Research design considerations for chronic pain prevention clinical trials: IMMPACT recommendations.

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (ie, chronic postsurgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (ie, surgery, viral infection, injury, and toxic or noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

A Comparison of the Assay Sensitivity of Average and Worst Pain Intensity in Pharmacologic Trials: An ACTTION Systematic Review and Meta-Analysis.

Identifying methods to improve assay sensitivity in randomized clinical trials (RCTs) may facilitate the discovery of efficacious pain treatments. RCTs evaluating pain treatments typically use average pain intensity (API) or worst pain intensity (WPI) as the primary efficacy outcome. However, little evidence is available comparing the assay sensitivity of these 2 measures. In this systematic review and meta-analysis, we comprehensively reviewed all low back pain, osteoarthritis pain, fibromyalgia, diabetic peripheral neuropathy pain, and postherpetic neuralgia RCTs that used a parallel group design. Eligibility required: 1) primary RCT report published between 1980 and 2016, 2) comparing 1 or more active, efficacious pharmacologic pain treatment(s) with placebo, and 3) providing data on the standardized effect size (SES) for API as well as WPI for all treatment arms. Twenty-seven active versus placebo comparisons were identified in 23 eligible articles. Using a random-effects meta-analysis, API SES and WPI SES did not differ significantly (difference = -.021, 95% confidence interval = -.047 to .004, P = .12). The findings indicate that, depending on the objectives of the study, either API or WPI could be used as a primary outcome measure in clinical trials for the chronic pain conditions included in this analysis. PERSPECTIVE: Understanding the comparative assay sensitivity of API and WPI may advance pain treatment research. A meta-analysis of trials of efficacious pharmacologic treatments in 5 pain conditions did not show a statistically significant difference between the assay sensitivity of API and WPI.

The Potential Role of Sensory Testing, Skin Biopsy, and Functional Brain Imaging as Biomarkers in Chronic Pain Clinical Trials: IMMPACT Considerations.

Valid and reliable biomarkers can play an important role in clinical trials as indicators of biological or pathogenic processes or as a signal of treatment response. Currently, there are no biomarkers for pain qualified by the U.S. Food and Drug Administration or the European Medicines Agency for use in clinical trials. This article summarizes an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials meeting in which 3 potential biomarkers were discussed for use in the development of analgesic treatments: 1) sensory testing, 2) skin punch biopsy, and 3) brain imaging. The empirical evidence supporting the use of these tests is described within the context of the 4 categories of biomarkers: 1) diagnostic, 2) prognostic, 3) predictive, and 4) pharmacodynamic. Although sensory testing, skin punch biopsy, and brain imaging are promising tools for pain in clinical trials, additional evidence is needed to further support and standardize these tests for use as biomarkers in pain clinical trials. PERSPECTIVE: The applicability of sensory testing, skin biopsy, and brain imaging as diagnostic, prognostic, predictive, and pharmacodynamic biomarkers for use in analgesic treatment trials is considered. Evidence in support of their use and outlining problems is presented, as well as a call for further standardization and demonstrations of validity and reliability.

Research design considerations for chronic pain prevention clinical trials: IMMPACT recommendations.

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (ie, chronic postsurgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (ie, surgery, viral infection, injury, and toxic or noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

The Patient-Reported Outcome (PRO) Consortium: Lessons Learned Along the Path to PRO Instrument Qualification.

Established in 2008, the Patient-Reported Outcome (PRO) Consortium is a collaboration among the US Food and Drug Administration's Center for Drug Evaluation and Research, the Critical Path Institute, the pharmaceutical/biotechnology industry, and other stakeholders. The purpose of the consortium is to qualify PRO instruments through the Center for Drug Evaluation and Research's drug development tool qualification process for use as clinical trial endpoints to support drug approval and product labeling claims. The PRO Consortium has made notable progress toward collaborative development of PRO instruments in the following areas: asthma, mild cognitive impairment, depression, functional dyspepsia, irritable bowel syndrome, non-small cell lung cancer, and rheumatoid arthritis. This progress has come with considerable challenges, including navigating a new and evolving regulatory initiative, gaining consensus on key issues, and maintaining communication and engagement in a precompetitive environment. The purpose of this paper is to describe some of the challenges and lessons learned since the creation of the PRO Consortium in hopes that this information may provide direction and insight for similar collaborations.

Pain palliation measurement in cancer clinical trials: the US Food and Drug Administration perspective.

