Is there still a place for docetaxel rechallenge in prostate cancer?

The efficacy and safety of immune checkpoint inhibitors in metastatic castration-resistant prostate cancer: A systematic review and meta-analysis

BACKGROUND

We aim to assess the efficacy and safety profiles of immune checkpoint inhibitors in patients with metastatic castration-resistant prostate cancer using a meta-analysis.

METHODS

We extracted and examined data from phase I, II and III clinical trials from PubMed, Embase, Web of Science, and Cochrane Library, which included patients with metastatic castration-resistant prostate cancer who were treated with immune checkpoint inhibitors. We performed a meta-analysis to investigate several indexes of efficacy and safety, including the objective response rate, 1-year overall survival (OS) rate, prostate-specific antigen response rate, and adverse event rate of immune checkpoint inhibitors. The material data were calculated and pooled using The R Project for Statistical Computing and STATA 12.0 software.

RESULTS

We identified 12 clinical trials in our study. We assessed the pooled frequencies of all-grade AEs and grade ≥ 3 AEs first and showed 0.82 (95% CI: 0.74-0.91, I2 = 94%, P < .01) and 0.42 (95% CI: 0.33-0.54, I2 = 96%, P < .01), respectively. The objective response rate was 0.10 (95% CI: 0.04-0.19, I2 = 70%, P < .01), and the 1-year OS and prostate-specific antigen response rate were 0.55 (95% CI: 0.45-0.67, I2 = 93%, P < .01) and 0.18 (95% CI: 0.16-0.20, I2 = 43%, P = .03), respectively.

CONCLUSION

The immune checkpoint inhibitors therapy was well tolerated and showed potential to improve tumor responses in patients with metastatic castration-resistant prostate cancer.

Multiple Docetaxel Retreatments Without Prednisone for Metastatic Castration-Resistant Prostate Cancer in the Docetaxel-Only Era: Effects on PSA Kinetics and Survival

Introduction

This study aimed to assess the effects of multiple docetaxel (DOC) treatments on prostate-specific antigen (PSA) kinetics and survival among patients with metastatic castration-resistant prostate cancer (mCRPC) who were sensitive to first-line DOC and received no other life-prolonging agents. To eliminate the effect of cortisone on serum PSA, only patients who were treated without prednisone were included.

Methods

This IRB-approved retrospective study evaluated 52 patients with mCRPC who were retreated using DOC after first-line DOC (without prednisone in both cases), based on a PSA response of > 50% and no radiographic progression. Twenty-three PSA-based factors, including static and kinetic PSA measures, were evaluate for their ability to predict overall survival (OS)

Results

The patients received 688 cycles of DOC in 143 series, including 91 courses of retreatments (1 cycle: 28 patients, 2 cycles: 14 patients, 3 cycles: 8 patients, 4 cycles: 1 patient, and 7 cycles: 1 patient). The median overall number of cycles per patient was 12 (range: 7–31). The median durations of the first, second, and third holidays were 18 weeks (6–60 weeks), 16 weeks (3–44 weeks), and 17 weeks (8–51 weeks), respectively. The median OSs were 22 months (10.5–70 months) after the first DOC treatment and 14 months (3–65 months) after the second DOC treatment. The > 50% PSA decline rate was 48% after retreatment. Short treatment holidays (< 3 months) were associated with shortened OS (p = 0.01). In the multivariate analysis, a 25% PSA increase over the nadir was the strongest predictor of survival (HR: 3.20, 95% CI: 1.47–6.99, p = 0.003).

Conclusions

DOC retreatment without prednisone had anti-tumor activity in a considerable proportion of mCRPC cases that were initially sensitive to first-line DOC. A 25% PSA increase over the nadir might predict acquired DOC resistance.

Role of novel hormonal therapies in the management of non-metastatic castration-resistant prostate cancer: a literature-based meta-analysis of randomized trials

BACKGROUND

Novel hormonal therapies have been recently investigated in non-metastatic castration-resistant prostate cancer (CRPC). We performed a meta-analysis to assess the efficacy and safety of novel hormonal therapies in non-metastatic CRPC.

MATERIALS AND METHODS

The primary outcome was metastasis-free survival (MFS). The secondary endpoints were overall survival (OS), time to PSA progression and safety. We planned a subgroup analysis according to the PSA doubling time (> 6 vs < 6 months), Eastern Cooperative Oncology Group (ECOG) performance status (1 vs 0) and concomitant use of bone-targeting agent (yes vs no).

