Dr. Mary-Ellen Taplin is the Director of Clinical Research at the Lank Center for Genitourinary Oncology at Dana-Farber Institute. Prostatepedia spoke with her about the impact Zytiga (abiraterone), Xtandi (enzalutamide), and Erleada (apalutamide) have had on how we treat prostate cancer patients.
Why did you become a doctor?
Dr. Mary-Ellen Taplin: I was drawn to medicine because I really like the science behind cell biology and cell growth. I was attracted to oncology because I like being able to think about how to attack unbridled cell growth. Oncology is about understanding mechanisms of response and resistance. My goal is to give patients the highest level of care through application of basic discovery and not just go with the same status quo. For me, it was the intellectual pursuit of cell biology that then connected with oncology and oncology patients.
Have you had any particular patients over the years whose cases have changed either how you see your own role as a doctor or how you practice medicine?
Dr. Taplin: I treat all my patients as if they were family. I try to go to where they are, provide support, and be a healer. I give them the best go at the best quality of life and length of life that they can have.
Can you talk to us a bit about how Zytiga (abiraterone), Xtandi (enzalutamide), and Erleada (apalutamide) have changed the treatment landscape for men with prostate cancer?
Dr. Taplin: First, in castrate-resistant cancer, these agents have provided patients with fairly well-tolerated oral therapies that work well in most people, at least for a significant period of time. It’s never long enough, but for a year or two, they work well.
Prior to these agents, all we had was ketoconazole, which works similarly to Zytiga (abiraterone) but is less targeted and has a lot of side effects. Ketoconazole wasn’t approved specifically for prostate cancer and wasn’t an optimal drug. We also had chemotherapy. Patients’ lifestyles are always more hindered by having to come in for IV chemotherapy every three weeks compared to taking oral medications.
These newer drugs not only provide effective therapy, but also provide therapy that is more conducive to keeping patients in their regular lifestyles.
Secondly, with newer data that has since evolved, these agents have also been found to improve outcomes for patients when used earlier, like in patients with non-metastatic castrate-resistant prostate cancer, in the case of Erleada (apalutamide), and for hormone-sensitive metastatic disease, in the case of Zytiga (abiraterone).
So, firstly: men with castrate resistant metastatic prostate cancer have more tolerable options, an improved life expectancy, reduced cancer related symptoms on many levels, reduced intensive pain, reduced need for narcotics, and reduced need for early chemotherapy. All things that go along with improving people’s quality of life while treating them.
And then secondly, moving these agents up earlier in disease progression has provided benefits to earlier stage patients. There are a lot of ongoing investigations looking at using these drugs earlier in conjunction with radiation and even prostatectomy. The field is not done with trying to optimize the timing and improving outcomes for patients with these particular clinical tools.
Which combinations are being explored, and which might be the most promising in the long run?
Dr. Taplin: To date, there are no combinations that have been proven effective in any sequential therapy in castrate-resistant prostate cancer (CRPC), but combinations are important and should be evaluated. There is strong biologic rationale to combine Xtandi (enzalutamide) with a CPY-17 inhibitor (abiraterone), Xtandi (enzalutamide) and a PD-1 inhibitor, or Xtandi (enzalutamide) or Erleada (apalutamide) with a PI3 kinase pathway inhibitor.
These are important combinations to explore. But in prostate cancer, at least in the 28 years that I’ve been practicing, despite many trials, not one combination regimen has been approved in CRPC. It’s tough to build a combination therapy in prostate cancer for unclear reasons. That doesn’t mean we shouldn’t explore them, but it means it’s unclear how effective combination therapy will be, at least in the short term.
There is a Phase III Alliance trial looking at Xtandi (enzalutamide) and Zytiga (abiraterone) together in patients with castrate-resistant prostate cancer. Dr. Mike Morris is the Principal Investigator. The biologic rationale is strong to explore more intense androgen receptor pathway inhibition with the combination of a second-generation AR antagonist with a ligand antagonist like Zytiga (abiraterone).
The preclinical rationale is promising, but to date, combination therapy in prostate cancer has been an unfulfilled dream.
What are the side effects like for each of these agents?
