Initiation of Intrathecal Drug Delivery Dramatically Reduces Systemic Opioid Use in Patients With Advanced Cancer

Education and Experience in Intrathecal Drug Delivery Systems (IDDS) During Pain Medicine Fellowships

Objective

Targeted drug delivery (TDD) via intrathecal drug delivery systems (IDDS) exposure and clinical adoption remains low despite multiple well-designed trials that demonstrate safety, efficacy, reliability, and cost-saving benefits. This study aims to understand the possible contributing factors starting with Pain Medicine fellowship training.

Materials and Methods

An internet-based, anonymous pilot survey was distributed to pain medicine fellows enrolled in an Accreditation Council for Graduate Medical Education (ACGME) accredited pain medicine training program during the 2021-2022 academic year. Fellowship programs were identified using published online ACGME accreditation data. The survey was distributed via email to fellowship program directors and coordinators and was made available through pain medicine societies.

Results

Seventy-one of four hundred and twenty-three pain medicine fellows (17% response rate) completed the survey. Nine percent of respondents evidence-informed opinion coincided with the most recent Polyanalgesic Consensus Conference (PACC) guidelines recommendations for IDDS treatment indications. Fifty-one percent of respondents felt there was an unmet need for IDDS training. About one-third of respondents felt that lack of curriculum, faculty, and cases were barriers to IDDS use, respectively. Thirty-one percent of fellows reported sufficient training for IDDS in their fellowship programs. The majority (70%) of respondents somewhat or strongly support direct training by IDDS manufacturers.

Conclusion

A wide variability exists surrounding IDDS training during ACGME accredited pain medicine fellowship. Insufficient case exposure and lack of a standardized curriculum may play a role in future therapy adoption. The results from this study call for a more standardized training approach with an emphasis on adequate clinical exposure, utilization of peer reviewed educational curriculum and supplemental material to aid pain medicine fellows' education.

Dorsal Versus Ventral Intrathecal Catheter Tip Location and Effect on Dose Escalation and Opioid Use in Patients With Cancer Pain

OBJECTIVES

In the practice of intrathecal drug delivery, consensus exists regarding the cephalad to caudad location of the catheter tip relative to dermatomal distribution of pain. However, data are lacking on the importance of dorsal vs ventral tip location relative to the spinal cord. We hypothesize that a dorsally placed catheter tip improves efficacy because of closer proximity to nociceptive pathways.

MATERIALS AND METHODS

A retrospective review of 298 patients with cancer with intrathecal drug delivery systems implanted at the Huntsman Cancer Institute from May 2014 to June 2020 was performed. Patients were stratified by catheter tip location zones based on available radiographic studies. Patient-controlled intrathecal medication dose requirements and rate of change were compared with catheter zone and other variables, including the presence of adjuncts such as bupivacaine and ziconotide.

RESULTS

A total of 158 patients were suitable for analysis demonstrating a dorsal tip in 63.9% (n = 101) and ventral tip in 36.1% (n = 57), with a median follow-up of 17 days (interquartile range [IQR], 10-24). There was no difference in daily dose change from implant to discharge between the dorsal group 8.2% (IQR, 0.0-41.5) and ventral group 20.8% (IQR, 0.0-66.7; p = 0.12). Daily dose change from discharge to follow-up was 2.6% (IQR, 0.0-7.1) in the dorsal group and 1.8% (IQR, 0.0-5.7) in the ventral group (p = 0.92). Catheter tip location had no impact on systemic opioid use.

CONCLUSIONS

We did not find significant associations between dorsal vs ventral catheter tip location and measures of pain relief, including change in intrathecal dose or systemic opioid use.

Early Interventional Treatments for Patients with Cancer Pain: A Narrative Review

Between 10% and 20% of patients with cancer-related pain cannot achieve adequate control following the three-step ladder guidelines by the World Health Organization. Therefore, a "fourth step", including interventional approaches, has been suggested for those cases. Systematic reviews support the early use of interventional procedures to treat refractory cancer pain, control symptoms and prevent opioid dose escalation. There is strong evidence of the efficacy of celiac plexus or splanchnic neurolysis, vertebroplasty, kyphoplasty and intrathecal drug delivery. Those procedures have been found to be associated with a decrease in the symptom burden and opioid consumption, improved quality of life, and suggested as having a potentially positive impact on survival. Several studies have recommended using specific interventional techniques at earlier stages, possibly even when opioid treatment is first being considered. Conversely, leaving these options as a last analgesic resource might not be advisable since the burden these procedures might impose on too ill patients is significant. The objective of this review was to collect the available evidence published on the use of interventional treatments for refractory cancer pain with a particular interest in comparing early versus late indications. The results of the search demonstrated a very low number and quality of articles particularly addressing this question. This scarce number of evidence precluded performing a systematic analysis. A detailed and narrative description of the potential benefits of integrating interventional techniques into clinical guidelines at the early stages of the disease is provided.

