Background for NeurogesX and Neuropathic Pain
This is a guest series from Drew Waight a graduate student at NYU. Leave him a comment if you like his analysis and maybe he’ll send another one in. I should be back in August when I’ve finally made my escape from the lab and no longer have two jobs. Until then, you can catch my analysis of big biotech (and pharma too) at The Fool.
IPO date: 05/02/2007
Market Cap : $101 million
Shares Outstanding : 12.49mln
Neurogesx (NGSX) is a biopharmaceutical company developing and commercializing novel pain management therapies. More specifically, their main niche involves the area of neuropathic pain. Let’s take a closer look at the details and prevalence of this affliction, focusing specifically on the treatments NGSX has in the pipeline.
Neuropathic pain is caused by diseases or trauma that produce lesions in the central (e.g., stroke, spinal cord injury, multiple sclerosis [MS]) or peripheral (e.g., surgery, diabetic neuropathy, herpes zoster) nervous system. Peripheral neuropathy (neural damage in the extremities) is the most common which mainly affects the feet and legs. The most recent studies suggest that more than two million adults in the U.S. suffer from neuropathic pain.
Post-herpetic neuralgia (PHN) constitutes about 200k cases per year. In this disorder, factors such as age, illness, stress or medications can reactivate an otherwise dormant chickenpox virus (varicella-zoster), causing shingles (herpes zoster). The virus travels along nerve fibers, causing pain. When the virus reaches the skin, it produces a rash and blisters. These cases of shingles usually heal within a month, however in roughly 20% of cases the patient continues to feel pain long after the rash and blisters heal. This pain is known as postherpetic neuralgia.
Painful HIV-Associated Neuropathy (HIV-DSP) is among the most common of the pain syndromes afflicting HIV-infected individuals. It is thought that nearly one third of people with HIV/AIDS experience some peripheral nerve damage caused either by the virus itself, by certain drugs used in the treatment of HIV/AIDS, or by secondary complications from the disease.
Almost 16 million Americans had diabetes in 2005. Of these “complications” 60-70% of diabetics have mild to severe forms of nervous system damage. While the first sign of diabetic neuropathy is usually numbness, Painful diabetic neuropathy (PDN) often manifests in the form of a burning or other painful sensation most commonly in the feet and lower extremities.
Over the counter analgesics such as acetaminophen and non-steroidal anti-inflammatory drugs have not been shown to be highly effective in the treatment of neuropathic pain. The treatments that are available for the above conditions are largely similar and the common underlying mechanism of action is reduction of neuronal hyperexcitability. Topically, Capsaicin creams derived from natural chili pepper plants have long been known to provide temporary relief. Similarly, Lidocaine (topical local anesthetic) patches are also effective for pain management. Both of these treatments last between 4 and 12 hours however, and require multiple applications per day. Both tricyclic antidepressants (TCA) and serotonin reuptake (SSRI) inhibitors are used to treat neuropathic pain, it should be noted that while generally SSRIs are safer for use in the general population, they have less consistent effects than the TCA class. Finally, anticonvulsants such as phenytoin (Dilantin), carbamazepine (Tegretol) and gabapentin (Neurontin) are frequently prescribed for neuropathic pain and have been shown to be effective in double-blind placebo controlled studies. Some caveats to the anticonvulsant class of medications include a relatively notorious list of adverse side-effects and unpredictable response to the treatment.
In summary, the therapeutic focus on neuropathic pain does in fact constitute an area of unmet medical needs. The major diseases which cause the neuropathies above (herpes zoster, HIV and especially diabetes) are ubiquitous illnesses which are not predicted to be decreasing in the future. Furthermore, treatment for these neuropathies (with the exception of topical agents), largely revolve around the secondary analgesic effects of neurological pharmacologics which in some cases may be beneficial if the patient is already depressed. Nevertheless, it seems there is still plenty of room in the market for a more subtle topical treatment option such as Neurogesx has developed.
Next time: Neurogesx flagship product, the trans-capsaicin patch. I’ll also cover their clinical trial status and scientific patents protecting their quasi-novel approach to management of neuropathic pain disorders.
Filed under: NeurogesX (NGSX)