Phase I/II trial of cabazitaxel plus abiraterone in patients with metastatic castration-resistant prostate cancer (mCRPC) progressing after docetaxel and abiraterone

Comprehensive analysis of 33 human cancers reveals clinical implications and immunotherapeutic value of the solute carrier family 35 member A2

Background

Solute carrier family 35 member A2 (SLC35A2), which belongs to the SLC35 solute carrier family of human nucleoside sugar transporters, has shown regulatory roles in various tumors and neoplasms. However, the function of SLC35A2 across human cancers remains to be systematically assessed. Insights into the prediction ability of SLC35A2 in clinical practice and immunotherapy response remains limited.

Materials and methods

We obtained the gene expression and protein levels of SLC35A2 in a variety of tumors from Molecular Taxonomy of Breast Cancer International Consortium, The Cancer Genome Atlas, Gene Expression Omnibus, Chinese Glioma Genome Atlas, and Human Protein Atlas databases. The SLC35A2 level was validated by immunohistochemistry. The predictive value for prognosis was evaluated by Kaplan-Meier survival and Cox regression analyses. Correlations between SLC35A2 expression and DNA methylation, genetic alterations, tumor mutation burden (TMB), microsatellite instability (MSI), and tumor microenvironment were performed using Spearman's correlation analysis. The possible downstream pathways of SLC35A2 in different human cancers were explored using gene set variation analysis. The potential role of SLC35A2 in the tumor immune microenvironment was evaluated via EPIC, CIBERSORT, MCP-counter, CIBERSORT-ABS, quanTIseq, TIMER, and xCell algorithms. The difference in the immunotherapeutic response of SLC35A2 under different expression conditions was evaluated by the tumor immune dysfunction and exclusion (TIDE) score as well as four independent immunotherapy cohorts, which includes patients with bladder urothelial carcinoma (BLCA, N = 299), non-small cell lung cancer (NSCLC, N = 72 and N = 36) and skin cutaneous melanoma (SKCM, N = 25). Potential drugs were identified using the CellMiner database and molecular docking.

Results

SLC35A2 exhibited abnormally high or low expression in 23 cancers and was significantly associated with the prognosis. In various cancers, SLC35A2 expression and mammalian target of rapamycin complex 1 signaling were positively correlated. Multiple algorithmic immune infiltration analyses suggested an inverse relation between SLC35A2 expression and infiltrating immune cells, which includes CD4+T cells, CD8+T cells, B cells, and natural killer cells (NK) in various tumors. Furthermore, SLC35A2 expression was significantly correlated with pan-cancer immune checkpoints, TMB, MSI, and TIDE genes. SLC35A2 showed significant predictive value for the immunotherapy response of patients with diverse cancers. Two drugs, vismodegib and abiraterone, were identified, and the free binding energy of cytochrome P17 with abiraterone was higher than that of SLC35A2 with abiraterone.

Conclusion

Our study revealed that SLC35A2 is upregulated in 20 types of cancer, including lung adenocarcinoma (LUAD), breast invasive carcinoma (BRCA), colon adenocarcinoma (COAD), and lung squamous cell carcinoma (LUSC). The upregulated SLC35A2 in five cancer types indicates a poor prognosis. Furthermore, there was a positive correlation between the overexpression of SLC35A2 and reduced lymphocyte infiltration in 13 cancer types, including BRCA and COAD. Based on data from several clinical trials, patients with LUAD, LUSC, SKCM, and BLCA who exhibited high SLC35A2 expression may experience improved immunotherapy response. Therefore, SLC35A2 could be considered a potential predictive biomarker for the prognosis and immunotherapy efficacy of various tumors. Our study provides a theoretical basis for further investigating its prognostic and therapeutic potentials.