Refractory Cancer Pain and Intrathecal Therapy: Critical Review of a Systematic Review

This critical review assessed the advantages of invasive procedures that were recently included in systematic reviews, to evaluate whether the definition of refractory pain condition was correctly followed to select patients for invasive interventions and to analyze how data were positively interpreted. A total of 21 studies were selected for the purpose of this review. Three were randomized controlled studies, ten were prospective studies, and eight were retrospective studies. Analysis of these studies showed evident lack of proper assessment before implantation for different reasons. These included an optimistic interpretation regarding the outcomes, poor consideration of complications, and inclusion of patients with short survival. Moreover, the indication of intrathecal therapy as a condition in which a patient has failed to respond to multiple therapies provided by a pain or palliative care physician or at sufficient doses for adequate durations, as suggested by a recent research group, has been disregarded. Regretfully, this can discourage the use of intrathecal therapy in patients who are unresponsive to multiple opioid strategies subtrahend a potent means to be used in a very selective population.

Ziconotide for the Management of Cancer Pain: A Budget Impact Analysis

OBJECTIVES

Recent recommendations on starting dose, smaller dose increments, and longer intervals between dose increase have the potential to increase the safety of ziconotide administration in addition to improving its value for money. Ziconotide is not routinely commissioned in England, with one of the concerns being whether it represents the best use of resources. The aim of this project is to conduct a budget impact analysis to estimate the costs or savings associated with the changes in ziconotide dosage in addition to its use in combination with morphine for the management of cancer pain.

MATERIALS AND METHODS

An open, Markov-like cohort decision analytic model was developed to estimate the budget impact of ziconotide in combination with morphine (ziconotide combination therapy) vs morphine monotherapy through intrathecal drug delivery (ITDD) for the management of cancer pain. The perspective adopted was that of the UK National Health Service, with a five-year time horizon. Sensitivity analyses were conducted to evaluate different scenarios.

RESULTS

Ziconotide combination therapy was more expensive than treatment with morphine monotherapy. The total costs of ziconotide combination therapy and morphine monotherapy for the first year were £395,748 and £136,628 respectively. The estimated five-year cumulative budget impact of treatment with ziconotide combination therapy for the five-year time horizon was £2,487,539, whereas that of morphine monotherapy was £913,804. The additional costs in any of the first five years are below the resource impact significance level of £1 million for medical technologies in England.

CONCLUSIONS

The results of this budget impact analysis suggest that although a combination of intrathecal ziconotide in combination with morphine is associated with higher costs to the health care system in England, the incremental costs are not significant. Routine commissioning of ziconotide alone or in combination with morphine would provide an alternative for a population with limited ITDD treatment options.

Effectiveness and Safety of Intrathecal Drug Delivery Systems for the Management of Cancer Pain: A Systematic Review and Meta-Analysis

OBJECTIVES

Intrathecal drug delivery systems (IDDS) and spinal cord stimulation (SCS) have been proposed and assessed for the management of cancer pain; however, such treatments remain underused. We conducted a systematic review to evaluate the effectiveness and safety of IDDS and SCS for cancer pain.

MATERIALS AND METHODS

Electronic databases MEDLINE, CENTRAL, EMBASE, and WikiStim were searched from 1988 to March 2021. Randomized controlled trials and observational studies of adults with pain related to cancer or its treatment who received an implantable IDDS or SCS were eligible for inclusion. The primary outcome of the review was change in pain intensity from baseline to the last available follow-up, measured using a visual analog scale or numerical rating scale. The protocol for this review is registered on PROSPERO (CRD42021240717).

RESULTS

A total of 22 studies (24 reports) included a total of 3043 participants who received either IDDS or SCS for cancer pain. Eight studies reporting data for 405 participants with an IDDS could be included in the meta-analysis of pain intensity that showed a statistically significant reduction at the latest posttreatment follow-up time compared with baseline (mean difference [MD], -3.31; 95% CI, -4.18 to -2.45; p < 0.001). Six studies reporting data for 325 participants with an IDDS could be included in the meta-analysis of pain intensity that showed a statistically significant reduction up to one month after treatment compared with baseline (MD, -3.53; 95% CI, -4.06 to -3.00; p < 0.001). A meta-analysis including studies of participants with either an IDDS or an SCS device showed similar results. Improvements in other outcomes following implantation of IDDS also were observed. Postdural puncture headache was the most reported complication, whereas urinary retention, nausea, and vomiting were commonly reported side effects.

CONCLUSION

Our findings suggest that IDDS is effective in reducing pain intensity for patients with cancer pain when compared with pretreatment.

Physicochemical Stability Study of the Morphine-Ropivacaine-Ziconotide Association in Implantable Pumps for Intrathecal Administration

PURPOSE

This study aimed to investigate the physicochemical stability of morphine-ropivacaine-ziconotide mixtures used in intrathecal analgesia.

MATERIALS AND METHODS

Eight mixtures were studied to assess their stability profiles according to the initial drug concentrations used. The solutions obtained were put in implantable pumps and stored at 37 °C over a period of 60 days. Assays were performed using ultra high-pressure liquid chromatography. Turbidity and pH were also measured throughout the study.