BACKGROUND: Pain palliation resulting from antitumor therapy provides direct evidence of treatment benefit when combined with evidence of antitumor activity. The US Food and Drug Administration (FDA) previously issued guidance regarding the use of patient-reported outcome (PRO) measures to support labeling claims. The purpose of this article is to identify common challenges and key design strategies when measuring pain palliation in antitumor therapy clinical trials that are consistent with PRO Guidance principles. METHODS: Antitumor clinical protocols submitted to the FDA between 1995 and 2012 that included pain palliation as a primary or secondary endpoint were reviewed. Challenges in critical trial design components were identified. Design strategies consistent with PRO Guidance principles are proposed. RESULTS: The challenges identified were measurement of pain intensity and analgesic use, enrollment eligibility criteria, data collection methods, responder definitions, missing data, and blinding. Strategies included the use of well-defined, reliable, PRO assessments of pain intensity and analgesics; ensuring that enrollment criteria define patients with clinically significant pain attributable to cancer on an optimal analgesic regimen; defining responders using both pain and analgesic use criteria; incorporating an analysis of tumor response to support evidence of pain response; and minimizing missing data and inadvertent unblinding. CONCLUSIONS: Improvement in cancer-related pain resulting from antitumor therapy is an important treatment benefit that can support drug approval and labeling claims when adequately measured if study results demonstrate statistically and clinically significant findings. Sponsors are encouraged to discuss pain palliation assessment methods with the FDA early in and throughout product development.

Discrepancies between registered and published primary outcome specifications in analgesic trials: ACTTION systematic review and recommendations.

The National Institutes of Health released the trial registry ClinicalTrials.gov in 2000 to increase public reporting and clinical trial transparency. This systematic review examined whether registered primary outcome specifications (POS; ie, definitions, timing, and analytic plans) in analgesic treatment trials correspond with published POS. Trials with accompanying publications (n = 87) were selected from the Repository of Registered Analgesic Clinical Trials (RReACT) database of all postherpetic neuralgia, diabetic peripheral neuropathy, and fibromyalgia clinical trials registered at ClinicalTrials.gov as of December 1, 2011. POS never matched precisely; discrepancies occurred in 79% of the registry-publication pairs (21% failed to register or publish primary outcomes [PO]). These percentages did not differ significantly between industry and non-industry-sponsored trials. Thirty percent of the trials contained unambiguous POS discrepancies (eg, omitting a registered PO from the publication, "demoting" a registered PO to a published secondary outcome), with a statistically significantly higher percentage of non-industry-sponsored than industry-sponsored trials containing unambiguous POS discrepancies. POS discrepancies due to ambiguous reporting included vaguely worded PO registration; or failing to report the timing of PO assessment, statistical analysis used for the PO, or method to address missing PO data. At best, POS discrepancies may be attributable to insufficient registry requirements, carelessness (eg, failing to report PO assessment timing), or difficulty uploading registry information. At worst, discrepancies could indicate investigator impropriety (eg, registering imprecise PO ["pain"], then publishing whichever pain assessment produced statistically significant results). Improvements in PO registration, as well as journal policies requiring consistency between registered and published PO descriptions, are needed.

U.S. Food and Drug Administration approval: ruxolitinib for the treatment of patients with intermediate and high-risk myelofibrosis.

On November 16, 2011, the U.S. Food and Drug Administration (FDA) granted full approval to ruxolitinib, (Jakafi; Incyte Corp.), an inhibitor of the Janus kinases 1 and 2, for the treatment of patients with intermediate- or high-risk myelofibrosis, including primary myelofibrosis, postpolycythemia vera myelofibrosis, and postessential thrombocythemia myelofibrosis. This approval was based on the results of 2 large randomized phase III trials that enrolled patients with intermediate-2 or high-risk myelofibrosis and compared ruxolitinib with placebo (study 1) or best available therapy (study 2). The primary efficacy endpoint was the proportion of patients who experienced a reduction in spleen volume of ≥ 35% at 24 weeks (study 1) or 48 weeks (study 2). The key secondary endpoint in study 1 was the proportion of patients who experienced a ≥ 50% improvement from baseline in myelofibrosis total symptom score at 24 weeks. The results of these studies showed that a greater proportion of patients treated with ruxolitinib experienced a ≥ 35% reduction in spleen volume as compared with those treated with placebo (42% vs. 1%, P < 0.0001) or best available therapy (29% vs. 0%, P < 0.0001). A greater proportion of patients in study 1 experienced a ≥ 50% reduction in the myelofibrosis total symptom score during treatment with ruxolitinib than with placebo (46% vs. 5%, P < 0.0001). Ruxolitinib treatment was associated with an increased incidence of grades III and IV anemia, thrombocytopenia, and neutropenia. This is the first drug approved for myelofibrosis.

