Biotech Strategy Blog

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

Posts tagged ‘Prostate Cancer New Products’

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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The 102nd Annual meeting of the American Association for Cancer Research (AACR) ended yesterday in Orlando, and it was only the diehards who kept going till the last session of the last day for an update on “Novel Androgen Receptor Antagonists.”

As I mentioned in an earlier post, there is a lot of excitement in the prostate cancer field at the moment with three new therapies approved last year (cabazitaxel, sipuleucel-T, denosumab), and more expected over the next two years (abiraterone acetate, MDV3100, cabozantinib/XL-184).

What I took from the AACR session I attended, is that there are also other products in the pipeline that are worth watching.  Below is a list of some of the products that were mentioned. It’s not intended to be a comprehensive review of the prostate cancer landscape, only my notes and thoughts on some of the new products that the speakers touched upon.

Abiraterone Acetate: The postive phase III trial results were reported last year at ESMO and ASCO GU, and the approval of this drug is currently being considered by the FDA.  Approval is expected shortly, and possibly in time for launch at the forthcoming annual meeting of the American Urological Association (AUA) meeting in Washington, DC.

Abiraterone (brand name Zytiga) inhibits the enzymes (17-alpha hydroxylase and C17, 20 lyase) responsible for adrenal androgen formation.

The phase III results were impressive in very sick patients who were close to the end of their lives in very advanced disease.  Overall survival increased from 10.9 to 14.8 months in the second line chemotherapy setting post docetaxel.  It’s expected that the results will be more dramatic pre-chemotherapy.

Once the FDA approval is obtained, it’s hard to see how oncologists will not consider abiraterone instead of cabazitaxel in the second-line chemotherapy setting.  An easily taken pill with fewer less side effects may be a more convenient option for elderly or frail men with prostate cancer.  Abiraterone’s approval will not be good news for sanofi-aventis.

I also expect we will see significantly off-label usage of abiraterone pre-chemotherapy by urologists as they seek to maintain hormone-sensitivity in their patients after several lines of anti-hormonal therapies.  There is a phase III trial ongoing in this setting that is expected to show promising data by the end of the year.

However, it’s a good strategy to come market as soon as possible to provide wider access to patients in need, and the post-docetaxel second line setting allowed the overall survival benefit to be shown before the pre-chemo data would be available.

However, what I learned at the meeting is that abiraterone acetate may not be the best product in the long term.  Currently it requires the corticosteroid, prednisone, to be given at the same time to attenuate the mineralocorticoid effects.  Questions that were raised in the AACR session about long-term treatment with abiraterone included, “Must a corticosteroid be given concurrently?” and “What about hypertension?”

Other questions remain, such as possible development of resistance to abiraterone. Often the first drug to market is not the best, and it’s possible that second generation new products in the pipeline may be better than abiraterone and delay the time to resistance further.

However, what abiraterone does have is first mover advantage and depending on the pricing strategy adopted by Johnson & Johnson, the ability to capture market share earlier.  It will be interesting to see what happens with this drug, but it’s certainly an exciting time for patients with prostate cancer.

TAK-700: This drug from Takeda/Millennium is a more potent inhibitor of C17α-hydroxylase than abiraterone.  One of the panelists at AACR believed that TAK-700 “may in the long run surplant abiraterone acetate due to less need for mineralocorticoids.” TAK 700 entered phase III clinical trials late last year.

MDV3100:  This drug is being developed by Medivation/Astellas and is also in phase III trials, with data expected by the end of this year or early 2012.  It has a high affinity for the androgen receptor. However, what came across in the AACR presentation by Howard Scher, was his view that the second compound developed by Charles Sawyers, ARN-509 may be better than MDV3100.

ARN-509: This drug from Aragon Pharmaceuticals is in phase I/II clinical trials and is definitely one to watch.  As Dr Scher pointed out, ARN-509 is more potent than MDV3100 and I expect we will see publication of more data on ARN-509 in the near future.

If you are interested in prostate cancer, AACR are offering webcasts and podcasts of scientific sessions this year.  Further information can be found on their website.  AACR have also announced a scientific special session on “Advances in Prostate Cancer Research” from February 6-9 2012.  It’s certainly an interesting and exciting time in this field as new products become available, something that is likely to make a real difference to how this disease is treated.

 

One of the challenges with cancer is being able to detect the disease early enough for effective treatment. The staging or progression of the cancer at time of diagnosis is correlated with 5 year overall survival (OS) rates. Biomarkers that may be expressed by a cancer are, therefore, potentially useful for diagnosis and monitoring of treatment.

There is an ongoing debate about the effectiveness of prostate specific antigen (PSA) as a biomarker for early detection of Prostate Cancer (PC). As Sally Church on Pharma Strategy Blog discusses, PSA measurements can offer false positives and up to 75% of men have a negative biopsy. There is clearly a need for alternatives to PSA measurements.

In the March 1, 2011 online edition of Clinical Cancer Research (a journal of the American Association for Cancer Research, AACR), Richard Morgan and colleagues from the Postgraduate Medical School at the University of Surrey in Guildford, assessed the potential of the Engrailed-2 (EN2) protein as a prognostic biomarker for PC.

Their research found that EN2 is secreted into the urine of men with PC (92%, n=104), but does not appear in the urine of those without PC (0%, n=11). Presence of EN2 in the urine showed a 66% sensitivity for the detection of PC without a digital rectal exam (DRE) when compared to biopsy findings of those with confirmed PC (54 of 82 men). The specificity of the test is almost 90%, i.e. it can pick out men with prostate cancer versus those without cancer.

Interestingly, there was no correlation between serum PSA levels and the presence or absence of EN2. EN2 is measured in small quantities of unprocessed urine (100μl) by means of a simple enzymatic assay.

The investigators state in their paper that a multicenter clinical trial is planned to investigate whether EN2 measurements can be used as a tool for monitoring disease progression after hormonal treatment, radiotherapy or surgery.

However, despite the promising preliminary results in this paper, it is still too early to say whether EN2 will evolve into a clinically useful predictive biomarker for PC.  The fact that EN2 was secreted in patients with non-PSA secreting PC, raises the possibility that it might have a diagnostic role to play in combination with other biomarkers.

EN2 has also been shown to be an oncogene in breast cancer, so it will be interesting to see if there is any further information presented at the forthcoming AACR annual meeting from April 2 to 6 in Orlando.

I recommend reading Pharma Strategy Blog for further insight on cancer biomarkers.

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