying agents have become part of the overall treatment strategy for mCRPC, in which denosumab and zoledronic acid reduce skeletal-related events. Recently, androgen receptor-signaling inhibitors (ARSIs) and docetaxel have been used upfront against metastatic castration-sensitive prostate cancer. Further, triplet therapy with ARSI, docetaxel, and androgen deprivation therapy is emerging. However, cross-resistance may occur between these treatments, and the optimal treatment sequence must be considered. The sequential administration of ARSIs, such as abiraterone and enzalutamide, is associated with limited efficacy; however, cabazitaxel is effective for patients with mCRPC who were previously treated with docetaxel and had disease progression during treatment with ARSI. Radioligand therapy with 177Lu-PSMA-617 is a new effective class of therapy for patients with advanced PSMA-positive mCRPC. Tumors with gene alterations that affect homologous recombination repair, such as BRCA1 and BRCA2 alterations, are sensitive to poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors in mCRPC. This review sought to highlight recent advances in systemic therapy for mCRPC and strategies to support patient selection and treatment sequencing.

Prostate Cancer Review: Genetics, Diagnosis, Treatment Options, and Alternative Approaches

Prostate cancer is one of the malignancies that affects men and significantly contributes to increased mortality rates in men globally. Patients affected with prostate cancer present with either a localized or advanced disease. In this review, we aim to provide a holistic overview of prostate cancer, including the diagnosis of the disease, mutations leading to the onset and progression of the disease, and treatment options. Prostate cancer diagnoses include a digital rectal examination, prostate-specific antigen analysis, and prostate biopsies. Mutations in certain genes are linked to the onset, progression, and metastasis of the cancer. Treatment for localized prostate cancer encompasses active surveillance, ablative radiotherapy, and radical prostatectomy. Men who relapse or present metastatic prostate cancer receive androgen deprivation therapy (ADT), salvage radiotherapy, and chemotherapy. Currently, available treatment options are more effective when used as combination therapy; however, despite available treatment options, prostate cancer remains to be incurable. There has been ongoing research on finding and identifying other treatment approaches such as the use of traditional medicine, the application of nanotechnologies, and gene therapy to combat prostate cancer, drug resistance, as well as to reduce the adverse effects that come with current treatment options. In this article, we summarize the genes involved in prostate cancer, available treatment options, and current research on alternative treatment options.

Health-related quality of life with enzalutamide versus flutamide in castration-resistant prostate cancer from the AFTERCAB study

Background

Patient-reported outcome (PRO) measures can provide valuable information in evaluating patients’ health-related quality of life (HRQoL). Post hoc analysis of the AFTERCAB study was conducted to evaluate the HRQoL benefit of enzalutamide plus androgen deprivation therapy (ADT) compared to flutamide plus ADT for the treatment of patients with castration-resistant prostate cancer (CRPC) in Japan.

Methods

The open-label AFTERCAB study was conducted from November 2016 to March 2020 in Japanese men aged ≥ 20 years with asymptomatic or mildly symptomatic CRPC. Patients received enzalutamide plus ADT or flutamide plus ADT, respectively, as first-line alternative androgen therapy (AAT). HRQoL was analyzed through the Functional Assessment of Cancer Therapy–Prostate, EuroQoL 5-Dimension 5-Level instruments, Brief Pain Inventory–Short Form, and Brief Fatigue Inventory. The longitudinal changes in HRQoL, HRQoL deterioration based on minimally important difference (MID), and time to HRQoL deterioration were evaluated for first-line AAT.

Results

Overall, HRQoL between the enzalutamide and flutamide groups was similar during first-line treatment. No statistically significant HRQoL difference in change from baseline to week 61 (least square mean difference; p value) was observed. Furthermore, proportions of pain progression, symptom worsening, and HRQoL deterioration based on MID, were not significantly different between groups.

Conclusions

The results were similar in all subscales of each PRO, demonstrating similar HRQoL deterioration based on MID criteria between the enzalutamide and flutamide groups.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10147-022-02221-w.

Enzalutamide + androgen deprivation therapy (ADT) versus flutamide + ADT in Japanese men with castration‐resistant prostate cancer: AFTERCAB study

Objectives

The objective of the study is to compare the efficacy and safety of alternative androgen therapy (AAT) with enzalutamide + androgen deprivation therapy (ADT) and flutamide + ADT in the treatment of Japanese men with metastatic or nonmetastatic castration‐resistant prostate cancer (CRPC) who progressed despite combined androgen blockade (CAB) with bicalutamide + ADT. AAT treatment sequence was also investigated.

