AZD3514 Fails to Live up to Preclinical Promise in CRPC at ASCO 2013

AZD3514 is a novel Selective Androgen Receptor Down-Regulating Drug (SARD) that showed early preclinical promise for the treatment of Castration-Resistant Prostate Cancer (CRPC).

However the development of this drug in advanced prostate cancer has been terminated by AstraZeneca according to Dr Aurelius Omlin, a Clinical Research Fellow at The Royal Marsden Hospital who presented clinical data on AZD3514 at the 2013 annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago.

I previously wrote about the promising preclinical data for AZD3514 presented by Sarah Loddick at the 2012 annual meeting of the American Association for Cancer Research (AACR) and sometimes drugs when they transition to the clinic just don’t live up to their promise.

That’s what happened here, and it reminds us that testing of drugs on human volunteers remains a key part of drug development despite the inherent risks. (See my post on the TLS deaths on the AbbVie/Genentech ABT-199 CLL dose finding trial)

The results from a first-in-human clinical trial with in men with CRPC were presented by Dr Omlin at ASCO 2013 (abstract 4511). In his oral presentation, he first noted that:

“AZD3514 is a first-in-class, non-steroidal small molecule androgen receptor (AR) down-regulator that inhibits nuclear AR translocation and results in proteasomal AR protein degradation.”

The phase 1 clinical trial to assess safety and tolerability explored doses ranging from 100mg once daily (OD) to 1000mg OD in capsule formulation, and from 1000mg OD to 2000mg taken twice daily (BID) in tablet formulation. A pretty comprehensive range, but……

“Tolerability of AZD3514 was problematic,” said Omlin. “80% of patients had Grade 1-2 Nausea (n=39 out of 49) and 49% Grade 1-2 Vomiting (n=24 out of 49).” Additionally, grade 1-2 thrombocytopenia was seen in 33% of patients. There was no dose limiting toxicity reported.

What killed it for AZD3514 was the fact that according to Omlin,

“Nausea and vomiting were characteristic from the very first dose level starting about 30-60 minutes after dosing and lasting for several hours thereafter.”

However, the drug did show activity in CRPC patients with several patients showing PSA declines including one patient with prior abiraterone exposure. Two patients with soft tissue disease had confirmed responses according to Recist 1.1. There was also evidence of clinical activity from changes in the number of circulating tumor cells.

Industry analyst, David Miller (@BiotechStockRsr) commented on Twitter, while watching the presentation, that he thought it hard to see the drug progressing in development, and he turned out to be correct:

AZD-3514 $AZN had huge G1/2 vomiting and nausea #s even with anti-emetics. Not sure this drug can go forward with that. . #ASCO13

— BiotechStockResearch (@BiotechStockRsr) June 3, 2013

Dr Omlin concluded his presentation by stating that, “the development of this compound by AstraZeneca as a selective androgen receptor down-regulator in mCRPC has been terminated.”

Sometimes promising preclinical data just doesn’t hold up when it moves into human clinical trials. Another AstraZeneca drug with preclinical promise has gone to what Sally Church, PhD (@MaverickNY) refers to as “dog drug heaven.”

ASCO 2012 What is the Optimal Sequencing of Advanced Prostate Cancer Drugs?

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?

There 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.

Cabozantinib Prostate Cancer Bone Scans – Part 2 of an interview with Dr Maha Hussain

This is part 2 of my interview with Dr Maha Hussain, Professor of Medical Oncology at the University of Michigan. You can read part 1 about cabozantinib and pain here.

At the 2011 ASCO annual meeting, Dr Hussain presented data from a non-randomized phase 2 trial with cabozantinib that showed dramatic improvements in bone scans before and after treatment.

Bones are living tissues that are constantly being remade, a dynamic process that involves formation of new bone and taking up of old bone, a process known as bone resorption. Cancer cells can interfere with bone remodeling, resulting in increased new bone formation (osteoblastic response) or excessive bone resorption (osteoclastic response).

