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Commentary on Science, Innovation & New Products with a focus on Oncology, Hematology & Cancer Immunotherapy

Posts tagged ‘castrate resistant prostate cancer’

We’ve heard much about the role of PARP inhibitors in ovarian and breast cancers where there is sensitivity to these agents in women with DNA damage repair defects, but what about advanced prostate cancer?

Following the publication of the phase 2 trial TOPARP in the NEJM in 2015, we’ve been eagerly awaiting the outcome of a series of phase 3 studies with these agents in metastatic prostate cancer in multiple different lines of therapy.

Dr Oliver Sartor at ESMO19

Following on from our daily coverage from ESMO in Barcelona last week where we looked at some of the pros and cons as they appeared during the presentation by Dr Maha Hussain (Chicago) from the PROfound trial, it’s time to share some expert opinions.

The study she presented evaluated the PARP inhibitor, olaparib, versus next generation AR anatgonists abiraterone or enzalutamide in refractory metastatic castrate-resistant prostate cancer (mCRPC).  Interestingly, it soon became rapidly clear that many casual observers missed some important nuances from the myriad of top-line news articles and summaries.

The devil, as always, is in the details.

To further our readers education on this important topic, BSB interviewed a prostate cancer thought leader, Dr Oliver Sartor (right) for his personal perspectives and look at the take homes from the lens of an experienced triallist in this niche.

Let’s see what he had to say about PARP inhibitors in advanced prostate cancer, as well as the PROfound and TRITON studies…

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With the launch of Episode 4 of the Novel Targets podcast today, I wanted to provide some more detailed background and a roadmap for this part of the journey for subscribers. There’s tremendous wealth of data now building up in several areas related to cancer immunotherapy and both interviewees, Drs Oliver Sartor (Tulane) and James Gulley (NCI), touched on many of them.

Thanks to Tom Gajewski’s exciting work, we can broadly think about different tumour types as inflamed (immunogenic) versus non-inflamed (non-immunogenic), which is a helpful starting point. Not all tumours thought to be responsive to immunotherapy will actually respond though, so we still have much work to do on the 70–80% of patients with solid tumours that don’t respond to these therapies.

Anyone who is interested can listen to the latest Novel Targets podcast.

The latest episode explores non-immunogenic tumours, using prostate cancer as an example. In the last third of the show, we do indeed talk about a promising new target that may have relevance not just to prostate cancer, but other tumour types too.

Listen to Episode 4  (open access thanks to our sponsors, Genentech)

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PREVAIL trial EAU 2015We’ve been following the updates on the PREVAIL study evaluating enzalutamide (Xtandi) versus placebo in metastatic castrate-resistant prostate cancer (CRPC) in the pre-chemotherapy setting for a while now. It’s interesting to see how the data evolves over time as it becomes more mature.

The first presentation, back in January 2014 at ASCO GU by Dr Tom Beer (OHSU) reported on the first 540 deaths and was subsequently followed by an update of the survival data at AUA in May of the same year by Dr Chris Evans (UCLA).

This morning at the European Urology Association (EAU) in Madrid in the late breaking session on prostate cancer, the honour fell to Professor Bertrand Tombal (Leuven), who did a very nice job of reviewing the mature PREVAIL data (based on 765 deaths) and providing some context for how the CRPC landscape is being impacted by AR pathway inhibitors.

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We have been following the results of the checkpoint inhibitors for several years now, first with ipilimumab (Yervoy) and lately with anti-PD1 and PD-L1 inhibitors such as nivolumab, pembrolizumab and MPDL3280A. Irrespective of the antibody used, the best results we’ve seen have in melanoma, lung and bladder, but some tumour types such as colon and prostate cancers have barely been responsive at all.

Why is that?

Can we find ways to make non-responsive solid tumours responsive to immune therapies, and if so, what strategies could we employ to enable improved responses and outcomes?

At the ASCO Genitourinary (GU) meeting in Orlando this weekend there were some interesting hints of what might be possible in the not too distant future.

