Improving Study Conduct and Data Quality in Clinical Trials of Chronic Pain Treatments: IMMPACT Recommendations

The estimated probability of progressing from phase 3 analgesic clinical trials to regulatory approval is approximately 57%, suggesting that a considerable number of treatments with phase 2 trial results deemed sufficiently successful to progress to phase 3 do not yield positive phase 3 results. Deficiencies in the quality of clinical trial conduct could account for some of this failure. An Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials meeting was convened to identify potential areas for improvement in trial conduct in order to improve assay sensitivity (ie, ability of trials to detect a true treatment effect). We present recommendations based on presentations and discussions at the meeting, literature reviews, and iterative revisions of this article. The recommendations relate to the following areas: 1) study design (ie, to promote feasibility), 2) site selection and staff training, 3) participant selection and training, 4) treatment adherence, 5) data collection, and 6) data and study monitoring. Implementation of these recommendations may improve the quality of clinical trial data and thus the validity and assay sensitivity of clinical trials. Future research regarding the effects of these strategies will help identify the most efficient use of resources for conducting high quality clinical trials. PERSPECTIVE: Every effort should be made to optimize the quality of clinical trial data. This manuscript discusses considerations to improve conduct of pain clinical trials based on research in multiple medical fields and the expert consensus of pain researchers and stakeholders from academia, regulatory agencies, and industry.

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.

Montreal Accord on Patient-Reported Outcomes (PROs) use series - Paper 6: creating national initiatives to support development and use-the PROMIS example

BACKGROUND

Patient-reported outcome (PRO) data are beneficial to a range of stakeholders including patients, clinicians, researchers, national funding and regulatory agencies, health system administrators, and policymakers.

OBJECTIVE

Because stakeholders represent diverse groups and needs, it is challenging to reach consensus on how to advance PRO development and harmonize data across settings to enable use for multiple secondary purposes. Collaborative national networks can facilitate the sharing of expertise, resources, and necessary infrastructure; create development, use, and reporting standards; optimize formats to efficiently store and transfer data; and disseminate tools and information for widespread uptake.

DISCUSSION

In the United States, the National Institutes of Health's Patient-Reported Outcomes Measurement Information System offers an example of how collaborators can work across distances to form essential partnerships, create a common vision, and leverage technology to accelerate the development and testing of universal PROs that are broadly applicable across health conditions and settings.

Item response theory, computerized adaptive testing, and PROMIS: assessment of physical function

OBJECTIVE

Patient-reported outcome (PRO) questionnaires record health information directly from research participants because observers may not accurately represent the patient perspective. Patient-reported Outcomes Measurement Information System (PROMIS) is a US National Institutes of Health cooperative group charged with bringing PRO to a new level of precision and standardization across diseases by item development and use of item response theory (IRT).

METHODS

With IRT methods, improved items are calibrated on an underlying concept to form an item bank for a "domain" such as physical function (PF). The most informative items can be combined to construct efficient "instruments" such as 10-item or 20-item PF static forms. Each item is calibrated on the basis of the probability that a given person will respond at a given level, and the ability of the item to discriminate people from one another. Tailored forms may cover any desired level of the domain being measured. Computerized adaptive testing (CAT) selects the best items to sharpen the estimate of a person's functional ability, based on prior responses to earlier questions. PROMIS item banks have been improved with experience from several thousand items, and are calibrated on over 21,000 respondents.

RESULTS

In areas tested to date, PROMIS PF instruments are superior or equal to Health Assessment Questionnaire and Medical Outcome Study Short Form-36 Survey legacy instruments in clarity, translatability, patient importance, reliability, and sensitivity to change.

CONCLUSION

Precise measures, such as PROMIS, efficiently incorporate patient self-report of health into research, potentially reducing research cost by lowering sample size requirements. The advent of routine IRT applications has the potential to transform PRO measurement.

