Beyond Frontline Therapy with Abiraterone and Enzalutamide in Metastatic Castration-Resistant Prostate Cancer: A Real-World US Study

BackgroundReal-world evidence suggest that next generation hormonal agents (NHAs) abiraterone and enzalutamide were preferred as first-line (1L) therapies for metastatic castration-resistant prostate cancer (mCRPC) in the United States (US) pre-2020, with chemotherapies, particularly docetaxel, being preferred in subsequent lines (2L+). This real-world study described patient characteristics, treatment patterns, time on treatment (ToT) and overall survival (OS) among patients with mCRPC treated with 2L and 3L docetaxel post-NHAs in the mCRPC setting.MethodsAdults with confirmed adenocarcinoma mCRPC diagnosis and ≥1 month of follow-up post-diagnosis were selected from a US electronic health record-derived oncology de-identified database (01/2013–03/2019). Based on the observed line of therapy sequences post-mCRPC diagnosis, patients who received NHA therapy in 1L and docetaxel therapy in 2L were included in the 2L docetaxel cohort, and patients who received NHA therapy in both 1L and 2L and docetaxel therapy in 3L were included in the 3L docetaxel cohort. ToT and OS were evaluated using Kaplan-Meier analysis.ResultsAmong 5,213 patients with mCRPC, 278 and 166 were included in the 2L and the 3L docetaxel cohorts, respectively (median age: 73 years for both cohorts). ADT was the most used class of medication pre-mCRPC (>75%). For the 2L cohort, the most common sequence post-mCRPC was 1L abiraterone → 2L docetaxel (52.5%), while the median ToT and OS post-2L start were 4.1 and 10.5 months, respectively; for the 3L cohort, the most common sequence post-mCRPC was 1L abiraterone → 2L enzalutamide → 3L docetaxel (67.5%), while the median ToT and OS post-3L start were 3.8 and 8.7 months, respectively.ConclusionsThis real-world study provides novel data on patients treated with docetaxel post-NHAs in a mCRPC setting and highlights the critical unmet need for developing more effective treatment options in this population.     

Cross-resistance between taxanes and new hormonal agents abiraterone and enzalutamide may affect drug sequence choices in metastatic castration-resistant prostate cancer

IntroductionTreatment options for patients with metastatic castration-resistant prostate cancer (mCRPC) have expanded in recent years with the introduction of cabazitaxel, abiraterone and enzalutamide. With new systemic therapies available, the optimal treatment sequence of these drugs in mCRPC becomes increasingly important. As shown recently, patients who had previously been treated with abiraterone showed impaired responses to docetaxel, suggesting clinical cross-resistance [1]. In the present study, we aimed to identify cross-resistance between taxanes (docetaxel and cabazitaxel) and the new hormonal agents abiraterone and enzalutamide. As a potential mechanism for cross-resistance, we investigated the effects on androgen receptor (AR) nuclear translocation of these compounds.MethodsTo identify cross-resistance, we determined the effects of docetaxel, cabazitaxel, abiraterone and enzalutamide on cell viability in prostate cancer cell lines with acquired resistance to abiraterone and enzalutamide. Time-lapse confocal microscopy was used to study the dynamics of AR nuclear translocation.ResultsWe observed impaired efficacy of docetaxel, cabazitaxel and enzalutamide in the abiraterone-resistant cell line, compared to the non-resistant cell line, providing evidence for in vitro cross-resistance. Impaired efficacy of docetaxel, cabazitaxel and abiraterone was observed in the enzalutamide-resistant cell line. Furthermore, docetaxel and cabazitaxel inhibited AR nuclear translocation, which was also observed for abiraterone and enzalutamide.ConclusionsIn conclusion we found substantial preclinical evidence for cross-resistance between the taxanes docetaxel and cabazitaxel, and AR targeting agents abiraterone and enzalutamide. Since these compounds all interfere with AR-signalling, this strongly suggests a common mechanism of action, and thus a potential mechanism for cross-resistance in mCRPC.     