To learn more about this phenomenon, we conducted an interview with a leading cancer immunologist to find out what they are doing to make a difference in the GU space.

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It’s now time to turn our attention to genitourinary oncology and, in particular, prostate, renal and urothelial bladder cancers. This week brings this ASCO GU meeting (#GU15), which is being held in Orlando this year and began this morning.

There are quite a few interesting topics being covered here, particularly in the poster sessions over the next three days. Hopefully, 2015 will also bring more good news in this space as 2014 was a rather dismal one on several fronts!

We decided to highlight some of the most interesting abstracts on castrate resistant prostate cancer and urothelial bladder cancer in our latest conference preview.

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Medivation-LogoThere’s nothing better than seeing good news in the early morning email alerts I have set up on cancer research!

 

astellas-logo-no-sloganToday, it was the turn of Astellas and Medivation to announce the results of the TERRAIN study, which is a primarily European phase 2 trial that began in March 2011 in the prechemotherapy setting for castrate resistant prostate cancer (CRPC). The trial met its primary endpoint of progression free survival (PFS).

 

Why is this an important landmark in CRPC and what does the initial data show?

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Over the last few years we have seen new therapies emerge for the treatment of advanced prostate cancer from immunotherapy to chemotherapy and second generation hormone therapies. Each of these has increased survival and outcomes. Along the way though, a host of other agents have fallen by the wayside with a raft of negative phase III trials that did not live up to their phase II promise. These include atrensentan, dasatinib, ipilimumab, lenalidomide and more recently, custirsen.

Much of the focus has, however, been on the hormonal drugs, abiraterone (Zytiga) and enzalutamide (Xtandi) in both the pre and post chemotherapy settings. One thing has become clear though – over time the responses attentuate as resistance sets in. This is very common with oral therapies.

Some big questions to consider here are:

  • What causes it?
  • How can we overcome adaptive resistance?
  • Would combination approaches produce synergistic results?
  • Or should we consider new targets with a different mechanism of action (MOA)?

The answers to these questions are now being eagerly explored through basic, translational and clinical research. I was very impressed with the quality of research and breadth of fresh ideas and approaches emerging from the SBUR, SUO and UOR sessions at AUA this year, including new combination trials already in the planning phase.

In the past, Bertrand Tombal (Belgium) talked about the Grand Cru year for clinical research in CRPC. In the future we may well look back at 2014 as a similar Grand Cru year for basic research for prostate cancer, if the findings translate to clinic. The bench-to-bedside process is very much alive and well in urologic research.

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This week we turn our focus to the American Society of Clinical Oncology Genitourinary (ASCO GU) symposium being held in San Francisco.

The hottest topic is highly likely to be the Medivation and Astellas data for enzalutamide (Xtandi) in the pre-chemotherapy setting in men with advanced prostate cancer who are asymptomatic or slightly symptomatic and naive to chemotherapy.  Previously, I wrote in detail about the Medivation announcement regarding the interim analysis where the PREVAIL trial was found to meet its primary endpoint (open access).

Dr Tom Beer, OHSU

Dr Tom Beer, OHSU

The company subsequently stated that the data had been accepted as a late breaker for the the ASCO Genitourinary meeting in San Francisco this weekend.  That data is being presented on Thursday morning in the oral prostate cancer session by Dr Tomasz Beer (OHSU), who is the Deputy Director of the Knight Cancer Institute and a prostate cancer specialist.

The ASCO GU 2014 abstracts will be available for perusing as of 5pm ET today.

This week I caught up with Dr Beer to discuss not only the details relating to the PREVAIL data, but also how enzalutamide (Xtandi) potentially fits in the advanced prostate cancer competitive landscape given that he also participated in the abiraterone (Zytiga) COU-AA-302 trial in the same clinical setting.

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TBMS Sprycel Logohe results of the phase 3 clinical trial of dasatinib (Sprycel) plus docetaxel/prednisone versus placebo and docetaxel/prednisone in men with castration-resistant metastatic prostate cancer (CRPC) are expected soon.

