Docetaxel-rechallenge in castration-resistant prostate cancer: defining clinical factors for successful treatment response and improvement in overall survival

The second docetaxel rechallenge for metastatic castration-resistant prostate cancer: a case report

Background

Docetaxel combined with prednisone plus androgen deprivation therapy (ADT) is the preferred treatment option for metastatic hormone-sensitive prostate cancer (mHSPC) or metastatic castration-resistant prostate cancer (mCRPC). With the development of next-generation hormonal agents (NHAs) and poly (ADP-ribose) polymerase (PARP) inhibitors, more aggressive first-line or later-line treatment strategies have been added to the treatment of mHSPC and mCRPC. However, docetaxel rechallenge (DR) has special clinical significance in patients with "docetaxel-sensitive" prostate cancer. There are no reports on the efficacy and safety of the second DR in mCRPC patients.

Case presentation

We report one patient diagnosed with mCRPC who showed progression-free survival (PFS) and overall survival (OS) benefits and safety and good lower urinary tract function after the second DR.

Conclusion

The second DR as a potential alternative later-line treatment strategy should be considered for patients with mCRPC who worry about the high economic burden of multigene molecular testing and PARP inhibitors as well as repeated prostate needle biopsy.

UnCHAARTED territory: The role of docetaxel rechallenge following chemohormonal therapy for metastatic castration-sensitive prostate cancer

OBJECTIVE

To assess the effectiveness of docetaxel rechallenge (DR) for metastatic castration-resistant prostate cancer (mCRPC) following chemohormonal therapy for metastatic castrate-sensitive prostate cancer (mCSPC). Additionally, we sought to define clinical factors predicting treatment response.

PATIENTS AND METHODS

Retrospective analysis of men treated with docetaxel for mCSPC and then rechallenged in the mCRPC setting from four cancer centers in Ontario, Canada. Prostate specific antigen (PSA) response, progression-free survival (PFS), and overall survival (OS) following DR were evaluated.

RESULTS

Fifty five patients were identified between 2015 and 2020. Prior to DR, 94.5% of patients received androgen-receptor axis targeted therapy, 20% received radium-223, and 1.8% received cabazitaxel. Among 54 evaluable patients, 27.8% had a PSA decline ≥50%. Median PFS was 4.1 months (95% CI, 2.1-4.8) and median OS from androgen deprivation therapy initiation was 38.3 months (95% CI, 32.9-41.0). A Gleason Score of ≥8 was an independent predictor of prolonged PFS (HR 0.32, 95% CI, 0.12-0.81; P=0.02).

CONCLUSIONS

DR following chemohormonal therapy for mCSPC produced a meaningful PSA response in approximately one-quarter of patients, with relatively short PFS. The impact of Gleason Score on docetaxel response warrants further investigation.

Appropriate Patient Status for Ra-223 Treatment in the Treatment Sequence for Castration-resistant Prostate Cancer

BACKGROUND/AIM

Radium (Ra)-223 is widely used for treating castration-resistant prostate cancer (CRPC) with bone metastasis based on evidence of increased survival and decreased skeletal-related events. However, the timing of Ra-223 use in the treatment sequence of CRPC remains controversial. Therefore, this study aimed to explore the appropriate patient status for Ra-223 use in the CRPC treatment sequence by examining patients treated with Ra-223 from the time of CRPC diagnosis until death.

PATIENTS AND METHODS

The medical records of 67 CRPC patients with bone metastasis who were treated with Ra-223 at two institutes were retrospectively analysed. The impact of 13 factors from the time of CRPC diagnosis until death was analysed using univariate and multivariate Cox hazard ratio models to evaluate the appropriate patient status for Ra-223 treatment.

RESULTS

The median survival time following CRPC diagnosis for all the patient groups was 3.82 years. Univariate analysis identified a higher-than-normal alkaline phosphatase (ALP) level, bone scan indexes ≥2, and prostate-specific antigen (PSA) doubling time <3 months before Ra-223 treatment as predominant adverse prognostic factors. Ra-223 therapy discontinuation was not a significant factor. The survival of CRPC patients with these factors was significantly worse than that of patients without these factors. In the multivariate analysis, a higher-than-normal ALP level at the start of treatment was identified as a poor prognostic factor for mortality.

CONCLUSION

The appropriate patient status for Ra-223 use includes low bone metastasis burden and well-controlled PSA levels.