Frailty and survival among veterans treated with abiraterone or enzalutamide for metastatic castration-resistant prostate cancer

IntroductionAbiraterone and enzalutamide are treatments for metastatic castration-resistant prostate cancer (mCRPC). Due to a lack of head-to-head trials, they are prescribed interchangeably. However, the drugs have different pharmacokinetics and thus may have differing efficacy and adverse effects influenced by patient functional status and comorbid diseases. Additionally, mCRPC mainly affects older adults and since the prevalence of frailty increases with age, frailty is an important patient factor to consider in personalizing drug selection.Materials and MethodsWe conducted a retrospective observational study of US veterans treated with abiraterone or enzalutamide for mCRPC from September 2014 to June 2017. Frailty was assessed using the Veterans Affairs Frailty Index (VA-FI), which utilizes administrative codes to assign a standardized frailty score. Patients were categorized as frail if VA-FI scores were > 0.2. The primary outcome was difference in overall survival (OS) between the two treatment groups. Cox regression modeling and propensity score matching was used to compare between abiraterone and enzalutamide treatments.ResultsWe identified 5,822 veterans, 57% of whom were initially treated with abiraterone and 43% with enzalutamide. Frail patients (n = 2,314; 39.7%) were older, with a mean age of 76.1 versus 74.9 years in the non-frail group (n = 3,508; 60.3%, p < 0.001) and had shorter OS compared to non-frail patients regardless of treatment group (18.5 vs. 26.6 months, p < 0.001). Among non-frail patients there was no significant difference in OS between abiraterone and enzalutamide treatment (27.7 vs 26.1 months, p = 0.07). However, frail patients treated with enzalutamide versus abiraterone had improved OS (20.7 vs 17.2 months, p < 0.001). In a propensity score matched analysis of frail patients (n = 2,070), enzalutamide was associated with greater median OS (24.1 vs 20.9 months, p < 0.001). In patients with dementia, enzalutamide was associated with longer OS (19.4 vs. 16.6 months, p = 0.003).DiscussionIn this study of 5822 US veterans with mCRPC, treatment with enzalutamide was associated with improved OS compared to abiraterone among frail veterans and veterans with dementia, but not among non-frail veterans. Future studies should evaluate interactions between frailty and cancer treatments to optimize selection of therapy among frail adults.     

Treatment Patterns and Outcomes in Patients With Metastatic Castration-resistant Prostate Cancer in a Real-world Clinical Practice Setting in the United States

BackgroundClinical trials have demonstrated the efficacy of several life-prolonging therapies for metastatic castration-resistant prostate cancer (mCRPC); however, real-world data on their use, survival effect, and safety are limited. Using electronic health record data from the Flatiron Health database, we studied real-world treatment patterns and health outcomes in patients with mCRPC.Patients and MethodsWe conducted a retrospective, non-interventional cohort analysis of electronic health record data of patients with confirmed mCRPC between January 2013 and September 2017. The primary objective was to describe real-world treatment patterns, including treatment type, duration, and sequencing. Secondary objectives included describing patient characteristics and clinical outcomes.ResultsOf 2559 patients with mCRPC, 1980 (77%) received at least 1 line of life-prolonging therapy (abiraterone, enzalutamide, docetaxel, cabazitaxel, sipuleucel-T, or radium-223). Of patients receiving first-line therapy, 49% received second-line therapy, and of these, 43% received third-line therapy. Abiraterone/prednisone and enzalutamide accounted for 65% of first-line therapies and 54% of second-line therapies. Docetaxel was the most common third-line therapy (24%). Back-to-back use of abiraterone/prednisone and enzalutamide was common. Radium-223 monotherapy use was 2% in the first-line setting, 3% in the second-line setting, and 8% in the third-line setting. The median overall survival was longer in patients who received life-prolonging therapies (23.7 months; 95% confidence interval: 22.3-25.1 months) than in those who did not (10.1 months; 95% confidence interval: 9.1-11.5 months).ConclusionThese real-world insights on over 2500 patients with mCRPC supplement findings from randomized controlled trials and may help to inform clinical trial design, treatment guidelines, and clinical decision-making.     

Systemic Therapy in Men with Metastatic Castration-resistant Prostate Cancer: A Systematic Review

