Category Archives: Prostate cancer therapy

Rising PSA – When to start therapy


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One of the most frequent situations I encounter in my small “prostate cancer only” practice is a man who has had treatment (usually surgery or radiation) several years ago and now has a rising PSA. He feels absolutely fine, may be exercising daily, and his PSA is often so low that a routine scan won’t show anything. What to do?

The options in this situation are changing. Treating oligometastatic disease (few metastases) is somewhat of a new frontier in this situation. In the “old days” when I wrote about this subject, we reviewed the non-randomized data that suggested no advantage to starting ADT earlier. More recently, the idea of treating some men with radiation or surgery directed at the mets if they have only a few has become more popular. Added to this is the increased sensitivity of the newer PET scans (choline, acetate, PSMA targeted) that may reveal metastases even with PSA values less than 1.0. While it is hoped that some men could be cured by this approach, it is also possible that one could delay the implementation of ADT and its side effects. There are multiple ongoing clinical trials looking at this issue. With such rapidly changing technology, it will be difficult to come up with a “right choice” in every situation. What may have been considered “non-metastatic rising PSA” last year could become “oligometastatic” simply by the implementation of the new scans.

Beyond this is the issue of treatment-related side effects. In an article this week in Lancet Oncology, the side effects of treating men with asymptomatic, non-curable prostate cancer (TOAD and TROG studies) was reported. This study is one of the few randomized studies in this setting. The men were about 70 years old with rising PSA’s, most having been previously treated. They were randomized 1:1 to starting ADT immediately or waiting until at least 2 years later unless “symptoms or metastases developed or PSA doubling times decreased to 6 months or less”. Earlier, the investigators published the survival data in this study, indicating some advantage to starting earlier, as shown in this graph. Screen Shot 2017-09-12 at 9.14.48 PM

However, keep in mind that the men who were in the immediate ADT arm also experienced the ADT side effects sooner according to the new report. The most important areas of symptoms were the hot flashes and decreases in sexual activity (reported only in the men who were sexually active) which were significantly worse with the immediate treatment, as might be expected. In a “global quality of life” measurement there was also worse quality of life, although it was not significant (the score number was 72.39 for delayed therapy vs. 70.83 for the immediate group). Further, the type of ADT used varied, and included both intermittent and continuous therapy (usually intermittent therapy has at least some improvement in quality of life). Finally, none of the men in these studies received the newer (and vastly more expensive -but probably more effective) ADT agents, abiraterone or enzalutamide which have been shown to improve survival when used “up front” in the metastatic setting.

Thus, a rising PSA is obviously a reason for concern, but choosing a management strategy is quite complicated at the present time. The best news to come out of this study is that prostate cancer is a slow disease. “Overall, 18 (6%) men died from prostate cancer, 12 (8%) in the delayed treatment arm and six (4%) in the immediate arm…” This is not to say that as time goes on there will not be more prostate cancer deaths, and there was earlier metastatic progression in the delayed group, but it is equally important to realize that at age 70 there will be significant competing causes of mortality. Something will get us eventually, so the key is to not let prostate cancer (or the PSA) dominate our thinking. What other things can you work on? Stop smoking. Exercise. Improve your diet. And most of all, enjoy each day as a gift and live it to the fullest regardless of how you decide to deal with a rising PSA.

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Filed under General Prostate Cancer Issues, Oligometastatic prostate cancer, Prostate cancer therapy

3 Articles and a forth


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OK, I admit to a sleazy, seemingly misspelled word to attract attention. At least I didn’t tweet it at 3AM. So what about the “forth”? I’m using it to remind you to sally forth in your search for information about prostate cancer. I previously wrote a blog giving some practical instructions on how to find the latest research publications on prostate cancer that you can find here. Another possibility, if you want to be overwhelmed is to subscribe to the Prostate Cancer Daily, published by Uro Today. So far as I can tell it is open to all, presents the original abstracts, and links via PubMed to the article itself. I now realize that the prediction of patients knowing more than their doctors about a given condition is glaringly obvious, something I discussed when I first wrote about the Internet and Oncology two decades ago.

So, on to the 3 articles: Typically, the most important articles in medicine are published in high profile journals. The premier one for medical oncology is the Journal of Clinical Oncology, JCO. The editors recently published a “best of genitourinary cancer, 2017” edition in coordination with what we medical oncologists call “GU ASCO” (actually co-sponsored by ASCO, ASTRO, and SUO). I thought it would be of interest to briefly re-cap the 3 prostate articles chosen for that edition.