The synergistic anticancer effect of salinomycin combined with cabazitaxel in CD44+ prostate cancer cells by downregulating wnt, NF-κB and AKT signaling

BACKGROUND

Tumor-initiating or cancer stem cells (CSCs) reduce the effectiveness of conventional therapy. Thus, it is crucial to eliminate CSCs while killing bulky cancer cells using a combination of conventional chemotherapy and anti-CSC drugs. Salinomycin is a selective inhibitor against CSCs and shows promise in combination applications. The aim of the study was to examine the efficacy of co-administered cabazitaxel and salinomycin on the survival of prostate cancer cells and CSCs.

METHODS AND RESULTS

CD44 + stem cells were isolated from human PC3 prostate cancer cells by using magnetic activated cell sorting. The cells were concomitantly exposed to salinomycin and cabazitaxel, and the cell survival was determined by MTT test. Apoptosis was assessed by image-based cytometer, and cell migration was evaluated by wound healing assay. The expression of target mRNA and protein were assessed by RT-qPCR and Western blot, respectively. Combination index (CI) analysis showed that simultaneous administration of salinomycin and cabazitaxel was able to exert strong synergistic effect on CD44 + subpopulation (CI = 0.33), but no synergism was observed in PC3 cells. The combination of the two agents significantly increased Bax, cytochrome c, caspase-3 and - 8 mRNA expression in CD44 + CSCs, causing apoptosis. The applied therapy strategy strongly inhibited the phosphorylation of Akt, protein expression of Akt1, NF-κB and Wnt.

CONCLUSIONS

In conclusion, our data suggest that combining salinomycin with cabazitaxel shows promise as a prostate cancer treatment approach that can target CSCs.

Abiraterone plus prednisone added to androgen deprivation therapy and docetaxel in de novo metastatic castration-sensitive prostate cancer (PEACE-1): a multicentre, open-label, randomised, phase 3 study with a 2 × 2 factorial design

BACKGROUND

Current standard of care for metastatic castration-sensitive prostate cancer supplements androgen deprivation therapy with either docetaxel, second-generation hormonal therapy, or radiotherapy. We aimed to evaluate the efficacy and safety of abiraterone plus prednisone, with or without radiotherapy, in addition to standard of care.

METHODS

We conducted an open-label, randomised, phase 3 study with a 2 × 2 factorial design (PEACE-1) at 77 hospitals across Belgium, France, Ireland, Italy, Romania, Spain, and Switzerland. Eligible patients were male, aged 18 years or older, with histologically confirmed or cytologically confirmed de novo metastatic prostate adenocarcinoma, and an Eastern Cooperative Oncology Group performance status of 0-1 (or 2 due to bone pain). Participants were randomly assigned (1:1:1:1) to standard of care (androgen deprivation therapy alone or with intravenous docetaxel 75 mg/m2 once every 3 weeks), standard of care plus radiotherapy, standard of care plus abiraterone (oral 1000 mg abiraterone once daily plus oral 5 mg prednisone twice daily), or standard of care plus radiotherapy plus abiraterone. Neither the investigators nor the patients were masked to treatment allocation. The coprimary endpoints were radiographic progression-free survival and overall survival. Abiraterone efficacy was first assessed in the overall population and then in the population who received androgen deprivation therapy with docetaxel as standard of care (population of interest). This study is ongoing and is registered with ClinicalTrials.gov, NCT01957436.

FINDINGS

Between Nov 27, 2013, and Dec 20, 2018, 1173 patients were enrolled (one patient subsequently withdrew consent for analysis of his data) and assigned to receive standard of care (n=296), standard of care plus radiotherapy (n=293), standard of care plus abiraterone (n=292), or standard of care plus radiotherapy plus abiraterone (n=291). Median follow-up was 3·5 years (IQR 2·8-4·6) for radiographic progression-free survival and 4·4 years (3·5-5·4) for overall survival. Adjusted Cox regression modelling revealed no interaction between abiraterone and radiotherapy, enabling the pooled analysis of abiraterone efficacy. In the overall population, patients assigned to receive abiraterone (n=583) had longer radiographic progression-free survival (hazard ratio [HR] 0·54, 99·9% CI 0·41-0·71; p<0·0001) and overall survival (0·82, 95·1% CI 0·69-0·98; p=0·030) than patients who did not receive abiraterone (n=589). In the androgen deprivation therapy with docetaxel population (n=355 in both with abiraterone and without abiraterone groups), the HRs were consistent (radiographic progression-free survival 0·50, 99·9% CI 0·34-0·71; p<0·0001; overall survival 0·75, 95·1% CI 0·59-0·95; p=0·017). In the androgen deprivation therapy with docetaxel population, grade 3 or worse adverse events occurred in 217 (63%) of 347 patients who received abiraterone and 181 (52%) of 350 who did not; hypertension had the largest difference in occurrence (76 [22%] patients and 45 [13%], respectively). Addition of abiraterone to androgen deprivation therapy plus docetaxel did not increase the rates of neutropenia, febrile neutropenia, fatigue, or neuropathy compared with androgen deprivation therapy plus docetaxel alone.