AimsSince 2004, docetaxel-based chemotherapy has been the standard of care for men with metastatic castration-resistant prostate cancer (mCRPC), but recently randomised controlled trials (RCTs) of novel agents have shown promise in extending overall survival. These trials have evaluated agents delivered before chemotherapy, to replace or supplement docetaxel, or addressed treatment options for men who have progressed on docetaxel therapy. This review was undertaken to determine which systemic therapies improve cancer- or patient-related outcomes in men with mCRPC.Materials and methodsSearches were carried out in MEDLINE, EMBASE, the Cochrane Library and relevant conference proceedings. Eligible articles included RCTs comparing systemic therapy or combination (excluding primary or secondary androgen deprivation therapy, bone protective agents or radionuclides) with placebo or other agents in men with mCRPC.ResultsTwenty-five RCTs met the selection criteria. In chemotherapy-naive patients, targeted therapy with tasquinimod conferred a benefit in progression-free survival. Immunotherapy with sipuleucel-T extended overall survival and was well tolerated, but had no effect on the time to disease progression. Hypercastration with abiraterone extended progression-free survival, whereas overall survival was improved but not statistically proven. In the chemotherapy setting, updated and new trials of docetaxel alone confirmed the survival benefit seen in previous studies. A survival benefit with the addition of estramustine to docetaxel shown in a previous study did not lead to an improvement in pain palliation or quality of life. Trials of combining targeted therapies with docetaxel generally did not extend survival. The addition of bevacizumab improved progression-free survival, but not overall survival. The addition of GVAX immunotherapy or calcitriol was harmful. In the post-chemotherapy setting, progression-free and overall survival benefits were detected with cabazitaxel, abiraterone and enzalutamide. Cabazitaxel was associated with greater toxicity, whereas abiraterone and enzalutamide had less severe adverse effects. Satraplatin and sunitinib both extended progression-free survival, but did not improve overall survival.ConclusionDocetaxel-based chemotherapy remains the standard of care in men with mCRPC who are candidates for palliative systemic therapy. Promising results are emerging with sipuleucel-T and abiraterone in the pre-docetaxel setting and cabazitaxel, abiraterone and enzalutamide in patients who progress on or after docetaxel. Further research to determine the optimal choice, sequence or even the combination of these agents is necessary.     

Patient characteristics and overall survival in patients with post-docetaxel metastatic castration-resistant prostate cancer in the community setting

It is unclear how treatment sequencing for metastatic castration-resistant prostate cancer (mCRPC) affects real-world patient outcomes. We assessed treatment sequences, patient characteristics and overall survival (OS) in post-docetaxel mCRPC patients. mCRPC patients receiving second-line cabazitaxel or androgen receptor-targeted therapy (ART; abiraterone/enzalutamide) post-docetaxel were identified using electronic medical records. OS was assessed from second-line therapy initiation using Cox regressions adjusting for: metastases; prostate-specific antigen (PSA); hemoglobin; alkaline phosphatase (ALP); albumin; second-line therapy initiation year. Following docetaxel (n = 629), 123 (19.6%) and 506 (80.4%) patients received cabazitaxel and ART, respectively. One hundred and ninety-five patients received additional treatments thereafter (54 following cabazitaxel; 141 following ART). Although patients receiving second-line cabazitaxel versus ART had similar disease characteristics at first-line therapy initiation, at second-line therapy initiation they had higher mean PSA (386.6 vs. 233.9 ng/mL) and ALP (182.0 vs. 167.3 u/L), lower mean hemoglobin (10.8 vs. 11.5 g/dL), and more frequently had intermediate/high-risk Halabi scores (61.8 vs. 48.4%); all p < 0.05. Overall, crude survival was not significantly different. Among Halabi high-risk patients, adjusted median OS was significantly longer in patients receiving cabazitaxel versus ART (HR 0.48; 95% CI 0.24–0.93; p = 0.030). Low albumin and hemoglobin led to similar findings (HR 0.43; 95% CI 0.23–0.80; p = 0.0077; HR 0.60; 95% CI 0.40–0.90; p = 0.014). Most post-docetaxel patients received second-line ART. Patients receiving second-line cabazitaxel had more high-risk features; however, second-line cabazitaxel administered after docetaxel may improve OS in patients with Halabi high-risk scores or low albumin/hemoglobin.     

Clinical activity of abiraterone acetate in patients with metastatic castration-resistant prostate cancer progressing after enzalutamide

BackgroundAbiraterone acetate and enzalutamide both improve outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC). Optimal sequencing for these agents and whether cross-resistance occurs is unknown.MethodsMulticentre review of patients with mCRPC treated with abiraterone acetate and prednisone after progressing on enzalutamide. Primary objective was to determine abiraterone acetate response.ResultsThirty patients identified from four North American centres. At abiraterone initiation, median age was 70 years (56–84 years); 70% had ECOG performance status of 0–1; all had prior docetaxel. Median prior enzalutamide treatment duration was 41 weeks (6–95 weeks), with 70% (21 of 30) having a ≥30% prostate-specific antigen (PSA) decline. Median abiraterone acetate treatment duration was 13 weeks (1–52). No objective radiographic responses were observed. Median abiraterone time to progression (PSA, objective or symptomatic) was 15.4 weeks [95% confidence interval (CI) 10.7–20.2]. Median overall survival was 50.1 weeks (95% CI 28.3–72.0). Three patients had a ≥30% PSA decline with abiraterone. Two of these patients had PSA progression as best response with prior enzalutamide.ConclusionsIn this study of patients progressing after enzalutamide, treatment with abiraterone was associated with a modest response rate and brief duration of effect. Primary progression on enzalutamide may not preclude a response to abiraterone.     