RESULTS

Pooled analysis of novel hormonal therapies revealed significantly increased MFS compared with placebo (hazard ratio (HR): HR = 0.32, 95% CI 0.25-0.41; p < 0.00001). The subgroup analysis showed a statistically significant MFS advantage in favour of men with the lower ECOG performance status. Other secondary endpoints favoured the novel hormonal therapies. The relative risk (RR) of grade ≥ 3 adverse events and ≥ 3 hypertension was 1.31 and 1.39, respectively.

CONCLUSIONS

This study confirmed the efficacy and safety of the novel hormonal therapies in non-metastatic CRPC.

Corticosteroid switch after progression on abiraterone acetate plus prednisone

INTRODUCTION

Abiraterone acetate plus prednisone is approved in metastatic castration-resistant prostate cancer. There is some evidence in favour of the steroid switch from prednisone to dexamethasone in patients who progressed whilst on abiraterone acetate plus prednisone or prednisolone.

MATERIALS AND METHODS

The aim of this review is to discuss the results from the clinical studies available, examining potential mechanisms of action and patient selection criteria for this treatment option.

RESULTS

A total of four studies were evaluated. Among possible eligibility criteria for steroid switch, we found: PSA progression without any radiological or clinical progression during abiraterone acetate + prednisone; no high-grade adverse events related to CYP-17 inhibition; and unfitness for chemotherapy or radium-223.

CONCLUSION

Although large randomized prospective trials are warranted, steroid switch seems to offer a good option for certain patients treated with abiraterone acetate plus prednisone or prednisolone.

Is there still a place for vinorelbine in advanced metastatic castration resistant prostate cancer?

The aim of this paper was to evaluate the activity and tolerability of oral vinorelbine in patients with advanced castration resistant prostate cancer (CRPC) who progressed after a minimum of three lines including: abiraterone acetate, docetaxel, cabazitaxel, and enzalutamide.Treatment consisted of weekly oral vinorelbine 60 mg/m. Chemotherapy was administered until disease progression or unacceptable toxicity.Twenty-six patients received vinorelbine: their median age was 74 years (range 58-84 years). Twenty-four (92.3%) patients had bone metastases. A decrease in PSA levels ≥50% was observed in 2 patients (7.7%). Among the subjects who were symptomatic at baseline, pain was reduced in 3 patients (13.6%) with a significant decrease in analgesic use. Median progression-free survival was 9 weeks (95% CI: 7 to 11) and median overall survival was 17 weeks (95% CI: 12 to 22). Treatment was well tolerated, and no grade 4 toxicities were observed.Our findings do not suggest the use of oral vinorelbine on a weekly schedule, in CRPC heavily pre-treated.

A multicenter observational study of the real-world use of docetaxel for metastatic castration-resistant prostate cancer in China

Aim

To investigate the use of docetaxel for the treatment of metastatic castration‐resistant prostate cancer (mCRPC) in real‐world clinical practice in China.

Methods

This single‐arm, prospective, observational study was conducted at 32 study centers in China and included male patients aged ≥18 years with histologically confirmed prostate cancer who received ≥1 dose of docetaxel following failure of hormonal therapy (disease progression with serum testosterone <50 ng/dL). The primary aim was to investigate patterns of docetaxel treatment.

Results

Overall 403 patients were included between August 2011 and June 2016; patients initiated docetaxel after failure of first‐ (42.2% [170]), second‐ (31.0% [125]) and ≥third‐line (12.7% [51]) hormonal therapy, estramustine (11.4% [46]) or other (2.7% [11]). The planned cycles of docetaxel therapy were completed by 30.8% of patients, and the mean (SD) number of cycles received was 4.4 (2.86). Median overall survival (mOS) was 22.4 (95% CI, 20.4–25.8) months and the prostate‐specific antigen (PSA) response rate in patients with available data was 70.9% (168/237), with no differences in mOS and PSA response rates between treatment settings. Subgroup analysis revealed higher mOS in patients without visceral metastasis versus those with such metastases (22.9 vs. 17.4 months; P = 0.022). No new safety signals were observed and the most common adverse events associated with docetaxel were granulocytopenia (5%) and leukopenia (4.5%).

Conclusion

Data from this study showed that around three‐quarters of Chinese patients with mCRPC treated with docetaxel initiated treatment following first‐ or second‐line hormonal therapy and no new safety signals were observed.

