Study to Evaluate Safety and MTD of Epidural Resiniferatoxin Injection for Treatment of Intractable Cancer Pain

Inclusion Criteria: * Histologically confirmed advanced cancer or metastasis, which has not responded to standard therapy, producing intractable chronic pain in any area below the mid-thoracic level. * Male or female subjects must be at least 18 years of age. * Must have a worst pain score ≥6 on the NPRS at Screening visit. * Subjects not seeking or receiving potentially curative therapies for cancer. Palliative therapy is acceptable if the therapy started and is stable prior to IP administration. * Sexually active female subjects of childbearing potential and male subjects capable of fathering a child must be willing to use an effective method of contraception to avoid pregnancies. * Must be willing and capable of understanding and cooperating with the requirements of the study. * Must be able to understand and complete study-related forms and adequately communicate with the investigator and/or site staff. * Must have provided written informed consent prior to participating in any study-related activity. * Subjects able to complete the study duration. Exclusion Criteria: * Subjects with leptomeningeal metastases in lumbar area. * Undergoing or have plans to undergo changes to current cancer treatment during the study through the Day15 assessment. * Had prior lumbar spine surgical procedures that could impair the ability to perform the injection. * Evidence of brain pathology or increase intracranial pressure. * Presence of an IT shunt. * Has evidence or a coagulopathy or hemostasis problem. * Subjects with a total neutrophil count \<1500 cells/mm3. * Subjects with serum creatinine ≥1.5 mg/dL. * Is febrile or has other evidence of an infection within 7 days of planned injection. * Has an allergy or hypersensitivity to chili peppers, capsaicin, or radiographic contrast agents. * Female subjects who are pregnant, are planning on becoming pregnant, or are currently breastfeeding. * Subjects with any medical condition that could adversely impact study participation or assessments. * Subjects who have received new anti-cancer treatments and there is less than one week or four half-lives of the investigational drug, whichever is greater, between the last dose of the new drug and the planned day of IP administration; or had a change in the dose or schedule of the anti-cancer treatments within one week or four half-lives, whichever is greater, between the last dose of the anti-cancer treatment and the planned day of IP administration; or are scheduled to receive a new anti-cancer therapy or investigational product prior to completion of the Day 15 visit. * Subjects with additional loci of pain above the mid-thoracic level or other pain disorder due to non-cancer etiology, unless both the investigator and the subject are clearly able to distinguish the additional pain from the target pain due to cancer. * Liver cirrhosis or severe hepatic impairment, with liver function test 3 times above ULN. * Sensory/peripheral neuropathy of CTCAE Grade 2 or higher. * Nonstudy related minor surgical procedure ≤5 days or major surgical procedure ≤21 days prior to Screening visit. * Subjects who have not completely recovered from any toxicities from previous chemotherapy, hormone therapy, immunotherapy, or radiotherapies that are CTCAE Grade 3 or higher. * Arterial thrombi (including stroke), myocardial infarction, admission for unstable angina, cardiac angioplasty, or stenting within 3 months prior to Screening visit. * Corrected QT using Fridericia's formula (QTcF) prolongation. * Evidence or history of bleeding disorder within 4 weeks prior to IP administration. * Known HIV or acquired immunodeficiency syndrome-related illness, acute or history of chronic hepatitis B or C.