Antitumour activity of abiraterone acetate against metastatic castration-resistant prostate cancer progressing after docetaxel and enzalutamide (MDV3100)

BackgroundAndrogen receptor (AR) signalling remains critically important in metastatic castration-resistant prostate cancer (mCRPC) as confirmed by recent phase III trials, showing a survival advantage for abiraterone acetate and enzalutamide (MDV3100). The antitumour activity of abiraterone and prednisolone in patients pre-treated with enzalutamide is as yet unknown.Patients and methodsWe investigated the antitumour activity of abiraterone and prednisolone in patients with mCRPC who had progressed following treatment with docetaxel (Taxotere) and enzalutamide. Clinical data were retrospectively analysed for prostate-specific antigen (PSA) and RECIST responses, clinical benefit and survival.ResultsThirty-eight patients were included in the analysis. The median age was 71 years (range 52–84); metastatic sites included bone disease in 37 patients (97%), lymph nodes in 15 patients (39%) and visceral disease in 10 patients (26%). Abiraterone was well tolerated. Three patients (8%) attained a PSA response, defined as ≥50% decline in PSA confirmed after ≥4 weeks, while seven patients (18%) had a ≥30% PSA decline. The median progression-free survival (PFS) was 2.7 months (95% CI 2.3–4.1). Of the 12 patients assessable radiologically, only 1 (8%) attained a confirmed partial response.ConclusionAbiraterone and prednisolone have modest antitumour activities in patients with mCRPC pretreated with docetaxel and enzalutamide.     

Checkpoint Inhibitors in Metastatic EGFR-Mutated Non–Small Cell Lung Cancer—A Meta-Analysis

IntroductionWe performed a meta-analysis to assess the role of immune checkpoint inhibitors as second-line therapy in EGFR-mutant advanced NSCLC.MethodsRandomized trials comparing immune checkpoint inhibitors against chemotherapy were identified. We retrieved the hazard ratio (HR) and 95% confidence interval (CI) for overall survival (OS) of the intention-to-treat population and EGFR mutation–defined subgroups. We used the fixed-effects inverse variance–weighted method to pool estimates of treatment efficacy. Statistical tests were two sided.ResultsIn the three included studies that compared immune checkpoint inhibitors (nivolumab [n = 292], pembrolizumab [n = 691], and atezolizumab [n =144]) against docetaxel (n = 776), immune checkpoint inhibitors significantly prolonged OS over that with docetaxel overall (n = 1903, HR = 0.68, 95% CI: 0.61–0.77, p < 0.0001) and in the EGFR wild-type subgroup (n = 1362, HR = 0.66, 95% CI: 0.58–0.76, p < 0.0001) but not in the EGFR-mutant subgroup (n = 186, HR = 1.05, 95% CI: 0.70–1.55, p < 0.81; treatment-mutation interaction p = 0.03).ConclusionIn EGFR-mutant advanced NSCLC, immune checkpoint inhibitors do not improve OS over that with docetaxel. Mechanisms of acquired resistance to first-line tyrosine kinase inhibitor therapy should be elucidated to guide selection of second-line treatment for these patients.     

High subcutaneous adipose tissue predicts the prognosis in metastatic castration-resistant prostate cancer patients in post chemotherapy setting

BackgroundCancer studies have shown that body mass index (BMI), skeletal muscle mass (SMM) and adipose tissue indexes are linked to overall survival (OS) and progression-free survival (PFS). New treatments (abiraterone acetate, enzalutamide cabazitaxel, radium-223, sipuleucel-T) have improved patient outcomes in metastatic castration-resistant prostate cancer (mCRPC). Our objective was to analyse whether body composition parameters exert a prognostic role in mCRPC patients treated with next generation of androgen receptor (AR) axis inhibitors (abiraterone and enzalutamide).MethodsAll mCRPC patients from our institution who were enrolled in two prospective trials, assessing the efficacy of abiraterone acetate and the efficacy of enzalutamide, were selected. SMM, visceral and subcutaneous adipose tissue (SAT) indexes were assessed with computed tomography imaging by measuring cross-sectional areas of the tissues.ResultsIn the 120 patients with available data, median OS and PFS were respectively: 16 months (95% confidence interval [CI] = 12–19) and 4 months (95% [CI] = 3–6). OS was associated with the SAT index: median survival was 15 months (95% [CI] 9–18) for patients with a SAT index < median value and 18 months (95% [CI] 13–30) for patients with a SAT index above (P = 0.008). In multivariate analyses, only the occurrence of visceral metastasis (P = 0.004), pain (P = 0.015) and SAT index (P = 0.036) were statistically significant predictors of OS. From baseline to 3 months, the SMM index loss was 2.49 ± 0.44 cm²/m² (P < 0.001) corresponding to nearly 3.4 kg of muscle loss.ConclusionsHigh volume of SAT is independently associated with overall survival in mCRPC patients treated with next generation AR axis inhibitors.     

