Neuroendocrine Cancer – Exciting Times Ahead!  

exciting-times-ahead_edited

In the last 12-24 months, there seems to have been announcement after announcement of new and/or upgraded/enhanced diagnostics and treatment types for Neuroendocrine Cancer.  Scans, radionuclide therapies, combination therapies, somatostatin analogues, biological therapies, etc.  Some of the announcements are just expansions of existing therapies having been approved in new (but significant) regions. Compared to some other cancers, even those which hit the headlines often, we appear to be doing not too badly.  However, the pressure needs to stay on, all patients need access to the best diagnostics and treatments for them; and at the requisite time.  There’s even more in the pipeline and I’m hoping to continue to bring you news of new stuff as I have been doing for the last year.

Some of these new diagnostics and treatments will benefit eligible patients who are in diagnosis/newly diagnosed and also those living with the disease. As we’re now in our awareness month, let’s recap:

Scans

Many NET Patients will undergo a nuclear scan to confirm CT results and/or to detect further neuroendocrine activity.  Basically, a nuclear substance is mixed with a somatostatin analogue, injected into the patient who is then scanned using a 360-degree gamma camera.  As gamma cameras are designed to show up radioactive activity; and as Neuroendocrine Tumour cells will bind to the somatostatin analogue, it follows that the pictures provided will show where Neuroendocrine tumours are located.  Many people will have had an ‘Octreotide’ Scan (or more formally – Somatostatin Receptor Scintigraphy) which is still the gold standard in many areas. The latest generation of nuclear scans is based on the platform of the Gallium (Ga) 68 PET Scan. The principles of how the scan works is essentially as described above except that the more efficient radioactive/peptide mix and better scan definition, means a much better picture providing more detail (see example below). It’s important to note that positive somatostatin receptors are necessary for both scans to be effective. Europe and a few other areas have been using the Ga-68 PET scans for some time (although they are still limited in availability by sparse deployment). The latest excitement surrounding this new scan is because they are currently being rolled out in USA.  Read about the US FDA approval here.  You may hear this scan being labelled as ‘NETSPOT’ in USA but this is technically the name for the preparation radiopharmaceutical kit for the scan which includes a single-dose injection of the organic peptide and the radionuclide material. Take a look at a comparison of both scans here:

octreo-vs-g68
Octreoscan output vs Gallium 68 PET output

This slide from a recent NET Research Foundation conference confirms the power of more detailed scanning.

Peptide Receptor Radionuclide Therapy (PRRT)

Similar to above, this treatment has been in use in Europe and other places for some time but is also to be formally deployed in USA if, as is expected, the US FDA approval is positive at the end of this year (Read here).  In the most basic terms, this is a treatment whereby a peptide is mixed with a radionuclide and is drip fed over a number of treatments (normally up to 4 spaced out over a year). The concept of delivery of the ‘payload’ to the tumours is actually very similar to the preparation for a radionuclide scan as described above, the key difference is the dosage and length of exposure whilst the tumours are attacked. Once again, receptors are important. The NETTER series of trials showed good results and this is an excellent addition to the portfolio for those patients who are eligible for this treatment. Fingers crossed for the US FDA announcement due by the end of this year.  Also fingers crossed that PRRT returns to the NHS England & Wales portfolio of available treatments next year.  The Carcinoid Cancer Foundation has an excellent summary of PRRT here.

PRRT and Chemo Combo

Whilst on this subject, I also want to highlight the innovative use of combo therapies in Australia where they are combining PRRT and Chemo (PRCRT).  I blogged about this here:

PRRT CAPTEM

Somatostatin Analogues and their Delivery Systems

Somatostatin analogues are a mainstay treatment for many NET Patients.  These drugs target NET cell receptors which has the effect of inhibiting release of certain hormones which are responsible for some of the ‘syndromic’ effects of the disease.  Again, receptors are important for the efficacy of this treatment.  You can read the ‘geeky’ stuff on how they work here.  These drugs mainly comprise Octreotide (provided by Novartis) and Lanreotide (provided by Ipsen). The latter has been around in Europe for 10 years and was introduced to North America earlier this year.  Octreotide has been around for much longer, almost 17 years.  When you consider these peptides have also been used to support nuclear scans that can detect the presence of tumours; and that studies have shown they also have an anti-tumour effect, they really are an important treatment for many NET Patients.  I’ve blogged about new somatostatin analogues in the pipeline and you can read this here.  This blog also contains information about new delivery systems including the use of oral capsules and nasal sprays (…….. very early days though).