INTERPRETATION

Combining androgen deprivation therapy, docetaxel, and abiraterone in de novo metastatic castration-sensitive prostate cancer improved overall survival and radiographic progression-free survival with a modest increase in toxicity, mostly hypertension. This triplet therapy could become a standard of care for these patients.

FUNDING

Janssen-Cilag, Ipsen, Sanofi, and the French Government.

Docetaxel and prednisone with or without enzalutamide as first-line treatment in patients with metastatic castration-resistant prostate cancer: CHEIRON, a randomised phase II trial

BACKGROUND

Pre-clinical data suggest that docetaxel and enzalutamide interfere with androgen receptor translocation and signalling. The aim of this study is to assess the efficacy of their concurrent administration in the first-line treatment for metastatic castration-resistant prostate cancer (mCRPC).

METHODS

In this open-label, randomised, phase II trial, previously untreated mCRPC patients were randomised 1:1 to receive eight 21-d courses of docetaxel 75 mg/m2, oral prednisone 5 mg twice daily and oral enzalutamide 160 mg/d (arm DE), or the same treatment without enzalutamide (arm D). The primary end-point was the percentage of patients without investigator-assessed disease progression 6 months after the first docetaxel administration.

RESULTS

The 246 eligible patients were randomly assigned to receive docetaxel, prednisone and enzalutamide (n = 120) or docetaxel and prednisone (n = 126). The 6-month progression rate was 12.5% (95% confidence interval [CI] 8.1-20.6) in arm DE and 27.8% (95% CI 22.8-39.4) in arm D (chi-squared test 10.01; P = 0.002). The most frequent grade III-IV adverse events were fatigue (12.5% in arm DE versus 5.6% in arm D), febrile neutropenia (9.3% versus 4.0%) and neutropenia (7.6% versus 5.6%).

CONCLUSIONS

The combination of enzalutamide and docetaxel appears to be more clinically beneficial than docetaxel alone in previously untreated mCRPC patients, although serious adverse events were more frequent. Our findings suggest that first-line treatment with this combination could lead to an additional clinical benefit when prompt and prolonged disease control is simultaneously required. Clearly, these results should be considered cautiously because of the study's phase II design and the absence of an overall survival benefit.

TRIAL REGISTRATION NUMBERS

EudraCT 2014-000175-43 - NCT02453009.

Mechanisms of Taxane Resistance

The taxane family of chemotherapy drugs has been used to treat a variety of mostly epithelial-derived tumors and remain the first-line treatment for some cancers. Despite the improved survival time and reduction of tumor size observed in some patients, many have no response to the drugs or develop resistance over time. Taxane resistance is multi-faceted and involves multiple pathways in proliferation, apoptosis, metabolism, and the transport of foreign substances. In this review, we dive deeper into hypothesized resistance mechanisms from research during the last decade, with a focus on the cancer types that use taxanes as first-line treatment but frequently develop resistance to them. Furthermore, we will discuss current clinical inhibitors and those yet to be approved that target key pathways or proteins and aim to reverse resistance in combination with taxanes or individually. Lastly, we will highlight taxane response biomarkers, specific genes with monitored expression and correlated with response to taxanes, mentioning those currently being used and those that should be adopted. The future directions of taxanes involve more personalized approaches to treatment by tailoring drug-inhibitor combinations or alternatives depending on levels of resistance biomarkers. We hope that this review will identify gaps in knowledge surrounding taxane resistance that future research or clinical trials can overcome.

