Resiniferatoxin Shows Promise as Cancer Pain Treatment
Intractable pain improved with single injection
Investigators from the National Institutes of Health (NIH) have presented data highlighting results from the first two dosing cohorts of the phase I/II trial of resiniferatoxin (Sorrento Therapeutics) for the treatment of intractable cancer pain. The findings were presented April 3 at the 39th Annual Regional Anesthesia and Acute Pain Meeting in Chicago.
Data from six patients with advanced cancer and severe refractory pain, who received either a 13-mcg or a 26-mcg injection of resiniferatoxin into the intrathecal space, showed a clinically meaningful improvement in quality of life after the single injection.
The overall average improvement across the seven Brief Pain Index pain interference items was 1.6 at week 2, and patients reported a comparable 6.5-point improvement in the overall score of the Functional Assessment of Cancer Therapy–General scale (FACT-G). Patients achieved, on average, a 20% reduction (range, 3.6%–54.0%) in their pain-intensity numerical rating scale (NRS) score at 2 weeks. Of note, most patients were able to increase their activity levels, and one-third of patients who were bed- or wheelchair-bound because of pain were able to resume ambulation soon after the injection.
The drug was well tolerated, with no unexpected side effects. One additional cohort with an increased dose is planned to determine the optimal dose level for further development. A randomized controlled confirmatory trial is being prepared.
Resiniferatoxin is a non-opioid–based pain treatment that selectively binds to the transient receptor potential vanilloid-1 (TRPV-1) receptor, creating a potent agonist signal. This leads to calcium influx-induced apoptosis of TRPV-1 nerve cells, resulting in elective ablation.
A single intraspinal injection of resiniferatoxin is expected to permanently block the transmission of pain signals without affecting normal sensation or motor control, and without causing the impairment of mental or physical faculties often seen with opioid treatment.
The ongoing study is an investigator-sponsored clinical trial at the NIH, under a company-sponsored collaborative research and development agreement, designed to evaluate the safety of resiniferatoxin for the treatment of intractable cancer pain.
Source: PR Newswire; April 4, 2014.