SAN DIEGO, Oct. 13, 2021 (GLOBE NEWSWIRE) -- Sorrento Therapeutics, Inc. (NASDAQ: SRNE, "Sorrento") announced that the company has received FDA clearance to proceed with a global Phase 2 clinical study of resiniferatoxin (RTX), entitled “A Multicenter, Phase 2 Study to Assess the Safety and Efficacy of Epidural Resiniferatoxin for the Treatment of Intractable Pain Associated with Advanced Cancer”. The Phase 2 trial, a multi-center, double blind, controlled study will assess the “efficacy and safety of several RTX doses vs. placebo controls to manage intractable pain in up to 120 patients with advanced cancer” (NCT05067257). Three RTX dose groups (15, 20 and 25 mcg) will be evaluated against both a vehicle control group and a concurrent control group over a year of follow up. The primary objective of the study is to identify the recommended Phase 3 dose for later studies.
The decisions related to this indication follow the analysis of the significant observations from the Phase 1b trial results (NCT03226574). The Phase 1 was an ascending dose safety study in 17 patients to assess the safety and preliminary efficacy of epidural administration of resiniferatoxin for the treatment of intractable pain due to cancer. RTX was generally well tolerated after epidural administration at doses up to 30 mcg with the most common adverse event of “procedural pain” experienced by just over half of subjects (52.9%) and all of these events were considered at most moderate severity and lasted only a few hours. Pharmacokinetic sampling showed no measurable systemic RTX levels in nearly all subjects. Preliminary efficacy showed promising long-standing benefit in pain reduction.
In the Phase 1 study, clinical efficacy was defined as a 30% decrease in average pain scores (CE30), calculated for both average pain for three consecutive days from original baseline score of ≥ 6 on a scale of 1 to 10 (NRS rating scale) and worst average pain, compared to baseline using the NRS during the 3 months post injection. Eleven of 17 subjects achieved this efficacy endpoint with subjects receiving 15 or 25 mcg showing the best results. For CE50 and CE70, 6 and 4 subjects, respectively, achieved these endpoints again with those receiving 15 or 25 mcg showing best results. These results are promising in view of the challenging, intractable pain conditions due to advanced cancer, however the somewhat small sample size enrolled requires confirmation in larger follow-on studies.
About Resiniferatoxin (RTX)
Resiniferatoxin is a small-molecule derivative (diterpene ester), purified from a cactus-like plant (Euphorbia sp.). It is a highly potent agonist of the transient receptor potential vanilloid-1 (TRPV1) receptor which are specifically upregulated with chronic severe noxious pain. A thousand times “hotter” than pure capsaicin (16 billion Scoville units versus 16 million), and with a high affinity for afferent sensory pain nerves, resiniferatoxin binds to TRPV1 receptors and selectively ablates the neurons responsible for perpetuating chronic severe pain signals experienced by patients.
More information on this trial can be found at www.clinicaltrials.gov (NCT03542838).
