Tagged: receptor

The Acorda’s Tozadenant Phase III clinical trials

The biotech company Acorda Therapeutics Inc. yesterday announced that it was halting new recruitment for the phase III program of its drug Tozadenant (an oral adenosine A2a receptor antagonist).

In addition, participants currently enrolled in the trial will now have their blood monitoring conducted on a weekly basis. 

The initial report looks really bad (tragically five people have died), but does this tragic news mean that the drug should be disregarded?

In todays post, we will look at what adenosine A2a receptor antagonists are, how they may help with Parkinson’s, and discuss what has happened with this particular trial.


Dr Ron Cohen, CEO of Acorda. Source: EndpointNews

Founded in 1995, Acorda Therapeutics Ltd is a biotechnology company that is focused on developing therapies that restore function and improve the lives of people with neurological disorders, particularly Parkinson’s disease.

Earlier this year, they had positive results in their phase III clinical trial of Inbrija (formerly known as CVT-301 – Click here to read a previous post about this). They have subsequently filed a New Drug Application with the US Food and Drug Administration (FDA) to make this inhalable form of L-dopa available in the clinic, but the application has been delayed due to manufacturing concerns from the FDA (Click here to read more about this). These issues should be solvable – the company and the FDA are working together on these matters – and the product will hopefully be available in the new year.

So what was the news yesterday?

Acorda Therapeutics has another experimental product going through the clinical trial process for Parkinson’s disease.

It’s called Tozadenant.

Source: Focusbio

Tozadenant is an oral adenosine A2a receptor antagonist (and yes, we’ll discuss what all that means in a moment).

Yesterday Acorda Therapeutics Inc announced that they have halted new recruitment for their phase III clinical program. In addition the company is increasing the frequency of blood cell count monitoring (from monthly to weekly) for participants already enrolled in the company’s Phase 3 program of Tozadenant for Parkinson’s disease.

The Company took this action due to reports of cases of agranulocytosis.

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PACAP and a snail model of Parkinson’s

We are going to talk about a snail model of Parkinson’s disease. I kid you not.

Love them or hate them, recent research on snails is helping us to better understand a potential therapeutic target for Parkinson’s disease, called Pituitary adenylate cyclase-activating polypeptide (or PACAP).

In today’s post we will look at what PACAP is, outline the new snail research, and discuss what they mean for people living with Parkinson’s disease.


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The humble snail. Source: Warrenphotographic

In a recent post, I talked about a class of drugs called Dipeptidyl peptidase-4 (or DPP-4) inhibitors (Click here to read that post). DPP-4 is a ubiquitous enzyme (it is present on most cells in your body) that breaks down certain proteins.

In that post, I listed some of the proteins that DPP-4 targets – they include:

  • Gastrin-releasing peptide (GRP)
  • Glucagon
  • Glucagon-like peptide-1 (GLP-1)
  • Glucagon-like peptide-2 (GLP-2)
  • Granulocyte-macrophage colony-stimulating factor (GM-CSF)
  • GHRH and IGF-1
  • High-mobility group box 1 (HMGB1)
  • Macrophage-derived chemokine (MDC)
  • Macrophage inflammatory protein-1 α (MIP-1 α), chemokine (C-C motif) ligand 3-like 1 (CCL3L1), or LD78β
  • Pituitary adenylate cyclase-activating polypeptide (PACAP)
  • Neuropeptide Y (NPY)
  • Regulated on activation, normal T cell expressed and secreted (Rantes)
  • Stromal cell-derived factor-1 (SDF-1)
  • Substance P (SP)

Lots of interesting proteins with regards to Parkinson’s disease on this list, including GLP-1 which has been turned in the drug Exenatide (which has demonstrated positive effects in recent clinical trials for Parkinson’s disease – click here and here to read more about this). Another interesting protein on the list is ‘Granulocyte-macrophage colony-stimulating factor‘ (GM-CSF) which we have also discussed in a previous post (Click here to read that post). A synthetic version of GM-CSF (called Sargramostim) has recently been tested in a clinical trial of Parkinson’s disease in Nebraska, and the results of that Phase I trial have been very encouraging.

By treating people with DPP-4 inhibitors (also known as ‘gliptins’), one would be blocking the breaking down of these potentially beneficial proteins – increasing the general amount of GLP-1 and GMCSF that is floating around in the body.