Treatment for Carcinoid Syndrome

telotristat-etiprate-clinical-trial-serotonin-as-a-key-driver-of-carcinoid-syndrome

For maintenance and quality of life, the release of a Telotristat Ethyl for Carcinoid Syndrome is an exciting development as is the first new treatment for Carcinoid Syndrome in 17 years.  This is a drug which is taken orally and inhibits the secretion of serotonin which causes some of the symptoms of the syndrome including diarrhea.  It must be emphasised it’s only for treating diarrhea caused by syndrome and might not be effective for diarrhea caused by other factors including surgery.  Read about how it works and its target patient group in my blog here.

Oncolytic Virus

oncolytic

The announcement of a clinical trial for the Oncolytic Virus (an Immunotherapy treatment) specifically for Neuroendocrine Tumours is also very exciting and offers a lot of hope. Click the photo for the last progress update.  

Everolimus (Afinitor)

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Earlier this year, AFINITOR became the first treatment approved for progressive, non-functional NETs of lung origin, and one of very few options available for progressive, non-functional GI NET, representing a shift in the treatment paradigm for these cancers.  It’s been around for some time in trials (the RADIANT series) and is also used to treat breast and kidney cancer.  It’s manufactured by Novartis (of Octreotide fame).  It has some varying side effects but these appear to be tolerable for most and as with any cancer drug, they need to weighed against the benefits they bring.

In technical terms, AFINITOR is a type of drug known as an ‘mTOR’ inhibitor (it’s not a chemo as frequently stated on NET patient forums).  Taken in tablet form, it works by blocking the mTOR protein. In doing so, AFINITOR helps to slow blood vessels from feeding oxygen and nutrients to the tumour.

Check out Novartis Afinitor website for more detailed information.  There’s an excellent update about AFINITOR rom NET expert Dr James Yao here.  The US FDA approval can be found here.

Summary

………. and relax!   Wow, I’ve surprised myself by collating and revising the last 12-24 months.  Dr James Yao also agrees – check out his upbeat message in the attached 2 page summary.  You may also like another upbeat message from Dr Jonathan Strosberg by clicking here.

Neuroendocrine Cancer – who’d have thought it?  ….. a bit of a dark horse.

Thanks for reading

Ronny

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Remember ….. in the war on Neuroendocrine Cancer, let’s not forget to win the battle for better quality of life!

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Neuroendocrine Cancer: Somatostatin Receptors

ct compare to g68 pet
CT and G68 PET fused showing somatostatin receptor pick up

Don’t understand Somatostatin Receptors?  Join the club!  I got my head around the term ‘Somatostatin’ and ‘Somatostatin Analogues’ some time ago but the term ‘Somatostatin Receptor’ (SSTR) is still a bit of a mystery and it’s come to the top of my list of things to study.  SSTRs do come up in conversation quite often and I’m fed up of nodding sagely hoping it will eventually become clear! On analysis it looks like a technical subject – and therefore a challenge 🙂

I’ve taken a logical approach working from ‘Somatostatin’ to ‘Somatostatin Analogue’ before commencing on the ‘receptor’ bit.  It is intentionally brief and (hopefully) simplistic!

Somatostatin

It’s important to understand this hormone and then why your ‘butt dart’ is generically called a ‘Somatostatin Analogue’.

Some Neuroendocrine Tumours secrete hormones and peptides that cause distinct clinical syndromes, including amongst others, carcinoid syndrome.  Somatostatin is a naturally occurring hormone and a known inhibitor of some of these NET related hormones and peptides that can be over secreted and cause syndromes. For example, somatostatin from the hypothalamus inhibits the pituitary gland’s secretion of growth hormone (GH) and Thyroid Stimulating Hormone (TSH). In addition, somatostatin is produced in the pancreas and inhibits the secretion of other pancreatic hormones such as insulin and glucagon.  However, the naturally produced Somatostatin does not have the lifespan to have any effect on Neuroendocrine Tumours which are over secreting these hormones and peptides. ……. cue manufactured versions that can!

Somatostatin Analogue (SSA)

These are manufactured versions of Somatostatin known as Somatostatin Analogues.  These are designed to have a lasting effect to inhibit for much longer and therefore reduce the symptoms caused by the over secretion (i.e. the syndrome).  Examples of Somatostatin Analogue include Octreotide (Sandostatin), Lanreotide (Somatuline) and Pasireotide (Signifor).

So how do Somatostatin Analogues actually work? 

