A Phase 1 interventional study of Intrathecal Resiniferatoxin in Intractable Pain and Palliative Care, sponsored by National Institute of Dental and Craniofacial Research (NIDCR). Completed at 1 site in United States. Open to participants aged 18 Years to 99 Years. Per ClinicalTrials.gov, last updated 2026-10-30.
Sponsored by National Institute of Dental and Craniofacial Research (NIDCR) · Phase 1, Interventional, and Treatment
This study will examine the safety of giving the experimental drug, resiniferatoxin (RTX), to treat severe pain in patients with advanced cancer. RTX is a chemical extracted from a cactus-like plant. It is similar to capsaicin, the active ingredient in hot pepper. RTX has relieved pain and reduced the need for pain medication in several animal experiments. It works by destroying nerves that transmit pain information.
People at least 18 years of age with severe pain from advanced cancer at or below the level of the chest that cannot be controlled with standard treatments may be eligible for this study. Participants undergo the following procedures:
Pretreatment Visit
Before beginning treatment with RTX, patients give a medical history and undergo a physical examination that includes:
Questionnaires to collect information on health, personality, mood, pain levels and symptoms.
2-Day Hospitalization
Patients are hospitalized for 2 days for RTX injection and monitoring, as follows:
Outpatient followup
Pain continues to be a major problem in patients with advanced cancer. Resiniferatoxin (RTX), a potent member of the family of drugs that includes capsaicin, selectively and irreversibly destroys the neurons (or their axons) transmitting chronic pain sensation. Intrathecal injection of RTX in several animal species has demonstrated a high level of safety, specificity, and efficacy in treating severe pain. This first-in-human, dose-escalation study is investigating the intrathecal administration of RTX in cancer patients with severe pain.
PRIMARY OBJECTIVE:
To investigate the safety and efficacy of RTX administered intrathecally in subjects with severe refractory pain associated with advanced cancer.
STUDY POPULATION:
Up to 45 subjects will be accrued. Eligible subjects will be greater than or equal to 18 years of age, have a clinical and histological diagnosis of advanced malignancy, and have severe pain due to malignancy that is at or below the level of the chest and not adequately relieved by other pain control therapies.
DESIGN:
This is a single site, non-randomized, open-label, dose-escalation study using a modified Fibonacci scheme. The starting dose of RTX was 13 micrograms given as a 2 mL injection via an intra-spinal catheter over approximately 30 seconds followed by a 1 mL flush. Six subjects were dosed at this level and 3 were dosed at the 26 microgram dose level at the same volume of injectate, flush and injection time. Under the study design, RTX doses were to be increased in progressively smaller percentage increments with each dose-escalation to occur in sequential groups of 3 subjects until 1 escalation above the effective dose in 100% of subjects (ED100), completion of the 100 microgram dose level, or establishment of the maximum tolerated dose (MTD), whichever occurs first. The total duration of study participation for any subject will be up to 7 months.
The amended RTX injection technique reduced the injection volume and increased the injection time to reduce the spread of RTX to above the T6 (sixth thoracic) vertebral level. The present technique is a 1 mL injection over 2 minutes (0.5 mL/minute) given via infusion pump, followed by flushing of the IT catheter with the minimum volume of sterile, preservative-free saline necessary to clear the internal volume of the catheter used for the injection. Three patients were treated at the new starting dose of 13 micrograms with the new injection technique. The next 3-patient cohort will receive a dose of 26 micrograms. The subsequent subject dose tier will receive a dose of 44 micrograms consistent with the protocol s dose-escalation algorithm. Administering this dose will require an infusion volume of 1.76 mL of the present 25 micrograms/mL RTX formulation.
OUTCOME MEASURES:
The primary study outcome is the ED100, the MTD, or the maximum dose administered, whichever is achieved first during dose-escalation. The primary pain variable for determining the ED100 is the daily worst pain intensity score averaged over a 4 to 7-day period during the 3 weeks before RTX dosing and during Days 8 through 14 after dosing. The numerical rating scale (NRS), administered verbally during a daily telephone interview, will be the primary pain assessment instrument. For a given subject, the treatment will be considered effective if the subject experiences a greater than or equal to 50% reduction in the mean daily worst pain score assessed by NRS (evaluated on Study Day 15). We may also consider RTX treatment to be successful if there is greater than or equal to 50% reduction in opiate intake, measured by morphine milligram equivalents (MME) per day, even if pain levels are unchanged after RTX treatment.
Secondary outcome measures will be other surveys of pain, including an assessment of worst daily pain by the visual analog scale, and assessments of function and quality of life.