Pharmacokinetic drug–drug interactions: an insight into recent US FDA-approved drugs for prostate cancer

Pharmacokinetic drug–drug interaction is a significant safety and efficiency concern as it results in considerable concentration changes. Drug–drug interactions are a substantial concern in anticancer drugs that possess a narrow therapeutic index. These interactions remain as the principal regulatory obstacle that can lead to termination in the preclinical stage, restrictions in the prescription, dosage adjustments or withdrawal of the drugs from the market. Drug metabolizing enzymes or transporters mediate the majority of clinically relevant drug interactions. Cancer diagnosed aged patients use multiple medications and are more prone to significant drug–drug interactions. This review provides detailed information on clinically relevant drug–drug interactions resulting from drug metabolism by enzymes and transporters with a particular emphasis on recent FDA approved antiprostate cancer drugs.

The Wnt non-canonical signaling modulates cabazitaxel sensitivity in prostate cancer cells

Background

Despite new drugs, metastatic prostate cancer remains fatal. Growing interest in the latest approved cabazitaxel taxane drug has markedly increased due to the survival benefits conferred when used at an earlier stage of the disease, its promising new therapeutic combination and formulation, and its differential toxicity. Still cabazitaxel’s mechanisms of resistance are poorly characterized. The goal of this study was thus to generate a new model of acquired resistance against cabazitaxel in order to unravel cabazitaxel’s resistance mechanisms.

Methods

Du145 cells were cultured with increasing concentrations of cabazitaxel, docetaxel/ taxane control or placebo/age-matched control. Once resistance was reached, Epithelial-to-Mesenchymal Translation (EMT) was tested by cell morphology, cell migration, and E/M markers expression profile. Cell transcriptomics were determined by RNA sequencing; related pathways were identified using IPA, PANTHER or KEGG software. The Wnt pathway was analyzed by western blotting, pharmacological and knock-down studies.

Results

While age-matched Du145 cells were sensitive to both taxane drugs, docetaxel-resistant cells were only resistant to docetaxel and cabazitaxel-resistant cells showed a partial cross-resistance to both drugs concomitant to EMT. Using RNA-sequencing, the Wnt non-canonical pathway was identified as exclusively activated in cabazitaxel resistant cells while the Wnt canonical pathway was restricted to docetaxel-resistant cells. Cabazitaxel-resistant cells showed a minimal crossover in the Wnt-pathway-related genes linked to docetaxel resistance validating our unique model of acquired resistance to cabazitaxel. Pharmacological and western blot studies confirmed these findings and suggest the implication of the Tyrosine kinase Ror2 receptor in cabazitaxel resistant cells. Variation in Ror2 expression level altered the sensitivity of prostate cancer cells to both drugs identifying a possible new target for taxane resistance.

Conclusion

Our study represents the first demonstration that while Wnt pathway seems to play an important role in taxanes resistance, Wnt effectors responsible for taxane specificity remain un-identified prompting the need for more studies.

Current opinion and mechanistic interpretation of combination therapy for castration-resistant prostate cancer

Recent advances in genomics technology have led to the massive discovery of new drug targets for prostate cancer; however, none of the currently available therapeutics is curative. One of the greatest challenges is drug resistance. Combinations of therapies with distinct mechanisms of action represent a promising strategy that has received renewed attention in recent years. Combination therapies exert cancer killing functions through either concomitant targeting of multiple pro-cancer factors or more effective inhibition of a single pathway. Theoretically, the combination therapy can improve efficacy and efficiency compared with monotherapy. Although increasing numbers of drug combinations are currently being tested in clinical trials, the mechanisms by which these combinations can overcome drug resistance have yet to be fully understood. The purpose of this review is to summarize recent work on therapeutic combinations in the treatment of castration-resistant prostate cancer and discuss emerging mechanisms underlying drug resistance. In addition, we provide an overview of the current preclinical mechanistic studies on potential therapeutic combinations to overcome drug resistance.

