XL184 Prostate Cancer | Biotech Strategy Blog

Will Exelixis Cabozantinib COMET-1 prostate cancer trial be positive?

The share price of Exelixis ($EXEL) is starting a run-up (after months in the doldrums) in advance of anticipated results from the COMET-1 phase 3 trial in metastatic castrate resistant prostate cancer (mCRPC) for cabozantinib (Cometriq, formerly XL184).

Cabozantinib is a small molecule tyrosine kinase inhibitor of c-Met and VEGFR2. It has been shown to significantly improve bone scans and decrease pain, but the $64,000 questions are will patients taking it live longer and feel better?

The answers will come from the COMET-1 trial that has a primary end point of overall survival (OS). It’s a placebo-controlled trial of 960 men with advanced prostate cancer randomly assigned to cabozantinib 60mg (n=640) or prednisone (5mg twice daily) (NCT01605227) who have disease progression after treatment with docetaxel chemotherapy and abiraterone (Zytiga) or enzalutamide (Xtandi).

We previously predicted this trial would be a miss, but did it turn out that way and why?

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AACR Advances in Prostate Cancer Research Meeting

By Pieter Droppert on January 31, 2012

A scientific meeting that I would have liked to have attended and one where I think attendees will obtain a lot of insight into the future of prostate cancer research is the forthcoming American Association for Cancer Research (AACR) Advances in Prostate Cancer Research meeting.

Chaired by Charles Sawyers (MSKCC) and Arul Chinnayan (Michigan) it has an impressive line-up of speakers and sessions. The meeting takes place next week (Feb 6-9) in Orlando.

There are two presentations on cabozantib (XL184) that may offer new insights into the mechanism of action of the drug and its potential:

Cabozantinib (XL-184) and prostate cancer: Preclinical and clinical profile of a novel agent

Maha Hussain, University of Michigan Medical School, Ann Arbor, MI

Cabozantinib (XL184) inhibits androgen-sensitive and castration-resistant prostate cancer in the bone and increases bone formation in non-tumored bones Eva Corey, University of Washington, Seattle, WA

A few of the presentations at the meeting that caught my attention include:

Role of inflammation (William Nelson)
Influence of tumor microenvironment on progression and resistance (Christopher Logothetis),
Novel therapeutic targets in prostate cancer (Arul Chinnaiyan)
Overcoming castration-resistant prostate cancer  (Charles Sawyers)

If you have in an interest in prostate cancer research, February 6-9 in Orlando is the place to be.

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Chemotherapy Foundation Symposium Prostate Cancer Update

This 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)

The 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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ASCO 2011 Cabozantinib (XL184) may be an exciting new prostate cancer drug

It’s hard to believe that the countdown to the 2011 annual meeting of the American Society of Clinical Oncology (ASCO) is now underway, but yesterday at 6pm, the ASCO abstracts were released.

Oliver Sartor at the recent annual meeting of the American Urological Association (AUA) highlighted the prostate cancer potential of cabozantinib (XL184), an oral inhibitor of MET and VEGF kinases, so it was interesting to see that new data will be presented at ASCO.

What makes cabozantinib interesting?

The preliminary data shows that it not only has an anti-tumor effect, but also has an effect on bone metabolism.

The data presented at EORTC last year and at ASCO GU this year confirms what was seen in animal models, in that it had both an anti-metastatic effect on soft tissue and blockade of bone lesions. Such dual action on both bone mets and the tumor microenvironment makes it an exciting new compound in prostate cancer.

By all accounts, the novel effect of cabozantinib on bone mets is unexpected.

At the forthcoming ASCO meeting, abstract 3010, whose lead author is Dr Michael Gordon of Pinnacle Oncology Hematology in Scottsdale, AZ will present data on:

“Activity of cabozantinib (XL184) in soft tissue and bone: Results of a phase II randomized discontinuation trial (RDT) in patients (pts) with advanced solid tumors.”

According to Dr Gordon in the ASCO press teleconference yesterday, the phase II data at ASCO for cabozantinib in prostate cancer will show:

Complete or partial bone scan resolution in majority of patients (86%), often accompanied by pain relief

Unprecedented bone scan improvement

On the basis of these promising results, according to Dr Gordon, “Exelixis plans to initiate the first pivotal trial in prostate cancer by the end of 2011.”

It will be interesting to see whether cabozantinib can impact overall survival (OS) in advanced prostate cancer, something that denosumab (Xgeva®) failed to show in the 147 trial that was just presented at AUA.

There are several abstracts on cabozantinib at the ASCO 2011 annual meeting. Another one that caught my attention was abstract 4516, whose lead author is Maha Hussein of the University of Michigan.

Dr Hussein will present data on cabozantinib in metastatic castrate resistant prostate cancer (mCRPC). The abstract’s conclusion is that:

Cabo showed clinical activity regardless of prior D in mCPRC pts, particularly in pts with bone disease, as reflected by high rates of b-scan resolution and pain relief, in addition to improvements in Hb and tumor regression.

I’ll be at ASCO in a few weeks time, so look forward to hearing more detail on the cabozantinib results. The data is still very preliminary, but cabozantinib (XL184) is certainly a drug to watch, and may be an exciting new prostate cancer drug in the future.

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