Bone scans involve the injection of radioactive tracers such as technetium-99m-MDP. In simple terms, the radioactive material detects bone turnover and areas of high bone metabolism. These show up as darker “hot spots” where the tracers accumulate.

Bone scans have poor specificity because tumors, fractures and infection all lead to hot spots. Also, not all tumors or lesions are detected by a bone scan. Bone scans have a sensitivity of around 62-89%.

At the 2011 Society for Translational Oncology Prostate Cancer Symposium, Professor Johann de Bono (The Institute for Cancer Research) noted that bone scans do not accurately reflect the activity of the disease in men with prostate cancer.

This raises the question as to what we should conclude from the bone scans seen with cabozantinib. I put this question to Professor Hussain.

BSB: What is the significance of the bone scans that we see and what should we interpret from them given that bone scans don’t accurately reflect the disease?

Dr Hussain: I will refer you back to my presentation at ASCO originally and my recent AACR presentation.

I have specifically put a slide (together) to address, is what we are seeing a fluke, a function of a technique issue because you are targeting the osteoblasts? Consequently if you inhibit osteoblastic function, you are not going to see much changes on the scan, or is there more too it?

The specific slide actually puts in columns the (percentage of) patients who had a partial or a complete resolution on the bone scan, versus those who had stable or progressive disease, and then matches it with other evidence of an anti-tumor effect as in target lesion regressions, progression free survival at I think the 6 month mark if I recall correctly, as in the pain improvement, narcotic use.

Recognizing that by the way the pain and narcotic use, both of these were post-hoc assessments that were done. Once we saw the observation, the sponsor went back and began asking all the investigators to record these things. Clearly, the ALK phosph going down, the bone turnover markers going down.

The short audio clip below expands on Dr Hussain’s viewpoint about cabozantinib and bone. Click here if you can’t see the SoundCloud audio player.

Dr Hussain’s conclusion is interesting from a marketing strategy perspective. She does not position cabozantinib as a bone targeted drug such as Xgeva or a bone targeted radiopharmaceutical such as Alpharadin. Instead, her view is that cabozantinib should be developed as a “prostate cancer specific drug that does have the added advantage of significant anti-tumor effect in the bone” ie an anti-cancer tyrosine kinase inhibitor (TKI).

This is at odds with how Exelixis appear to be positioning it. The corporate presentation at the Cowen Annual Healthcare Conference on March 6, 2012 had a strong focus on bone metastases: “Cabozantinib demonstrates unique ability to resolve bone metastases and decrease bone pain in CRPC,” one slide said.

If Dr Hussain is correct and we should consider cabozantinib as a prostate cancer specific drug, then it will need to compete on endpoints with other drugs that have shown an impact on overall survival.

Cabozantinib will likely not obtain regulatory approval on the basis of the bone scans, whatever they may show.

Without demonstrating a significant effect on overall survival, it’s hard to believe that cabozantinib will be able to compete effectively in what is fast becoming a very competitive prostate cancer market.

The final installment of the Biotech Strategy Blog interview with Dr Hussain will cover her perspective on the mechanism of action of cabozantinb, and where the drug, theoretically, might be expected to have most impact in prostate cancer.

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Cabozantinib & Pain in Prostate Cancer – an interview with Dr Maha Hussain

Maha Hussain MB ChB is Professor of Medical Oncology at the University of Michigan. She is an international expert into genitourinary malignancies with a focus on clinical research into prostate and bladder cancer.

Cabozantinib is a new drug in development by Exelixis for multiple indications. It captured a lot of attention at the ASCO 2011 annual meeting last year, when Dr Hussain presented data from a phase 2 prostate cancer trial that showed a dramatic improvement in bone scans and pain reduction in those men receiving it.

Unlike other new prostate cancer drugs such as abiraterone (Zytiga) or MDV3100 that target the androgen receptor, cabozantinib is a multi-kinase inhibitor of MET and VEGFR. It has both an anti-tumor effect and an effect on bone metabolism.