Personalized medicine and opioid analgesic prescribing for chronic pain: opportunities and challenges

Use of opioid analgesics for pain management has increased dramatically over the past decade, with corresponding increases in negative sequelae including overdose and death. There is currently no well-validated objective means of accurately identifying patients likely to experience good analgesia with low side effects and abuse risk prior to initiating opioid therapy. This paper discusses the concept of data-based personalized prescribing of opioid analgesics as a means to achieve this goal. Strengths, weaknesses, and potential synergism of traditional randomized placebo-controlled trial (RCT) and practice-based evidence (PBE) methodologies as means to acquire the clinical data necessary to develop validated personalized analgesic-prescribing algorithms are overviewed. Several predictive factors that might be incorporated into such algorithms are briefly discussed, including genetic factors, differences in brain structure and function, differences in neurotransmitter pathways, and patient phenotypic variables such as negative affect, sex, and pain sensitivity. Currently available research is insufficient to inform development of quantitative analgesic-prescribing algorithms. However, responder subtype analyses made practical by the large numbers of chronic pain patients in proposed collaborative PBE pain registries, in conjunction with follow-up validation RCTs, may eventually permit development of clinically useful analgesic-prescribing algorithms.

PERSPECTIVE

Current research is insufficient to base opioid analgesic prescribing on patient characteristics. Collaborative PBE studies in large, diverse pain patient samples in conjunction with follow-up RCTs may permit development of quantitative analgesic-prescribing algorithms that could optimize opioid analgesic effectiveness and mitigate risks of opioid-related abuse and mortality.

Considerations for improving assay sensitivity in chronic pain clinical trials: IMMPACT recommendations

A number of pharmacologic treatments examined in recent randomized clinical trials (RCTs) have failed to show statistically significant superiority to placebo in conditions in which their efficacy had previously been demonstrated. Assuming the validity of previous evidence of efficacy and the comparability of the patients and outcome measures in these studies, such results may be a consequence of limitations in the ability of these RCTs to demonstrate the benefits of efficacious analgesic treatments vs placebo ("assay sensitivity"). Efforts to improve the assay sensitivity of analgesic trials could reduce the rate of falsely negative trials of efficacious medications and improve the efficiency of analgesic drug development. Therefore, an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting was convened in which the assay sensitivity of chronic pain trials was reviewed and discussed. On the basis of this meeting and subsequent discussions, the authors recommend consideration of a number of patient, study design, study site, and outcome measurement factors that have the potential to affect the assay sensitivity of RCTs of chronic pain treatments. Increased attention to and research on methodological aspects of clinical trials and their relationships with assay sensitivity have the potential to provide the foundation for an evidence-based approach to the design of analgesic clinical trials and expedite the identification of analgesic treatments with improved efficacy and safety.

Improving the pharmacologic management of pain in older adults: identifying the research gaps and methods to address them

OBJECTIVE

There has been a growing recognition of the need for better pharmacologic management of chronic pain among older adults. To address this need, the National Institutes of Health Pain Consortium sponsored an "Expert Panel Discussion on the Pharmacological Management of Chronic Pain in Older Adults" conference in September 2010 to identify research gaps and strategies to address them. Specific emphasis was placed on ascertaining gaps regarding use of opioid and nonsteroidal anti-inflammatory medications because of continued uncertainties regarding their risks and benefits.

DESIGN

Eighteen panel members provided oral presentations; each was followed by a multidisciplinary panel discussion. Meeting transcripts and panelists' slide presentations were reviewed to identify the gaps and the types of studies and research methods panelists suggested could best address them.

RESULTS

Fifteen gaps were identified in the areas of treatment (e.g., uncertainty regarding the long-term safety and efficacy of commonly prescribed analgesics), epidemiology (e.g., lack of knowledge regarding the course of common pain syndromes), and implementation (e.g., limited understanding of optimal strategies to translate evidence-based pain treatments into practice). Analyses of data from electronic health care databases, observational cohort studies, and ongoing cohort studies (augmented with pain and other relevant outcomes measures) were felt to be practical methods for building an age-appropriate evidence base to improve the pharmacologic management of pain in later life.