ARTICLE 1: Enzalutamide Versus Bicalutamide in Castration-Resistant Prostate Cancer: The STRIVE Trial. This study compared the more potent anti-androgen, enzalutamide (Xtandi™) to the older drug, bicalutamide (Casodex™) in patients who had become resistant to initial hormonal therapy. About 2/3 of the men had positive scans, while in 1/3 the resistance was detected only by a rising PSA without a positive scan. As we might have expected from the way enzalutamide was developed, it was clearly superior, with progression free survival of 19 months for enzalutamide vs. 6 months for bicalutamide. In an ideal world, we would use enzalutamide instead of bicalutamide in almost all cases where an antiandrogen is indicated. However, the increased cost of this drug is dramatic, and there may be other options or confounding issues with interpretation of the study.

ARTICLE 2: Randomized Phase III Noninferiority Study Comparing Two Radiotherapy Fractionation Schedules in Patients With Low-Risk Prostate Cancer. This article reports on one of many studies looking at whether radiation therapy treatment times can be safely shortened by increasing the dose of radiation given with each treatment and giving fewer treatments (fractions). The underlying principles are that tumor cells cannot repair DNA damage from radiation as quickly as normal cells, so giving radiation in small fractions daily allows killing of the tumor while normal cells repair most of the damage. Giving all of the radiation at once would kill every cell (and the patient).  Experimentally, prostate cancer cells may be more susceptible to larger fractions, and this study demonstrated that a radiation therapy course could be safely shortened from 41 sessions to 28 sessions with similar “cure” rates at 5.8 years of followup. This is a general trend in radiation therapy for prostate cancer. Using newer radiation focusing technologies (IMRT, IGRT, Stereotactic radiosurgery, etc.) it is possible to treat prostate cancer with as few as 5 treatments, although the long term efficacy is still unknown, and the addition of androgen deprivation to radiation treatment at any dose also improves efficacy. How to combine these approaches, the optimal duration of ADT, and which patients should stay with the older methods is still uncertain.

ARTICLE 3: Improved Survival With Prostate Radiation in Addition to Androgen Deprivation Therapy for Men With Newly Diagnosed Metastatic Prostate Cancer. Proudly, many of the authors on this article are from the University of Colorado Cancer Center. The authors used the National Cancer Database to determine whether patients with metastatic prostate cancer, traditionally treated with hormone therapy (ADT) only (although more recently with hormone therapy plus chemotherapy) benefit from also radiatiScreen Shot 2015-10-30 at 11.02.16 AMng the prostate itself. The analogy would be burning down the barn after the horse has left (with apologies to my radiation therapy colleagues who never like to compare radiation
treatments to burning). The patients who had their prostates radiated
had a 5 year survival of 49% compared to 33% for those receiving ADT alone. Removing the prostate surgically also worked. The prostate may also be a site where metastatic cells from another location return, as illustrated in this picture and discussed here. The take home message is that the cancerous prostate may continue to “seed” cancer cells to the rest of the body, or be a home for circulating tumor cells and getting rid of it, even though not curative, may be a good idea (toxicities and costs aside).

Consider yourselves updated! (sort of…)

 

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Precision medicine and AR-V7


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Much of the news this week in prostate cancer will be generated by the annual ASCO Meeting in Chicago where VP Joe Biden will be speaking tomorrow about the moon shot. It will be hard to miss the excitement – perhaps even eclipsing (for a day or so) the ongoing circus that is our presidential politics at the moment.

In prostate cancer, there are likely to be considerable news releases regarding precision medicine, and especially AR-V7, so I thought I would explain this a bit. Precision medicine is the broad terminology that (in oncology) refers to looking at the individual patient’s tumor genetic profile. In the broadest sense, it can also refer to all of our genetic makeup that can influence, for example, how we metabolize drugs. The optimal dose for you might be different from that for me based on our inheritance of slightly different enzymes that are involved in breaking down a certain drug. In oncology, it is now possible to perform whole exome sequencing (WES) on circulating tumor cells that give a nearly complete picture of an individual’s cancer – what is driving it, and what it might be susceptible to. In metastatic prostate cancer, as you know from my previous post, the tumor cells circulating in the blood stream could be coming from a variety of places, and likely each individual cell might have slightly different genetics – creating a considerable challenge in the long run for picking out “the” drug that is best for that patient, even with this high-tech approach. Nevertheless, WES has already demonstrated exceptional ability to find targetable mutations in cancer cells, often with several different pathways of potential susceptibility in each patient. Two challenges arise: 1) the drugs that target each “driver pathway” are often frightfully expensive, and 2) which one or ones would be the best to target?