At the AACR Advances in Prostate Cancer Research conference last month, chaired by Charles Sawyers (MSKCC) and Arul Chinnayan (Michigan), Dr Hussain gave a presentation on “Cabozantinib (XL-184) and prostate cancer: preclinical and clinical profile of a novel agent.”

I was privileged to have the opportunity to interview Dr Hussain by phone recently and obtain her insight into cabozantinib as a potential new treatment for prostate cancer.

We covered a lot of ground, too much for one blog post, so I’ve broken down the interview into segments that I will be posting separately.

Cabozantinib & Pain

As many readers will be aware, one of the dramatic results presented at ASCO last year, was the impact that cabozantinib had on pain.

At the AACR Molecular Targets meeting in San Francisco last November, further pain data was presented by Howard Scher’s group at Memorial Sloan-Kettering Cancer Center. They showed in a non-randomized phase 2 trial that:

Cabozantinib treatment resulted in high rates of pain improvement and analgesic reduction or discontinuation in patients with moderate to severe pain at baseline

– Rapid and durable pain relief

– Pain relief observed regardless of prior lines of therapy

– Improvement in pain accompanied by reduced interference with sleep and daily activity

Exelixis has since moved forward with clinical trials focusing on prostate cancer pain.

Pain response is the primary outcome in the phase III trial (COMET-2) of cabozantinib (XL184) Versus Mitoxantrone Plus Prednisone in Men With Previously Treated Symptomatic Castration-resistant Prostate Cancer (COMET-2 trial formerly known as XL184-306). Overall survival is a secondary endpoint.

The challenge with using pain as a primary endpoint is that all the advanced prostate cancer drugs that have recently been approved by the FDA such as cabazitaxel (Jevtana), abiraterone (Zytiga), and those for whom approval is expected, such as MDV3100 and radium-223 (Alpharadin), have all shown an improvement in overall survival.

I was, therefore, interested to hear Dr Hussain’s perspective on cabozantinib and its effect on pain in prostate cancer.

BSB: Can pain be a surrogate for survival that regulatory agencies might accept?

Dr Hussain: Honestly, I am not the expert on what the regulatory agencies will do. I know what they have done and I would say that pain has been an indication for regulatory approval of prostate cancer. That’s a long story, it’s an old story. Mitoxantrone was approved based on pain, so I don’t think that is going to be an issue.

Whether it is a surrogate for survival remains to be seen, and to be honest with you, I think that it may not be if you are really using it in far advanced cancer. As we have seen with mitoxantrone, it didn’t seem to make an impact on survival and it is really more about disease progression and pain and quality of life type issues.

I am not aware of a trial that has been done with a primary endpoint being pain, and another key primary endpoint or a secondary endpoint being survival, that has been positive. Having said that, I think in my view, it is a mistake to just focus on the pain.

Pain, as far as I can tell from our experience and others, it’s very late in the setting of the disease by a nowadays standard. I would argue that using this drug as a pain only type drug, you could do it cheaper and less toxic with other agents, with morphine for example.

My point here is, I go back and say to focus it on pain only, my average patient is interested in living longer, not just in controlling their pain.

You can hear more about this in the SoundCloud audio clip below. Prostate cancer patients are not just interested in “how will this drug make me feel,” but also “will I live longer?” Click here if you can’t see the audio file.

Dr Hussain: My point is in a perfect world if the drug delivers, the importance is going to be a totality of effect, that is prolonging life and improving quality of life overall.

BSB: Thank you

The next installment of the Biotech Strategy Blog interview with Dr Hussain will focus on the clinical significance of the dramatic bone scans seen with cabozantinib.

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Update on Orteronel TAK-700 from EAU 2012 Paris #EAU12

There are no major presentations of phase III clinical trial data at the European Association of Urology (EAU) Congress in Paris this weekend, but interesting clinical and scientific data is still being presented.