The Evolving Systemic Treatment Landscape for Patients with Advanced Prostate Cancer

Prostate cancer (PC) is a major health issue in developed countries, with, on the one hand, men suffering from sequelae related to unnecessary treatment of non-lethal PC, and, on the other hand, still dying because of advanced PC that progresses to castration-resistant disease. Systemic treatment is the mainstay of therapy of castration-resistant PC (CRPC). To date, a multitude of systemic agents have been tested and many of these have failed to provide a clinically meaningful benefit in CRPC, while others have been approved by the US Food and Drug Administration and/or the European Medicines Agency, including antiandrogen hormonal drugs (abiraterone, enzalutamide, apalutamide), chemotherapy (docetaxel and cabazitaxel), immunotherapy (Sipuleucel-T), and radiopharmaceutical (Radium-223) agents. In this review, systemic treatments regarded as most likely to have an impact in clinical practice are presented and discussed. In addition to the pivotal clinical studies, selected retrospective and non-randomized clinical trials are also discussed if deemed to have an impact on clinical practice or future research. A comprehensive appraisal of the expanding landscape of systemic therapies for advanced PC is provided from an expert perspective, with a focus on novel classification and diagnostic tools that have been paving the way for the development of precision medicine in PC.

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.

Phenotypes of circulating tumour cells predict time to castration resistance in metastatic castration-sensitive prostate cancer

OBJECTIVES

To identify biomarkers that predict the response to standard androgen deprivation therapy (ADT) of patients newly diagnosed with metastatic castration-sensitive prostate cancer (CSPC) in order to improve therapeutic decision-making, and to investigate whether the characterization of baseline circulating tumour cells (CTCs) would predict the effective period of standard ADT.

MATERIALS AND METHODS

The study included 108 patients newly diagnosed with high-volume metastatic CSPC. Enumeration and characterization of patients' baseline CTCs (CTCs+ and CTCs-, indicating detectable and undetectable CTCs, respectively) were performed using the CanPatrol technique, which detects markers of the epithelial to mesenchymal transition (EMT) in CTCs, and classifies CTCs into epithelial, biophenotypic and mesenchymal phenotypes.

RESULTS

After a median follow-up of 24 months, 90 patients (83.3%) progressed to castration-resistant prostate cancer (CRPC), 93 patients (86.1%) had detectable CTCs, and the median number of CTCs was 4. The rate of progression to CRPC was significantly higher for patients with mesenchymal CTCs+ than for patients with CTCs+/mesenchymal CTCs- and CTCs- (93.1% vs 71.4% and 73.3%; P = 0.013). The median time to CRPC for patients with mesenchymal CTCs+ was significantly shorter than for those with CTCs+/mesenchymal CTCs- and CTCs- (10.5 months vs 18.0 and 14.0 months; P = 0.003). Multivariate Cox regression analysis suggested that the CTC phenotype was the only independent prognostic factor influencing the progression of disease from CSPC to CRPC.

CONCLUSIONS

Characterization of baseline CTCs according to the EMT phenotype predicted the effective period of standard ADT for patients newly diagnosed with metastatic CSPC. These findings are important for counselling patients and designing clinical trials.

Abiraterone acetate and its use in the treatment of metastatic prostate cancer: a review

Abiraterone acetate, which targets enzymatic complexes playing a central role in steroidogenesis, demonstrated to increase survival significantly in both chemo-naive and docetaxel pretreated, becoming one of the drugs of choice for metastatic castration-resistant prostate cancer. More recently, this agent in combination to androgen deprivation therapy demonstrated to be efficacious also in metastatic castration-sensitive prostate cancer. The present review is aimed to outline the clinical development of abiraterone acetate, the pivotal trials which led to its approval for the clinical practice, new evidence about its efficacy in metastatic castration-sensitive prostate cancer, its place in the therapeutic landscape of prostate cancer and future directions of development.

