GU Cancers 2021 | Real-world survival in mHSPC following abiraterone or docetaxel therapy

We looked at a very common question, common population and this is unfortunately men who have metastatic hormone-sensitive prostate cancer who are treatment-naïve, meaning they were just been diagnosed with metastatic disease. They have not been on hormone therapy.

And the treatment of these men has really evolved greatly since about 2015. Prior to 2015, the standard of care has been simply androgen deprivation therapy. You lower a man’s testosterone, and that was always the first step and that’s it. Then since 2015, there have been a number of new drugs that have been approved in the space, starting with docetaxel, followed by abiraterone, and now several others such as enzalutamide and apalutamide, that are either hormonal drugs or chemotherapy that we would add to the androgen deprivation therapy in order to improve on overall survival. This has been shown to be quite beneficial, statistically and very significantly clinically, in all of the trials, but none of the approaches have been compared head-to-head. So, docetaxel and chemotherapy has never been compared, for example, head-to-head in a randomized trial to abiraterone. And so although both approaches are better than androgen deprivation therapy alone, we don’t know if one is better than the other.

So, what we aim to do is to actually look at a real-world sample using the FLATIRON database, which is a database of patients, about 280 oncology practices in the United States, and take a look at men who are starting on systemic therapy for metastatic hormone-sensitive prostate cancer, and ask if those starting on docetaxel or those starting on abiraterone, which would’ve been the two most common agents used up to this point, have similar outcomes. The second point was to actually compare these outcomes to the outcomes in the clinical trials that got the drugs approved by actually pulling out the individual data points from the curves of the trials and comparing it to our results in the real world.

The two key findings are the following, number one, the 12 and 24 months overall survival between docetaxel and abiraterone seems to be very similar in this real-world population. Number two, although they’re similar, they are inferior to the outcomes in the clinical trials. The second part is not surprising. Patients who go on clinical trials typically are healthier, typically sometimes are younger, there have fewer co-morbidities, tend to do somewhat better than the real-world population. The first conclusion that docetaxel and abiraterone seem to be similar is also, sort of been shown in meta-analyses before, but never sort of in this real-world patient setting and is encouraging. It, I think, provides support that one could use either approach and it also really leads the way into more of a discussion with the patient about their preferences. Do they want chemotherapy for six cycles and then be done and continue hormone therapy shots alone? Do they care about costs? Do they care about certain parts of toxicity that are differential between the two approaches? Again, it supports that both treatment options are valid, and that were the key findings.