Project description:Two phase 3 trials, COMET-1 and COMET-2, have reported that cabozantinib did not significantly extend overall survival (OS) compared to prednisone and prednisone plus mitoxantrone, respectively, in post-docetaxel patients with metastatic castration-resistant prostate cancer (mCRPC). We conducted a retrospective analysis of a combined data set from these trials to identify a benefit in subsets of patients according to prognostic risk factors. The prognostic ability of factors to predict survival was evaluated using Cox proportional hazards regression models. Evaluation of potential beneficial subsets was performed using interaction terms between factors and cabozantinib. All tests were two-sided and p≤0.05 was considered statistically significant. A total of 1147 post-docetaxel patients with mCRPC were available (1028 from COMET-1 and 119 from COMET-2). The following factors were prognostic for OS: age, disease-free interval, hemoglobin, prostate-specific antigen, alkaline phosphatase, albumin, bone scan lesion area, lactate dehydrogenase, Eastern Cooperative Oncology Group performance status, and pain (all p<0.05). There was no interaction effect on survival between cabozantinib versus comparator arms and any prognostic group. After adjusting for prognostic factors, cabozantinib was associated with better OS (hazard ratio 0.80, 95% confidence interval 0.67-0.95; p=0.012). Further investigation of cabozantinib in a better-powered trial or a rational patient population based on a molecular biomarker may be warranted. PATIENT SUMMARY: Two phase 3 trials have reported no survival benefit for cabozantinib, a multitarget oral drug, in metastatic castration-resistant prostate cancer. This analysis pooled 1147 patients from these trials to identify a survival benefit for cabozantinib. This study suggests that further rational development may be justified.
Project description:Although most prostate cancers are localized, and the majority are curable, recurrences occur in approximately 35% of men. Among patients with prostate-specific antigen (PSA) recurrence and PSA doubling time (PSADT) less than 15 months after radical prostatectomy, prostate cancer accounted for approximately 90% of the deaths by 15 years after recurrence. An immunosuppressive tumor microenvironment (TME) and impaired cellular immunity are likely largely responsible for the limited utility of checkpoint inhibitors (CPIs) in advanced prostate cancer compared with other tumor types. Thus, for immunologically "cold" malignancies such as prostate cancer, clinical trial development has pivoted towards novel approaches to enhance immune responses. Numerous clinical trials are currently evaluating combination immunomodulatory strategies incorporating vaccine-based therapies, checkpoint inhibitors, and chimeric antigen receptor (CAR) T cells. Other trials evaluate the efficacy and safety of these immunomodulatory agents' combinations with standard approaches such as androgen deprivation therapy (ADT), taxane-based chemotherapy, radiotherapy, and targeted therapies such as tyrosine kinase inhibitors (TKI) and poly ADP ribose polymerase (PARP) inhibitors. Here, we will review promising immunotherapies in development and ongoing trials for metastatic castration-resistant prostate cancer (mCRPC). These novel trials will build on past experiences and promise to usher a new era to treat patients with mCRPC.
Project description:ObjectiveTo evaluate the safety and efficacy of cabozantinib combined with docetaxel.Patients and methodsThis was a phase 1/2 multicentre study in patients with metastatic castration-resistant prostate cancer (mCRPC). Docetaxel (75 mg/m2 every 3 weeks with daily prednisone 10 mg) was combined with escalating doses of daily cabozantinib (20, 40 and 60 mg). Based on the results of the phase 1 study, the investigation was expanded into a randomized study of docetaxel with prednisone (hereafter 'docetaxel/prednisone') plus the maximum tolerated dose (MTD) of cabozantinib compared with docetaxel/prednisone alone.ResultsA total of 44 men with mCRPC were enrolled in this phase 1/2 trial. An MTD of 40 mg cabozantinib plus docetaxel/prednisone was determined. Dose-limiting toxicities were neutropenic fever and palmar-plantar erythrodysesthesia, and there was one death attributable to a thromboembolic event. In addition, grade 3 or 4 myelosuppression, hypophosphataemia and neuropathy were seen in three or more patients. In the phase 1 study, the median time to progression (TTP) and overall survival (OS) time were 13.6 and 16.3 months, respectively. In the phase 2 study, which was terminated early because of poor accrual, the median TTP and OS favoured the combination (n = 13) compared to docetaxel/prednisone alone (n = 12; 21.0 vs 6.6 months; P = 0.035 and 23.8 vs 15.6 months; P = 0.072, respectively).ConclusionDespite the limited number of patients in this study, preliminary data suggest that cabozantinib can be safely added to docetaxel/prednisone with possible enhanced efficacy.