If you want to understand the competitive dynamics of the prostate cancer market and the market opportunity with urologists, then you need to be at meetings such as EAU in Europe and AUA in the United States.

There was a lot of interest in yesterday’s advanced prostate cancer poster session at EAU 2012.

I mentioned in a previous post that the radium-223/Alpharadin poster showed the data on skeletal-related events presented last month at ASCO GU in San Francisco.

Another poster that caught my attention for a variety of reasons was the one on orteronel (TAK-700), something that we have not heard too much about.

Activity and Safety of the Investigational Agent Orteronel in Men With Nonmetastatic Castration-resistant Prostate Cancer and Rising Prostate-specific Antigen: Results of a Phase 2 Study

Orteronel (TAK-700) is a selective, non-steroidal inhibitor of 17, 20 lyase, a key enzyme involved in the production of androgens such as testosterone. This is a similar mode of action to abiraterone acetate (Zytiga) that was approved last year in the US & Europe.

Orteronel is being developed by Millennium. Two phase III castration-resistant prostate cancer trials are currently enrolling. The post-chemotherapy trial (NCT01193257) is scheduled to have a primary completion date of September 2013 and the chemotherapy-naïve trial has a primary completion date of January 2013 (NCT01193244) according to clinicaltrials.gov at the time of writing.

It is worth noting that both phase III trials are using the drug in combination with prednisone. I doubt very much that the chemotherapy-naïve trial will show overall survival results by January 2013 (a date earlier than the post-chemo trial). This date must reflect when data on the primary outcome measure of radiographic progression free survival (rPFS) will be obtained.

Does rPFS correlate with overall survival? Many oncology new products have shown progression free survival, but no overall survival.

Is there a market for a “me too” of abiraterone? By the time orteronel comes to market, MDV3100 and Alpharadin will both most likely be approved, plus we will have greater insight into combinations and sequencing by then.

In talking to urologists, there is a clear preference for drugs such as MDV3100, which do not require the administration of concomitant steroids.

The phase II data in the poster presented at EAU yesterday concluded:

In patients with nmCRPC and rising PSA, single agent oral orteronel, at a dose of 300 mg BID without prednisone, was feasible and had manageable toxicities.

While it may be possible to administer orteronel without steroids, given the mechanism of action would it still be as effective? The authors also noted in the poster that 2 patients (out of 38) discontinued treatment due to adrenal insufficiency, suggesting that giving the drug without steroids is going to require active surveillance.

Finally, in thinking about TAK-700, I’m left with the question of whether phase III placebo controlled clinical trials are still ethical in advanced prostate cancer patients? In the post-docetaxel indication, we now have cabazitaxel and abiraterone approved, both of which offer an overall survival benefit. MDV3100 and Alpharadin are also expected to be approved by the FDA later this year.

If we have four new agents available after docetaxel that offer a survival advantage, is it ethical for men with advanced prostate cancer to be offered a placebo? If not, then this means that new products will have to go head-to-head with one of the approved drugs, or offer some additive effect if used in combination.

It will be interesting to see if this important issue is taken up by any of the patient advocacy groups and whether physicians start to raise concerns. Recruitment into placebo controlled trials could end up slower as a result.

Orteronel to me is too similar to abiraterone, which I think will face serious challenge from MDV3100. What the market opportunity for Millennium will be as a result of being late to market is an open question.

Alpharadin Expanded Access Program is Recruiting #EAU12

radium-223-Alpharadin-Expanded-Access-Program-Clinical-Trial-Notice

Picture with permission of Bayer

No new data on radium-223 (Alpharadin) was presented at the European Association of Urology 2012 Congress in Paris today.

Dr Chris Parker presented a poster with similar data to his oral presentation on Alpharadin at the recent ASCO GU meeting. The phase III ALSYMPCA trial results were first presented at ECCO/ESMO in Stockholm last year.

However, one of things I did learn at EAU12 was that Bayer have opened an Expanded Access Program for Alpharadin, that allows eligble advanced prostate cancer patients access to this radiopharmaceutical pending regulatory approval.