For the inhibition to work effectively, there needs to be a route into the over secreting tumours, normally via short or long acting injections or even intravenously. On the tumour cells, there are currently 5 known sub-types of ‘Somatostatin Receptors’  (SSTR) which are ‘expressed’ by most NETs.   These are known as SSTR1 through to SSTR5.  The naturally occurring hormone Somatostatin attempts to bind with all 5 but as above, it lacks the lifespan to make any impact to inhibit sufficiently in cases of overecretion. However, SSAs can overcome this with the longer lifespan.  They can successfully in most cases bind with these receptors to inhibit the hormones and peptides causing the problems, particularly SSTR2 with modest affinity to SSTR5. Clearly it’s therefore advantageous to target SSTR2.

Somatostatin Receptors

The subtypes expressed by NETs are variable and the efficiency of different SSAs in binding to each SSTR subtype also varies. For example the table below lists the variability of Somatostatin Receptor efficiency in different types of NET.  Interesting to note that non-functional NETs might not have efficient SSTRs but SSAs will still try to bind to them albeit it might not work or have a lesser effect.

Somatostatin receptors are found in high numbers on the surface of NET’s. Most receptors are in the inactive state (based on something called the phosphorylation status). Traditionally, agents such as dotatate have only bound to activated receptors on the surface.  Scientists are looking at ways to bind to inactive receptors to increase therapy success (for example see clinical trial OPS 201)

Table 1 – Somatostatin receptor subtypes in neuroendocrine tumours (mRNA) (See Copyright)

Tumour SSTR1 (%) SSTR2 (%) SSTR3 (%) SSTR4 (%) SSTR5 (%)
Gastrinoma 79a 93 36 61 93
Insulinoma 76 81 38 58 57
Non-functioning pancreatic tumour 58 88 42 48 50
Gastro-intestinal NET 76 80 43 68 77

This table above clearly shows the variability of SSTRs when binding with different types of NETs.  It follows that manufacturers of SSAs will be using this data in the formulation of their drugs.  If you now look at the table below, you can see how efficiently the 3 well-known SSAs inhibit NETs on each SSTR.

Compound SSTR1 SSTR2 SSTR3 SSTR4 SSTR5
RECEPTOR SUBTYPE AFFINITY (IC50, nM)
Octreotide 1140 0.56 34 7030 7
Lanreotide 2330 0.75 107 2100 5.2
Pasireotide 9.3 1 1.5 >100 0.16

View it in a separate window

You can see from the data why Octreotide and Lanreotide target SSTR2 and to a lesser extent SSTR5 but Pasireotide (Signifor or SOM-230) is interesting as it appears to have affinity for SSTRs 1-3 and 5, probably why it has been approved for Cushing’s Disease (ATCH producing).  However, to date, there has not been enough evidence showing that Pasireotide has a progression-free survival benefit over the other 2 therapies. It is also associated with hyperglycemia. You may find this video interesting as the doctor (Strosberg) is suggesting it could be used by NET patients in certain scenarios.

What about SSA labelled diagnostics?

The same principles apply.  For example, an Octreotide Scan (actually known as ‘Somatostatin Receptor’ Scintigraphy (SRS)) works by taking pictures using a gamma camera which is designed to see radiation from a ‘tracer’.  The tracer in question is a radio labelled with an Octreotide variant (such as pentetreotide) which will bind to somatostatin receptors on the surface of the tumour cells  In the simplest of terms, this shows up where NETs are.  The same principles apply to Ga 68 PET scans which are more advanced and more sensitive than SRS.

What about SSA labelled therapies?

With (say) Peptide Receptor Radiotherapy (PRRT), there is a similar binding mechanism going on.  In PRRT, Octreotide or a variant, is combined with a therapeutic dose of the radionuclides, e.g. Yttrium 90 (Y-90) and Lutetium 177 (Lu-177).  It binds with the SSTRs on the tumour cells and the therapeutic dose attacks the tumour having been brought there by the binding effect.  Simple isn’t it?

Do Somatostatin Receptors work for everyone?

Unfortunately not.  Some people have more sensitive receptors than others and the figure of 80% appears to be the most common statistic indicating one-fifth of all NET patients may not be able to respond correctly to SSA treatment or get the right results from Octreoscans/Ga 68 PET and/or PRRT.  However, that needs to be taken into context and probably applies to midgut NETs measured against SSTR2 – the tables above tend to confirm this figure.  During my research, I did read that higher than normal doses of SSAs may have some effect on those with less sensitive SSTRs.  Also, SSAs seem to work much better with well-differentiated tumours.