So what about AR-V7? 14 of the 214 prostate cancer abstracts (keep that in mind when you ask your doctor, “Hey doc, is there anything new out there?”) deal with this biomarker. AR-V7 stands for Androgen Receptor – Splice Varient 7. I know…”too complicated for me to understand”. Think of it this way: The AR is the energizer bunny, and testosterone is the battery. Put the battery in the bunny, and he hops into the nucleus of the cancer cell and turns on all sorts of genes (including psa) that drive the cancer cell to do bad things (divide, invade surrounding tissue, metastasize, etc.). Now suppose the bunny becomes autonomous – no need for a battery – he can hop in and do his thing whether or not testosterone is present. This means that all of the new treatments that target testosterone (abiraterone/Zytiga™, enzalutamide/Xtandi™, etc.) really won’t do much. We call this resistance. Castrate resistant prostate cancer (CRPC) used to mean “simply” tumor progressing in spite of very low levels of testosterone (achieved with drugs like leuprolide/Lupron™, goserelin/Zoladex™, etc) or T-blockers like bicalutamide/Casodex™. What we now know is that patients whose cancers are expressing the AR-V7 form of the AR will not respond well to any of these drugs. This means that it could make more sense to proceed directly to treating with chemotherapy with a drug like docetaxel/Taxotere™. Dr. Scher and colleagues at MSKI report in this weeks JAMA Oncology and at the ASCO meeting on the utility of looking for AR-V7 in circulating tumor cells to guide therapy. Screen Shot 2016-06-05 at 8.21.17 AMUsing special immunofluorescent stains, they can identify the “bunny” (shown in white on this photograph from their publication) in the nucleus of some cells in some patients, and these patients are better treated with chemotherapy than with approaches targeting the AR. The implications of this are that we may be able to use such tests to avoid the expense and wasted time of trying to use AR directed therapies in some patients. As often happens, the science is far ahead of the insurance companies however. The Hopkins group have commercialized the test and in an abstract show that it can be cost effective in populations of patients where AR-V7 is likely to be >5% prevalent. Better yet, these insights are now in clinical trial to hopefully develop new treatments for these patients such as galeterone, which may be able to degrade (“kill”) the bunny as described in this abstract from the ASCO meeting.

So YES, we are making progress, and there is a LOT that is new “out there”. Scan the abstracts for yourself – it really isn’t that hard – and kudos to the prostate cancer researchers who are moving this fight forward so quickly.

 

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No pain, no gain?


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One of my patients last week had a heartfelt discussion regarding the survival benefit of ADT vs his quality of life. He enjoys body building and showed me some pretty dramatic pictures of himself during his last ADT cycle (on intermittent therapy) versus now, when he had been off treatment for ~6-9 months. Added to his concern was his decline in libido and sexual function during ADT, a common complaint especially among younger patients. The question of quality vs quantity of life was,of course, utmost on his mind.

Starting from the initial diagnosis, every (maybe that should be every !!) prostate cancer patient will experience a decrement in quality of life. Those who elect “watchful waiting” will nevertheless experience anxiety regarding the shadow of CANCER following their footsteps. Sure, you can put it out of your mind, but turn around and there it is, like the neighbor’s unwanted cat stalking you. Then there is the anxiety over what the next PSA will be. And if on active surveillance, what will that next biopsy show?? These issues are both real, disturbing, and often under-appreciated in the discussions surrounding screening…”we should still be screening, but not treat the men who don’t need it…” Really? What about the 80% of men who die at age 90 with prostate cancer at autopsy who never had to deal with the shadow? (The inevitable counter-argument is, “yes, and what about those who had early detection of a high grade cancer whose life was saved?”)

We also tend to ignore the impact of competing mortality in our discussions. “Sure you had a stent placed last year, and you already survived that small colon cancer, so why wouldn’t we be aggressive in treating this new problem?” Dr. Sartor provided an elegant discussion of this in an editorial on the PIVOT trial you can read here. Whatever the flaws in that study, it remains clear that we are not very good at predicting the non-prostate cancer “future” for our patients, and the older you are, the thinner the ice gets regardless of how many marathons you run.