CONCLUSION

Addressing the gaps presented in the current report was judged by the panel to have substantial potential to improve the health and well-being of older adults with chronic pain.

Research design considerations for confirmatory chronic pain clinical trials: IMMPACT recommendations

There has been an increase in the number of chronic pain clinical trials in which the treatments being evaluated did not differ significantly from placebo in the primary efficacy analyses despite previous research suggesting that efficacy could be expected. These findings could reflect a true lack of efficacy or methodological and other aspects of these trials that compromise the demonstration of efficacy. There is substantial variability among chronic pain clinical trials with respect to important research design considerations, and identifying and addressing any methodological weaknesses would enhance the likelihood of demonstrating the analgesic effects of new interventions. An IMMPACT consensus meeting was therefore convened to identify the critical research design considerations for confirmatory chronic pain trials and to make recommendations for their conduct. We present recommendations for the major components of confirmatory chronic pain clinical trials, including participant selection, trial phases and duration, treatment groups and dosing regimens, and types of trials. Increased attention to and research on the methodological aspects of confirmatory chronic pain clinical trials has the potential to enhance their assay sensitivity and ultimately provide more meaningful evaluations of treatments for chronic pain.

EULAR recommendations for the management of primary small and medium vessel vasculitis

OBJECTIVES

To develop European League Against Rheumatism (EULAR) recommendations for the management of small and medium vessel vasculitis.

METHODS

An expert group (consisting of 10 rheumatologists, 3 nephrologists, 2 immunologists, 2 internists representing 8 European countries and the USA, a clinical epidemiologist and a representative from a drug regulatory agency) identified 10 topics for a systematic literature search using a modified Delphi technique. In accordance with standardised EULAR operating procedures, recommendations were derived for the management of small and medium vessel vasculitis. In the absence of evidence, recommendations were formulated on the basis of a consensus opinion.

RESULTS

In all, 15 recommendations were made for the management of small and medium vessel vasculitis. The strength of recommendations was restricted by low quality of evidence and by EULAR standardised operating procedures.

CONCLUSIONS

On the basis of evidence and expert consensus, recommendations have been made for the evaluation, investigation, treatment and monitoring of patients with small and medium vessel vasculitis for use in everyday clinical practice.

EULAR recommendations for the management of large vessel vasculitis

OBJECTIVES

To develop European League Against Rheumatism (EULAR) recommendations for the management of large vessel vasculitis.

METHODS

An expert group (10 rheumatologists, 3 nephrologists, 2 immunolgists, 2 internists representing 8 European countries and the USA, a clinical epidemiologist and a representative from a drug regulatory agency) identified 10 topics for a systematic literature search through a modified Delphi technique. In accordance with standardised EULAR operating procedures, recommendations were derived for the management of large vessel vasculitis. In the absence of evidence, recommendations were formulated on the basis of a consensus opinion.

RESULTS

Seven recommendations were made relating to the assessment, investigation and treatment of patients with large vessel vasculitis. The strength of recommendations was restricted by the low level of evidence and EULAR standardised operating procedures.

CONCLUSIONS

On the basis of evidence and expert consensus, management recommendations for large vessel vasculitis have been formulated and are commended for use in everyday clinical practice.