How do I know if my Somatostatin Receptors work?

When I was completing my NET checks after diagnosis, my Oncologist declared I was “Octreotide avid” shortly after my Octreoscan was compared with my CT.  I’m guessing that is a simple and crude test and how most people find out they have working receptors.  I also suspect that if your syndrome symptoms are abated somewhat by SSA injections, then you there is a good chance your SSTRs are working normally.  I also suspect those who show clear signs of tumour on CT but not on Octreoscan or Ga 68 PET, could have a receptor issue.

The advent of modern PET scanning (e.g. Ga68) has meant more accurate methods of working out if someone has the right receptors for PRRT through analysis of something known as standardized uptake values (SUV).

A more modern approach is to use a ‘Theranostic Pair” where the same radiolabelled tracer is used with the advantage that the diagnostic element can predict suitability for the therapy component  – read more here

lutathera owl - Copy


Somatostatin Receptor Research – Interest Point

I was please to see a piece of research ongoing to look at the issues with lack of somatostatin receptors.  The research is looking at novel imaging agents for NETs which do not have working receptors.  Read more here.

Summary

I hope this gives you a very basic outline of why Somatostatin Receptors are important to support the diagnosis and treatment of NETs.

My article “If you can see it, you can detect it” is almost 100% accurate but having working receptors really helps with nuclear scans.

Preclinical and clinical studies have indicated that somatostatin receptor (SSTR)expressing tumors demonstrate higher uptake of radiolabeled SSTR antagonists than of the currently approved SSTR agonist versions. See clinical trial OPS 201 for an example of the next generation of somatostatin receptor based theranostics where the use of a somatostatin antagonists.

thanks for reading

PRRT and the NHS England Cancer Drugs Fund

cost cutting vs life cutting?
cost cutting vs life cutting?

As of 4 Nov 15, PRRT was delisted from the NHS England Cancer Drugs Fund. Appeals were made but were rejected, despite the glowing results from the NETTER-1 trial.  Although a replacement system is now in place, PRRT remains barred from routine NHS use.

Please see the following post for the very latest on PRRT worldwide – CLICK HERE

I was extremely disappointed to learn of the decision to remove PRRT (Lutetium or Yttrium) from the Cancer Drugs Fund (CDF) as reported by the NET Patient Foundation. You can read the detail of the decision here: CDF Statement.  PRRT has regularly been described by NET specialists and patients as the “magic bullet” due to its potential to shrink or kill tumours.

This is the second Neuroendocrine Cancer treatment to be withdrawn this year, after the earlier decision on Everolimus (Afinitor) in April . In fact, the recent cuts to the CDF were described in the media as a “massacre” as the list was reduced by two-thirds.  You can see the current CDF list by clicking here.

The timing of these cuts is extraordinary and when you look at the output from recent trial reports presented at the Europetwo-thirdsCongress (ECC) for both Neuroendocrine Cancer related drugs recently cut:

Everolimus

The RADIANT-4 trial said that Everolimus had a significant effect in non-functional NETs which are very difficult to treat.  This is particularly important for Lung NETs as no treatment currently exists.  The RADIANT-2 trial had already proven the efficacy of the drug for advanced carcinoid (in conjunction with Octreotide) and the RADIANT-3 trial proved good data for treatment with advanced functional pNETs.  Read the report here.

PRRT – 177Lu-DOTATATE

The ECC also reported a significant finding from the NETTER-1 trial.  Treatment with the novel peptide receptor radionuclide therapy (PRRT) Lutathera significantly increased progression-free survival (PFS) over Octreotide LAR (Sandostatin) in patients with advanced midgut NETs.  It shows a PFS that has never been shown before in this type of cancer adding that this was significant because these patients have a real unmet medical need.

Lutathera is a 177Lu-DOTATATE PRRT that targets somatostatin receptors, which are overexpressed in about 80% of NETs, to deliver cytotoxic radiation directly to the tumor – See more by clicking here.

To fully understand the background to the problem, you need to understand both PRRT and the Cancer Drugs Fund and a quick primer on both follows.

What is PRRT?

For those who are not entirely sure what PRRT is, here’s a quick primer from The Society of Nuclear Medicine and Molecular Imaging:

Peptide receptor radionuclide therapy (PRRT) is a molecular therapy (also called radioisotope therapy) used to treat a specific type of cancer called neuroendocrine carcinoma or NETs (neuroendocrine tumors). PRRT is also currently being investigated as a treatment for prostate and pancreatic tumors.

