A Phase 3, Randomized, Double-blind Trial of Pembrolizumab (MK-3475) Plus Enzalutamide Versus Placebo Plus Enzalutamide in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC) (KEYNOTE-641)
This important study, called KEYNOTE-641, is researching a new treatment approach for men with advanced prostate cancer. This is specifically for prostate cancer that has spread to other parts of the body (metastatic) and is no longer responding to standard hormone therapy (castration-resistant). The study is comparing a combination of two medicines: pembrolizumab (also known as Keytruda) plus enzalutamide, against enzalutamide plus a dummy treatment (placebo). The main goals are to find out if the new combination helps men live longer and if it slows down how quickly the cancer grows or spreads. Researchers will also look at other things like how the cancer responds to treatment, changes in PSA levels, and side effects. This is a large, advanced-stage study (Phase III) to confirm if this new treatment is better than current options.
At a glance
What is this study about?
This clinical trial, known as KEYNOTE-641, is focused on finding better treatments for men with advanced prostate cancer. Specifically, it's for men whose prostate cancer has spread to other parts of their body (this is called metastatic prostate cancer) and is no longer responding to typical hormone treatments (this is known as castration-resistant). We understand that facing such a diagnosis can be very challenging, and studies like this are crucial for developing new and effective options.
The study is testing a combination of two medicines. One is pembrolizumab, also called Keytruda, which is a type of immunotherapy. Immunotherapy helps your body's own immune system fight cancer. The other medicine is enzalutamide, which is already used to treat prostate cancer. Patients in the study will be split into two groups: one group will receive pembrolizumab plus enzalutamide, and the other group will receive a dummy treatment (placebo) plus enzalutamide. This comparison helps researchers understand if adding pembrolizumab makes the treatment more effective.
Researchers are particularly interested in two main things: whether men live longer with the new treatment combination (this is called 'overall survival') and if the new treatment can slow down the cancer's growth or spread (this is called 'radiographic progression-free survival'). They will also carefully monitor other aspects, such as how the cancer responds, changes in blood tests like PSA, and any side effects the treatments might cause. This is a 'Phase 3' study, which means it's a large, final stage of testing to confirm if a new treatment is safe and genuinely better than existing options before it can be widely used.
Key takeaways
- This study tests a new combination of drugs for advanced prostate cancer.
- It's for men whose cancer has spread and is not responding to hormone treatment.
- The main goal is to see if the new treatment helps men live longer and slows cancer growth.
- Participants will receive either pembrolizumab plus enzalutamide or a dummy treatment plus enzalutamide.
- Regular clinic visits, tests, and scans will monitor your health and the cancer's response.
- This is a Phase III study, aiming to confirm if the new treatment is effective.
Who may be eligible?
To join this study, you must be a man aged 18 or older. You need to have prostate cancer that has spread to other parts of your body. Also, your cancer must no longer be responding to hormone therapy, meaning your testosterone levels are low due to treatment, but the cancer is still growing.
There will be other important health checks to make sure this study is safe and right for you. These might include looking at your general health, how well your kidneys and liver are working, and if you have certain other medical conditions. The study doctors will go through all these details with you to see if you are a good fit.
Could this study suit you?
Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.
- Are you a man?
- Are you 18 years old or older?
- Has your prostate cancer spread to other parts of your body?
- Is your prostate cancer still growing despite hormone treatment that keeps your testosterone low?
What does participation involve?
If you decide to join this study, you would receive either the active study drug (pembrolizumab) or a dummy treatment (placebo), along with enzalutamide. Both pembrolizumab and the placebo are given as an infusion into your vein, which means you'd come to the clinic for these treatments. You'd also take enzalutamide tablets, usually at home.
Throughout the study, you'd have regular visits to the clinic for medical check-ups, blood tests (including PSA levels), scans (like CT or bone scans) to monitor your cancer, and to discuss any side effects. These visits are very important for your safety and to track how the treatment is working. The total time you'd be in the study would depend on how your cancer responds to treatment, but there would also be a period of follow-up once treatment finishes, to track your long-term health. The study team will explain the full schedule of visits and tests during the consent process.
Potential risks and benefits
Locations (11)
- —UnverifiedAustria
- —UnverifiedItaly
- —UnverifiedNetherlands
- —UnverifiedGermany
- —UnverifiedHungary
- —UnverifiedIreland
- —UnverifiedSpain
- —UnverifiedBulgaria
- —UnverifiedCzechia
- —UnverifiedPoland
- —UnverifiedFrance
Common questions
What is metastatic castration-resistant prostate cancer?
It means your prostate cancer has spread to other parts of your body and is growing even though you've been on hormone therapy to lower testosterone.
What is Keytruda (pembrolizumab)?
It's a type of immunotherapy medicine that works by helping your body's immune system to recognise and fight cancer cells.
What is enzalutamide?
It's a hormone therapy medicine used to treat prostate cancer that blocks the effects of male hormones that help cancer grow.
Will I know if I'm getting Keytruda or a dummy treatment?
No, this is a 'blinded' study, meaning neither you nor your doctors will know which treatment you are receiving until the study is over.
How long will I be in the study?
The length of your participation can vary, but typically it involves regular treatment and check-ups for a period, followed by a longer follow-up period to track your health.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
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