Artesunate Inhibits the Growth Behavior of Docetaxel-Resistant Prostate Cancer Cells

Novel therapeutic strategies are urgently needed for advanced metastatic prostate cancer (PCa). Phytochemicals used in Traditional Chinese Medicine seem to exhibit tumor suppressive properties. Therefore, the therapeutic potential of artesunate (ART) on the progressive growth of therapy-sensitive (parental) and docetaxel (DX)-resistant PCa cells was investigated. Parental and DX-resistant PCa cell lines DU145, PC3, and LNCaP were incubated with artesunate (ART) [1-100 µM]. ART-untreated and 'non-cancerous' cells served as controls. Cell growth, proliferation, cell cycle progression, cell death and the expression of involved proteins were evaluated. ART, dose- and time-dependently, significantly restricted cell growth and proliferation of parental and DX-resistant PCa cells, but not of 'normal, non-cancerous' cells. ART-induced growth and proliferation inhibition was accompanied by G0/G1 phase arrest and down-regulation of cell cycle activating proteins in all DX-resistant PCa cells and parental LNCaP. In the parental and DX-resistant PC3 and LNCaP cell lines, ART also promoted apoptotic cell death. Ferroptosis was exclusively induced by ART in parental and DX-resistant DU145 cells by increasing reactive oxygen species (ROS). The anti-cancer activity displayed by ART took effect in all three PCa cell lines, but through different mechanisms of action. Thus, in advanced PCa, ART may hold promise as a complementary treatment together with conventional therapy.

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.

Maintenance Long-Term Multiple Cycles Treatment with Docetaxel in Metastatic Castration-Resistant Prostate Cancer: A Report of Three Cases

Prostate cancer (PCa) is one of the most common types of malignancy, most patients with PCa will eventually progress to metastatic castration-resistant prostate cancer (mCRPC), which has a poor prognosis. Since 2004, chemotherapy has been approved by the FDA as the first-line treatment for mCRPC, and docetaxel-based regimens have been shown to improve both the patients’ symptoms and overall survival (OS). 10 cycles of docetaxel therapy are usually given to patients with mCPRC, but there is still no consensus on the optimal number of treatment cycles. Here, we present three cases of mCRPC patients that received maintenance long-term multiple-cycles docetaxel treatment. We believe that this new treatment strategy may benefit carefully selected mCRPC patients and provide several key advantages such as maximum exposure to drugs, improvements in drug efficacy, and reduce the risk of developing drug resistance.

Emerging promising biomarkers for treatment decision in metastatic castration-resistant prostate cancer

Prostate cancer is one of the most common causes of death in males. Even if treatment is often of curative intent in early stages of the disease, up to 50% of patients relapse after primary therapy. Moreover, 10% to 15% of patients present in a primary metastatic stage of disease. In the past years the treatment landscape of metastatic castration-resistant prostate cancer expanded due to the development of second-generation antiandrogens (abiraterone acetate, enzalutamide), chemotherapeutic agents and radium-223. With the availability of several therapeutic lines, we are now confronted with the problem of choosing the most suitable therapy in each state of disease. As often observed in clinical routine, prostate specific antigen is not sufficient for early prediction of a therapy response. Furthermore, biomarkers for prediction of the optimal first-line therapy are badly needed in order to avoid primary resistance. Therefore, the present short review article gives an overview of currently available clinical and preclinical biomarkers for treatment response to metastatic castration-resistant prostate cancer therapeutic agents with the aim of providing support for a personalized decision-making process in everyday use.

Docetaxel Rechallenge in Patients with Metastatic Prostate Cancer: A Comprehensive Review

BACKGROUND

Recent years have witnessed a huge shift in the management and prognosis of metastatic prostate cancer with the advent of new-generation anti-hormonal treatments. Docetaxel, which was initially approved in the castrate-resistant prostate cancer setting, has been approved in the earlier course of the disease as it is still castrate sensitive.

SUMMARY

Apart from cabazitaxel and in the absence of other effective chemotherapies, docetaxel rechallenge (DR) in patients with proved sensitivity to docetaxel in the earlier stage of the disease remains a possible option. Unfortunately, the pivotal trials rarely reported on the outcomes of docetaxel retreatment which seems a plausible option in patients initially responding to docetaxel and maintaining a minimum progression-free interval of 3-6 months. In this review, a summary of the clinical evidence and potential concerns for the use of DR in patients with metastatic prostate cancer will be presented. Key Messages: Pivotal trials of docetaxel in metastatic castrate-sensitive prostate cancer as well as metastatic castrate-resistant prostate cancer have not reported on the outcomes of DR except in the GETUG-AFU 15 trial where the outcomes were disappointing. Based on the published retrospective data, DR may be effective in patients who initially responded to docetaxel and maintained a progression-free interval exceeding 6 months.

