Repurposing Cancer Drugs to Combat Opioid Dependency


December 19, 2017   Thomas G. Kimball, PhD

There is a strong connection between those who suffer from chronic pain and the opioid epidemic. Well-meaning doctors, to alleviate the chronic pain suffered by their patients, have prescribed a tremendous amount of opioid pain medication. Although highly effective for acute pain, opioids are not ideal for chronic pain situations.

New research on drugs used for cancer treatment is showing promise as a possible replacement for prescription opioids. These drugs could be one important tactic in curbing the opioid crisis gripping our nation.

The chronic pain problem

A hundred million Americans suffer from chronic pain. Different than acute or short-term pain, chronic pain is long-lasting and enduring. According to the American Academy of Pain Medicine, chronic pain is described the following way:

“While acute pain is a normal sensation triggered in the nervous system to alert you to possible injury and the need to take care of yourself, chronic pain is different. Chronic pain persists. Pain signals keep firing in the nervous system for weeks, months, even years. There may have been an initial mishap (i.e., sprained back, serious infection) or there may be an ongoing cause of pain (i.e., arthritis, cancer, ear infection), but some people suffer chronic pain in the absence of any past injury or evidence of body damage. Many chronic pain conditions affect older adults. Common chronic pain complaints include headache, low back pain, cancer pain, arthritis pain, neurogenic pain—pain resulting from damage to the peripheral nerves or to the central nervous system itself.”

If we do not suffer from it ourselves, we all know and love people who suffer from chronic pain.

Chronic pain, doctors, and opioids

Those who experience chronic pain benefit from meaningful medical treatment, including responsibly utilizing prescription drugs to improve quality of life and daily functioning. Many of the estimated 100 million people who experience chronic pain reach out for help to their primary care physicians and other family medicine/pain doctors. In an effort to assist their patients, doctors have made use of prescription painkillers, particularly opioid analgesics, to address chronic pain. Unfortunately, there is a connection between the amount of opioid prescription pain medication prescribed and the opioid epidemic we are currently facing.

It is important to note that not all people who utilize pain medication develop a severe substance use disorder. Also, most doctors responsibly prescribe and monitor their patients when it comes to prescription painkillers. However, the use of the powerful pain medication, specifically opioids taken over time, certainly is a factor which increases the probability a person will develop a problem. Chronic pain, coupled with opioids, creates a perfect storm in increasing the probability of abuse and dependency (marked by tolerance and withdrawal), leading to the chronic brain disease of addiction manifesting.

Dr. Nora D. Volkow and Dr. A. Thomas McLellan (2016) recently published an article in The New England Journal of Medicinehighlighting the connection between prescription opioid use and the nation’s opioid epidemic. They stated that although prescription opioid medication is excellent for acute pain, the use of such medication for chronic pain is medically questionable. Further, this improper use has led to a “flooding” of opioids in our communities. More specifically they declared:

“Opioid analgesics are widely diverted and improperly used, and the widespread use of the drugs has resulted in a national epidemic of opioid overdose deaths and addictions. More than a third (37%) of the 44,000 drug-overdose deaths that were reported in 2013 (the most recent year for which estimates are available) were attributable to pharmaceutical opioids; heroin accounted for an additional 19%.”

It should not be lost on any of us that twice as many overdose deaths are due to pharmaceutical opioids versus the street drug heroin. This is not only astounding but also disconcerting.

What is even more disconcerting is that the vast majority of available opioids on the street are from doctor prescriptions. Because of the powerful potential of opioid abuse, and in the presence of this epidemic, doctors are taking notice. Volkow and McLellan report:

“The major source of diverted opioids is physician prescriptions. For these reasons, physicians and medical associations have begun questioning prescribing practices for opioids, particularly as they relate to the management of chronic pain. Moreover, many physicians admit that they are not confident about how to prescribe opioids safely, how to detect abuse or emerging addiction, or even how to discuss these issues with their patients.”

Assessing the appropriateness of prescribing opioids for chronic pain is important. We, as healthcare and mental health providers, must also become more proficient and willing to find suitable alternatives as well as to detect/assess when prescription pain medications have become a problem. Once detected, meaningful help must be administered in caring and kind ways.

Repurposing drugs to fight chronic pain

One group of scientists are seeing promise in using cancer drugs to treat chronic pain in animal subjects. A receptor in the brain, called epidermal growth factor receptor or (EGFR), and its natural ligand epiregulin (EREG) has traditionally been targeted in cancer treatments. More recently, Martin, Smith, Khoutorsky, et al, (2017), have found inhibiting EGFR reduced pain reaction in mice who were experiencing inflammation and chronic pain symptoms.

From the study:

“We show that inhibition of EGFR with clinically available compounds strongly reduced nocifensive (pain reaction) behavior in mouse models of inflammatory and chronic pain. EREG-mediated activation of EGFR enhanced nociception through a mechanism involving the PI3K/AKT/mTOR pathway and matrix metalloproteinase-9. Moreover, EREG application potentiated capsaicin-induced calcium influx in a subset of sensory neurons. Both the EGFR and EREG genes displayed a genetic association with the development of chronic pain in several clinical cohorts of temporomandibular disorder. Thus, EGFR and EREG may be suitable therapeutic targets for persistent pain conditions.”

This is promising research that could have application to people experiencing chronic pain. I hope they are right. I hope we can find “suitable therapeutic targets”, safer than opioids that will stand the test of human trials. If approved, such pain medication could be safely and effectively utilized to increase the quality of life for those who suffer from chronic pain.

The opioid crisis is real. People are dying every day from this epidemic. Finding effective and safer alternatives to pain management is essential in the fight. It is a preventative measure worth exploring to the fullest. However, it is only one of many areas to be targeted and improved.

In addition to this effort, identifying, assessing, and treating those who suffer and those who love them is also extremely important. These intervention strategies are not used often enough. When identified as having a problem, most people who suffer from opioid addiction do not have access to treatment due to financial, familial, and cultural barriers. We can and must focus our collective efforts and resources into both preventing opioid abuse and intervening when someone suffers from opioid addiction.


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