Taxane-based Combination Therapies for Metastatic Prostate Cancer

CONTEXT

Multiple single-agent therapies improving survival are approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC), including two chemotherapies, two androgen-signaling axis-targeting agents, an immunotherapeutic vaccine, and a radiopharmaceutical. Combination therapy can target multiple oncogenic pathways simultaneously, while potentially curbing the development of treatment resistance.

OBJECTIVE

To provide a succinct overview of taxane-based combination therapies currently being evaluated for the treatment of metastatic prostate cancer.

EVIDENCE ACQUISITION

We searched MEDLINE/PubMed^® and relevant congress databases for literature focused on taxane-based combination therapies being evaluated for the treatment of metastatic prostate cancer. In addition, a systematic search of www.clinicaltrials.gov was performed to gather information regarding ongoing taxane-based combination trials in prostate cancer. This search included phase II or III trials starting after January 1, 2010, which included the terms "docetaxel" or "cabazitaxel" and "prostate", and was then manually filtered for combination studies.

EVIDENCE SYNTHESIS

Single-agent therapy yields modest increments in survival. The success of combining docetaxel with androgen deprivation to improve overall survival (OS) for metastatic hormone-sensitive disease suggests the potential of similar approaches in mCRPC. Several classes of biological drugs have previously been combined with docetaxel for mCRPC in clinical trials without improvement in OS. However, combining docetaxel or cabazitaxel with newer agents with established single-agent benefit, such as radium-223, second-generation androgen pathway-targeted agents, or other chemotherapies, has the potential to benefit patients when compared with taxane chemotherapy alone. Our search revealed that the majority of trials currently assessing taxanes are focused on combination therapies: a combination approach is being evaluated in 37 of 47 trials assessing docetaxel and in 18 of 34 trials assessing cabazitaxel.

CONCLUSIONS

Despite prior failures, novel taxane-based combination therapies have the potential to improve outcomes in mCRPC. Challenges include the absence of validated predictive biomarkers for the selection of suitable patients and the potential for enhanced toxicity.

PATIENT SUMMARY

Patients with metastatic prostate cancer have access to multiple therapies improving survival. Many advanced epithelial cancers are treated with combinations of drugs; however, prostate cancer has remained an exception. A number of clinical studies have shown that combining chemotherapy with other classes of therapy may improve patient outcomes in prostate cancer. Here, we summarize the various combinations that are tested in the clinic and review the results.

Influence of Enzalutamide on Cabazitaxel Pharmacokinetics: a Drug-Drug Interaction Study in Metastatic Castration-resistant Prostate Cancer (mCRPC) Patients

Purpose: In ongoing clinical research on metastatic castration-resistant prostate cancer (mCRPC) treatment, the potential enhanced efficacy of the combination of taxanes with AR-targeted agents, that is, enzalutamide and abiraterone, is currently being explored. Because enzalutamide induces the CYP3A4 enzyme and taxanes are metabolized by this enzyme, a potential drug-drug interaction needs to be investigated.Experimental Design: Therefore, we performed a pharmacokinetic cross-over study in mCRPC patients who were scheduled for treatment with cabazitaxel Q3W (25 mg/m²). Patients were studied for three consecutive cabazitaxel cycles. Enzalutamide (160 mg once daily) was administered concomitantly after the first cabazitaxel cycle, during 6 weeks. Primary endpoint was the difference in mean area under the curve (AUC) between the first (cabazitaxel monotherapy) and third cabazitaxel cycle, when enzalutamide was added.Results: A potential clinically relevant 22% (95% CI, 9%-34%; P = 0.005) reduction in cabazitaxel exposure was found with concomitant enzalutamide use. The geometric mean AUC_0-24h of cabazitaxel was 181 ng*h/mL (95% CI, 150-219 ng*h/mL) in cycle 3 and 234 ng*h/mL (95% CI, 209-261 ng*h/mL) in cycle 1. This combination did not result in excessive toxicity, whereas PSA response was promising.Conclusions: We found a significant decrease in cabazitaxel exposure when combined with enzalutamide. In an era of clinical trials on combination strategies for mCRPC, it is important to be aware of clinically relevant drug-drug interactions. Because recent study results support the use of a lower standard cabazitaxel dose of 20 mg/m², the clinical relevance of this interaction may be substantial, because the addition of enzalutamide may result in subtherapeutic cabazitaxel exposure. Clin Cancer Res; 24(3); 541-6. ©2017 AACR.

