investigator decision

This study is to assess the efficacy and safety of a four-week treatment with intranasal esketamine (56 mg) twice a week combined with opioid analgesic and adjuvant standard therapy in the management of adult patients with severe and opioid refractory chronic cancer pain.

Inclusion Criteria:

• Patient with refractory cancer pain, this pain defined when:

  • Multiple evidence- based biomedical therapies used in a clinically appropriate and acceptable fashion have failed to reach treatment goals that mainly include adequate pain reduction and/or improvement in daily living functioning activities.
  • Patients' functional activities do not allow a quality of life which is acceptable and/or pharmaceutical therapies have resulted in intolerable adverse effects.

• Psychiatric disorders and psychosocial factors that could influence pain outcomes have been assessed and appropriately addressed

• Cancer pain classified as chronic (persistent or recurrent pain lasting longer than 3 months), and currently refractory despite optimized analgesic therapy including an opioid.

  • Optimized analgesic therapy is arbitrarily defined as: oral morphine equivalent of 60 mg/d or more (or another strong opioid at optimized dose) plus at least one adjuvant analgesic drug, for at least 2 weeks.

• No increase in baseline long acting opioid dose or addition of a new adjuvant analgesic drug within 2 weeks prior to study entry

• Ability to communicate the intensity of pain using the NPRS pain scale ranging from (0 as no pain to 10 with severe pain).

• Ability to give fully informed written consent.

• Expect survival more than 3 months.

Exclusion Criteria:

• History of allergy or intolerance to esketamine or ketamine.
• History of allergy to disinfecting products containing quaternary ammonium, who might be susceptible to be allergic to denatonium benzoate.
• Concomitant use of xanthine derivatives (e.g. aminophylline, theophylline), ergometrine, or monoamine oxidase inhibitors.
• Active nasal/sinus dysfunction (e.g. allergic or infectious rhinitis) or presence of any lesion of the nasal mucosa.
• Pregnancy, breastfeeding and women of childbearing potential not using a highly effective contraception method.
• Uncontrolled hypertension, arrhythmia, heart failure, or untreated coronary artery disease. History of transient ischemic attacks, stroke, neurovascular disease, hemorrhage, severe head injury, hydrocephalus or elevated intracranial pressure within the last 3 months.
• History of primary or metastatic malignant brain lesions (uncontrolled or without previous treatment).
• Known aneurysmal vascular disease (including thoracic and abdominal aorta, intracranial, and peripheral arterial vessels) or arteriovenous malformation
• Uncontrolled psychiatric illness with psychosis/ hallucination (e.g. schizophrenia, acute psychosis).
• Alcohol abuse, drug abuse/ dependence within the past 6 months as self-reported.
• Cirrhosis or severe hepatic impairment defined as 5-fold elevation of transaminases
• Uncontrolled hyperthyroidism.
• Globe injuries or increased intraocular pressure (e.g. glaucoma).
• History of ulcerative or interstitial cystitis.
• Subjects scheduled to receive radiotherapy (RT) to a site of pain during the study period, or who have received RT to a site of pain within 2 weeks before study entry.
• Subjects scheduled to undergo surgical treatment during the study period likely to affect pain.
• Subjects on or starting chemotherapy if there is a significant expectation of that therapy affecting pain.
• Subjects who have not provided signed informed consent form.
• Concomitant use of drugs moderately or severely affecting cytochrome P450 activity.

All investigators, patients, care providers, outcome assessors, and study statisticians will remain blinded with respect to the treatment allocation. Allocation sequence will be concealed for everyone involved in the trial, except for the pharmacist and the nurse responsible for patient's allocation.