San Diego Business Journal

Local drugmaker Sorrento Therapeutics Inc. just got the OK from regulators to start human trials for a non-opioid medicine that might treat chronic pain. Considering the high substance abuse associated with opioids, a chronic pain alternative could be a high priority for the FDA.

The U.S. Food and Drug Administration not only approved the company’s Investigational New Drug application, but it also gave the drug “Orphan” status. This designation gives the company a number of incentives that lighten the burden of development, including guidance, reduced fees, and extended market exclusivity once the drug is approved.

The medicine is called Resiniferatoxin, or RTX, and it’s a naturally-occurring chemical found in resin spurge, a cactus-like plant found in Morocco. The chemical is related to capsaicin, the active ingredient in chili peppers, only RTX is ultrapotent. The substance is 1,000 times hotter than pure capsaicin.

As a drug, RTX has been extensively tested in animals, according to Sorrento.

"Given its unique mechanism of action, we view RTX as a franchise molecule, uniquely positioned to halt the neurogenic inflammation cycle in a number of clinical indications,” said Sorrento’s CEO and president Henry Ji. “Our intention is to commence our clinical path in cancer since more than 80 percent of cancer patients experience uncontrolled pain during their disease and 20 percent of these patients remain unresponsive or intolerant to mainstay, opioid therapy.”

RTX is currently in Phase 1 clinical trials at the National Institutes of Health (NIH), with 12 patients being treated. Early results show that, in contrast to opioid treatments, RTX did not result in cognitive impairment, sedation, or respiratory depression. It also enabled patients to increase their activity levels.

Sorrento plans to enter a Phase 1b human trial of the RTX, administering it by epidural injection for the treatment of intractable pain associated with cancer. The FDA granted Orphan status for the pain associated with end stage disease.