In PRRT, a cell-targeting protein (or peptide) called octreotide is combined with a small amount of radioactive material, or radionuclide, creating a special type of radiopharmaceutical called a radiopeptide. When injected into the patient’s bloodstream, this radiopeptide travels to and binds to neuroendocrine tumor cells, delivering a high dose of radiation to the cancer.

The cells in most neuroendocrine tumors have an abundance (called an overexpression) of a specific type of surface receptor—a protein that extends from the cell’s surface—that binds to a hormone in the body called somatostatin. Octreotide is a laboratory-made version of this hormone that binds to somatostatin receptors on neuroendocrine tumors. In PRRT, octreotide is combined with a therapeutic dose of the radionuclides. Yttrium 90 (Y-90) and Lutetium 177 (Lu-177) are the most commonly used radionuclides.  

What conditions are treated with PRRT?

PRRT may be used to treat NETs, including carcinoids, islet cell carcinoma of the pancreas, small cell carcinoma of the lung, pheochromocytoma (a rare tumor that forms in the adrenal glands), gastro-enteropancreatic (stomach, intestines and pancreas) neuroendocrine tumors, and rare thyroid cancers that are unresponsive to treatment with radioiodine.

PRRT is an option for patients:
• who have advanced and/or progressive neuroendocrine tumours
• who are not candidates for surgery
• whose symptoms do not respond to other medical therapies.

The main goals of PRRT are to provide symptom relief, to stop or slow tumor progression and to improve overall survival.

These video’s on Nuclear Medicine are by Professor Val Lewington – the UK’s most experienced person on PRRT.  I was at this presentation and she is absolutely amazing. It’s slightly dated but still very current.  This presentation also covers Octreotide and Gallium 68 scans under the heading of Nuclear Medicine – if you are still unsure about PRRT or Nuclear Medicine in general, these videos are definitely worth a watch.

The Role of Nuclear Medicine in NETs

Q&A Sessions

This is also a great source of information maintained by NET Patients in the USA.  Click here

What was the Cancer Drugs Fund?

The Cancer Drugs Fund was money the UK Government has set aside to pay for cancer drugs that haven’t been approved by the National Institute for Health and Care Excellence (NICE) and aren’t available within the NHS in England. This may be because the drugs haven’t been looked at yet. Or it may be because NICE have said that they don’t work well enough or are not cost-effective. This was introduced as a ‘political statement’ by the then Conservative/Liberal Democrat coalition government in 2010/11.  The aim of the fund is to make it easier for people to get as much treatment as possible.

The Cancer Drugs Fund was for people who live in England. The governments of Scotland, Wales and Northern Ireland decide on how they spend money on health and so far haven’t decided to have a similar programme.

Worth noting that on 1 April 2013, NHS England took on responsibility for the operational management of the Cancer Drugs Fund (CDF). The NHS spends approximately £1.3 billion annually on the provision of cancer drugs within routine commissioning. The CDF was established as an additional funding source to this.

There was a national list of drugs available through the fund – you may have heard this called the priority list. If you met the conditions for a drug that was on the list, you should have been able to have it on the NHS if you live in England. The Fund would also have considered applications on behalf of individual patients for other drugs that are not on the list.  However, under the new system, Individual funding requests (IFRs) relating to cancer drugs will no longer be considered via the CDF process.  All IFRs relating to cancer drugs will now be considered using NHS England’s single, national IFR system, which was updated in January 2016.

The new system came info force on 29 July 2016 and you can read more if you click this link

Summary

Although the decision is shocking to most, it was not totally unexpected as the Government and NHS have been hinting for sometime that the costs of the fund need to be reined in.  In any case if was only ever a temporary arrangement until a another model could be put into place.  There is a political element as the fund was set up by David Cameron with healthcare experts suggesting that it made no sense as a response to rising drug prices.  Moreover, by topping up the fund, the same experts claimed this was making the manufacturers the real beneficiaries of the fund as they have been able to sell their drugs to the NHS at prices that are unaffordable (and therefore unsustainable) for the NHS.

UK NET patients who have advanced and/or progressive neuroendocrine tumours which cannot be removed by surgery and whose symptoms do not respond to other medical therapies, still need help.

Ironically, the UK seems to be intent on cutting provision of the treatment (at least for NHS patients) as the US is trying very hard to formally introduce it.  This is a disgraceful situation and advanced Neuroendocrine Cancer patients and those who may need this treatment in the future are being terribly let down.

I will keep this blog ‘live’ in order to add information as things progress.

Thanks for reading

Ronny
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