Encouraged by continued legal and regulatory developments, more pharmaceutical companies are exploring cannabis as a basis for new medicines.
Scientists have long had reason to believe that cannabinoids, chemical compounds derived from the cannabis plant, have therapeutic potential, particularly in the areas of chronic pain, cancer and spasticity, a muscular condition.
A number of cannabinoids are derived from cannabis, such as cannabidiol or CBD, and tetrahydrocannabinol, or THC. There are 146 different known cannabinoids, according to Stuart Titus, the CEO of Medical Marijuana, Inc., an investment holding company, developer and distributor.
As early as 2003, studies suggested cannabinoids may have anti-tumor effects. Over 23,000 studies have been published about cannabinoids' medical potential, Titus said. But the field has been hampered by marijuana's reputation as a recreational drug.
"There's a stigma attached to [medical marijuana]," said Bill Kinney, the chief scientific officer at Kannalife Sciences Inc., which is developing cannabinoid-based medicines. "You have to find someone who believes in the benefits."
The legalization of medical marijuana in 30 U.S. states and in Canada may mitigate some of that stigma, as well as some recent commercial advances.
Tilray Inc., which closed its initial public offering in July, partnered with Novartis to distribute cannabis-based treatments in Canada, where medical marijuana has been legal since 2001. GW Pharmaceuticals PLC's epilepsy medication Epidiolex was approved in June as the first marijuana-based medicine approved by the U.S. FDA. GW's multiple sclerosis spasticity treatment Sativex is EU-approved and marketed in 21 European countries, though it has not yet been cleared in the U.S.
Meanwhile, clinical trials for cannabis treatments for pain are underway amid a need for alternatives to opioid medicines. INSYS Therapeutics Inc., for example, emphasized during their second-quarter earnings call on Aug. 8 that they plan to shift their focus from opioids to cannabinoids. Insys had manufactured opioids such as Subsys, a fentanyl spray for cancer pain, and is under fire over alleged marketing practices such as promoting Subsys for off-label use.
One of the challenges of successfully developing a cannabis-based treatment is establishing a safe dosage, according to Kannalife's Kinney. A dosage that is too much can injure neurons, and developers face the additional challenge of actually getting the treatment into the bloodstream.
"You want 50% of the dose you swallow to get into the bloodstream, which is pretty typical of a drug," he said. "In cannabidiol, less than 10% gets absorbed, and when it's that low, different patients will absorb [it] at different rates."
Cannabidiol can limit the body's ability to absorb other medicines, presenting another conundrum for drug developers, he said.
Another challenge is fundraising to support expensive trials, Kinney said. In therapeutic areas such as pain and anesthesia, for example, the three phases of clinical trials usually required for regulatory approval could cost $71.3 million, according to a study by Eastern Research Group submitted to the U.S. Department of Health and Human Services in 2014.
The rocky road of regulation
Drug approval is a complicated process that perhaps proves all the more complex when cannabis, a Schedule 1 drug, is involved. Schedule 1 products are defined by the U.S. Drug Enforcement Agency as drugs with "no currently accepted medical use and a high potential of abuse." That makes even simple, early-stage studies challenging, Titus said.
Companies like Medical Marijuana are working to advocate for the descheduling of cannabis amid the shifting perception of medical cannabis, Titus said.
"Clinical research with cannabis-based medicines in the U.S. remains severely restricted and much more work has been done abroad," Ethan Russo, director of research and development at the International Cannabis and Cannabinoids Institute, said. "There is little opportunity for change in this status short of congressional action."
While GW Pharma has successfully pushed through a medical marijuana treatment, there is still a significant "lack of clinical work" despite the increase in companies entering the space, according to the company's vice president of investor relations, Steven Schultz.
Schultz said he does not believe there is a scientifically established understanding in the field of safe cannabinoid dosages. He emphasized the importance of a reliable product, especially if the FDA has not seen anything like it before.
"Physicians need to know how a medicine works when they're prescribing it, what the side effects potentially may be, and they need to know whether the medicine interacts with other medicines the patient may be taking," he said. "The developed medicine has to be exactly the same product every time it's prescribed, every time the patient takes it."
Nicholas Vita, CEO of medical marijuana manufacturer and distributor Columbia Care, said growing cannabis for pharmaceutical purposes has many limitations, namely environmental controls such as temperature and even light bulb control. These minute variations can add to the difficulties of providing precise dosages.
Vita acknowledged GW Pharma's U.S. approval of Epidiolex as a "great service for the rest of the field." The approval, he said, proves cannabidiol application and the potential for other active pharmaceutical ingredients that can be derived from the cannabis plant.
On the rise
Despite regulatory difficulties, still more products are stewing in the preclinical pot. Kannalife is among the companies looking to develop effective and safe medications, having obtained a manufacturing license from the National Institutes of Health for their cannabidiol molecule.
The molecule, KLS13019, currently targets hepatic encephalopathy, which stems from liver failure, and chronic traumatic encephalopathy, a degenerative brain disease common in football players suffering repetitive head injuries. The molecule, Kannalife's Kinney said, addresses many of the concerns of cannabinoids, such as harmful dosages and absorption issues.
According to Kinney, KLS13019 works in a "much lower concentration," which is safer for neurons. In addition, 60% of the established dose gets into the patient's blood circulation.
The molecule's efficacy has been tested in animals, but not yet in humans, he said.
Other potential uses for cannabis-based drugs include difficult-to-treat conditions like Alzheimer's, though Kinney said it would take "years and years" to develop such a treatment.
Some companies, such as GW Pharma, are looking into treating schizophrenia, autism spectrum disorder and Parkinson's disease. Cannabinoids may even be shown to alleviate opioid abuse and other drug addictions, according to Titus.
Possible side effects stemming from too much THC are "brief, reversible," Russo said, and there are other cannabinoid constituents with "greater safety margins." Cannabidiol, for example, is preferable for the lack of side effects and psychoactive properties, Titus said, and cannabigerol is another substance with medical potential.
The broadening spectrum of active pharmaceutical ingredients that now includes cannabinoid constituents could grow to include other drugs typically categorized as recreational such as ketamine, LSD and psilocybin, otherwise known as the active ingredient in so-called "magic mushrooms."
Ketamine is being leveraged by the likes of Johnson & Johnson and Allergan PLC, who are researching the ability of a related molecule to treat depression. A 2017 publication detailed LSD's possible therapeutic areas, particularly in treating patients with anxiety "associated with life-threatening disease."
"It's always good to have an open mind in science," Kinney said, in reference to other recreational drugs potentially entering the pharma world. "Especially in the field of cannabis, it's inevitable that there will be a modified natural product that is actually more effective and more drug-like."