The influence of prior novel androgen receptor targeted therapy on the efficacy of cabazitaxel in men with metastatic castration-resistant prostate cancer

IntroductionThe treatment armamentarium for metastatic castration-resistant prostate cancer (mCRPC) has expanded with the introduction of several new therapies. In this treatment continuum, it is unclear whether the efficacy of cabazitaxel is affected by prior novel androgen receptor targeted therapies (ART) such as abiraterone and enzalutamide. In this study, we investigated the influence of prior ART on the efficacy of cabazitaxel in men with mCRPC.Patients and methodsData from an ongoing multicentre, phase II trial were used comprising 114 men with mCRPC treated with cabazitaxel in the post-docetaxel setting. The primary endpoints of the current analysis were prostate-specific antigen (PSA) response (⩾50%), and overall survival (OS). Univariate and multivariable analyses were conducted to investigate the influence of prior ART on the efficacy of cabazitaxel.ResultsFrom the 114 patients included in this analysis, 44 men received prior ART and 70 men did not receive prior ART before treatment with cabazitaxel. PSA response rates while on cabazitaxel treatment were similar in patients with and without prior ART (34% versus 40%, respectively, P = 0.53). Likewise, median OS was not significantly different between men with and without prior ART (13.0 versus 14.0 months, respectively, logrank P = 0.65). In multivariable analysis, the only variables significantly associated with OS were performance status, serum albumin and alkaline phosphatase.ConclusionOur study showed that prior treatment with ART may not influence the efficacy of cabazitaxel in men with mCRPC. With emerging evidence of cross-resistance in the treatment of mCRPC, cabazitaxel provides a good treatment option irrespective of prior ART.     

Survival Outcomes From a Cumulative Analysis of Worldwide Observational Studies on Sequential Use of New Agents in Metastatic Castration-Resistant Prostate Cancer

IntroductionThe sequential use of a number of new agents (NAs) have improved the overall survival (OS) of patients with metastatic castration-resistant prostate cancer whose disease progresses after docetaxel (DOC) treatment. The aim of this study was to assess the cumulative survival outcomes of different sequencing strategies by evaluating the individual data from published studies of patients treated with a post-DOC treatment sequence of 2 NAs.Patients and MethodsThe patients’ individual data were analyzed to investigate whether different sequencing strategies lead to differences in OS.ResultsWe analyzed the data of 1099 evaluable patients. Among the patients treated with a second-line new hormone agent (NHA), median OS from the start of third-line treatment was significantly longer in the patients treated with cabazitaxel (CABA) than in those treated with abiraterone acetate or enzalutamide. Median cumulative OS (cumOS) from the start of second-line treatment was 21.1 months in the patients who received NHA then NHA, 22.1 months in those who received NHA then CABA, and 21.0 months in those who received CABA then NHA. Among the patients with a second-line progression-free survival of ≥6 months, median cumOS was significantly longer in patients who received CABA-including sequences than in those treated with NHA then NHA sequences (29.5 vs. 24.8 months; P = .03).ConclusionOur findings suggest that the sequential use of NAs with different mechanisms of action improves cumOS regardless of the order in which they are administered, thus supporting the hypothesis of cross-resistance between the 2 NHAs.     

