Study Comparing Systemic, Intrathecal Opioid Therapy

ASCO—A new multicenter international trial is comparing standard systemic pain management with intrathecal therapy for chronic cancer patients.

Thomas Smith, MD, of the Department of Medical Oncology, Medical College of Virginia, Richmond, discussed the study design at a poster session of the 36^th Annual Meeting of the American Society of Clinical Oncology, New Orleans.

Previous studies have shown that intrathecal opiate therapy using an implantable drug delivery system relieves pain in 64% to 95% of chronic cancer pain patients with opioid dosages 200 to 300 times lower than used in systemic therapy, but, he noted, these studies have not been controlled against adequate systemic therapy.

This randomized controlled trial is comparing the effectiveness of Comprehensive Medical Management (CMM), defined as standard pain management using all available non-intraspinal techniques, with intrathecal therapy using the implantable Medtronic SynchroMed Drug Delivery System (IDDS) plus CMM. Treatments such as radiation for palliation, chemotherapy for palliation, bisphosphonates for pain, etc, will be allowed in both study arms.

To date, the trial has enrolled 79 of a planned 200 patients with moderate to severe chronic pain secondary to cancer or cancer therapy, Dr. Smith told ONI. He said that an interim analysis of results in the first 100 patients should be ready for presentation at next year’s ASCO.

The primary endpoint is improvement in pain scores, and the study is powered to detect a 20% difference in pain scores using a 0 to 10 visual analog scale (VAS). Equal pain scores with improved opioid side effect scores would also be an acceptable outcome, Dr. Smith said. Secondary objectives are quality of life, drug side effect profile, and cost of care.

He noted that in terms of cost, fewer hospital days and expensive oral/trans-dermal drugs in the CMM group may offset pump and implant costs in the IDDS group.

Eligible patients have end-stage cancer requiring palliation only and a life expectancy of 3 months or longer. They must have moderate to severe cancer pain (VAS of 5 or more) uncontrolled by systemic opiates equivalent to at least 200 mg of oral morphine daily, or with intolerable, therapy-resistant side effects at lower opiate doses.

Dr. Smith said that study data will be collected at baseline, 2, 4, 6, 8, 10, and 12 weeks, and then at 4, 5, and 6 months after enrollment, for a total of 6 months of follow-up.

Crossover is allowed 1 month after enrollment in either arm if patients continue to have moderate to severe pain despite receiving the maximum therapy available in their treatment arm. All patient data will be analyzed according to intention to treat.