rhNGF (no, it's not a misprint)

If you have been surfing the web looking for useful information about neuropathy, you may well have come across the unusually named, rhNGF as one of three proven effective treatments for neuropathic pain and problems. The other two are cannabis and capsaicin and have been extensively covered on this Blog but rhNGF is for most people, a complete mystery and when you try to research it on the Net, you can understand why!

Recombinant human nerve growth factor (rhNGF) is regarded as the most promising therapy in decades, for neurodegeneration of the central and peripheral nervous systems as well as for several other pathological conditions involving the immune system. However, rhNGF is not commercially available as a drug. For a start, it hasn’t been approved by the major, international medical authorities as yet, so any discussion at the moment is pretty much irrelevant but its day will come and it will be useful to have some idea of what it is and what it does.

At this point it might be advisable to avoid all websites ‘selling’ this as a product. It’s one of those things that attracts health and fitness fanatics, (like anabolic steroids for instance although there is absolutely no connection)and I have no idea why but because the national organisations haven’t as yet approved it for neuropathy treatment... you know the story for HIV patients... throwing any doubtful ‘variable’ into the mix is rarely advisable.

Giving a simple definition of rhNGF, is however, easier said than done because it is an extremely complex chemical structure. I certainly don’t understand much about it but will attempt here to simplify the information available on the Net. If you know better, or have any information to offer, please use the contact form at the top of the page, to put us all better in the picture.

First of all, the letters stand for Recombinant Human Nerve Growth Factor. ‘Recombinant means the new entity (e.g., gene, protein, cell, individual) that results from genetic recombination.

In short, NGF is a protein that is involved in the growth of peripheral nerve cells and was discovered 50 years ago as a molecule that promoted the survival and differentiation of sensory and sympathetic neurons. It is a small secreted protein that is important for the growth, maintenance, and survival of certain target neurons (nerve cells). It also functions as a signalling molecule.

While "nerve growth factor" refers to a single factor, "nerve growth factors" refers to a family of factors also known as neurotrophins. Neurotrophins represent an important family of regulatory proteins essential for sensory nerve development. Several neurotrophins have been identified, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin 3 (NT3). NGF is one of the most studied neurotrophins. It is a key regulator of sensory neurone excitability and an important mediator of injury-induced nociceptive and neuropathic pain.

It is an immensely complex biological process for the layman but NGF ‘s have shown very promising results in animal studies. Recombinant human nerve growth factor (rhNGF) has been in phase III trials (essentially meaning it's taken seriously!) and the results are also extremely encouraging.

Particular attention is given to a growing body of evidence that suggests that among other roles, NGF signalling, aids neuroprotective and repair functions. The analysis points to many interesting unanswered questions and to the potential for continuing research on NGF to substantially enhance our understanding of the mechanisms and treatment of neurological disorders.

The administration of nerve growth factor (NGF) has been found to prevent neuropathies induced by anti-cancer drugs such as cisplatin, vincristine and taxol. However, it is clinically important to know whether NGF is beneficial once the neuropathy is already established and this is one of the reasons why medical authorities are not yet ready to approve commercial drugs. It’s something with great potential and something which will require a lot more research and assessment.

Regarding our own situation as HIV patients with neuropathy, recombinant human nerve growth factor (rhNGF) was used in a multicenter, placebo-controlled, randomized trial by Justin McArthur of Johns Hopkins University and colleagues to evaluate its efficacy as a treatment for HIV-associated peripheral neuropathy. Nearly 300 individuals were randomized to receive two different doses of nerve growth factor or placebo. After 18 weeks of randomized treatment, there was a significant difference in average and maximum pain intensity favouring rhNGF. However, there were no differences in terms of mood, analgesic use, or epidermal nerve fibre density between the groups.

Giovanni Schifitto of the University of Rochester and colleagues reported on data from the 48-week open-label phase of the rhNGF study described above. After the randomized phase, 200 of the 235 eligible patients continued taking either 0.1 or 0.3 mcg/ kg of rhNGF. Neurological and quantitative sensory testing was performed at baseline and at week 48. Consistent pain improvement was observed in all groups, with the high-dose recipients demonstrating better outcomes than low-dose participants.

I'm sorry, I don't understand enough about it to be able to describe it more simply and for once, research on the Web leads you to very complicated scientific journals and papers which are way above my head. So why write a post about it you may ask? The reason is that a) you will probably see it mentioned in passing (but not in detail) and b) if it is one of three things they are pretty sure about, then it's only a matter of time before it becomes available in an approved format. It's a treatment for the future then and the more questions patients ask, the more likely the whole treadmill will turn more quickly, to everyone's benefit.

Good luck looking for information and if you do find something useful to share with us, please do - knowledge is always power, especially concerning medical issues.