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Showed that a drug blocking the androgen receptor itself, rather than the hormones that feed it, adds nearly five months of life after chemotherapy has failed.
AFFIRM randomised 1,199 men with castration-resistant prostate cancer after docetaxel 2:1 to enzalutamide 160 mg daily (800) or placebo (399), stratified by ECOG performance status and pain intensity. The trial was stopped at a planned interim analysis after 520 deaths.
Median overall survival was 18.4 months (95 percent confidence interval 17.3 to not yet reached) with enzalutamide against 13.6 months (11.3 to 15.8) with placebo, hazard ratio 0.63 (0.53 to 0.75, p<0.001). Every secondary endpoint favoured enzalutamide: PSA fall of 50 percent or more in 54 against 2 percent, soft-tissue response 29 against 4 percent, quality-of-life response 43 against 18 percent, time to PSA progression 8.3 against 3.0 months (hazard ratio 0.25), radiographic progression-free survival 8.3 against 2.9 months (0.40) and time to first skeletal-related event 16.7 against 13.3 months (0.69), all p<0.001.
Fatigue, diarrhoea and hot flushes were more common with enzalutamide. Seizures occurred in five men (0.6 percent), which is the toxicity that defines the drug's contraindications and the reason it is used cautiously in men with a seizure history or brain metastases.
In England NICE TA316 recommends enzalutamide within its marketing authorisation for metastatic hormone-relapsed prostate cancer that has progressed during or after docetaxel, with the patient access scheme discount, and explicitly states that use after abiraterone is not covered by that guidance.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
1,199 enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Overall survival (median)primary | Enzalutamide 160 mg daily | 800 | 18.4 months | 0.63 (0.53 to 0.75) | <0.001 | link |
| Placebo | 399 | 13.6 months | ||||
| Radiographic progression-free survival (median) | Enzalutamide 160 mg daily | 800 | 8.3 months | 0.4 | <0.001 | link |
| Placebo | 399 | 2.9 months | ||||
| PSA decline of 50 percent or more | Enzalutamide 160 mg daily | 800 | 54% | - | <0.001 | link |
| Placebo | 399 | 2% |
Shares COU-AA-301, PREVAIL, Androgen receptor pathway inhibitor (ARPI), What follows what in castration-resistant prostate cancer.
Shares PSA50 / PSA90 response, CARD, What follows what in castration-resistant prostate cancer, Quality of life and patient-reported outcomes (QoL, PRO).
Shares ARMOR3-SV, Androgen receptor pathway inhibitor (ARPI), Castration-resistant prostate cancer (CRPC), Androgen receptor.
Shares Androgen receptor pathway inhibitor (ARPI), What follows what in castration-resistant prostate cancer, Enzalutamide, Castration-resistant prostate cancer (CRPC).
Shares COU-AA-301, PSA50 / PSA90 response, What follows what in castration-resistant prostate cancer, Quality of life and patient-reported outcomes (QoL, PRO).
Shares Androgen receptor pathway inhibitor (ARPI), Enzalutamide, Castration-resistant prostate cancer (CRPC), Androgen receptor.
Shares Enzalutamide, Androgen deprivation & AR pathway inhibitors, Pfizer (incl. Seagen), Metastatic castration-resistant prostate cancer.
Shares Astellas, Enzalutamide, Castration-resistant prostate cancer (CRPC), Androgen receptor.