RESULTS

Results confirmed excellent physicochemical stability for morphine and ropivacaine. Concerning ziconotide, three of the eight mixtures did not show any sign of chemical instability: average concentrations remained constant throughout the 60 days. A decrease of the concentration was observed for the five other mixtures. Moreover, the appearance of a degradation product linked to oxidation confirmed the ziconotide degradation.

CONCLUSIONS

All these results are in favor of a physicochemical stable preparation for three of the mixture profiles when stored in implantable pumps at 37 °C up to 60 days. For the five others, the efficacy should decrease over time owing to the degradation of ziconotide. The decrease in kinetics of the ziconotide concentration depends on the mixing profile. One possibility is to adapt the filling intervals according to the profile of the mixture. Finally, the results show the period of stability ensuring maximum analgesic efficacy for the eight mixture profiles studied.

Initial Intrathecal Dose Titration and Predictors of Early Dose Escalation in Patients With Cancer Using a 100:1 Oral to Intrathecal Morphine Conversion Ratio

OBJECTIVE

Pain is common in patients with advanced cancer, and intrathecal drug delivery (IDD) has been successfully used for recalcitrant pain. We report on our experience using a 100:1 oral-to-intrathecal morphine conversion ratio for initial dosing and factors predictive of early dose escalation.

MATERIALS AND METHODS

Retrospective review of an intrathecal drug delivery system (IDDS) data base at the Huntsman Cancer Institute-University of Utah in cancer patients initiated on IDD with morphine or hydromorphone. Demographic characteristics, preoperative opioid use, and initial and hospital discharge IDD settings were collected.

RESULTS

A total of 275 patients were identified between June 2014 and May 2020. The median oral-to-intrathecal morphine conversion ratio for initial IDD dosing was 105.5:1 (interquartile range [IQR] 90-120, range 75-150). No serious adverse effects including respiratory depression or sedation were noted and the median length of stay was one night (IQR 1-2, range 1-22). Ninety-six percent of patients discontinued opioids immediately following IDDS implant. Initial IDD dosing was adequate in 42% of patients. Dose reduction was required in 4% prior to discharge due to nausea, patient request, weakness, pruritus, or urinary retention. Dose escalation was required in 54%, with a median dose increase of 66.7% (IQR 33-150%, range 5-1150%). Patients in the highest quartile of dose escalation, ≥70% between IDD initiation and discharge, had associations with younger age, higher preoperative opioid use, and inpatient status. No significant associations were found in patients who required dose reduction as compared to other patients.

CONCLUSIONS

An oral-to-intrathecal morphine conversion ratio of approximately 100:1 for initiation of IDD in patients with cancer pain was safe and well tolerated and may facilitate rapid elimination of systemic opioids. Dose reduction was rare, while a majority of patients required further dose escalation prior to discharge.

The American Society of Pain and Neuroscience (ASPN) Best Practices and Guidelines for the Interventional Management of Cancer-Associated Pain

Moderate to severe pain occurs in many cancer patients during their clinical course and may stem from the primary pathology, metastasis, or as treatment side effects. Uncontrolled pain using conservative medical therapy can often lead to patient distress, loss of productivity, shorter life expectancy, longer hospital stays, and increase in healthcare utilization. Various publications shed light on strategies for conservative medical management for cancer pain and a few international publications have reviewed limited interventional data. Our multi-institutional working group was assembled to review and highlight the body of evidence that exists for opioid utilization for cancer pain, adjunct medication such as ketamine and methadone and interventional therapies. We discuss neurolysis via injections, neuromodulation including targeted drug delivery and spinal cord stimulation, vertebral tumor ablation and augmentation, radiotherapy and surgical techniques. In the United States, there is a significant variance in the interventional treatment of cancer pain based on fellowship training. As a first of its kind, this best practices and interventional guideline will offer evidenced-based recommendations for reducing pain and suffering associated with malignancy.

Neuromodulation techniques for cancer pain management

PURPOSE OF REVIEW

Advanced pain management techniques may be indicated in 5-15% of cancer patients. Despite this, a recent review identified that, over the course of 1 year in England, only 458 patients received a procedure intended to provide analgesia and only 30 patients had intrathecal drug delivery (ITDD) devices implanted. This article describes the emerging evidence for ITDD in cancer pain and provides a narrative review of other neuromodulatory techniques (including spinal cord stimulation, peripheral nerve stimulation and acupuncture), approaches that might be employed to address this area of significant unmet clinical need.

RECENT FINDINGS

Numerous studies have been published within the last year reporting positive outcomes associated with ITDD in cancer pain management. Neuromodulation represents an important strategy in the management of persistent pain. Whilst the nonmalignant pain evidence-base is rapidly growing, it remains sparse for cancer pain management. The growing cohort of cancer survivors may significantly benefit from neuromodulatory techniques.

SUMMARY

ITDD and other neuromodulatory techniques for cancer pain management appear underutilised in the UK and offer the prospect of better treatment for cancer patients with refractory pain or intolerable side-effects from systemic analgesics.