Interpreting the clinical importance of treatment outcomes in chronic pain clinical trials: IMMPACT recommendations

A consensus meeting was convened by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) to provide recommendations for interpreting clinical importance of treatment outcomes in clinical trials of the efficacy and effectiveness of chronic pain treatments. A group of 40 participants from universities, governmental agencies, a patient self-help organization, and the pharmaceutical industry considered methodologic issues and research results relevant to determining the clinical importance of changes in the specific outcome measures previously recommended by IMMPACT for 4 core chronic pain outcome domains: (1) Pain intensity, assessed by a 0 to 10 numerical rating scale; (2) physical functioning, assessed by the Multidimensional Pain Inventory and Brief Pain Inventory interference scales; (3) emotional functioning, assessed by the Beck Depression Inventory and Profile of Mood States; and (4) participant ratings of overall improvement, assessed by the Patient Global Impression of Change scale. It is recommended that 2 or more different methods be used to evaluate the clinical importance of improvement or worsening for chronic pain clinical trial outcome measures. Provisional benchmarks for identifying clinically important changes in specific outcome measures that can be used for outcome studies of treatments for chronic pain are proposed.

PERSPECTIVE

Systematically collecting and reporting the recommended information needed to evaluate the clinical importance of treatment outcomes of chronic pain clinical trials will allow additional validation of proposed benchmarks and provide more meaningful comparisons of chronic pain treatments.

Stimulating the development of mechanism-based, individualized pain therapies

Biomedical science has greatly improved our understanding of pain in recent decades, but few novel molecular entities that address fundamentally new pain mechanisms have entered the clinic, despite dramatically increased pharmaceutical investment. Indeed, virtually all new analgesics approved over the past 25 years are derivatives or reformulations of opioids or aspirin-like drugs, existing drugs given for a new indication or older drugs given by a different route of administration. Here, we discuss factors contributing to this lack of innovation in therapies for pain and advocate public-private partnerships (PPPs) to translate new knowledge into more efficacious and safer treatments.

Outcomes from studies of antineutrophil cytoplasm antibody associated vasculitis: a systematic review by the European League Against Rheumatism systemic vasculitis task force

OBJECTIVES

We undertook a systematic literature review as a background to the European League Against Rheumatism (EULAR) recommendations for conducting clinical trials in anti-neutrophil cytoplasm antibody associated vasculitis (AAV), and to assess the quality of evidence for outcome measures in AAV.

METHODS

Using a systematic Medline search, we categorised the identified studies according to diagnoses. Factors affecting remission, relapse, renal function and overall survival were identified.

RESULTS

A total of 44 papers were reviewed from 502 identified by our search criteria. There was considerable inconsistency in definitions of end points. Remission rates varied from 30% to 93% in Wegener granulomatosis (WG), 75% to 89% in microscopic polyangiitis (MPA) and 81% to 91% in Churg-Strauss syndrome (CSS). The 5-year survival for WG, MPA and CSS was 74-91%, 45-76% and 60-97%. Relapse (variably defined) was common in the first 2 years but the frequency varied: 18% to 60% in WG, 8% in MPA, and 35% in CSS. The rate of renal survival in WG varied from 23% at 15 months to 23% at 120 months.

METHOD

used to assess morbidity varied between studies. Ignoring the variations in definitions of the stage of disease, factors influencing remission, relapse, renal and overall survival included immunosuppressive therapy used, type of organ involvement, presence of ANCA, older age and male gender.

CONCLUSIONS

Factors influencing remission, relapse, renal and overall survival include the type of immunosuppressive therapy used, pattern of organ involvement, presence of ANCA, older age and male gender. Methodological variations between studies highlight the need for a consensus on terminology and definitions for future conduct of clinical studies in AAV.

Standardizing assessment and reporting of adverse effects in rheumatology clinical trials II: the Rheumatology Common Toxicity Criteria v.2.0

OBJECTIVE

The OMERACT Drug Safety Working Group focuses on standardization of assessment and reporting of adverse events in clinical trials and longitudinal and observational studies in rheumatology. This group developed the Rheumatology Common Toxicity Criteria (RCTC) in 1999, building on the Oncology Common Toxicity Criteria. At OMERACT 8, a workshop group reviewed the use of the RCTC and other instruments in rheumatology clinical trials to date, to revise and to stimulate its implementation.