I was told by a Bayer representative that a license is required but that they are now approving sites so that they can administer Alpharadin in the United States pending regulatory approval.

Further information is available about the trial (NCT01516762), and inclusion/exclusion criteria are available on the clinicaltrials.gov website. This is good news for advanced prostate cancer patients.

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Preview of ASCO GU 2012 Prostate Cancer Data

After the recent JP Morgan Healthcare conference, San Francisco remains the destination of choice for forthcoming medical meetings.

Yesterday, saw the start of the 2012 ASCO Gastrointestinal Cancers Symposium (ASCO GI) at Moscone West from Jan 19-21.

In a few weeks time, the 2012 ASCO Genitourinary Cancers Symposium (ASCO GU) will be held at the San Franciso Marriott Marquis from Feb 2-4.

If you are based in San Francisco, you are at the heart of the action. It’s less optimal if you are East Coast based, unless you need the frequent flyer miles and have a good travel budget!

According to the ASCO GU preliminary program there are eight oral abstracts on prostate cancer that will be presented at the meeting on Thursday, February 2. Here’s my preview of a few that caught my attention:

ASCO GU Abstract #1:

MDV3100 Phase 3 AFFIRM trial results

The first presentation of the MDV3100 AFFIRM phase 3 trial results are a late-breaking abstract and my prediction for the highlight of the prostate cancer session at ASCO GU.

So far, all that is known from the November 3, 2011 press release from Medivation/Astellas is that MDV3100 produced a 4.8 month advantage in median overall survival compared to placebo in men with advanced prostate cancer.

This met the primary endpoint of the phase 3 AFFIRM trial, and the study was stopped early as a result. As the press release notes, MDV3100 provided a 37% reduction in risk of death compared to placebo (hazard ratio = 0.631).

Howard Scher (MSKCC) will present the AFFIRM trial results at ASCO GU, and a closer look at the MDV3100 data is eagerly awaited.

ASCO GU Abstract #6:

Effect of denosumab on prolonging bone-metastasis-free survival (BMFS) in men with nonmetastatic castrate-resistant prostate cancer (CRPC) presenting with aggressive PSA kinetics.

Amgen are seeking a new indication for denosumab (Xgeva) in prostate cancer on the grounds that it prolongs bone metastasis-free survival in men with non-metastatic CRPC. The supplemental Biologics Application (sBLA) for denosumab will be discussed at the Oncologic Drugs Advisory Committee (ODAC) meeting on February 8, 2012.

The results from the phase 3, 147 trial were published in The Lancet last November and showed that use of denosumab delayed time to first bone metastasis by 3.7 months and improved bone-metastasis free survival.

Sally Church on Pharma Strategy Blog wrote about the denosumab 147 data presented at the annual meeting of the American Urological Association (AUA 2011) last year.

However, the challenge that Amgen faces is that they have yet to show that use of denosumab in men with prostate cancer results in an improvement in overall survival. While it may delay the spread of prostate cancer to the bone, the gold standard for all the prostate cancer drugs approved to date has been overall survival.

The 147 trial showed that overall survival was similar between those taking placebo and those receiving denosumab (HR 1.01; 95 percent CI: 0.85, 1.20; p=0.91). Hypernatremia and osteonecrosis of the jaw were also reported with a higher frequency in the denosumab group

It is possible that there may be updated data at ASCO GU, but most likely it will be a review of The Lancet data with some subset analysis.

The FDA Center for Drug Evaluation & Research (CDER) plans to provide a free of charge, live webcast of the February 8, 2012 meeting of the Oncologic Drugs Advisory Committee, so I am looking forward to what the committee makes of Amgen’s filing.

ASCO GU Abstract #7:

Vitamin E & the Risk of Prostate Cancer – updated results of the Selenium and Vitamin E Cancer Prevention Trial (SELECT)

Eric Klein will be presenting updated results from the SELECT trial that were previously reported in the October 12, 2011 issue of the Journal of the American Medical Association (JAMA).