New horizons in the management of castrate-resistant prostate cancer

Castrate-resistant prostate cancer is an incurable disease. It continues to be an area of intense research to save prostate cancer patients’ lives. We aim from this review to explore the new lines of treatment that aim at extending disease-specific survival. We conducted a PubMed research on available literature pertaining to key words alone and in combination: prostate cancer, castrate-resistant, immunotherapy, hormonal therapy, chemotherapy, radiation therapy, metastasis, survival and quality of life. We also reviewed the following guidelines on castrate-resistant prostate cancer: National Comprehensive Cancer Network (NCCN), American Urological Association (AUA), the National Institute for Health and Care Excellence (NICE) and the European Association of Urology (EAU). There are four new lines of treatment in castrate-resistant prostate cancer. An immunotherapy, sipuleucel T (Provenge); new hormonal therapies – in the form of a new androgen receptor blocker, enzalutamide (Xtandi) and new adrenal androgen synthesis inhibitor, abiraterone acetate (Zytiga); a new chemotherapy, cabazitaxel (Jevtana) and new radioactive agent, radium 223 (Xofigo). There is an agreement between guidelines that patients with M0 castrate-resistant prostate cancer should not be offered any of these treatments. Similarly, patients with castrate-resistant prostate cancer and poor performance status should be offered only palliative care. There are several new lines of treatment that can be used in castrate-resistant prostate cancer, and hopefully in the near future castrate-resistant prostate cancer will be changing from a lethal disease to more of a chronic disease.

ABCB1 Mediates Cabazitaxel-Docetaxel Cross-Resistance in Advanced Prostate Cancer

Advancements in research have added several new therapies for castration-resistant prostate cancer (CRPC), greatly augmenting our ability to treat patients. However, CRPC remains an incurable disease due to the development of therapeutic resistance and the existence of cross-resistance between available therapies. Understanding the interplay between different treatments will lead to improved sequencing and the creation of combinations that overcome resistance and prolong survival. Whether there exists cross-resistance between docetaxel and the next-generation taxane cabazitaxel is poorly understood. In this study, we use C4-2B and DU145 derived docetaxel-resistant cell lines to test response to cabazitaxel. Our results demonstrate that docetaxel resistance confers cross-resistance to cabazitaxel. We show that increased ABCB1 expression is responsible for cross-resistance to cabazitaxel and that inhibition of ABCB1 function through the small-molecule inhibitor elacridar resensitizes taxane-resistant cells to treatment. In addition, the antiandrogens bicalutamide and enzalutamide, previously demonstrated to be able to resensitize taxane-resistant cells to docetaxel through inhibition of ABCB1 ATPase activity, are also able to resensitize resistant cells to cabazitaxel treatment. Finally, we show that resensitization using an antiandrogen is far more effective in combination with cabazitaxel than docetaxel. Collectively, these results address key concerns in the field, including that of cross-resistance between taxanes and highlighting a mechanism of cabazitaxel resistance involving ABCB1. Furthermore, these preclinical studies suggest the potential in using combinations of antiandrogens with cabazitaxel for increased effect in treating advanced CRPC. Mol Cancer Ther; 16(10); 2257-66. ©2017 AACR.

The Effects and Mechanism of YK-4-279 in Combination with Docetaxel on Prostate Cancer

Background: Docetaxel is the first-line treatment for castration-resistant prostate cancer (CRPC). The limited survival benefit associated with the quick emergence of resistance and systemic toxicity diminishes its efficacy in high-dose monotherapy. YK-4-279 is a small molecule inhibitor of ETV1 that plays an important role in the progression of prostate cancer. The aim of this study was to evaluate the hypothesis that the combination of docetaxel and YK-4-279 will have a synergistic effect on inhibiting growth and accelerating apoptosis in human prostate cancer cells. Methods: Cell growth assessed using CCK-8 and trypan blue exclusion assays. Cell apoptosis was determined by morphological assessment in cells stained with propidium iodide. Standard scratch migration and Matrigel-coated transwell invasion assays were used to assess cell migration and invasion, respectively. Western blotting was used to investigate the levels of ETV1, AR, PSA, p-STAT3, survivin, Bcl-2, and p-Akt in prostate cancer cells. Results: The combination of low-dose docetaxel and YK-4-279 synergistically inhibited growth and induced apoptosis in human prostate cancer cells. The combination also more efficiently suppressed the migration and invasion of LNCaP and PC-3 cells. The combination of low-dose docetaxel and YK-4-279 caused a stronger decrease in the levels of ETV1, AR, PSA, p-STAT3, survivin, Bcl-2, and p-Akt in LNCaP cells and of p-Akt, Bcl-2, and p-STAT3 in PC-3 cells compared with either drug alone. Conclusions: These data suggest that the combination of docetaxel and YK-4-279 may be an effective approach for inhibiting the growth and metastasis of prostate cancer. This could permit a decrease in the docetaxel dose necessary for patients with CRPC and thereby lower its systemic toxicity.