Overexpression of SLC6A1 associates with drug resistance and poor prognosis in prostate cancer

Background

Solute Carrier Family 6 Member 1 (SLC6A1) has been identified as a cancer-promoting gene in various human cancers, such as clear cell renal cell carcinoma and ovarian cancer. However, its roles in prostate cancer (PCa) has not been fully elucidated. The aim of this study was to investigate the expression and clinical significance of SLC6A1 in PCa tissues and its effect on drug resistance to docetaxel in PCa.

Methods

Expression patterns of SLC6A1 protein in PCa tissues were examined by immunohistochemistry based on Tissue microarray. Associations of SLC6A1 protein expression with various clinicopathological features and patients’ prognosis of PCa were also statistically evaluated based on TCGA data. Roles of SLC6A1 deregulation in prostate carcinogenesis and drug resistance was further determined in vitro and in vivo experiments.

Results

Based on TCGA Dataset, SLC6A1 expression was markedly higher in patients with high Gleason score, advanced clinical stage and positive biochemical recurrence than those with control features (all P < 0.05). Both unvariate and multivariate analyses demonstrated that SLC6A1 expression was significantly associated with biochemical recurrence-free survival in PCa patients. In addition, enforced expression of SLC6A1 effectively promoted cell proliferation, migration and invasion of PCa cells in vitro. Moreover, the inhibition of SLC6A1 suppressed the tumor growth in vivo. Additionally, immunohistochemical notches of PCNA and MMP-9 in the low-expression cluster were pointedly lower compared to those of NC group. Finally, the cell viability revealed that the overexpression of SLC6A1 obviously promoted the PCa cell resistant to docetaxel (DTX), and the transplanted tumor in the overexpression group had no significant reduction compared with the untreated group.

Conclusions

Our data suggest that SLC6A1 overexpression may be associated with aggressive progression and short biochemical recurrence-free survival of PCa, and may be related to the resistance to docetaxel therapy.

Docetaxel rechallenge in metastatic castration-resistant prostate cancer: A retrospective, single-center study

Purpose

To assess the efficacy and safety of docetaxel rechallenge in the salvage setting in metastatic castration-resistant prostate cancer (mCRPC) patients.

Materials and Methods

Clinicopathologic data from patients treated with docetaxel rechallenge were collected from a single-center cancer registry. Among 227 patients who received first-line docetaxel for mCRPC between January 2011 and June 2019, 23 undergo rechallenge docetaxel after failure to androgen receptor targeting agents and/or cabazitaxel treatment. Endpoints included radiologic progression-free survival (PFS), treatment duration, and prostate-specific antigen (PSA) response and safety.

Results

Overall, 30%, 44%, 13%, and 13% of patients received docetaxel rechallenge as either the third, fourth, fifth, or sixth-line therapy, respectively, at a median of 23.6 months after stopping first-line docetaxel. With first-line docetaxel and rechallenge, median treatment duration was 6.4 and 3.3 months, respectively. With docetaxel rechallenge, PSA response was 35% (95% confidence interval [CI], 15% to 54%) and median PFS was 4.5 months (95% CI, 1.9 to 7.1 months). The median OS was 24.3 months (95% CI, 4.6 to 44.0 months). There were 7 severe adverse events (grade 3 or more) including anemia (8.7%), neutropenia, thrombocytopenia, leukopenia, diarrhea, and nausea (4.3% each).

Conclusions

Docetaxel rechallenge showed meaningful anti-tumor activity with acceptable toxicity in heavily pretreated patients with mCRPC.

Sequencing strategies in the new treatment landscape of prostate cancer

Over the last 10 years, a number of new agents approved for the treatment of metastatic castration-resistant prostate cancer have led to a significant improvement in overall survival. The addition of new agents to androgen deprivation therapy has also allowed a paradigmatic change in the treatment of metastatic hormone-sensitive prostate cancer by improving overall survival in comparison with androgen deprivation therapy alone. Furthermore, recent data concerning the efficacy of three different androgen receptor-targeting agents in patients with nonmetastatic castration-resistant prostate cancer have opened up new scenarios for future patients' management. Defining the best sequencing strategies for men with prostate cancer is a currently unmet medical need, and choosing treatment is often challenging for clinicians because of the lack of direct comparisons of the available agents. The aim of this paper is to provide a comprehensive review of the literature concerning current sequencing strategies for prostate cancer patients.