The data showed a 17% increase in prostate cancer risk with Vitamin E supplements. Although the program abstract advertises updated data, I’m not expecting the data to differ dramatically from last year’s JAMA paper.

ASCO GU Abstract #8:

Overall survival benefit and safety profile of radium-223 chloride (Alpharadin), a first-in-class alpha-pharmaceutical: Results from a phase III randomized trial (ALSYMPCA) in patients with castration-resistant prostate cancer (CRPC) with bone metastases.

The ALSYMPCA trial data is being presented for the benefit of attendees who did not hear Oliver Sartor’s presentation on radium-223 (Alpharadin) at the NY Chemotherapy Foundation or hear Chris Parker present the trial data at ECCO/ESMO in Stockholm. This makes strong commercial sense, especially as it’s a product that physicians in the United States may know little about.

I blogged extensively about the ALSYMPCA trial results presented last year, and had the privilege to do an interview with Chris Parker from the Royal Marsden Hospital at the 2011 European Multidisciplinary Cancer Congress (ECCO/ESMO/ESTRO) in Stockholm.

I am not expecting new data to be presented at ASCO GU on radium-223, but it will be interesting to see how the audience views a bone targeted radio-pharmaceutical that unlike denosumab, does provide an overall survival benefit.

The ALSYMPCA trial showed a significant delay in time to first skeletal-related event (SRE) of 13.6 months vs 8.4 months:

AND a median overall survival of 14 months compared to 11.2 months for placebo group:

Alpharadin is on the fast track to FDA approval this year.

My conclusion: If you plan to be at ASCO GU 2012, the prostate cancer data to watch is the first presentation of the MDV3100 AFFIRM trial results.

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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A potential new Immunotherapy in Breast and Ovarian Cancer

There has been a lot of negative publicity around Dendreon and sipuleucel-T (Provenge) recently, and the lack of a clear mechanism of action remains a concern to many.

Irrespective of the company’s commercial performance, sipuleucel-T remains an FDA approved therapeutic cancer vaccine that provides a benefit to some patients. It provided a proof-of-concept that immunotherapy can offer a survival advantage, albeit for a median of 4.1 months in asymptomatic advanced prostate cancer.

Dendreon is learning the hard way the failings in its commercial strategy, and no doubt these will be absorbed by others with other therapeutic vaccines in development.

Which brings me to an interesting paper published online first on November 8, 2011 in the American Association for Cancer Research journal, Clinical Cancer Research.

Researchers from the National Cancer Institute (NCI) published data from a small pilot trial showing a clinical response to a poxviral vaccine (PANVAC) in metastatic breast cancer and ovarian cancer patients.

Twenty six patients were in involved in the pilot NCI trial with PANVAC, a recombinant poxviral vaccine expressing the tumor-associated antigens (TAA), carcinoembryonic antigen (CEA) and mucin-1 (MUC-1).

The results showed a median overall survival of 13.7 months in the 12 breast cancer patients with four patients having stable disease, and one patient on study for 37 months. One patient had a 17% reduction in mediastinal mass.

In ovarian cancer, median overall survival for the 14 patients treated was 15.0 months.

This is promising early stage data in very sick patients. Mahsa Mohebtash and colleagues conclude in their paper that:

“Some patients who had limited tumor burden with minimal prior chemotherapy seemed to benefit from the vaccine. Further studies to confirm these results are warranted.”

Immunotherapy holds a lot of promise. Research suggests that cancer vaccines once they have provoked a response may improve a patients’ response to subsequent therapies through enhanced T-cell response.

The NCI researchers in their paper noted that time to progression and tumor shrinkage may not be good endpoints for evaluating immunotherapies given that it can take a few months for the optimal result after vaccination and there is often little impact on the tumor size, as judged by classical RECIST measurement.