METHODS

The Working Group drafted a revision of the RCTC after an iterative examination of its contents, terms, and definitions. The RCTC were compared with the Oncology Common Toxicity Criteria (CTC v.2.0), and the Common Terminology Criteria for Adverse Events (CTCAE v.3.0). In addition a pharmaceutical company focus group met to clarify the challenges of application of RCTC terms and definitions, relative to the standard in pharmaceutical clinical trials, i.e., verbatim recording of adverse events followed by mapping to Medical Dictionary of Drug Regulatory Activities (MedDRA) terms. The workshop focused on the proposed revision of RCTC to version 2.0 and on the research agenda, including a validation of the RCTC in future trials.

RESULTS

At OMERACT 8, breakout groups amended the contents of the 4 current and 2 new categories of adverse event terms within the draft RCTC v.2.0. Participants recognized the need to standardize the definitions for disease flares, infection, malignancy, and certain syndromes such as drug hypersensitivity and infusion reactions. Moderate consensus (62%) was reached in the final plenary session that the amended RCTC v.2.0 should be promulgated and tested in available trials of anti-tumor necrosis factor agents.

CONCLUSION

The RCTC has face validity and construct validity. However, documentation of discrimination and feasibility (the other elements of the OMERACT filter) is needed. Collaboration with drug safety working groups in rheumatology professional organizations is necessary to enable this project.

EULAR recommendations for conducting clinical studies and/or clinical trials in systemic vasculitis: focus on anti-neutrophil cytoplasm antibody-associated vasculitis

OBJECTIVES

To develop the European League Against Rheumatism (EULAR) recommendations for conducting clinical studies and/or clinical trials in systemic vasculitis.

METHODS

An expert consensus group was formed consisting of rheumatologists, nephrologists and specialists in internal medicine representing five European countries and the USA, a clinical epidemiologist and representatives from regulatory agencies. Using an evidence-based and expert opinion-based approach in accordance with the standardised EULAR operating procedures, the group identified nine topics for a systematic literature search through a modified Delphi technique. On the basis of research questions posed by the group, recommendations were derived for conducting clinical studies and/or clinical trials in systemic vasculitis.

RESULTS

Based on the results of the literature research, the expert committee concluded that sufficient evidence to formulate guidelines on conducting clinical trials was available only for anti-neutrophil cytoplasm antibody-associated vasculitides (AAV). It was therefore decided to focus the recommendations on these diseases. Recommendations for conducting clinical trials in AAV were elaborated and are presented in this summary document. It was decided to consider vasculitis-specific issues rather than general issues of trial methodology. The recommendations deal with the following areas related to clinical studies of vasculitis: definitions of disease, activity states, outcome measures, eligibility criteria, trial design including relevant end points, and biomarkers. A number of aspects of trial methodology were deemed important for future research.

CONCLUSIONS

On the basis of expert opinion, recommendations for conducting clinical trials in AAV were formulated. Furthermore, the expert committee identified a strong need for well-designed research in non-AAV systemic vasculitides.

Fibromyalgia syndrome

The objectives of the first OMERACT Fibromyalgia Syndrome (FM) Workshop were to identify and prioritize symptom domains that should be consistently evaluated in FM clinical trials, and to identify aspects of domains and outcome measures that should be part of a concerted research agenda of FM researchers. Such an effort will help standardize and improve the quality of outcomes research in FM. A principal assumption in this workshop has been that there exists a clinical syndrome, generally known as FM, characterized by chronic widespread pain typically associated with fatigue, sleep disturbance, mood disturbance, and other symptoms and signs, and considered to be related to central neuromodulatory dysregulation. FM can be diagnosed using 1990 American College of Rheumatology criteria. In preparation for the workshop a Delphi exercise involving 23 FM researchers was conducted to establish a preliminary prioritization of domains of inquiry. At the OMERACT meeting, the workshop included presentation of the Delphi results; a review of placebo-controlled trials of FM treatment, with a focus on the outcome measures used and their performance; a panel discussion of the key issues in FM trials, from both an investigator and regulatory agency perspective; and a voting process by the workshop attendees. The results of the workshop were presented in the plenary session on the final day of the meeting. A prioritized list of domains of FM to be investigated was thus developed, key issues and controversies in the field were debated, and consensus on a research agenda on outcome measure development was reached.