Radium-223 (Xofigo) with concurrent abiraterone or enzalutamide: predictive biomarkers of improved overall survival in a clinically advanced cohort

PurposeRadium-223 (Xofigo) is the first therapy with bone tropism for metastatic castrate-resistant prostate cancer (mCRPC) that has been shown to improve overall survival (OS). Although radium-223 has a positive effect on OS in men with mCRPC, there has been a paucity of reports from community practitioners, especially with regard to concurrent abiraterone and enzalutamide therapy. Significant differences in patient characteristics encountered may exist.Patients and methodsWe conducted a retrospective study of men with mCRPC who received at least 1 cycle of radium-223 (n = 35). Baseline pain and ECOG PS as well as concurrent usage of abiraterone or enzalutamide were recorded. Side effect profiles for each patient throughout treatment were noted.ResultsBaseline cohort characteristics include a median age of 75 years. 37% had an ECOG PS ≥ 2 and 23% reported severe pain at baseline. 31% received concomitant enzalutamide 31% concomitant abiraterone. Patients treated concurrently with either abiraterone or enzalutamide did not display additional toxicity. Median cohort OS was 10 months. Patients with no or mild pain had longer median OS than those with moderate or severe pain, 14 versus 7 months (P = 0.028). Patients with ECOG PS < 2 had longer median OS than those with ECOG PS ≥ 2, 13 versus 10 months (P = 0.0233).ConclusionThis study highlights key differences in patient characteristics encountered by community practitioners. In this population, which presented with clinically advanced disease, there was an improved survival benefit for those treated earlier in their disease. Radium-223 was well tolerated and concurrent treatment with abiraterone or enzalutamide did not add additional toxicity. These 2 points seem to advocate for aggressive and early treatment of patients with radium-223 in the community.     

Early PSA response is an independent prognostic factor in patients with metastatic castration-resistant prostate cancer treated with next-generation androgen pathway inhibitors

BackgroundThe optimal use of new therapies in metastatic castration-resistant prostate cancer (mCRPC) remains to be clarified. Prostate-specific antigen (PSA) response used as a pharmacodynamic end-point may help identify patients with early resistance to new androgen receptor-pathway inhibitors. We aimed to determine the clinical significance of early PSA response (EPR) during therapy with enzalutamide, abiraterone acetate (AA) and orteronel in mCRPC.MethodsData from patients recruited in clinical trials were studied. PSA values were obtained at baseline and 28 d after treatment initiation. EPR defined as a decline >50% from baseline was calculated according to the Prostate Cancer Working Group 2 criteria. The effects of clinical characteristics on radiographic progression-free survival (rPFS) and overall survival (OS) were examined using the Cox model.ResultsEPR was assessed in 118 patients treated in clinical trials and was found to be associated with longer rPFS and OS (P < 0.0001 for both). Median rPFS was 13.9 and 5.6 months (hazard ratio [HR]:0.38, P < 0.001) for patients with and without an EPR, respectively. Median OS was 32.2 months in patients with an EPR and 15.9 months in patients without an EPR (HR: 0.4, P < 0.01). EPR remained prognostic for OS in multivariate analyses (HR: 0.5, p = 0.009) that included validated pre-therapeutic prognostic factors for mCRPC. Prognostic values of EPR for rPFS and OS were confirmed in an independent cohort of 95 AA-treated non-trial patients.ConclusionsEPR is an independent prognostic factor in patients with mCRPC treated with next-generation androgen pathway inhibitors and may be useful for the therapeutic management of these patients.     

Cost-effectiveness Analysis of Innovative Therapy for Patients with Newly Diagnosed Hormone-Sensitive Metastatic Prostate Cancer

BackgroundThe optimal therapeutic strategies for patients with metastatic hormone-sensitive prostate cancer (mHSPC) followed by metastatic castrate-resistant prostate cancer (mCRPC), in terms of cost and effectiveness, remains unknown. This study aims to compare the cost-effectiveness of various potential strategies, from the start of first-line treatment in mHSPC to the death of the patients.MethodsTwo Markov decision-analysis models were developed, one for cohort A “asymptomatic/mildly symptomatic patients in mCRPC”, and one for cohort B “symptomatic patients in mCRPC”. Each strategy reflects daily practice for mHSPC until progression in mCRPC from the start of first treatment regimen with either docetaxel or abiraterone acetate plus prednisone (AA) in mHSPC to the death of the patient. The cost-effectiveness analysis was performed from the French public health care system perspective. Only direct medical costs were included. Survival data were extracted from results of published randomized clinical trials.ResultsFor cohort A, docetaxel followed by AA is the most cost-effective therapeutic strategy (€96,925 for 4.24 life-years). For cohort B, docetaxel followed by docetaxel is the most cost-effective therapeutic strategy (€81,463 for 4.05 life-years). Sensitivity analyses confirmed the robustness of our results except for a price reduction of 70% for AA or enzalutamide.ConclusionOur approach is innovative to the extent that our analysis considers various potential strategies for metastatic prostate cancer (mPC). Our economic evaluation suggests that a price reduction of AA or enzalutamide impacts on the results. This approach must continue, including new drugs for patients with mPC.     