Materials and methods

The open‐label, Phase 4 AFTERCAB study (NCT02918968) was conducted from November 2016 to March 2020 in Japanese men aged ≥20 years with asymptomatic or mildly symptomatic CRPC. Patients were initially randomized to enzalutamide (160 mg/day) + ADT (enzalutamide first) or flutamide (375mg/day [125mg three times daily]) + ADT (flutamide first) as first‐line therapy. Following prostate‐specific antigen (PSA) progression, other disease progression, or discontinuation of first‐line therapy due to an adverse event (AE), patients switched to the other treatment as second‐line therapy. The primary endpoint was time to PSA progression with first‐line therapy (TTPP1). Secondary endpoints included TTPP2 (TTPP1 + time to PSA progression with second‐line therapy). AEs were monitored to assess safety.

Results

Overall, 206 men were randomized (enzalutamide first, n = 102; flutamide first, n = 104) and stratified by study site and disease stage; 133 patients transitioned to second‐line therapy (enzalutamide first, n = 48; flutamide first, n = 85). TTPP1 was significantly improved with enzalutamide first versus flutamide first (median 21.4 months vs. 5.8 months; hazard ratio [HR] 0.42; 95% confidence interval [CI] [0.29, 0.61]). TTPP2 was numerically improved with enzalutamide first versus flutamide first (median not reached vs. 21.2 months; HR 0.76; 95% CI [0.48, 1.19]). Both treatments were generally well tolerated, with AEs consistent with their known safety profiles.

Conclusion

First‐line AAT with enzalutamide + ADT provided a significant improvement in time to PSA progression versus flutamide + ADT. Enzalutamide + ADT may therefore be the preferred first‐line AAT option in Japanese men with metastatic or nonmetastatic CRPC who progress despite CAB with bicalutamide + ADT.

Recent Development and Future Prospects of Molecular Targeted Therapy in Prostate Cancer

Prostate cancer (PC) is a rapidly increasing ailment worldwide. The previous decade has observed a rapid advancement in PC therapies that was evident from the number of FDA approvals during this phase. Androgen deprivation therapies (ADT) have traditionally remained a mainstay for the management of PCs, but the past decade has experienced the emergence of newer classes of drugs that can be used with or without the administration of ADT. FDA approved poly (ADP-ribose) polymerase inhibitors (PARPi), such as olaparib and rucaparib, after successful clinical trials against gene-mutated metastatic castration-resistant prostate cancer. Furthermore, drugs like apalutamide, darolutamide, and enzalutamide with an androgen-targeted mechanism of action have manifested superior results in non-metastatic castration-resistant prostate cancer (nmCRPC), metastatic castration-sensitive prostate cancer (mCSPC), and metastatic castration-resistant prostate cancer (mCRPC), respectively, with or without previously administered docetaxel. Relugolix, an oral gonadotropin-releasing hormone antagonist, and a combination of abiraterone acetate plus prednisone were also approved by FDA after a successful trial in advanced PC and mCRPC, respectively. This review aims to analyze the FDA-approved agents in PC during the last decade and provide a summary of their clinical trials. It also presents an overview of the ongoing progress of prospective molecules still under trial.

Enzalutamide with androgen deprivation therapy in Japanese men with metastatic hormone-sensitive prostate cancer: A subgroup analysis of the phase III ARCHES study

Objective

To evaluate the efficacy and safety of enzalutamide plus androgen deprivation therapy in Japanese men with metastatic hormone‐sensitive prostate cancer.

Methods

A post‐hoc analysis of the Japanese subgroup in the phase III, randomized, multinational ARCHES study (NCT02677896) was carried out. Patients with metastatic hormone‐sensitive prostate cancer were randomized to receive enzalutamide or a placebo, plus androgen deprivation therapy, stratified by disease volume and prior docetaxel therapy. The primary end‐point was radiographic progression‐free survival. Secondary end‐points included time to prostate‐specific antigen progression and overall survival.

Results

Of 1150 patients, 92 Japanese patients were randomized to enzalutamide (n = 36) or a placebo (n = 56), plus androgen deprivation therapy; none received prior docetaxel. Enzalutamide plus androgen deprivation therapy reduced the risk of radiographic progression or death in Japanese patients by 61% versus the placebo, similar to the overall population. Similar results were observed with secondary end‐points, showing clinical benefit of enzalutamide plus androgen deprivation therapy in Japanese patients. Overall survival data were immature. Grade 3–4 adverse events were reported in 47% and 25% of the enzalutamide and placebo groups, respectively. Nasopharyngitis, hypertension and abnormal hepatic function were reported more frequently in Japanese patients versus the overall population.

Conclusions

Enzalutamide plus androgen deprivation therapy has clinical benefit with a tolerable safety profile in Japanese men with metastatic hormone‐sensitive prostate cancer, consistent with the overall population.