Instead, overall survival (OS) should be considered a more relevant endpoint. Sipuleucel-T failed to show a benefit in progression free survival (PFS), but did show an impact on OS. In prostate cancer, OS remains the gold standard for regulatory approval, which is why Exelixis recently took a hit for not making this the primary endpoint in their phase III trial (306) for cabozantinib (XL184).

There are several challenges to consider with vaccine therapies:

How do we identify upfront which patients are most likely to respond to the vaccine?
The ideal setting is likely to be adjuvant rather than metastatic disease, but these trials will take a very long time and significant funding to come to fruition.
Cancer vaccines may allow some patients to live longer, but they have yet to show any meaningful benefit in other clinical measures such as bone pain, symptoms etc.
There are fewer side effects, but how do we evaluate how well patients are doing without clinically validated surrogate markers to aid in assessment?

This early research with a vaccine in breast and ovarian cancer, albeit on a very small number of patients, adds further support to the notion that vaccines may offer treatment benefits in the future.

We still, however, have a long way to go in understanding how best to use immunotherapy effectively and incorporate it into clinical treatment guidelines. We should also be wary of false hope and hype – I look forward to following the progress of PANVAC going forward.

Mohebtash, M., Tsang, K., Madan, R., Huen, N., Poole, D., Jochems, C., Jones, J., Ferrara, T., Heery, C., Arlen, P., Steinberg, S., Pazdur, M., Rauckhorst, M., Jones, E., Dahut, W., Schlom, J., & Gulley, J. (2011). A Pilot Study of MUC-1/CEA/TRICOM Poxviral-Based Vaccine in Patients with Metastatic Breast and Ovarian Cancer Clinical Cancer Research, 17 (22), 7164-7173 DOI: 10.1158/1078-0432.CCR-11-0649

radium-223 Alpharadin in Advanced Prostate Cancer – an interview with Dr Chris Parker

Radium-223 (Alpharadin) is a novel bone targeted treatment for advanced prostate cancer.

At the recent European Multidisciplinary Cancer Congress in Stockholm (EMCC 2011), Dr Chris Parker from The Royal Marsden Hospital presented results of the phase 3 ALSYMPCA trial that showed both delayed time to first skeletal-related event (SRE) AND an overall survival (OS) benefit for those men with advanced prostate cancer taking radium-223. This is the first time a product in the bone category has shown such a survival benefit – neither denosumab or zoledronic acid can claim that distinction.

Unlike the recent regulatory approvals for cabazitaxel (Jevtana) and abiraterone acetate (Zytiga), which focused on the post-docetaxel setting, the ALSYMPCA trial included not only those who had already received cytotoxic therapy, but also pre-docetaxel patients, who were unable to take chemotherapy.

As Dr Parker mentions in the interview that he kindly gave in Stockholm (the first video interview on Biotech Strategy Blog), radium-223, assuming it gains regulatory approval, will provide a new treatment option for the considerable population of men with bone metastases who may be too weak, too old or otherwise unable to take chemotherapy such as docetaxel.

Radium-223 is, therefore, potentially good news for this “neglected” population of prostate cancer patients.

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Biotech Strategy Blog

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

Posts tagged ‘Advanced Prostate Cancer’

AZD3514 Fails to Live up to Preclinical Promise in CRPC at ASCO 2013

ASCO 2012 What is the Optimal Sequencing of Advanced Prostate Cancer Drugs?

Cabozantinib Prostate Cancer Bone Scans – Part 2 of an interview with Dr Maha Hussain

Cabozantinib & Pain in Prostate Cancer – an interview with Dr Maha Hussain

Cabozantinib & Pain

Update on Orteronel TAK-700 from EAU 2012 Paris #EAU12

Activity and Safety of the Investigational Agent Orteronel in Men With Nonmetastatic Castration-resistant Prostate Cancer and Rising Prostate-specific Antigen: Results of a Phase 2 Study

Alpharadin Expanded Access Program is Recruiting #EAU12

Chemotherapy Foundation Symposium Prostate Cancer Update

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