Safety assessments will include hematology; serum clinical chemistry tests; cerebrospinal fluid examinations; physical, neurological, and eye examinations; reporting of adverse events; electrocardiograms; and findings on magnetic resonance imaging of the spine and brain.
90 studies on the registry are indexed under Pain, Intractable; 16 are open to participants now.
This study's enrollment of 36 is below the median of 60 across 64 interventional studies indexed under Pain, Intractable.
Browse Pain, Intractable studies →National Institute of Dental and Craniofacial Research (NIDCR) is the lead sponsor of 94 studies on the registry; 9 are open to participants now.
Of its 8 completed or terminated interventional studies of FDA-regulated products, 5 (63%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Subject inclusion criteria are based on inadequate control of pain despite best efforts, including appropriate use of analgesic medications. To be enrolled in the study, subjects must meet all of the following criteria:
Alternative methods of pain control are not sufficiently effective, not indicated, not tolerated, and/or refused by the subject, as determined by the Pain and Palliative Care Service (PPCS). Alternative methods of pain control include, but are not limited to, the following:
-Opioids (all routes of administration including neuraxial infusions)
-Adjuvant pain medications such as antidepressants, , local anesthetics, and antiseizure medications
-Procedures such as catheter or implantable pump placement for delivery of analgesic medication
the study by 3 separate persons:
A member of the PPCS at the NIH or institution s equivalent at other sites.
10. (INR; from prothrombin time [PT]) \< 1.5 and partial thromboplastin time (PTT) less than or equal to the upper limit of the reference range. The INR and PTT may be corrected (e.g., by administration of blood products, vitamin K, etc.), provided a repeat blood draw confirms that the values meet this inclusion criterion.
10. count greater than or equal to 50,000/mm\^3. Platelets will be transfused as necessary to raise the platelet count to greater than or equal to 100,000/mm\^3 prior to dosing.
11. Ability to stop any anticoagulant (e.g., Coumadin) and antiplatelet therapies (e.g., aspirin) before and during IT catheter placement according to accepted medical guidelines.1
12. Ability and willingness to undergo an eye examination.
13. Ability to read, speak, and understand English, and willingness to complete the study tools and forms.
14. For women of and men with partners of childbearing potential, the ability and willingness to use an effective method of during the study. Effective methods of birth control include:
surgical sterilization (hysterectomy, tubal ligation, or vasectomy).
15. Availability of a responsible adult to assist with activities of daily living as needed for the subject through the Day 15 visit.
16. Ability to assign a Durable Power of Attorney (DPA) for research and medical care at NIH
EXCLUSION CRITERIA:
Subjects will be excluded from the study if they meet any of the following criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
advanced cancer patients with pain
Drug: Intrathecal Resiniferatoxin
phase I, single-site, non-randomized, open-label, dose-escalation study to determine the safety and efficacy of IT RTX in subjects with severe refractory pain due to advanced malignancy
Investigate the safety and efficacy of RTX administered intrathecally in subjects with severe refractory pain associated with advanced cancer along with ED100, the MTD, or the maximum dose administered, whichever is achieved first during dose es...
Dose escalation decisions are based on both effectiveness (as assessed by mean worst pain on the NRS) and DLT. The dose escalation population will include all subjects who are dosed, complete the NRS, and have the DLT assessments from baseline through Day 15. Subjects who are not evaluable for dose escalation will be replaced.
Time frame: Day 7, Day 15, Day 68, Day 188
Secondary outcome measures will be other surveys of pain, including an assessment of worst daily pain by the visual analog scale, and assessments of function and quality of life.
The secondary outcome variables will be summarized over time by dose cohort as appropriate for the outcome measure. Absolute and percentage change in the NRS and VAS pain scores between the pre- and post-RTX dosing assessments (baseline period and study Days 8 through 14, respectively) will also be summarized.
Time frame: Day 7, Day 15, Day 68, Day 188
Plan to share: Undecided — We do plan to share IPD. we will share all IPD that results in a publication on a public repository, as required by most journals. the data will be de-identified and anonymized.
Ran from Aug 2009 to primary completion in Jul 2026, 203 months.
Since we started tracking on Sep 25, 2026, the dates moved once, on Oct 27, 2026: primary completion Feb 2027 → Jul 2026 and completion Feb 2027 → Jul 2026.
Earlier changes are on the record history on ClinicalTrials.gov ↗
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: Resiniferatoxin
National Institute of Dental and Craniofacial Research (NIDCR) →