Project description:Plasma androgen receptor (AR) gain identifies metastatic castration-resistant prostate cancer (mCRPC) patients with worse outcome on abiraterone/enzalutamide, but its relevance in the context of taxane chemotherapy is unknown. We aimed to evaluate whether docetaxel is active regardless of plasma AR and to perform an exploratory analysis to compare docetaxel with abiraterone/enzalutamide. This multi-institutional study was a pooled analysis of AR status, determined by droplet digital polymerase chain reaction, on pretreatment plasma samples. We evaluated associations between plasma AR and overall/progression-free survival (OS/PFS) and prostate-specific antigen (PSA) response rate in 163 docetaxel-treated patients. OS was significantly shorter in case of AR gain (hazard ratio [HR]=1.61, 95% confidence interval [CI]=1.08-2.39, p=0.018), but not PFS (HR=1.04, 95% CI 0.74-1.46, p=0.8) or PSA response (odds ratio=1.14, 95% CI=0.65-1.99, p=0.7). We investigated the interaction between plasma AR and treatment type after incorporating updated data from our prior study of 73 chemotherapy-naïve, abiraterone/enzalutamide-treated patients, with data from 115 first-line docetaxel patients. In an exploratory analysis of mCRPC patients receiving first-line therapies, a significant interaction was observed between plasma AR and docetaxel versus abiraterone/enzalutamide for OS (HR=0.16, 95% CI=0.06-0.46, p<0.001) and PFS (HR=0.31, 95% CI=0.12-0.80, p=0.02). Specifically, we reported a significant difference for OS favoring abiraterone/enzalutamide for AR-normal patients (HR=1.93, 95% CI=1.19-3.12, p=0.008) and a suggestion favoring docetaxel for AR-gained patients (HR=0.53, 95% CI=0.24-1.16, p=0.11). These data suggest that AR-normal patients should receive abiraterone/enzalutamide and AR-gained could benefit from docetaxel. This treatment selection merits prospective evaluation in a randomized trial. PATIENT SUMMARY: We investigated whether plasma androgen receptor (AR) predicted outcome in metastatic castration-resistant prostate cancer (mCRPC) patients treated with docetaxel, and we performed an exploratory analysis in patients treated with docetaxel or AR-directed drugs as first-line mCRPC therapy. We showed that plasma AR normal favored hormonal treatment, whilst plasma AR-gained patients may have had a longer response to docetaxel, suggesting that plasma AR status could be a useful treatment selection biomarker.
Project description:Two randomized clinical trials have demonstrated a survival advantage with enzalutamide over placebo in both docetaxel (D)-pretreated and D-naïve metastatic castration-resistant prostate cancer (mCRPC) patients. Cross-resistance between androgen receptor-directed therapies and taxanes has been suggested, possibly leading to lower efficacy of enzalutamide in the post-D setting.We aimed to examine the impact of prior D treatment on the clinical activity of enzalutamide in patients with mCRPC. We retrospectively reviewed an institutional database to identify men with mCRPC treated with standard-of-care enzalutamide. Patients were classified as D-naïve or D-pretreated. The efficacy end points were prostate-specific antigen (PSA) response rates (??50% PSA decline), time to PSA progression (TTPP) and clinical/radiographic progression-free survival (PFS) in response to enzalutamide. Differences between groups (D-naïve and D-pretreated) were assessed by univariate and multivariable analyses using logistic and Cox regression models.One-hundred-seven (107) consecutive patients were included: 60 were D-pretreated and 47 were D-naïve. PSA responses were 43.2% in D-naïve patients and 25.4% in D-pretreated patients (P?=?0.089). Median TTPP was 7.2 months (95% CI?=?4.5?-?17.2) in the D-naïve group versus 2.6 mo (95% CI?=?1.9?-?3.5) in the D-pretreated group (P?<?0.0001). Median PFS was not reached for D-naïve men and was 3.3 mo (95% CI?=?2.5?-?4.8) for D-pretreated men (P?<?0.0001). After adjusting for potential confounders including prior abiraterone use, differences remained statistically significant for TTPP (HR?=?2.32; 95% CI?=?1.19?-?4.50; P?=?0.013) and marginally significant for PFS (HR?=?1.90; 95% CI?=?0.94?-?3.84; P?=?0.073) in multivariable analyses. Among patients who achieved a PSA response to enzalutamide (n?=?34), results suggested a trend towards shorter duration of response in D-pretreated patients.The clinical activity of enzalutamide appears to be blunted in patients who have previously received docetaxel chemotherapy. These results support the concept of cross-resistance between these two agents.
