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

Posts tagged ‘Oliver Sartor’

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)

BSB Subscribers can learn more in-depth information and insights about this emerging field by signing in or you can sign-up in the box below.

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 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.

At the 2012 annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago, Oliver Sartor, Professor of Cancer Research and Medical Director of the Tulane Cancer Center in New Orleans told attendees in the educational session on castration-resistant prostate cancer (CRPC) that he was tired of being asked the question of what is the optimal sequence for new advanced prostate cancer drugs?

ASCO 2012 CRPC Prostate Cancer Education SessionThere is “No data,” Sartor told the ASCO 2012 audience. As a result he recommended the use of less toxic therapies first and that patients be involved in the decision making. Not quite the guidance the audience perhaps hoped for.

Sartor is, however, correct that we don’t yet have the data – the clinical trials have yet to be done that will answer the question of what is the optimal sequencing of prostate cancer drugs?

The approval of abiraterone acetate (Zytiga®) for the treatment of men with advanced prostate cancer, post chemotherapy, and the expected approval of enzalutamide (formerly MDV3100) and radium-223 (Alpharadin) have focused attention on sequencing and combination options.

A poster at ASCO 2012 showed that cross resistance may occur between abiraterone and enzalutamide, suggesting that if resistance to one develops it may lower the efficacy to the other if given subsequently. More data and research is needed to validate this finding and understand how resistance develops.

Reciprocal feedback between the PI3-Kinase and androgen receptor (AR) signaling pathways means that blocking the androgen receptor may stimulate the PI3K pathway and vice versa, leading to the tumor trying to ensure its survival. This is particularly important in prostate cancers that have the PTEN tumor suppressor gene, the result is that the targeting of both PI3K and the AR to avoid crosstalk may be required.

The scientific rationale for combining enzalutamide with a PI3-kinase inhibitor was discussed on Pharma Strategy Blog in Sally Church’s video from the 2011 American Urological Association annual meeting. Clinical trials are being planned to investigate the use of PI3-kinase inhibitors in prostate cancer.

I have written more from ASCO 2012 about the emerging challenges in prostate cancer drug development in a guest post published on Xconomy.  Many thanks to Luke Timmerman, National Biotech Editor, for the opportunity to contribute.

Hopefully, there will be more insights available at ESMO 2012 later this year and at ASCO next year on prostate cancer drug resistance, optimal sequencing and the benefits that combinations therapies may offer.

The abstracts for the forthcoming American Society of Clinical Oncology 2012 Genitourinary Cancers Symposium (ASCO GU) have been released and offer insight into some of the new data that will be presented at the meeting.

radium-223 Alpharadin Prostate CancerThe results of the phase III ALSYMPCA trial for radium-223 (Alpharadin) in prostate cancer were presented at ECCO/ESMO last September by Dr Chris Parker.

As expected, there is no change to data presented in Stockholm that showed radium-223 (Alpharadin) improves both Overall Survival and Skeletal Related Events:

radium-223 Overall Survival Benefit
median 14.0 vs 11.2 months; P value = 0.00185; HR = 0.695

radium-223 time to first SRE 
median 13.6 vs 8.4 months; P value = 0.00046; HR = 0.610

However, the meeting abstract published today shows that radium-223 in bone-metastatic castration resistant prostate cancer patients (CRPC), not only significantly prolonged time to first skeletal related event (SRE), but significantly prolonged 3 out of the 4 SRE components:

  • time to spinal cord compression,
  • time to pathological bone fracture
  • time to external beam radiation

No significant improvement in the SRE component of time to surgical intervention was seen with radium-223.

Subscribers to Premium Content can login to read commentary by Dr Oliver Sartor on the clinical significance of this data:

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Times-Square-NYC-November-11-2011This morning the 8am session at the Chemotherapy Foundation Symposium (The Greenspan Meeting) in NYC featured a review of current developments in Prostate Cancer.