Sipuleucel-T and Androgen Receptor-Directed Therapy for Castration-Resistant Prostate Cancer: A Meta-Analysis

New treatments, such as sipuleucel-T and androgen receptor- (AR-) directed therapies (enzalutamide (Enz) and abiraterone acetate (AA)), have emerged and been approved for the management of castration-resistant prostate cancer (CRPC). There are still debates over their efficacy and clinical benefits. This meta-analysis aimed to investigate the efficacy and safety of sipuleucel-T and AR-directed therapies in patients with CRPC. RevMan 5.1 was used for pooled analysis and analysis of publication bias. Seven studies were included in the meta-analysis, with three studies in sipuleucel-T (totally 737 patients, 488 patients in treatment group, and 249 patients in placebo group) and four in AR-directed therapies (totally 5,199 patients, 3,015 patients in treatment group, and 2,184 patients in placebo group). Treatment with sipuleucel-T significantly improved overall survival in patients with CRPC and was not associated with increased risk of adverse event of grade ≥3 (p > 0.05). However, treatment with sipuleucel-T did not improve time-to-progression and reduction of prostate-specific antigen (PSA) level ≥50% was not significantly different from that with placebo. AR-directed therapies significantly improved overall survival in patients with CRPC and improved time-to-progression and reduction of PSA level ≥50%. AR-directed therapies did not increase risk of adverse event of grade ≥3 (p > 0.05).

Targeting the androgenic pathway in elderly patients with castration-resistant prostate cancer: A meta-analysis of randomized trials

BACKGROUND

The novel hormonal drugs have recently entered in the armamentarium of therapies for treatment of metastatic castration-resistant prostate cancer (CRPC). First reports are available for their use in elderly men with CRPC.

METHOD

A meta-analysis of randomized controlled trials (RCTs) has been performed. PubMed, the Cochrane Library, and American Society of Clinical Oncology (ASCO) University Meeting were searched for data on the use of new hormonal treatment in elderly patients with CRPC.

RESULTS

Nine studies for a total of 3512 elderly patients were available for meta-analysis. Six studies reported outcomes of patients aged >75 years old while 2 studies reported on patients aged >70 years old. The pooled analysis of the androgen synthesis inhibitors revealed significantly increased overall survival (OS) due to antiandrogen agents compared with placebo or placebo and prednisone (hazard ratio (HR) for death: HR = 0.74, 95% CI: 0.67-0.82; P < 0.00001). Moreover, the new antiandrogenic therapy significantly improved the progression-free survival (HR = 0.45, 95% CI: 0.31-0.65; P < 0.0001). The incidence of any grade ≥3 adverse effect was only moderately higher during with the antiandrogenic therapy as compared to the control arms (response rate = 1.03, 95% CI: 0.88-1.20; P = 0.72).

CONCLUSION

This study confirmed that agents targeting the androgen axis (i.e., enzalutamide, abiraterone) significantly prolonged OS in elderly men with CRPC.

Role of the novel generation of androgen receptor pathway targeted agents in the management of castration-resistant prostate cancer: A literature based meta-analysis of randomized trials

BACKGROUND

Several novel androgen receptor pathway targeted agents have recently entered on to therapeutic landscape for metastatic castration-resistant prostate cancer (CRPC). We performed a meta-analysis to assess the effect of these novel androgen receptor pathway targeted agents in improving outcome of CRPC patients.

METHODS

A literature-based meta-analysis of randomized controlled trials (RCTs) in accordance with the preferences for reported items in systematic reviews and meta-analyses guidelines was undertaken. Relevant publications from PubMed, the Cochrane Library, and abstracts from American Society of Clinical Oncology meetings were searched. The primary outcome was overall survival. The secondary end-points were time to the first symptomatic skeletal event, progression-free survival, prostatic antigen specific (PSA) response rate, time to PSA progression and safety.

RESULTS

Pooled analysis from RCTs of novel androgen receptor pathway targeted agents revealed significantly increased overall survival compared with placebo or prednisone (hazard ratio [HR] for death: 0.79, 95% confidence interval [CI]: 0.71-0.87; P < 0.00001). All secondary end-points favoured the androgen receptor pathway targeted agents, although heterogeneity was high in some cases. The pooled analysis revealed that the androgen receptor pathway targeted agents significantly improved time to the first skeletal event (HR = 0.69, 95% CI: 0.63-0.75; P < 0.00001), progression-free survival (HR = 0.48, 95% CI: 0.37-0.62; P < 0.00001), time to PSA progression (HR = 0.37, 95% CI: 0.24-0.59; P < 0.0001) and PSA response rate (relative risk [RR] = 4.46, 95% CI: 2.63-7.55; P < 0.00001). The incidence of grade ≥3 adverse events was moderately higher with androgen receptor pathway targeted agents as compared with the control arms (RR = 1.11, 95% CI: 0.98-1.25; P = 0.09).

CONCLUSION

This study confirmed the efficacy and safety of the novel androgen receptor pathway targeted agents.