Real-World Cabazitaxel Use and Outcomes in Metastatic Castrate-Resistant Prostate Cancer: The Impact of Response to First ARPI

BackgroundFor post-docetaxel treatment of metastatic castrate-resistant prostate cancer (mCRPC), cabazitaxel has demonstrated superior third line PFS and OS compared to androgen receptor pathway inhibitors (ARPIs) in patients who progress within 12 months on first ARPI. The impact of first ARPI response, in particular responses beyond 12 months, on cabazitaxel outcomes in real-world populations is uncertain, as are other factors impacting cabazitaxel use.Materials and MethodsmCRPC patients in Alberta, Canada who received docetaxel from October 1, 2012 to December 31, 2017 were included. We reviewed mCRPC therapies, correlating cabazitaxel use with patient characteristics and TROPIC trial inclusion/exclusion criteria. OS and PFS were evaluated in patients who received cabazitaxel, stratified by time to progression on first ARPI ≤ 12 months (poor ARPI responders, PAR) or >12 months (strong ARPI responders, SAR), using the Kaplan-Meier method.ResultsPAR patients had inferior OS compared to SAR patients (12.3 vs. 24.8 months, P < .001). OS was longer in PAR patients receiving cabazitaxel compared to those not treated with cabazitaxel (16.9 vs. 10.3 months, P = .015), but this benefit was not seen in the SAR group (17.1 vs. 32 months, P = .084). Cabazitaxel use was associated with reduced PFS first line post-docetaxel in SAR (3.5 vs. 14.7 months, P < .001) but not PAR patients.Of 592 patients, 170 (29%) received cabazitaxel post-docetaxel, compared to 280 (47%) and 250 (42%) for abiraterone and enzalutamide. 238 patients (40%) did not have a discussion of cabazitaxel documented. Cabazitaxel use was increased in patients who fit TROPIC trial criteria (P < .001).ConclusionsIn a real-world mCRPC cohort, cabazitaxel use was associated with longer OS among PAR patients, but crucially not among strong ARPI responders. Cabazitaxel was used less frequently and later than ARPIs post-docetaxel. These data help support first ARPI progression time as a consideration in treatment sequencing.     

A Phase 2 Trial of Abiraterone Followed by Randomization to Addition of Dasatinib or Sunitinib in Men With Metastatic Castration-Resistant Prostate Cancer

BackgroundResistance to novel androgen signaling inhibition and metastatic castration-resistant prostate cancer (mCRPC) progression is likely dependent on tumor microenvironment interactions. The Src pathway and neoangiogenesis have been implicated in prostate cancer progression. We studied the effect of adding the targeted agents dasatinib and sunitinib to abiraterone acetate (AA) in men with mCRPC.Patients and MethodsIn this open-label randomized phase 2 study, mCRPC patients received AA. At resistance to AA, they were randomized 1:1 to combination with dasatinib or sunitinib. At second progression, patients crossed over. The primary end point was time to treatment failure (TTF), defined as time to progression or death. Secondary end points included overall survival and safety.ResultsFrom March 2011 to February 2015, a total of 179 patients were enrolled and 132 subsequently randomized. Median TTF was 5.7 months in the dasatinib group and 5.5 months in the sunitinib group. There was no difference between the two groups in terms of TTF (hazard ratio, 0.85; 95% confidence interval, 0.59-1.22). Median overall survival from study entry was 26.3 months in the dasatinib group and 27.7 months in the sunitinib group (hazard ratio, 1.02; 95% confidence interval, 0.71-1.47). Grade 3 or higher adverse events related to study medication were more frequent with sunitinib (n = 44, 46%) compared to dasatinib (n = 26, 24%). At data cutoff, 7 patients were experiencing a continuous response to AA, with a median duration of treatment of 5.7 years.ConclusionThere is no difference in overall survival and TTF between dasatinib and sunitinib combined with abiraterone in the treatment of patients with bone mCRPC.     