The informative 1.5 hour session covered a lot of ground with the presenters reviewing clinical data for:

  • Radium-223 Chloride: a new option for CRPC (Oliver Sartor)
  • Pomegranite extract for Rising PSA (Michael Carducci)
  • XL184 in mCRPC (David Smith)
  • Optimizing patient selection for sipuleucel-T (Simon Hall)
  • Intermittent androgen suppression for prostate cancer (Laurence Klotz)
  • Lenolidomide/docetaxel in CRPC (Daniel Petrylak)

Oliver-Sartor-MD-presenting-at-NYC-Chemotherapy-Foundation-Symposium-2011The highlight, in my opinion, was Oliver Sartor’s excellent presentation on radium-223 chloride (Alpharadin) in which he cogently outlined its mechanism of action.  He explained that radium-223:

  • targets osteoblastic bone metastases by acting as a calcium mimic
  • is a bone-seeking calcium mimetic that binds to hydroxyapatite
  • has preferential uptake in areas of new bone formation

As mentioned previously on this blog, there are critical differences between an alpha emitter such as radium-223 and other bone-seeking radiopharmaceuticals that are beta emitters.

Sartor presented some excellent slides that showed how alpha emitters require much fewer DNA hits to kill cells, are short range and have a higher initial energy per particle.  In other words they are very effective at short range within the bone microenvironment, something that Chris Parker from The Royal Marsden Hospital mentioned in his interview from ECCO/ESMO in Stockholm.

Sartor concluded his Chemotherapy Foundation Symposium presentation by reflecting on “where do we go from here” in prostate cancer?  Some of his observations were:

  • We are currently in a sequencing paradigm. Drug A then B then C
  • We need to combine active agents to give the best results, that is our next challenge
  • How are we going to afford it all?

Sartor succinctly highlighted where the rubber currently hits the road, and left the audience with plenty to reflect upon. I am sure we can expect further debate on sequencing and combination possibilities at medical and scientific meetings in 2012.

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There is a lot of focus at the annual meeting of the American Urological Association (AUA) here in Washington DC on metastatic castrate resistant Prostate Cancer (mCRPC), and the recently FDA approved adrenal steroid inhibitor, abiraterone acetate (Zytiga®).

Drugs in development that target the androgen receptor, such as MDV3100, are also generating a lot of interest from urologists.

However, Oliver Sartor (Tulane) in the Saturday morning satellite symposia that I attended, focused on emerging therapies in CRPC, beyond the androgen axis. His hypothesis:

“Cancers are devious and some of the mechanisms of AR activation appear to be ligand-independent and resistant to all current androgen-axis targeted therapies.”

What this means is that focusing on adrenal steroid inhibition or blocking the androgen receptor may not be sufficient to prevent disease progression. If we are looking for a Prostate Cancer cure, then will it take multiple drugs, including those that target various stromal sites? That is the intriguing question that Sartor raised.

Indeed, if there is one take home from this meeting, it is that the “desert” of prostate cancer therapies has now blossomed into a multiplicity of potential new therapies and development, which will mean that urologists and oncologists will soon be spoilt for choice as abiraterone and MDV3100 are not the end of the story.

Sartor highlighted some interesting ones on the horizon to watch out for:

Alpharadin: This is a bone targeted therapy that uses radioactive Radium 223 to kill cancer cells. It is being developed by Norwegian company, Algeta in partnership with Bayer Schering Pharma AG. The 900 patient phase III trial completed accrual earlier this year in Jan 2011. Phase II data was published in the Lancet in 2007 by Nilsson et al. Data from alpharadin will be “coming soon” according to Sartor.

XL-184 (cabozantinib): Activated MET is highly expressed in prostate bone metastases. Exelixis XL-184 is a small molecule tyrosine kinase inhibitor that specifically inhibits both MET and VEGFR2.

Data from a phase 2 study of XL-184 in castrate resistance patients was presented last year at the EORTC-AACR-NCI Symposium on Molecular Targets and Cancer Therapeutics in Berlin by David Smith et al (Abstract 406).

Both XL-184 and alpharadin would be potential competitors to Amgen’s denosumab (Xgeva®).

