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Abiraterone vs Docetaxel for De Novo Prostate Cancer in Real-World and Trial Settings

March 19, 2021

 

Daniel Geynisman, MD, Fox Chase Cancer Center, Philadelphia, PA, discusses results from a study which compared overall survival (OS) among men with de novo metastatic hormone-sensitive prostate cancer treated with abiraterone acetate or docetaxel in the real-world setting and compared these survival outcomes to those seen in clinical trials.

These results were presented at the virtual 2021 ASCO Genitourinary Cancers Symposium.

Transcript

Hello, my name is Dan Geynisman. I am a genitourinary medical oncologist at Fox Chase Cancer Center, and we presented our work at the GU ASCO 2021 meeting on the real‑world survival of men with metastatic hormone‑sensitive prostate cancer treated with abiraterone or docetaxel and comparing that with clinical trial outcomes.

There has been really a tremendous amount of progress in changing how men with metastatic hormone‑sensitive prostate cancer are managed over the last few years. For decades, the standard of care has been hormone therapy, androgen deprivation therapy by itself.

Then starting around 2015, multiple clinical trials showed that if you add some other agents to androgen deprivation therapy, you actually improve overall survival. That started with docetaxel and chemotherapy, then went onto abiraterone, now enzalutamide, apalutamide, and other hormonal therapies have shown this as well.

These therapies had never been compared head‑to‑head. In other words, there have never been prospective clinical trials looking at, for example, ADT with docetaxel vs ADT with abiraterone. These two drugs are very different. There are different costs associated with them. The length of treatment is very different.

Therefore, we wanted to ask, in the real‑world setting, are there clinically meaningful differences in outcomes? For this study, what we did is we conducted a retrospective observational study using the Flatiron Health electronic database. It's a deidentified database that covers about 280 oncology practices in the United States.

We looked at men diagnosed with metastatic hormone‑sensitive prostate cancer de novo and treated with either ADT and abiraterone or ADT and docetaxel. What we found is we had about 418 men in the abiraterone group, about 807 men in the docetaxel group.

The bottom line is, if you looked at either unadjusted or adjusted median overall survivals at 12 months or 24 months, they were very similar. They were not statistically different.

The other finding that we showed is that, if you compare to clinical trial outcomeswe took out the data from the actual clinical trials that got these drugs approvedand you compare it to the real‑world outcomes, you see that the real‑world outcomes are worse.

If you compare abiraterone via LATITUDe trial or docetaxel via the CHAARTED trial, the real‑world outcomes are worse, whether you do weighted analysis or unweighted analysis. There's a couple of conclusions here.

First of all, not expectedly, we can say that clinical trial patients do better. They're just more appropriately selected. They tend to be younger, tend to be healthier, fewer comorbidities. That's number one.

Number two, at least with this retrospective analysis, the efficacy outcomes are similar between abiraterone and docetaxel. Therefore, when you're having discussions with patients about treatment, particularly in patients with high‑volume or high‑risk disease, where we think docetaxel will be helpful, and where we typically use it, one can actually have discussions surrounding duration of treatment.

Docetaxel is six cycles, and then you're done. Abiraterone is continuous, sometimes for years. Cost, docetaxel clearly is much, much cheaper. We've done previous cost effectiveness showing that docetaxel certainly is more cost effective than abiraterone in this setting, and patient preferences.

This all becomes very important. This is just one piece of the puzzle that seems to show that efficacy‑wise, these show similar outcomes.


Geynisman DM, Correa AF, Ramamurthy C, et al. Real-world survival of men with metastatic hormone-sensitive prostate cancer (mHSPC) treated with abiraterone acetate (Abi) or docetaxel (Doc) and comparison with clinical trial outcomes. Presented at: the virtual 2021 ASCO Genitourinary Cancers Symposium; February 11-13, 2021. Abstract 53.

Dr Geynisman reports no relevant financial relationships.

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