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Enzalutamide for castrate resistant non-metastatic prostate cancer: next step

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Jim Marshall (not a doctor) said ...

  • First step in getting a new treatment accepted is telling your fellow researchers about your results at a conference.
  • Next step is publishing your results in a well respected journal.
  • Third step is convincing the national regulators that it should be made available. (FDA (Food and Drug Administration in the USA, TGA (Therapeutic Goods Administration) in Australia)
  • Forth step is convincing insurers that the treatment is worth the price the company is offering it at. (USA: various insurers, Australia: PBAC for listing on the PBS)

 

Back in February we reported that at the ASCO conference Dr Maha Hussain took the first step by presenting the initial results of the PROSPER clinical trial.

 

The second step was taken today with the publication of the results in a respected journal, the New England Journal of Medicine. 

 

So long as other doctors and researchers do not find major problems with the article, step three (regulators) and step four (insurers) still lie ahead before the treatment is affordably available to men. 

 

The team's results showed:

  • The median for the primary endpoint, metastasis-free survival, was 36.6 months for men who received enzalutamide compared to 14.7 months with ADT alone. 
  • Patients who received enzalutamide plus ADT had a 93% reduction in relative risk of PSA progression compared to patients who received ADT alone; enzalutamide plus ADT delayed the median time to PSA progression by 33.3 months vs 3.9 months with ADT alone. 
  • Enzalutamide plus ADT prolonged the median time to first use of new antineoplastic therapy by 21.9 months vs ADT alone (39.6 vs 17.7 months), a 79% relative risk reduction. [jm: antineoplastic therapy = next anti-cancer drug.]

... end Jim

 

N Engl J Med. 2018 Jun 28;378(26):2465-2474. doi: 10.1056/NEJMoa1800536.

Enzalutamide in Men with Nonmetastatic, Castration-Resistant Prostate Cancer.

Hussain M1Fizazi K1Saad F1Rathenborg P1Shore N1Ferreira U1Ivashchenko P1Demirhan E1Modelska K1Phung1Krivoshik A1Sternberg CN1.

 

Abstract

Background

Men with nonmetastatic, castration-resistant prostate cancer and a rapidly rising prostate-specific antigen (PSA) level are at high risk for metastasis. We hypothesized that enzalutamide, which prolongs overall survival among patients with metastatic, castration-resistant prostate cancer, would delay metastasis in men with nonmetastatic, castration-resistant prostate cancer and a rapidly rising PSA level.

Methods

In this double-blind, phase 3 trial, we randomly assigned, in a 2:1 ratio, men with nonmetastatic, castration-resistant prostate cancer and a PSA doubling time of 10 months or less who were continuing androgen-deprivation therapy to receive enzalutamide (at a dose of 160 mg) or placebo once daily. The primary end point was metastasis-free survival (defined as the time from randomization to radiographic progression or as the time to death without radiographic progression).

Results

A total of 1401 patients (median PSA doubling time, 3.7 months) underwent randomization. As of June 28, 2017, a total of 219 of 933 patients (23%) in the enzalutamide group had metastasis or had died, as compared with 228 of 468 (49%) in the placebo group. The median metastasis-free survival was 36.6 months in the enzalutamide group versus 14.7 months in the placebo group (hazard ratio for metastasis or death, 0.29; 95% confidence interval, 0.24 to 0.35; P<0.001). The time to the first use of a subsequent antineoplastic therapy was longer with enzalutamide treatment than with placebo (39.6 vs. 17.7 months; hazard ratio, 0.21; P<0.001; such therapy was used in 15% vs. 48% of patients) as was the time to PSA progression (37.2 vs. 3.9 months; hazard ratio, 0.07; P<0.001; progression occurred in 22% vs. 69% of patients). At the first interim analysis of overall survival, 103 patients (11%) receiving enzalutamide and 62 (13%) receiving placebo had died. Adverse events of grade 3 or higher occurred in 31% of the patients receiving enzalutamide, as compared with 23% of those receiving placebo.

Conclusions

Among men with nonmetastatic, castration-resistant prostate cancer with a rapidly rising PSA level, enzalutamide treatment led to a clinically meaningful and significant 71% lower risk of metastasis or death than placebo. Adverse events were consistent with the established safety profile of enzalutamide. (Funded by Pfizer and Astellas Pharma; PROSPER ClinicalTrials.gov number, NCT02003924 .).

PMID: 29949494 

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Admin

I forgot to note:

So far, while the study shows enzalutamide for non-metastatic castrate resistant does delay progression of the disease, early evidence of overall survival is not looking much different so far (11% vs 13%). True evidence of overall survival will not be available for some time.

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