Dr. Taplin: There are differences, but they all cause some degree of fatigue, muscle wasting, and hypertension. With Zytiga (abiraterone) we have to watch for low potassium and elevated liver enzymes. We don’t see those things with Xtandi (enzalutamide) or Erleada (apalutamide). In a subset of patients, there is some cognitive clouding, some reduced concentration even to the point of confusion with Xtandi (enzalutamide), though rarely with Zytiga (abiraterone). Erleada (apalutamide) can rarely cause hypothyroidism, which is specific to that drug, so it needs to be monitored.
In general, patients need to have laboratory and blood pressure monitoring on a regular basis, every 2-8 weeks depending on the patient and the individual risks.
At present most patients are castrate resistant when they start on these drugs, so they’ve already had years of adjusting to medical castration. These patients have usually adjusted to the typical side effects that you see with medical castration when you start them on Lupron (leuprolide) or similar LHRH agonists/antagonists and have been more or less familiar with side effects such as hot flashes and weight gain for years.
A lot of patients talk about the high price of these medications. Do you have any thoughts about that?
Dr. Taplin: It’s a big problem. The copays are anywhere from $0 to $4,000 if you have coverage. Then there are the people who don’t have any coverage. This is the nature of Big Pharma in the United States and because the United States bears the burden of research and development of these products for the rest of the world. They’re expensive, and as a society, we have not prioritized dealing with the costs. Sometimes what we would consider even a small copay for a particular patient is too much for them. They’re faced with paying their phone bill or getting their medication.
It’s been well documented that, especially in the elderly, these expensive medications lead to people not taking their medication correctly, trying to stretch them out, skipping days or reducing doses, or not taking them all together. It’s a little different for cancer medication than, say, for blood pressure medicine. Cancer patients are more motivated to take the medication, but probably, they do not often take it correctly to try to make it last longer.
Family members sometimes share the burden. The patient can’t afford the drug, so family members try to patch together the funding. It can be a family problem as well as an individual problem.
I don’t know what the answer is, but it’s definitely true that, as we develop more oral therapies in prostate cancer, patients could be on very expensive sequential oral therapies for many years. For instance, a patient may go from bicalutamide to Zytiga (abiraterone) to Xtandi (enzalutamide) to Lynparza (olaparib). Three out of those four are expensive oral therapies. You’re not just talking about big copays for a year—because Zytiga is only going to work for a year—but sequential copays. These patients are probably going to be on these oral drugs for many years.
Does that ever factor into your choice of which agents to use in which patient?
Dr. Taplin: If we had more choice, it would. Most insurance companies require, at least in castrate-resistant prostate cancer, that you use Zytiga (abiraterone) first because, though still expensive, it is less expensive than enzalutamide. You don’t have a choice as a physician because the insurance companies decide what will be covered. Zytiga (abiraterone) is less expensive than Xtandi (enzalutamide) by almost 50 percent. I’ve stopped doing appeals to insurance companies for these drugs because insurance denials are rarely over turned.
Do you have any thoughts for men who’ve been prescribed any of these agents?
Dr. Taplin: Get guidance from the physician who is prescribing them so that you understand the common potential side effects. Take them as prescribed. If there is toxicity, discuss with your doctors the potential for a dose reduction. Even though there’s the FDA-recommended dose, often these medicines work well at lower doses. You might have less toxicity or feel better, say, on 750 mg instead of 1,000 mg of Zytiga (abiraterone) or 120 mg instead of 160 mg of Xtandi (enzalutamide). Don’t do that on your own, but it’s something that could be discussed with your doctor.
Another important message to get out to patients on these medications is the importance of keeping strong and of regular exercise. Find exercise and activities that you like. Get a trainer. Join a YMCA. Do the LIVESTRONG program. Commit to some sort of strengthening activity to keep your muscles. That will reduce side effects over time and be helpful. Of course, diet is important. A good heart-healthy diet is a good prostate cancer patient diet as well. Exercise and diet are often neglected by patients and physicians but are really important tools for patients on second generation hormone inhibiting drugs.
Diet and exercise can put patients in a better place so that they don’t have a fall or other toxicity problems. If you get a prescription for Xtandi (enzalutamide), you should also get a prescription to go to the gym four times a week. You need more than just a walk to the mailbox and back or to go grocery shopping. You don’t have to be an Olympic athlete, but doing some type of strength training will help build muscle, or at least reduce the reduction in muscle tone that a lot of these men suffer from.