When patients choose one form of primary treatment vs another, they are weighing the different side effect profiles of surgery or radiation as much as which is “most effective”. I often give patients a copy of this article from NEJM and encourage them to spend some time looking at the graphics in Figure 1 to get some idea of what they will face in the way of side effects from treatment. As any honest physician would tell them, treatment will involve side effects, some permanent, in the best of circumstances.

In the setting of more advanced disease, for example a patient who presents with metastases outside the pelvis, the recent CHAARTED and STAMPEDE trials both suggest an advantage to the earlier use of docetaxel chemotherapy in combination with ADT as opposed to ADT alone. These data suggest that “pay me now or pay me later” analysis favors the “pay me now” approach in terms of overall survival. But at what price for quality of life? Fortunately most chemotherapy side effects are reversible, but distinctly unpleasant, potentially making the equation something like “4 months of misery to provide 14 months of longer life….not all of which will be great anyway”.

Even in the very advanced setting, there is some evidence that greater toxicity results in improved survival. A recent analysis of the TROPIC trial of cabazitaxel suggested that the patients who had the most “toxic response” in terms of dropping their neutrophil count benefited the most in terms of overall survival.

While all of this seems incredibly negative (for which I apologize), the history of oncology as a field has been the incremental improvement in survival AND the development of newer treatments that provide such advances with diminishing toxicity. Pediatric leukemia, as discussed extensively in “The Emperor of All Maladies” is a great example of how pioneering patients and physicians worked together to find cures and reduce side effects. We may only be at the beginning of such achievement in prostate cancer, but with the advent of the newer hormonal and imaging agents, increasingly sophisticated surgery and radiation, vaccines and immunotherapy, and even the chemotherapies now available, we have  no doubt reached the end of the beginning. Onward!

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Olaparib for resistant prostate cancer


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In what is the first (and hopefully one of many) example of using modern genomic methods to match treatments to the molecular defects in prostate cancer, the FDA has just granted “breakthrough designation” to olaparib, a drug made by AstraZeneca. This followed a publication in the NEJM with nearly as many authors as patients, illustrating the power of team science and international collaboration.

Cancer cells develop numerous mutations that provide them with the ability to divide, metastasize, escape immune surveillance and so forth. One of the drivers of this mutation cascade is genetic instability, in part due to the accumulation of mutations that keep the cells from correcting DNA alterations. These mutations in DNA-repair enzymes can leave the cancer susceptible to additional inhibitors of DNA repair, one of which is PARP, an enzyme found in the nucleus that detects DNA strand breaks and initiates repair. When olaparib interferes with this enzyme, cells can become so genetically unstable they die.

In the TOPARP-A trial, 50 patients who had castrate resistant prostate cancer and had progressed on second generation anti-androgen treatment and docetaxel were given olaparib. 16 of 49 evaluable patients responded, however the exciting finding was that because these patients participated in the clinical trial and allowed the investigators to biopsy their tumors, it was possible to relate response to the presence of defects in the DNA repair genes. For this subgroup, 14 of 16 responded, indicating that using the repair defects as a biomarker you could predict high response rates, while at the same time, patients without such genetic defects had a much lower response rate (2/33). There is an excellent video that illustrates the results accompanying the publication that you can find by clicking here.

Although this is terrific news for prostate cancer patients, it brings a number of challenges. Testing for genetic mutations is a growing (and somewhat expensive) process. When compared to giving patients a drug that predictably won’t work, however, it can be very cost effective. Second, when you biopsy a tumor, the results can vary depending on where you biopsy as I discussed in this previous blog. “Liquid biopsies” of circulating DNA or tumor cells may provide some help in meeting this challenge.  Third, responses to targeted therapies such as olaparib tend to be rather short-lived, as the cancer cells continue to mutate to find ways around the new agent. The hope would be that combining a targeted treatment like olaparib with an immune approach might bring more prolonged responses. Finally, we must find a way to deal with the extraordinary costs of the new oncology drugs. The actual cost of olaparib is $13,440/month according to this article in the ASCO post. I have previously opined on this issue and invite you to join the discussion by clicking here.

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Filed under General Prostate Cancer Issues, Prostate cancer therapy, Targeted treatment