EDITOR’S NOTE: DPP-4 inhibitors have not yet been clinically tested in Parkinson’s disease, and thus we have no idea if they are safe in people with this condition. They are being mentioned here purely as part of an academic discussion.


One protein on the list of DPP-4 targets above that we have not yet discussed is Pituitary adenylate cyclase-activating polypeptide (or PACAP).

And today we are going to have a look at it.

Why?

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A clever new Trk for Rasagiline

The protein Alpha Synuclein has long been considered the bad-boy of Parkinson’s disease research. Possibly one of the main villains in the whole scheme of things. 

New research suggests that it may be interfering with a neuroprotective pathway, leaving the affected cell more vulnerable to stress/toxins. But that same research has highlighted a novel beneficial feature of an old class of drugs: MAO-B inhibitors.

In today’s post we will outline the new research, discuss the results, and look at whether this new Trk warrants a re-think of MAO-B inhibitors.


The great Harry Houdini. Source: Wikipedia

I’m not sure about you, but I enjoy a good magic trick.

That exhilarating moment when you are left wondering just one thing: How do they do that?

(Seriously, at 4:40 a baguette comes out of thin air – how did he do that?)

Widely believed to have been one of the greatest magicians of all time (Source), Harry Houdini is still to this day revered among those who practise the ‘dark arts’.

Born Erik Weisz in Budapest (in 1874), Houdini arrived in the US in 1878. Fascinated with magic, in 1894, he launched his career as a professional magician and drew attention for his daring feats of escape. He renamed himself “Harry Houdini” – the first name being derived from his childhood nickname, “Ehrie,” and the last name paying homage to the great French magician Jean Eugène Robert-Houdin. In 1899, Houdini’s act caught the eye of Martin Beck, an entertainment manager, and from there the rest is history. Constantly upping the ante, his feats became bolder and more death defying.

And the crowds loved him.

From stage, he moved on to film – ultimately starting his own production company, Houdini Picture Corporation. In addition, he was a passionate debunker of psychics and mediums, his training in magic helping him to expose frauds (which turned him against his former friend Sir Arthur Conan Doyle, who believed deeply in spiritualism).

This is all very interesting, but what does any of it have to do with Parkinson’s?

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Dear FDA, this is bigly wrong…and you know it!

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Dopamine agonist treatments are associated with approximately 90% of hyper-sexuality and compulsive gambling cases that occur in people with Parkinson’s disease.

This issue does not affect everyone being treated with this class of drugs, but it is a problem that keeps popping up, with extremely damaging consequences for the affected people who gamble away their life’s saving or ruin their marriages/family life. 

The U.S. Food and Drug Administration (FDA) is yet to issue proper warning for this well recognised side-effect of dopamine agonists, and yet last week they gave clearance for the clinical testing of a new implantable device that will offer continuous delivery of dopamine agonist medication.

In today’s post, we will discuss what dopamine agonists are, the research regarding the impulsive behaviour associated with them, and why the healthcare regulators should acknowledge that there is a problem.


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Dopamine. Source: Wikimedia

Before we start talking about dopamine agonists, let’s start at the very beginning:

What is dopamine?

By the time a person is sitting in front of a neurologist and being told that they ‘have Parkinson’s disease’, they will have lost half the dopamine producing cells in an area of the brain called the midbrain.

Dopamine is a chemical is the brain that plays a role in many basic functions of the brain, such as motor co-ordination, reward, and memory. It works as a signalling molecule (or a neurotransmitter) – a way for brain cells to communicate with each other. Dopamine is released from brain cells that produce this chemical (not all brain cells do this), and it binds to target cells, initiating biological processes within those cells.

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Dopamine being released by one cell and binding to receptors on another. Source: Truelibido

Dopamine binds to target cells via five different receptors – that is to say, dopamine is released from one cell and can bind to one of five different receptors on the target cell (depending on which receptor is present). The receptor is analogous to a lock and dopamine is the key. When dopamine binds to a particular receptor it will allow something to happen in that cell. And this is how information from a dopamine neuron is passed or transmitted on to another cell.

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Dopamine acts like a key. Source: JourneywithParkinsons

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