Patient-reported outcomes supporting anticancer product approvals.

In 2006, the US Food and Drug Administration (FDA) published draft guidance to provide recommendations for development, validation, implementation, and interpretation of patient-reported outcome (PRO) measures that can support treatment benefit claims in product labeling. Here, we summarize and discuss FDA approvals of anticancer products in the context of the draft guidance. We identified anticancer product approvals having efficacy claim(s) based at least in part on a PRO. In addition, we collated limitations of PRO instruments commonly submitted for regulatory review over the period from October 1, 2004 to September 30, 2006. From 1995 onward, nine indications were approved for seven anticancer products based at least in part on a PRO. In eight of nine approvals, PRO data supplemented other evidence of clinical benefit. In seven approvals, the PRO measured a single symptom or functional domain that was directly attributable to the treatment benefit observed in the disease. The FDA's draft PRO guidance describes principles that have been used in anticancer product approvals for more than a decade. PRO end points typically support treatment benefit claims that refer to a patient's symptoms or ability to function. Single-item PROs may be acceptable. PRO data should be both internally consistent and aligned with other evidence of clinical benefit. The FDA encourages sponsors to consult with the FDA early in the process of PRO development.

Patient-reported outcomes assessment in cancer trials: taking stock, moving forward.

To evaluate and improve the use of cancer trial end points that reflect the patient's own perspective, the National Cancer Institute organized an international conference, Patient-Reported Outcomes Assessment in Cancer Trials (PROACT), in 2006. The 13 preceding articles in this special issue of the Journal were commissioned in preparation for or in response to the PROACT conference, which was cosponsored by the American Cancer Society. Drawing from these articles and also commentary from the conference itself, this concluding report takes stock of what has been learned to date about the successes and challenges in patient-reported outcome (PRO) assessment in phase III, phase II, and symptom management trials in cancer and identifies ways to improve the scientific soundness, feasibility, and policy relevance of PROs in trials. Building on this synthesis of lessons learned, this article discusses specific administrative policies and management procedures to improve PRO data collection, analysis, and dissemination of findings; opportunities afforded by recent methodologic and technologic advances in PRO data collection and analysis to enhance the scientific soundness and cost efficiency of PRO use in trials; and the importance of better understanding the usefulness of PRO data to the full spectrum of cancer decision makers, including patients and families, health providers, public and private payers, regulatory agencies, and standards-setting organizations.

Clinical trial endpoints in ovarian cancer: report of an FDA/ASCO/AACR Public Workshop.

OBJECTIVE: The unique characteristics of cancer, particularly issues involving the use of surrogate endpoints in clinical trials, present special challenges in the development of cancer drugs. In response, the U.S. Food and Drug Administration (FDA) has partnered with the American Society of Clinical Oncology, the American Association for Cancer Research, and the American Society of Hematology to conduct public workshops evaluating potential endpoints for drug approvals for the most common tumor types. METHODS: A workshop evaluating potential endpoints in ovarian cancer drug research was held in Bethesda, Maryland, in April 2006. Invited experts presented research findings and discussed endpoints in trials of drugs for treatment of Stage III and IV ovarian cancer. RESULTS: The panel responded to specific questions from FDA, discussing use of progression-free survival as a surrogate for overall survival and use of CA-125 levels as an indicator of response. Panel members also addressed endpoints in first-line therapy, second-line and subsequent therapy, and maintenance therapy. CONCLUSION: Expert commentary provided by panel members will inform FDA's draft guidance on clinical endpoints for cancer drug approvals and will be discussed at meetings of the FDA's Oncologic Drugs Advisory Committee. FDA intends to develop a set of principles that can be used to define efficacy standards for drugs used to treat ovarian and other cancers.

Challenges to use of health-related quality of life for Food and Drug Administration approval of anticancer products.

The U.S. Food and Drug Administration (FDA) approves labeling claims of drug efficacy based on substantial evidence of clinical benefit demonstrated in adequate and well-controlled investigations. Patient-reported outcomes (PROs) may support marketing claims of clinical benefit, either alone or with other study endpoints. Health-related quality of life (HRQL) is a PRO that comprehensively measures patients' reported health status. We present an overview of why HRQL-based efficacy claims have not to date been accepted by the FDA for inclusion in anticancer product labels. Persistent challenges to allowance of such claims include shortcomings in randomization and blinding of clinical trials, missing data, statistical multiplicity, and unclear intrinsic meaning of selected HRQL findings.