Individual responder analyses for pain: does one pain scale fit all?

The outcomes of clinical trials are based on the mean responses of large numbers of subjects but fail to address inter-individual differences. The molecular mechanisms that underlie pain vary among individuals over time and among different types of pain to produce wide inter-individual variations in pain perception and response. Gender, ethnicity, temperament and genetic factors also contribute to individual variation in pain sensitivity and responses to analgesics. Pain measurement scales can be used differently across individuals based on the past pain experiences of individuals. We propose that individual responder analyses could be used in clinical trials to better detect analgesic activity across patient groups and within sub-groups, and to identify molecular-genetic mechanisms that contribute to individual variation.

What can chronic arthritis pain teach about developing new analgesic drugs?

Chronic pain remains an important public health need with greater impact on the US economy than most other chronic conditions. Current pain management is largely limited to opioids and non-steroidal anti-inflammatory drugs, indicating a gap in the translation of new knowledge to the development of improved pain treatments. Strategies suggested include the re-evaluation of current drug screening methods, a recognition that molecular-genetic events occurring acutely contribute to the development of pain chronicity, the validation of analgesic targets in the intended patient population, consideration of the unique genetic profile that varies between individuals, and the introduction of individual response measures to improve the capture of outcomes in clinical trials.

Core outcome domains for chronic pain clinical trials: IMMPACT recommendations

OBJECTIVE

To provide recommendations for the core outcome domains that should be considered by investigators conducting clinical trials of the efficacy and effectiveness of treatments for chronic pain. Development of a core set of outcome domains would facilitate comparison and pooling of data, encourage more complete reporting of outcomes, simplify the preparation and review of research proposals and manuscripts, and allow clinicians to make informed decisions regarding the risks and benefits of treatment.

METHODS

Under the auspices of the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT), 27 specialists from academia, governmental agencies, and the pharmaceutical industry participated in a consensus meeting and identified core outcome domains that should be considered in clinical trials of treatments for chronic pain.

CONCLUSIONS

There was a consensus that chronic pain clinical trials should assess outcomes representing six core domains: (1) pain, (2) physical functioning, (3) emotional functioning, (4) participant ratings of improvement and satisfaction with treatment, (5) symptoms and adverse events, (6) participant disposition (e.g. adherence to the treatment regimen and reasons for premature withdrawal from the trial). Although consideration should be given to the assessment of each of these domains, there may be exceptions to the general recommendation to include all of these domains in chronic pain trials. When this occurs, the rationale for not including domains should be provided. It is not the intention of these recommendations that assessment of the core domains should be considered a requirement for approval of product applications by regulatory agencies or that a treatment must demonstrate statistically significant effects for all of the relevant core domains to establish evidence of its efficacy.

Chronic pain and fibromyalgia: the regulatory perspective

Chronic pain is an important clinical entity that represents a currently unmet medical need. Relief of pain is an important public health goal for patients of all ages, from perinatal to geriatric. This article will describe some of the current regulatory issues in developing and approving drugs to treat chronic pain. It will also begin to familiarize the reader with the importance of the so-called 'label' and some of its roles to enable the best 'risk-benefit' decisions be made for, and by, patients with chronic pain.

NIH-FDA Analgesic Drug Development Workshop: translating scientific advances into improved pain relief

Analgesic drug development as currently undertaken is limited by a number of factors that contribute to the paucity of new analgesics introduced into clinical practice despite marked advances in delineating of the molecular-genetic mechanisms contributing to acute and chronic pain. The participants in this workshop explored the unmet need in analgesia and recommended strategies for enhancing analgesic drug development in the future. The workshop concluded that translating scientific advances into improved pain relief will require new thinking and a cooperative effort among the pharmaceutical industry, regulatory agencies, funding agencies, the biomedical research community, professional societies and clinicians. The workshop also recommended that a better understanding of the epidemiology of pain could contribute to improvement in clinical trial methodology and outcome measures.

