The co-authors of Invasion of the Prostate Snatchers, blog alternate posts weekly. We invite you to post your comments.

Tuesday, May 3, 2011

Zytiga (abiraterone): A Breakthrough for Men with Prostate Cancer


One of the unique characteristics of prostate cancer is its responsiveness to the withdrawal of testosterone. This “Achilles Heel” of prostate cancer was discovered in the 1940’s when surgical removal of the testicles was shown to induce cancer remissions. In 1985, Lupron, an injectable medication that works by tricking the testicles into ceasing testosterone production, was FDA approved. Orchiectomy, or surgical removal of the testicles, has been declining in popularity ever since.

Lupron works for an average of 2-6 years in men with metastatic disease, and for more than ten years in men without metastasis. When Lupron stops working, other hormonal agents such as Casodex or Nilutamide are commonly employed.  Their effectiveness is measured by monitoring prostate specific antigen (PSA).  A good response is signaled by a declining level of PSA in the blood.

Controversy has raged in academia about the significance of these PSA responses and whether or not they are an indication of extended survival. Before approving new drugs, the FDA mandates that pharmaceutical manufacturers document improved survival in prospective placebo-controlled trials. A trial of abiraterone (Zytiga) in men with a rising PSA while on Lupron has shown just that—volunteers who received abiraterone lived 33% longer than men who received a placebo.

Zytiga is a designer drug that exploits the relatively recent discovery that cancer progression is a result of prostate cancer cells manufacturing their own testosterone instead of feeding on testosterone originating from the testicles and reaching the prostate cancer cells via the bloodstream. Zytiga works inside the cancer cell by blocking the function of an essential enzyme in the synthetic pathway of testosterone.  On April 28, 2011, the FDA approved Zytiga, a product of Centocor Ortho Biotech which is owned Johnson & Johnson. We have conducted one phase early access protocol (EAP) and two phase III trials of abiraterone in our Marina del Rey office.

Side effects of Zytiga can include changes in potassium levels in the blood and rare cases of liver irritation. Zytiga has to be administered with prednisone, a form of cortisone. Cortisone can be associated with gastric irritation and occasionally stomach ulcers.  People with diabetes may experience higher blood sugar levels.

Since Zytiga will be offered at a cost of $5,000.00 per month, many men will be interested to know that its chemical mechanism of action is very similar to another more affordable medication already on the market—ketoconazole.  And a month’s supply ketoconazole is only $60.00.  However, there has been subdued enthusiasm for ketoconazole due to a very high frequency of adverse interactions with other common medications like Lipitor, Zithromax, Norvasc, Glipizide, Paxil, Prozac, Coumadin, Coreg and antihistamines.  It can also cause side effects such as stomach upset or liver problems. To be used safely, close monitoring on therapy is essential. Even so, if used cautiously, after close to 20 years of experience with ketoconazole, I have found that many men can tolerate it quite well.

For men who can afford it, or at least have insurance to cover the cost, Zytiga will be popular thanks to the much lower incidence of side effects.  Even with the major cost considerations I predict Zytiga will become the standard of treatment for men who are resistant to Lupron.  And just as Lupron is continued indefinitely, even after PSA begins to rise, Zytiga will probably be used indefinitely as well, even if the cancer is progressing.  After all, now that we know that Zytiga can deny the cancer cells the capacity to manufacture their own testosterone, why would we want to stop the medicine and allow those out-of-control cells to start producing testosterone again?


Anonymous said...

Have you ever heard of any doctor prescribing Zytiga AND Lupron (i.e., patient is to continue on Lupron while now getting Zytiga?). Lupron effectiveness zilch at this point after short-term respite following "return" to Lupron after chemo treatments. Makes no sense and would like to hear what you have to say.

Anonymous said...

Has anyone experienced severe lower back pain?

Anonymous said...

Well. I have mild lower back pain and have had since starting ketoconazole + prednisone (over three years).
However, my neurologist insists it's a result of mild arthritis. I experience it only when I exert myself:
standing long periods, raking, bending over, etc.

Anonymous said...

