IRP scientists pioneer promising treatment for intractable cancer pain

Thursday, May 29, 2025

RTX is a non-addictive pain therapy derived from a cactus-like plant

National Institute of Health (NIH) scientists report that a first-in-human clinical trial of a new therapy based on the plant-derived molecule resiniferatoxin (RTX) shows that it is a safe and effective agent for pain control in patients with intractable cancer pain. Researchers tested a single injection of small quantities of RTX into the lumbar cerebral spinal fluid (by lumbar puncture) of advanced-stage cancer patients and found that it reduced their reported worst pain intensity by 38 percent and their use of pain-relieving opioids by 57 percent.

“The effects are immediate,” said Andrew Mannes, M.D., lead study author and chief of the NIH Clinical Center Department of Perioperative Medicine. “This is a potential new therapy from a new family of drugs that gives people with severe cancer pain an opportunity to return some normality to their lives.”

The trial enrolled research participants with terminal end-stage cancer who were among the 15% of cancer patients unable to find pain relief from standard of care pain interventions, including vast quantity of opiates without relief.

A single injection of RTX provided patients durable relief. Patients’ need for pain-relieving opioids declined sharply, and their quality of life improved. They no longer needed to spend significant periods being sedated with opioids and after treatment were able to reengage with their family, friends and communities.