Drug development in rheumatoid arthritis

In the United States, therapies to treat rheumatoid arthritis and juvenile rheumatoid arthritis are approved and regulated by the Food and Drug Administration. This article explores certain aspects of the current Food and Drug Administration guidance for drugs, devices, and biologic products intended to treat these diseases (in this article, the term "drug" refers to any therapy in rheumatoid arthritis). Newer therapeutics are targeting not only important molecular pathways but also new labeling claims intended to represent clinically relevant outcomes. Questions regarding whether the risks of these new therapies are balanced by their effectiveness will evolve. The process of improvement in clinical trial design and metrics, along with improved therapies, will undoubtedly present both familiar and new challenges in the future.

Inflammation and cartilage metabolism in rheumatoid arthritis. Studies of the blood markers hyaluronic acid, orosomucoid, and keratan sulfate

Single analyses of peripheral blood of rheumatoid arthritis (RA) patients showed a significant reduction in the mean value for keratan sulfate (KS) compared with that in control subjects, but the mean value for orosomucoid (OM) was elevated compared with that in control subjects. Some RA patients displayed highly elevated levels of hyaluronic acid (HA), while others exhibited normal levels. There was a significant inverse correlation between OM and KS content in RA patients, as well as a direct correlation between HA and OM. In longitudinal studies of RA patients, parallel changes in OM and HA and inverse changes between KS and OM or HA were commonly observed. Clinical analyses revealed that there was an inverse correlation between KS and morning stiffness, and direct correlations between the number of tender joints and HA, and between HA or the erythrocyte sedimentation rate and the number of joints with effusions. The reason(s) for the inverse correlation between KS and OM as an index of systemic inflammation remains to be established. Circulating HA represents an index of joint inflammation, for which a marker has not been previously available.

Immunodetection and characterization of the degradation of cartilage proteoglycans in vitro and in vivo

The large aggregating cartilage proteoglycans can be detected immunologically using antibodies directed against the hyaluronic acid-binding region, core protein, keratan sulfate, chondroitin sulfate, and hyaluronic acid. With radioimmunoassays we have detected proteoglycans released from adult human articular cartilage in vitro and in vivo. In vitro cleavage appears to occur mainly adjacent to the hyaluronic acid binding region with the release of the rest of the molecule. Two distinct populations have been observed, the larger of which is chondroitin sulfate-rich and the smaller keratan sulfate-rich. Although they are a little smaller and probably aggregate less with hyaluronic acid, these populations correspond in size and composition to two similar populations detected in situ in healthy adult human articular cartilage. In vivo studies of synovial fluid have revealed that the proteoglycan fragments are smaller and the most commonly detected fragment is the hyaluronic acid binding region. This suggests that in vivo further degradation occurs, probably due to degradation mediated by the inflamed synovium and polymorphonuclear leucocytes present in the synovial fluid of inflamed joints.

The immunologic detection and characterization of cartilage proteoglycan degradation products in synovial fluids of patients with arthritis

Antibodies were used in radioimmunoassays with gel chromatography to detect the hyaluronic acid-binding region, core protein, and keratan sulfate of human cartilage proteoglycan in the synovial fluids of patients with rheumatoid arthritis, juvenile rheumatoid arthritis, and osteoarthritis. All fluids contained proteoglycan that was mainly included on Sepharose CL-4B; this result indicates cleavage of proteoglycan (which is normally excluded). The hyaluronic acid-binding region was the smallest and most commonly detected fragment. It was relatively free of keratan sulfate and core protein, and it could sometimes bind to hyaluronic acid. Other larger fragments containing core protein and/or keratan sulfate were detected in every fluid.