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Imaging Clinical Trials.
Imaging clinical trialists face complexities not shared by other clinicians conducting clinical experiments. Although much has been written on the subject of Clinical Trials http://en.wikipedia.org/wiki/Clinical_trial, this Wiki serves as a resource for those imaging professionals who need more than mere familiarity with the design and conduct of clinical trials. Its content arose from key modules of the mentoring program conducted jointly by RSNA and NCI for select young imaging faculty who plan careers as professional clinical trialists. Consult the User's Guide for information on using the wiki software.----

Concepts and FAQ's addressed in this course

How does a screening trial differ from a therapeutic trial?

How does a randomized control trial (RCT) differ from an observational trial?

Must the control arm of a therapeutic RCT always be a placebo?

What distinguishes Phase 1, 2, 3 and 4 trials?

What are ‘Phase 0’ trials and what role would imaging have in them?

What data do you need to determine a statistically valid study size?

When does a trial need a Data Safety Monitoring (DSM) board?

What functions do interim and futility analyses serve?

What are the definitions of type 1 and type 2 errors?

How do you constitute an imaging central reading review panel and how does it function?

What is the regulatory definition (e.g. FDA) of a “surrogate’ biomarker?

How do “prognostic” biomarkers differ from ‘predictive’ markers?

What happens if an ‘adverse event’ occurs to a study subject?

Abbreviations and Definitions

• CR (Complete Response) after a therapy intervention implies that both 'target' and non-target tumor lesions are no longer visible
• Confirmed PR is a measure taken at the next interval (more than 6 weeks) after a declared first instance where tumor measurement meets the PR criteria (which for RECIST it is a reduction of 30%)
• DFS (Disease Free Survival) post-treatment measures the length of time before death during which there are no detectable tumor lesions
• ORR (Objective Response Rate) summarizes the percent of cases on an experimental therapy in which there is a measurable reduction in target tumor mass as depicted by imaging
• OS (Overall Survival) measures the length of time before death of cases on an experimental therapy
• PD (Progressive Disease) is defined by the time at which a case undergoing therapy is measured to have grown in dimension beyond a nadir measurement after the start of therapy. By the RECIST criteria it is defined as having reached a threshold of 20% growth in the summed diameters of measured target tumors that exceeds the nadir value reached after the inception of therapy. PD is also defined to have occured if there is the appearance of a new lesion.
• PR (Partial Response) a net measureable reduction in tumor dimensions amongst the 'target' lesions. For RECIST the threshold for PR is a 30% reduction.
• PFS (Progression Free Survival) the length of the interval for which there has neither been death nor a measureable increase in net tumor dimensions (in RECIST greater than a net 20% dimensional increase).
• RR (Response Rate) represents data that implies an reduction of the amount of tumor burden and can include either reduced symptoms or shrinkage of measured tumor size or both.
• RECIST Response Evaluation Criteria for Imaging in Solid Tumors. A solid tumor measurement method that uses the sum or 'target tumor' linear diameter measures to estimate time-sequence changes in tumor volume. Click here to see a table of the elements that define classification of RECIST Endpoints
• SD (Stable Disease) measurement intervals of 'target' lesions in which net their dimensions have neither increased by 30% nor decreased by 20%.
• TTP (Time to Progression) the time interval that has elapse before the tumor target measurements have not exceeded the threshold defined as 'PD' (in RECIST it is a net increase of 20%)
• Target Lesions tumors visible at baseline that are measured sequentially over time by the RECIST criteria  http://www.eortc.org/Recist/Default.htm
• WHO A solid tumor measurement method that uses two orthogonal tumor diameter measures to estimate time-sequence changes in tumor volume

Useful (out-of-Wiki) Websites

Thorough knowledge of what's available on these other Websites is probably worth 20 added points to your 'Clinical Trialist IQ'

Funding Sources and Key Resources

Software that's essential for your efficiency

You can't be efficient until you have a thorough knowledge of the following software applications. Spend some time learning them intimately - it will be worth it.

• Acrobat Professional – especially when you need to extract text (Select Tool) and images (Advanced  ->export all images); track changes (Comments & Markup); or publish a smaller, unchangeable PPT as a PDF;
• Word – convert to Adobe PDF using an Acrobat plug-in; Track changes (ctrl+shift+E); email document as a draft for comment; add images; has hierarchical outline view
• Endnote – links to Word; does its’ own PUBmed searching, constructs a complete bibliography and dynamically formats your references while you write
• PowerPoint (PPT) – you can incorporate and edit web pages and images for presentations. And it's an easy way to construct protocol flow schemas
• Quosa – http://www.quosa.com/  connects automatically to PubMed and extracts full article PDFs if you are allowed to do so by your institutional license.