Other new products in development “Beyond the Androgen Axis” that Dr. Sartor mentioned included Prostvac-VF, BPX-101 and ipilimumab. A phase III trial of ipilimumab, both pre- and post- docetaxel is now underway in mCRPC. A phase III trial of Prostvac-VF will start later this year with 1200 patients in a placebo controlled study with minimally symptomatic, castration-resistant metastatic prostate cancer patients.

Over the next few years a lot of data may emerge on exciting new treatment options. Coupled with the basic research that is going on, tremendous progress in the treatment of Prostate Cancer is already taking place.

According to Sartor “multiple drugs will be necessary to cure mCRPC and that is our greatest challenge today.” Major progress is now being made towards this.

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I am off to Washington DC tomorrow for the annual meeting of the American Urological Association (AUA).

If you are not able to attend, then you can follow the Twitter coverage on Pharma Strategy Blog where Sally Church (@MaverickNY) will be aggregating the tweets.  The conference hashtag is #AUA2011.  I also expect to be live-tweeting from the conference.

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Like many medical conferences in the United States, the AUA meeting kicks off with independent continuing medical education (CME) satellite symposia on topics of interest.

As a lawyer who has to pay for his own continuing legal education (CLE) credits, I have to confess that I am somewhat cynical that other professionals such as physicians expect to have their CME paid for through free industry-sponsored events.  These symposia are certainly not cheap to run.

However, compared with Europe, CME events in the United States are usually well-produced and fair balanced, albeit with a topical theme that obviously relates to the sponsor’s interest.

The two satellite symposia that I will be attending at AUA are Friday evening’s Amgen supported “Managing Skeletal-Related Events in Patients with Prostate Cancer” and the Saturday morning Astellas/Medivation supported “Reason for Hope: Key Advances in the Management of Castration-Resistant Prostate Cancer.”

While at Quintiles, I was lead CRA/European Project Manager for the phase III trial trial of risedronate in elderly women at risk of hip fracture, so I am interested in bone related treatments, and am looking forward to hearing more about denosumab (Xgeva®) and its impact on skeletal related events (SRE).

Oliver Sartor (Tulane) raises some excellent questions in a recent paper published in the Asian Journal of Andrology, “if a patient has a SRE, does it affect the way a patient feels, functions or survives?”

Sartor argues that a better definition of the benefit a drug has on SRE’s would be “a reduction in pain, analgesic consumption or improvement in quality of life (QoL)” instead of the current “feel, function or survive” standard.

He notes that patients with bone-metastatic castrate resistant prostate cancer (CRPC) have a limited life expectancy, so that QoL is a key issue. “An asymptomatic event linked to a future adverse event is less meaningful in a patient with metastatic CRPC.

Sartor concluded his paper by saying:

“The lack of effect of bisphosphonates or denosumab on patient-reported outcomes including QoL, pain or analgesic consumption continues to be a disappointment for this entire field.”

When we talk about a reduction in SRE’s what does this really mean for the patient?  I look forward to hearing what the expert panel at Friday evening’s symposia on this topic and hope it will be addressed.

Moving on to the other satellite symposium, supported by Medivation/Astellas, that I will be attending early on Saturday morning.  I expect this symposium will focus on new drugs in the pipeline such as MDV3011 and ARN-509 that target the androgen receptor. Hopefully they will also discuss other therapeutics, such as the recently approved abiraterone acetate (Zytiga®), as well TAK-700, which has a similar mechanism of action to abiraterone, i.e. they both inhibit CYP17 and testosterone production.

I’m looking forward to hearing what the expert panel has to say about the need to take prednisone with abiraterone, and whether there are any issues surrounding long-term usage if abiraterone ends up being used earlier in the pre-chemotherapy setting.  Updated data from the COU-AA-301 trial will be presented at AUA on Monday, and I expect a lot of interest from urologists in this.

The satellite symposia are set to be a good warm up act to the start of the main AUA meeting that runs from May 14 to 19 in Washington DC.  I’ll be writing more from the AUA 2011 over the next few days.

ResearchBlogging.orgSartor, O. (2011). Denosumab in bone-metastatic prostate cancer: known effects on skeletal-related events but unknown effects on quality of life Asian Journal of Andrology DOI: 10.1038/aja.2011.33

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