May 31, 2017

Understanding Chronic Cough

As part of our chronic cough program’s due diligence process, we interviewed many clinician experts in the field who identified chronic cough as an area with high unmet medical need. Not only does chronic cough affect a large proportion of the population - about 10% of adults in most industrialized countries - but there is a large percentage of highly underserved patients (10-40%1,2) that either don’t respond to current therapies (refractory patients) or have unexplained chronic cough, a form that is not easily treatable. The experts also noted the lack of therapeutic innovation: the last FDA approved therapy was dextromethorphan, the active ingredient in cough syrup, approved almost 60 years ago3!

Chronic Cough is Not Acute Cough: it’s Caused by Nerve Malfunction

Coughing is the body’s way of clearing irritants from the airways, and can be either acute or chronic in nature. By definition, chronic cough is a cough that lasts more than 8 weeks. Chronic cough is usually associated with an underlying respiratory condition, such as asthma or COPD, but can also be caused by other common non-respiratory conditions (e.g. allergic rhinitis or gastroesophageal reflux) or certain medications. Notably, many cases of chronic cough have no identifiable cause, a condition called unexplained chronic cough.

Chronic cough occurs when the nerves involved in the cough response become hypersensitive. For example, the coughing that occurs from a bad cold can sensitize the nerves involved in the cough response. The cough reflex can then become extremely sensitive to the point that a vicious cycle is formed: coughing itself triggers more coughing. This can continue for an extended period, even after the trigger, such as the cold, has resolved.

Chronic Cough has a Big Impact on Quality of Life

Having met many patients with chronic cough, we have seen that cases can vary in severity. Mild chronic cough, often described as a “nagging” cough, can be thought of as a very annoying cough that persists for at least 8 weeks. Severe chronic cough can be very distressing for patients as it has numerous physical (sleep deprivation, chest pain, vomiting), social (difficulty having conversations) and psychosocial (anxiety, depression) repercussions. Duration of the cough can also vary: some patients have recurring short bouts (8-12 weeks at a time), while others have coughed for decades without end.

The Current Standard of Care isn’t Addressing the Problem

The first course of action for patients with chronic cough is to try to treat the cough’s “trigger”, or underlying cause: treat the asthma; treat the allergic rhinitis or; stop taking the drug provoking the cough. But for unexplained chronic cough patients, or refractory patients that don’t respond to therapies for their underlying disease, there is no easy solution.

Treatment Options for Refractory/Unexplained Chronic Cough are Inadequate

The treatment options for refractory/unexplained chronic cough are limited: patients are often prescribed pain medications that act in the brain to treat their symptoms. Opioid narcotics can be effective, but have serious side effects and can become addictive. Certain physicians prescribe drugs used to treat nerve pain and damage on an off-label basis, however these are not approved for chronic cough and have limited efficacy that varies from patient to patient. Over-the-counter medications offer minimal relief.

Large Numbers of Refractory/Unexplained Chronic Cough Patients

Publications have estimated refractory/unexplained chronic cough patients to be 10-40% of the chronic cough patient population. Even at the most conservative level, this represents about 2.7M people in the United States, and when extrapolated to the major pharma markets4, represents more than 6M patients.

Plans to Better Understand Chronic Cough

With the vision of becoming world experts in this disease, we recently commissioned a market research firm to better understand chronic cough and how it impacts patients. This research will involve a thorough review of the literature as well as interviews with key opinion leaders and physicians treating chronic cough patients, mainly pulmonologists and general practitioners. Key areas of interest include the patient diagnosis process and the characterization and segmentation of mild, moderate and severe patients. We expect to have this work completed by Q3 of this year.

Chronic Cough: Significant Opportunity for a New Drug

An effective chronic cough treatment could positively impact the lives of millions of patients who currently suffer from this condition, particularly those with refractory/unexplained chronic cough. Ideally, this therapeutic would significantly reduce cough frequency and have a benign safety profile. At BELLUS, we think BLU-5937, a treatment that reduces the hypersensitivity of the sensory nerves involved in the cough response, could fit that role.

Click here to learn about BLU-5937, BELLUS’ potential treatment for chronic cough. 

1 Song et al., 2015. The global epidemiology of chronic cough in adults: a systematic review and meta-analysis. Eur Respir J. Vol 55 pp. 1479-1481
2 Zanasi et al., 2014. Chronic and unexplained cough. (Published online) Vol 4, No 3 pp. 159-164
3 https://en.wikipedia.org/wiki/Dextromethorphan#Cough_suppression
4 Major pharma markets include the U.S., Japan, and top five European countries

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