Efficacy and safety of post-docetaxel therapies in metastatic castration-resistant prostate cancer: a systematic review of the literature

OBJECTIVE

Prostate cancer is a highly prevalent form of cancer in older men and is one of the leading causes of death from cancer in men across the globe. Many therapeutic agents have been approved for patients with metastatic castration-resistant prostate cancer (mCRPC), particularly as a post-docetaxel treatment strategy. The objective of this systematic literature review was to assess published efficacy and safety data for select mCRPC therapies - such as abiraterone, cabazitaxel, and enzalutamide - in the post-docetaxel setting.

METHODS

Database searches of MEDLINE, Embase, and Cochrane CENTRAL, in conjunction with hand searches of multiple congress abstracts, yielded 13 randomized studies and 107 non-randomized studies that met the inclusion criteria.

RESULTS

Randomized studies demonstrated significant improvements in median overall survival (OS) outcomes over placebo for abiraterone (15.8 vs. 11.2 months) and enzalutamide (18.4 vs. 13.6 months), and similar significant improvements were noted for cabazitaxel over mitoxantrone (15.1 vs. 12.7 months). Differences in progression-free survival (PFS) were similarly significant, although variance in the criteria for measuring PFS may limit the extent to which these outcomes can be compared between studies. Non-randomized evidence included multiple publications from several early access and compassionate use programs with a primary objective to report safety outcomes. Results from these studies largely reflected the findings in randomized trials.

CONCLUSIONS

Overall, there is a growing body of evidence for post-docetaxel treatment options available in patients with mCRPC. Further head-to-head trials or indirect treatment comparisons may be a valuable method to assess the comparative efficacy of these therapies.

The evolution of chemotherapy for the treatment of prostate cancer

Chemotherapy has been explored as a treatment option for metastatic prostate cancer since the early 1980s. Docetaxel, a taxane chemotherapeutic, was approved for the treatment of men with metastatic castration-resistant prostate cancer in 2004, and is now standard of care for late stage disease. Recent clinical studies demonstrated that patients with metastatic castration-sensitive disease, and possibly those with high-risk localized prostate cancer also benefit from docetaxel administration, expanding the role of chemotherapy in the prostate cancer treatment landscape. Another taxane, cabazitaxel, is approved for post-docetaxel metastatic castration-resistant prostate cancer. Taxanes and other chemotherapeutics, such as carboplatin, are now being tested in combination regimens. This review presents an outline of recent and ongoing clinical studies assessing docetaxel and its derivative cabazitaxel at different stages of the disease, and in various combinations with other agents. We summarize current knowledge on biomarkers predictive of response to chemotherapy, which may in future be used to guide individualized treatment decisions.

Cabazitaxel in the treatment of metastatic castration-resistant prostate cancer: patient selection and special considerations

Cabazitaxel is an effective chemotherapeutic agent used in the treatment of metastatic castration-resistant prostate cancer (mCRPC) refractory to docetaxel. With the advent of new antiandrogen therapies, immune-based treatments, and radioactive-targeted therapy, there are now multiple effective and approved agents for this disease state. The optimal sequencing of these agents is unclear as there are no large-scale head-to-head comparisons. Clinicians must familiarize themselves with the most recent studies as well as drug toxicities to determine the best treatment option for their patients. In this review, we focus on the development of cabazitaxel for mCRPC, evaluate its efficacy, and highlight key strategies for toxicity management. Additionally, we summarize the studies that address cabazitaxel treatment sequencing and optimal dosing schedule.