Project description:BackgroundThe administration of docetaxel chemotherapy is one therapeutic option to delay disease progression and increase overall survival in metastatic castration resistant prostate cancer (mCRPC). However, about 15% of patients are primary resistant to chemotherapy and hence would benefit from an alternative mCRPC treatment. Despite intensive research, there are no robust clinical validated biomarkers to predict mCRPC therapy response. Thus, the aim of the study was to determine KDM5D expression in archival radical prostatectomy specimens of patients medicated with docetaxel at time of mCRPC development in order to correlate KMD5D expression with treatment response.MethodsWe used in situ hybridization (ISH) (RNA scope 2.5 HD) to determine KDM5D expression in tissue samples of 28 prostate cancer patients. KDM5D status was correlated to chemotherapy response (PSA and radiographic response).ResultsData revealed that KDM5D is significantly overexpressed in tumor cells (P<0.0001) but also in benign cells (P<0.02) of those patients who responded to chemotherapy compared to non-responders.ConclusionsTo summarize, KDM5D is a promising novel biomarker predicting response to docetaxel chemotherapy already at the time of localized disease and thus potentially avoiding metastatic biopsies in the mCRPC stage of disease.
Project description:Patients with metastatic castration-resistant prostate cancer (mCRPC) are divided into three groups based on their response to Abiraterone treatment: best responder, responder, and non-responder. In the latter two groups, successful outcomes may not be achieved due to the development of drug-resistant cells in the tumor environment during treatment. To overcome this challenge, a secondary drug can be used to control the population of drug-resistant cells, potentially leading to a longer period of disease inhibition. This paper proposes using a combination of Docetaxel and Abiraterone in some polytherapy methods to control both the overall cancer cell population and the drug-resistant subpopulation. To investigate the competition and evolution of mCRPC cancer phenotypes, as in previous studies, the Evolutionary Game Theory (EGT) has been used as a mathematical modeling of evolutionary biology concepts.
Project description:BACKGROUND:Multiple androgens drive prostate cancer progression and higher pre-treatment levels of androgens, even within the castrate range, have been previously shown to be associated with an improved overall survival (OS) in mCRPC. Docetaxel impairs microtubules, has androgen receptor (AR) inhibitory effects and is used in both the castration resistant and sensitive settings, where androgen dynamics may impact outcome. The present analysis evaluates the association of decline in serum androgen levels (Testosterone (T), Androstenedione (A) and DHEA in docetaxel-treated mCRPC patients with OS. METHODS:Data from 1050 men treated on CALGB 90401 with docetaxel, prednisone and either bevacizumab or placebo were evaluated. Eligibility required progressive mCRPC and no prior chemotherapy. Pre-treatment, 6 week and progression serum assays for T, A and DHEA were performed via tandem Liquid Chromatography-Mass Spectrometry (LC-MS/MS). Changes in T, A and DHEA levels from baseline to 6 weeks were calculated as the ratio of 6-week over baseline. The proportional hazards model was used to assess the prognostic significance of changes in T, A, and DHEA from baseline to 6 weeks in predicting OS adjusting for known prognostic factors. RESULTS:Median baseline values for T, A, and, DHEA were 1.0, 13.5, and 8.1?ng/dL respectively while 6 week levels were 0.64, 7.0, and 6.8?ng/dL respectively. Median OS for low testosterone decline is 20.9 months vs 26.3 months for high testosterone decline. In multivariable analysis including known prognostic variables, change in testosterone levels was independently associated with greater OS; the hazard ratio for death with each unit increase in the 6-week/baseline ratio is 1.02 (95% CI?=?1.01-1.03, p?=?0.001). Decline in A and DHEA were not significant predictors of OS. In multivariable analysis change in the serum changes did not predict PFS however the ratio of T at 6-weeks over baseline was prognostic of ?50% decline in PSA with an odds ratio of 0.93 (95% CI?=?0.85-0.98, p-value?=?0.039). CONCLUSIONS:Declines in testosterone during docetaxel treatment is associated with a longer survival, consistent with a favorable prognostic significance of higher serum androgens in the CRPC.
