Enzalutamide Receives FDA Approval for Metastatic Castration-Sensitive Prostate Cancer

Enzalutamide (Xtandi), for metastatic (stage 4), castration-sensitive, male hormone suppression-sensitive prostate cancer, received on 16 December 2019 US Food and Drug Administration (FDA) approval. Thus, it is approved for newly diagnosed stage 4 disease. Abiraterone in 2018 and apalutamide in 2019 previously received this indication. Earlier enzalutamide stage 4 approvals covered castration-resistant disease.

What Is Enzalutamide?

First approved in 2012, it prevents androgens, testosterone and dihydrotestosterone, from binding intracellular prostate cancer androgen receptors , a new-generation hormone-suppression treatment.

World Cancer Statisticsreport that in 2018, 1 million 280 thousand men were diagnosed. Approximately %10 present metastatic, so approval concerns globally more than 100 thousand patients .

ARCHES: Metastatic Castration-Sensitive Prostate Cancer

Efficacy was evaluated in 1150 patients, randomized 1 to 1: 574 received daily 1 oral dose of 160 mg, while 576 controls received placebo . All simultaneously received standard hormone suppression with a GnRH analogue or previously underwent bilateral orchiectomy .

Primary endpoint was radiological progression-free survival, time of disease control. It ended at progression or death within 24 weeks after stopping medication. Radiological progression meant on bone scanning 2 or more new bone metastases and/or soft tissue progression. Time to new cancer treatment was additional.

Median rPFS was 19.4 months with placebo but unreached with enzalutamide because over half remained progression-free (HR 0.39; 95% CI: 0.30, 0.50; p<0.0001); radiological progression risk fell by %61 . Time to new therapy also significantly improved (HR 0.28;% 95 CI: 0.20, 0.40; p <0.0001). PSA progression risk fell by %81 . Overall survival was immature at rPFS analysis.

The most frequent (>% 5) ARCHES adverse effectswere hot flashes, asthenia / fatigue, hypertension, fractures, and musculoskeletal pain.

Recommended doseis daily oral 160 mg with or without food (four 40 mg capsules).

Our country has no approval for enzalutamide or abiraterone in newly diagnosed castration-sensitive disease; only docetaxel chemotherapy is approved at this line. 

- Related topic: The latest in advanced prostate cancer treatment 

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