Informed Consent and Ethics

Informed consent is an essential part of the ethical conduct of clinical trials.For detailed discussion of how it impacts imaging clinical trials, follow the link below titled 'Informed Consent'

Other Wikipedia threads are available that deal with informed consent which are available as 'out-links' http://en.wikipedia.org/wiki/Informed_consent from which you can get a more extensive background on such important documents as the Tuskegee experiment (http://en.wikipedia.org/wiki/Tuskegee_Syphilis_Study), Belmont report (http://en.wikipedia.org/wiki/Belmont_Report) and Nuremberg Code (http://en.wikipedia.org/wiki/Nuremberg_Code). But with your focus on imaging you might wish to limit yourself to the particulars of informed consent primarily applicable to 'imaging' via the link

Informed Consent

Trials: their types

• Phase 1 - less than 30 subjects - purpose to determine therapy dose and delivery
• Phase 2 - 100 or so subjects - to determine 'efficacy'
• Phase 3 - large numbers of subjects - to determine effect relative to standard therapy
• Phase 4 - large subject numbers - to determine ' efficaciousness' after therapy is in widespread use
• Phase 0 (a new category often using nuclear imaging or MRI) - less than a dozen subjects - to determine if a 'targeted therapy' reaches the intended disease tissue

Diagnostic Technology Assessment Trials

Diagnostic tests are conducted to determine whether cancer is present, where it is located and its stage. Some diagnostic trials compare two or more techniques to diagnose cancer and determine whether one technique is superior. Genetic tests are being evaluated as diagnostic tools to further classify cancers so as to direct therapies or improve treatments for people with specific genetic changes.

Basic Protocol Considerations

Clinical trials must follow strict scientific guidelines. These guidelines should clearly define the study’s design and who will be able to participate in the study (patient eligibility). Every trial has principal investigator(s). The principal investigator prepares a plan for the study (a protocol) which describes the clinical trial in complete detail, including imaging acquisition and analysis procedures. The protocol explains what the trial will do, how the study will be carried out, and why each part of the study is necessary. It includes information on:

• The importance and rationale that justifies the study
• A statistically justified cohort size (for each arm)
• Eligibility criteria (requirements may involve type of cancer, general health, age, prior therapy)
• An easily understood 'schema' depicted as a flow-chart
• The intervention or therapy being tested (e.g. drug dosage, etc.)
• What tests participants will have and how often (a ‘patient calendar’)
• What information will be gathered about the participants and how their privacy will be protected
• The participants options if they choose to withdraw
• A readable consent form (at an eighth-grade readability level)
• The endpoints (primary and secondary) and correlative studies
• Methods of analysis
• Regulatory requirements and reporting obligations

Investigational Drugs and Devices

Investigational means any drug or device not currently marketed in the US in the exact form that you are using for the exact indication for which you are using it.  For example, updated device software is investigational, as is investigation of an marketed drug for a disease or histology that is not explicitly in the drug labeling. For more detailed discussion follow this link -- Investigational Drugs & Devices

Imaging as a Measure of Therapeutic Response

Suppose you were asked to devise an imaging acquisition protocol and analysis scheme for a new drug therapeutic trial that might be submitted to FDA. Can you come up with a list of the key considerations you might want to go through?

• If you'd like a Socratic list of 20 questions you ought to consider,

try this link -- Instructive use-case problems for clinical trial imagers

Why and How to Share Data

Because most clinical trials attempting to assess therapeutic efficacy are Phase I or II trials with small numbers of patients, there is a great need to assemble evidence by cross-analyzing the results of many trials thought to be similar ('meta-analysis'). Insufficient attention has been paid to be sure trial results permit that possibility therefore data-sharing begins with clear and fully defined protocols including detailed imaging parameters that can be understood by others. Case report forms (CRFs) should employ common vocabularies and common data elements (CDEs)so that results can be harmonized between trials. Cancer-applicable CRF templates, CDEs with vocabularies and Adverse Event definitions can be accessed from NCI clinical trials websites.

Images obtained during clinical trials have a special value of their own and the field greatly benefits from sharing those images in their original DICOM format with others so as to advance research in quantitative clinical image analysis. To share images one should understand the principles of de-identify and anonymize image sets.

Bibliography

Click to the Bibliography to access selected references, many of which are hot-linked, that offer more depth on topics specifically chosen to be relevant to imaging trialists.