Project description:BackgroundSWOG S0421 was a large randomized trial comparing docetaxel/prednisone plus placebo (DPP) to docetaxel/prednisone plus atrasentan over 12 cycles for patients with metastatic castration-resistant prostate cancer (mCRPC). The current report presents the PRO results for this trial, an important secondary endpoint.MethodsThe trial specified two primary PRO endpoints. Palliation of worst pain was based on the Brief Pain Inventory (BPI), where a 2 point difference is defined as clinically meaningful. Improvement of functional status was based on the Functional Assessment of Cancer Therapy - Prostate Cancer Trial Outcome Index (FACT-P TOI); a 5-point difference has been defined as clinically meaningful. We compared rates by arm using chi-square tests. Longitudinal analyses using linear mixed models addressed changes by arm over time.ResultsFour-hundred eighty-nine patients on each arm were evaluable for PRO endpoint data. There were no differences by arm in clinically meaningful pain palliation (41.7% for DPP vs. 44.0% for DPA, p = .70) or functional status (24.2% for DPP vs. 28.7% for DPA, p = .13). Longitudinal comparisons indicated no differences over time by arm for BPI Worst Pain scores (0.13 points, p = .23). Patients on the DPA arm had improved functional status of 1.78 points on average, a statistically significant (p = .02) but not clinically meaningful difference.ConclusionsThe SWOG S0421 PRO data showed little evidence of clinically meaningful differences by arm in either pain palliation or functional status.
Project description:Early studies of patients with castration-resistant metastatic prostate cancer (CRMPC) suggest that chemotherapy administered with a dose of a bone-seeking radiopharmaceutical is superior to chemotherapy alone. To build on this strategy and fully integrate a repetitively dosed bone-seeking radiopharmaceutical into a contemporary chemotherapy regimen, we conducted a phase I study of docetaxel and samarium-153 ((153)Sm) lexidronam.Men with progressive CRMPC were eligible. Cohorts of three to six patients were defined by dose escalations as follows: docetaxel 65, 70, 75, 75, 75 mg/m(2) and (153)Sm ethylenediaminetetramethylenephosphonate (EDTMP) 0.5, 0.5, 0.5, 0.75, 1 mCi/kg. Each cycle lasted a minimum of 6 (cohorts 1 through 5) or 9 (cohort 6) weeks. Docetaxel was administered on days 1 and 22 (and day 43 for cohort 6), and (153)Sm-EDTMP was administered on day -1 to 1 of each cycle. Patients with acceptable hematologic toxicities were eligible to receive additional cycles until progression.Twenty-eight men were treated in six cohorts. Maximum-tolerated dose was not reached, because full doses of both agents were well tolerated, even using an every-6-week dosing schedule of (153)Sm-EDTMP. Patients received an average of 5.6 docetaxel doses (range, one to 13 doses) and 2.9 (153)Sm-EDTMP doses (range, one to six doses). Fifteen patients demonstrated a more than 50% decline in prostate-specific antigen. Treatment significantly reduced indices of bone deposition and resorption.Docetaxel and (153)Sm-EDTMP can be combined safely at full doses over repeated cycles. Responses were seen in the small group of patients with taxane-resistant disease tested. The optimal phase II doses for patients with taxane-naïve disease may differ from those optimal for patients with taxane-resistant disease.