The Prognostic Significance of Homologous Recombination Repair Pathway Alterations in Metastatic Hormone Sensitive Prostate Cancer

IntroductionThe homologous recombination repair (HRR) pathway is a frequently mutated pathway in advanced prostate cancer. The clinical course of patients with HRR gene alterations who have metastatic hormone sensitive prostate cancer (mHSPC) has not been fully characterized. Here, we examine the outcomes of men with mHSPC with HRR alterations.MethodsWe conducted a single-center retrospective analysis of men with mHSPC who underwent next generation sequencing. The primary objective was to assess the time from diagnosis of mHSPC to metastatic castrate resistance prostate cancer (mCRPC) in patients with pathogenic HRR alterations compared to individuals lacking these alterations. Key secondary objectives included time to mCRPC in prespecified cohorts, PSA response, and overall survival.Results151 men with mHSPC were identified for the study. 24% (N = 37) had pathogenic HRR gene alterations detected with the most common alterations found in BRCA2 (n = 15), ATM (n = 10), and CDK12 (n = 7). Time to mCRPC was significantly decreased in patients with HRR gene alterations versus those without such alterations (12.7 vs. 16.1 months, HR 1.95, P = .02). In multivariate analysis, the effect of HRR gene alterations on time to CRPC remained significant when adjusting for age, mHSPC therapy, the volume of disease, the presence of visceral metastases, and PSA (adjusted HR 1.69, P = .02). Stratified by specific HRR gene alteration, patients with BRCA2 or CDK12 had significantly decreased time to mCRPC compared to other HRR alterations.ConclusionHRR gene alterations are associated with the worse outcomes in mHSPC with significantly shorter time to mCRPC. Given the established role of Poly (ADP-ribose) Polymerase (PARP) inhibitors in mCRPC, these data highlight an opportunity to examine PARP inhibitors earlier in the clinical course for prostate cancer patients. Ongoing prospective studies will further validate the role of PARP inhibitors in mHSPC patients.     

Antitumour activity of enzalutamide (MDV3100) in patients with metastatic castration-resistant prostate cancer (CRPC) pre-treated with docetaxel and abiraterone

BackgroundThe new generation anti-androgen enzalutamide and the potent CYP17 inhibitor abiraterone have both demonstrated survival benefits in patients with metastatic castration-resistant prostate cancer (CRPC) progressing after docetaxel. Preliminary data on the antitumour activity of abiraterone after enzalutamide have suggested limited activity. The antitumour activity and safety of enzalutamide after abiraterone in metastatic CRPC patients is still unknown.Patients and MethodsWe retrospectively identified patients treated with docetaxel and abiraterone prior to enzalutamide to investigate the activity and safety of enzalutamide in a more advanced setting. Prostate specific antigen (PSA), radiological and clinical assessments were analysed.Results39 patients with metastatic CRPC were identified for this analysis (median age 70 years, range: 54–85 years). Overall 16 patients (41%) had a confirmed PSA decline of at least 30%. Confirmed PSA declines of ⩾50% and ⩾90% were achieved in 5/39 (12.8%) and 1/39 (2.5%) respectively. Of the 15 patients who responded to abiraterone, two (13.3%) also had a confirmed ⩾50% PSA decline on subsequent enzalutamide. Among the 22 abiraterone-refractory patients, two (9%) achieved a confirmed ⩾50% PSA decline on enzalutamide.ConclusionOur preliminary case series data suggest limited activity of enzalutamide in the post-docetaxel and post-abiraterone patient population.     

Antitumour activity of docetaxel following treatment with the CYP17A1 inhibitor abiraterone: clinical evidence for cross-resistance?

BackgroundAbiraterone and docetaxel are both approved treatments for men with metastatic castration-resistant prostate cancer (mCRPC). Abiraterone pre-docetaxel is currently undergoing evaluation in a phase III study. In vitro studies indicate that taxanes may act by disrupting androgen receptor signalling. We hypothesised that prior abiraterone exposure would adversely impact docetaxel efficacy.Patients and methodsWe retrospectively evaluated activity of docetaxel in mCRPC patients previously treated with abiraterone, using Prostate Cancer Working Group and radiological criteria.ResultsOf the 54 patients treated with abiraterone, 35 subsequently received docetaxel. Docetaxel resulted in a prostate-specific antigen (PSA) decline of ≥50% in nine patients [26%, 95% confidence interval (CI) 13% to 43%], with a median time to PSA progression of 4.6 months (95% CI 4.2% to 5.9%). PSA declines ≥30% were achieved by 13 patients (37%, 95% CI 22% to 55%). The median overall survival was 12.5 months (95% CI 10.6–19.4). All patients who failed to achieve a PSA fall on abiraterone and were deemed abiraterone-refractory were also docetaxel-refractory (N = 8). In the 24 patients with radiologically evaluable disease, partial responses were reported in four patients (11%), none of whom were abiraterone-refractory.ConclusionThe activity of docetaxel post-abiraterone appears lower than anticipated and no responses to docetaxel were observed in abiraterone-refractory patients.