BMS recently updated the clinicaltrials.gov website to show that the dasatinib phase 3 randomized prostate cancer “READY” trial (NCT00744497) of 1500 men completed data collection in August.

Data is expected before year end and, If positive, could be a late breaker at the ASCO Genitourinary Cancers Symposiusm (ASCO GU) in Orlando from Feb 14-16, 2013.

Dasatinib inhibits Src-family kinases (SFK)

Dasatinib is approved for Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia and Ph+ acute lymphoblastic leukemia (ALL). It is a BCR/ABL, LYN and Src family tyrosine kinase inhibitor.

Src-family kinases (SFK) are involved with tumor proliferation and bone metabolism.

In the phase 1 & 2 clinical trials of dasatinib with docetaxel, many of the men with prostate cancer saw a decrease in PSA from baseline, reduction in tumor size and bone scan improvement and stabilization. Encouraging early results led to the start of a phase 3 randomized trial of dasatinib in combination with the chemotherapy, docetaxel.

However, the results for Src inhibitors in prostate cancer have been mixed to date, with not all agents generating positive data. Astra-Zeneca’s saracatinib (AZD0530), for example, showed little clinical effect on its own in a phase 2 prostate clinical trial.

It has been suggested by KOLs at numerous conferences that Src inhibitors may potentially be more effective in combination with other cancer agents. Data suggests that Src might be a resistance mechanism to enzalutamide (MDV3100), so it would be interesting to see whether a dasatinib/enzalutamide combination may be more effective than enzalutamide on its own.

Meanwhile, we await the data to see whether the combination of dasatinib with docetaxel generates a significant increase in overall survival over docetaxel alone. While some are “hopeful”, Dr Oliver Sartor, Professor of Cancer Research at Tulane Medical School noted in a prostate cancer session at ESMO 2012 that, “the docetaxel-combination graveyard is big!

Update Jan 26 2013: Dasatinib Phase 3 Data at ASCO GU

Results from the dasatinib phase 3 prostate cancer trial are a late breaking abstract at the 2013 ASCO Genitourinary Cancer Symposium (ASCO GU) in Orlando. The data will be presented on February 14 by John Araujo MD PhD, Assistant Professor in the Department of Genitourinary Medical Oncology at The University of Texas MD Anderson Cancer Center in Houston.

LBA #8: Overall survival (OS) and safety of dasatinib/docetaxel versus docetaxel in patients with metastatic castration-resistant prostate cancer (mCRPC): Results from the phase III READY trial.

With the collapse of the Dendreon share price today following poor sales data (Adam Feuerstein on The Street has an excellent write up about this), attention has again focused on the prostate cancer market.

Zytiga (abiraterone acetate) was recently approved by the European Medicines Agency (EMA), following FDA approval earlier this year.

The EMA Committee for Medicinal Products for Human Use granted the marketing authorization for Zytiga at it’s July 2011 meeting.  The approval noted,

“The poor prognosis of the target patient population represents a high unmet medical need while the novel mechanism of action of abiraterone has the potential to offer an alternative therapeutic option for these patients.”

What does this mean for sales of sanofi-aventis’ cabazitaxel (Jevtana), which was approved in Europe earlier this year?

Given that both drugs have approval in the same indication for metastatic castrate resistant prostate cancer (mCRPC) post-docetaxel chemotherapy, and the price is likely to be comparable, my guess would be that Jevtana sales will take a big hit.

After a sick prostate cancer patient has undertaken several cycles of chemotherapy with docetaxel, why would they not want to take an oral pill as opposed to another chemotherapy drug, which does have a less than stellar adverse-event profile.  The answer is they will probably take a chemo-holiday and use Zytiga.

Jevtana simply came to the market too late in Europe, and Zytiga gained accelerated approval.  It’s a reminder that we live in a dynamic pharmaceutical market place, as the news last night from Dendreon has also reminded us.

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