***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Enzalutamide ( formerly called MDV3100 ) targets multiple steps in the and rogen-receptor-signaling pathway , the major driver of prostate-cancer growth . We aim ed to evaluate whether enzalutamide prolongs survival in men with castration-resistant prostate cancer after chemotherapy . METHODS In our phase 3 , double-blind , placebo-controlled trial , we stratified 1199 men with castration-resistant prostate cancer after chemotherapy according to the Eastern Cooperative Oncology Group performance-status score and pain intensity . We r and omly assigned them , in a 2:1 ratio , to receive oral enzalutamide at a dose of 160 mg per day ( 800 patients ) or placebo ( 399 patients ) . The primary end point was overall survival . RESULTS The study was stopped after a planned interim analysis at the time of 520 deaths . The median overall survival was 18.4 months ( 95 % confidence interval [ CI ] , 17.3 to not yet reached ) in the enzalutamide group versus 13.6 months ( 95 % CI , 11.3 to 15.8 ) in the placebo group ( hazard ratio for death in the enzalutamide group , 0.63 ; 95 % CI , 0.53 to 0.75 ; P<0.001 ) . The superiority of enzalutamide over placebo was shown with respect to all secondary end points : the proportion of patients with a reduction in the prostate-specific antigen ( PSA ) level by 50 % or more ( 54 % vs. 2 % , P<0.001 ) , the soft-tissue response rate ( 29 % vs. 4 % , P<0.001 ) , the quality -of-life response rate ( 43 % vs. 18 % , P<0.001 ) , the time to PSA progression ( 8.3 vs. 3.0 months ; hazard ratio , 0.25 ; P<0.001 ) , radiographic progression-free survival ( 8.3 vs. 2.9 months ; hazard ratio , 0.40 ; P<0.001 ) , and the time to the first skeletal-related event ( 16.7 vs. 13.3 months ; hazard ratio , 0.69 ; P<0.001 ) . Rates of fatigue , diarrhea , and hot flashes were higher in the enzalutamide group . Seizures were reported in five patients ( 0.6 % ) receiving enzalutamide . CONCLUSIONS Enzalutamide significantly prolonged the survival of men with metastatic castration-resistant prostate cancer after chemotherapy . ( Funded by Medivation and Astellas Pharma Global Development ; AFFIRM Clinical Trials.gov number , NCT00974311 . ) BACKGROUND Sipuleucel-T , an autologous active cellular immunotherapy , has shown evidence of efficacy in reducing the risk of death among men with metastatic castration-resistant prostate cancer . METHODS In this double-blind , placebo-controlled , multicenter phase 3 trial , we r and omly assigned 512 patients in a 2:1 ratio to receive either sipuleucel-T ( 341 patients ) or placebo ( 171 patients ) administered intravenously every 2 weeks , for a total of three infusions . The primary end point was overall survival , analyzed by means of a stratified Cox regression model adjusted for baseline levels of serum prostate-specific antigen ( PSA ) and lactate dehydrogenase . RESULTS In the sipuleucel-T group , there was a relative reduction of 22 % in the risk of death as compared with the placebo group ( hazard ratio , 0.78 ; 95 % confidence interval [ CI ] , 0.61 to 0.98 ; P=0.03 ) . This reduction represented a 4.1-month improvement in median survival ( 25.8 months in the sipuleucel-T group vs. 21.7 months in the placebo group ) . The 36-month survival probability was 31.7 % in the sipuleucel-T group versus 23.0 % in the placebo group . The treatment effect was also observed with the use of an unadjusted Cox model and a log-rank test ( hazard ratio , 0.77 ; 95 % CI , 0.61 to 0.97 ; P=0.02 ) and after adjustment for use of docetaxel after the study therapy ( hazard ratio , 0.78 ; 95 % CI , 0.62 to 0.98 ; P=0.03 ) . The time to objective disease progression was similar in the two study groups . Immune responses to the immunizing antigen were observed in patients who received sipuleucel-T.  Adverse events that were more frequently reported in the sipuleucel-T group than in the placebo group included chills , fever , and headache . CONCLUSIONS The use of sipuleucel-T prolonged overall survival among men with metastatic castration-resistant prostate cancer . No effect on the time to disease progression was observed . ( Funded by Dendreon ; Clinical Trials.gov number , NCT00065442 . BACKGROUND Abiraterone 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 and rogen receptor signalling . We hypothesised that prior abiraterone exposure would adversely impact docetaxel efficacy . PATIENTS AND METHODS We retrospectively evaluated activity of docetaxel in mCRPC patients previously treated with abiraterone , using Prostate Cancer Working Group and radiological criteria . RESULTS Of the 54 patients treated with abiraterone  , 35 subsequently received docetaxel . Docetaxel result ed 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 . CONCLUSION The activity of docetaxel post-abiraterone appears lower than anticipated and no responses to docetaxel were observed in abiraterone-refractory patients BACKGROUND Mitoxantrone plus prednisone reduces pain and improves the quality of life in men with advanced , hormone-refractory prostate cancer , but it does not improve survival . We compared such treatment with docetaxel plus prednisone in men with this disease . METHODS From March 2000 through June 2002 , 1006 men with metastatic hormone-refractory prostate cancer received 5 mg of prednisone twice daily  and were r and omly assigned to receive 12 mg of mitoxantrone per square meter of body-surface area every three weeks , 75 mg of docetaxel per square meter every three weeks , or 30 mg of docetaxel per square meter weekly for five of every six weeks . The primary end point was overall survival . Secondary end points were pain , prostate-specific antigen ( PSA ) levels , and the quality of life . All statistical comparisons were against mitoxantrone . RESULTS As compared with the men in the mitoxantrone group , men in the group given docetaxel every three weeks had a hazard ratio for death of 0.76 ( 95 percent confidence interval , 0.62 to 0.94 ; P=0.009 by the stratified log-rank test ) and those given weekly docetaxel had a hazard ratio for death of 0.91 ( 95 percent confidence interval , 0.75 to 1.11 ; P=0.36 ) . The median survival was 16.5 months in the mitoxantrone group , 18.9 months in the group given docetaxel every 3 weeks , and 17.4 months in the group given weekly docetaxel . Among these three groups , 32 percent , 45 percent , and 48 percent of men , respectively , had at least a 50 percent decrease in the serum PSA level ( P<0.001 for both comparisons with mitoxantrone ) ; 22 percent , 35 percent ( P=0.01 ) , and 31 percent ( P=0.08 ) had predefined reductions in pain ; and 13 percent , 22 percent ( P=0.009 ) , and 23 percent ( P=0.005 ) had improvements in the quality of life . Adverse events were also more common in the groups that received docetaxel . CONCLUSIONS When given with prednisone , treatment with docetaxel every three weeks led to superior survival and improved rates of response in terms of pain , serum PSA level , and quality of life , as compared with mitoxantrone plus prednisone 
    Output:
    
Results Different sequences have been reported for the treatment of mCRPC : docetaxel after abiraterone , cabazitaxel after docetaxel and abiraterone , abiraterone after cabazitaxel and docetaxel , abiraterone after docetaxel and enzalutamide , and enzalutamide after docetaxel and abiraterone .
There are arguments from the pre clinical observations suggesting a cross-resistance between docetaxel and abiraterone , and between abiraterone and enzalutamide in mCRPC .
Conclusion No study of high level of evidence is available to support any recommendation on sequential treatment for mCRPC .