I have been on Zytiga for a month now. I have severe pain in my lower back sometimes, and also in my upper legs. Has anyone else had this? I'm barely able to function because of the pain medications I have to take and still have breakthrough pain.

Anonymous said...

My dad had the same symptoms. He did feel very bad and had a lot of back pain. After ca. a week of taking Zytiga, the pain improved. Now he is taking the pills for about a month - he is pain free. But the best news is, his PSA-level lowered from 1230 to 268. Isn't that amazing? His well-being is getting better by the day. Amazing drug. So everybody out there with severe back pain - hang in there. It will get better. We are so grateful for that breakthrough for men with advanced prostate cancer. Thank you, thank you, thank you.
Cornelia (09/13/2011)

David Rothschild said...

After one month on Zytiga my PSA jumped from 12.8 to 17.1 Has anyone else experienced a rise in PSA upon starting abiraterone? I am going to take it for another month and hope for the best!

Prostate Oncology Specialists said...

The Prostate Cancer Research Institute (PCRI) developed the Prostate Cancer Blue Community (PCBC): What's your Shade? It is a website to promote collaboration and facilitate access to the PCRI helpline personnel. Visit to learn more, register and post your questions.

Anonymous said...

I would have to agree with taking Ketoconazole. Just knowing the price list for Zytiga will give even a normal person a back pain.
Biochemical pathway of these two drugs follows the same route, but ketoconazole blocks the steps earlier meaning that you won't have problem with high blood pressure or high cortisol level. But individual with Zytiga will have the last steps blocked therefore will have a back up of substrate which will shift and push to cortisol and high aldosterone a result will increase your blood pressure and will put you on a higher cardiac risk. increase on cortisol will lead to Cushing disease moon faces truncal obesity,...

Anonymous said...

I have had a long fight with prostate cancer. It started 2 years ago with a high PSA number. I am on Lupron now and have had radiation along with chemo.
This past June I could hardly do normal functions, in fact I thought I was on my last leg. After getting put on Zytiga I began to recover within a week. After a month I feel as if my biological clock has been turned back 20 years and feel the best I have since this nasty disease started. The first couple months my PSA did rise but then took a steep drop back to 1. I am not experiencing any side effects except the intense hot flashes but then again I think the Lupron is doing that. Thanks to Zytiga I continue to live a very normal active life.

Anonymous said...

I was diagonsed 29 months ago with a psa of 1200 and metatasis to my bones. I was immediately put on Lupron which worked well for 9 months and then psa started rising and turmors grew and spread to more bones. Oncologist took over and went on first chemo Taxotere and then Jevtana. Borth failed, psa climbed to 1567. June 2011 went on Zytiga, and as of 1/12, psa is now down to 14 and I have been doing well. Had some liver problems, now over, and potasium, getting better. Zytiga has worked for me.

Prostate Oncology Specialists said...

Click link to hear Dr. Scholz and Dr. Barken discuss on 3 April 2012 "Ask Dr Barken Call In Show": For castration resistant prostate cancer, is it better to do Provenge first or Zytiga first?

Unknown said...

My dad is still getting lupron shots as well as Zytiga. He is in a clinical trial for men who haven't had chemo. He was diagnosed with metastatic prostate cancer in May of 2011, was immediately started on Lupron and that helped for about 7 months. He was started in the trial last March, 2012 and PSA has gone done significantly. He did experience some back pain early on but none since. I'm not sure why they are continuing Lupron as it stopped working for him. We see the doctor tomorrow to get the latest scan and blood test results. I am planning on asking the doctor about it. I'm just praying the PSA has gone down again!

JAS said...

three years hormonal treatment for Prostate cancer with bone metastasis. Transferred to oncology, casodex, Lupron radiation lowered PSA for a year.

2nd step: clinical trial with tasquinimod for 8 months. PSA rose.

Switched to Zytiga for the last four months. PSA continues to rise. Most recent lab: PSA 283. I will see my oncologist today. Expect him to stop Zytiga Don't know what the next step will be.

I suffer lower back pain most often connected to my arthritis. Fortunately I can keep it at tolerable levels with Advil.