Clinical Trials Glossary

A type of virus used in gene therapy to deliver genetic material to cells. AAV vectors are considered safe because they don't cause disease in humans.

FDA pathway allowing earlier approval of drugs for serious conditions based on surrogate endpoints, with requirement for confirmatory trials post-approval.

A condition or symptom that begins suddenly and is often severe but lasts a short time, as opposed to chronic conditions.

Any unfavorable medical occurrence in a clinical trial participant, whether or not related to the treatment being studied. Also called side effect.

A clinical trial testing whether anti-amyloid treatment can prevent Alzheimer's symptoms in people with elevated brain amyloid but no cognitive impairment.

Also known as Lou Gehrig's disease, a progressive neurodegenerative disease affecting nerve cells in the brain and spinal cord, causing loss of muscle control.

A progressive brain disorder that destroys memory and thinking skills. The most common cause of dementia in older adults.

Abnormal protein that can build up in organs and tissues. In Alzheimer's, amyloid-beta forms plaques in the brain.

Monoclonal antibodies designed to clear amyloid plaques from the brain in Alzheimer's patients. Examples include lecanemab and aducanumab.

A genetic variant that increases risk of developing Alzheimer's disease. People with one copy have 3x higher risk; two copies mean 8-12x higher risk.

A group or subgroup of participants in a clinical trial receiving specific interventions (or no intervention) according to the study protocol.

Short synthetic strands of DNA or RNA that can bind to specific RNA sequences to modify or reduce protein production. Used in treating genetic diseases.

The initial measurements or observations made at the beginning of a study, before participants receive treatment, used for comparison.

A group of rare, fatal, inherited disorders of the nervous system that typically begin in childhood, causing progressive neurological impairment.

An inherited blood disorder causing reduced hemoglobin production, leading to anemia. Now treatable with gene therapy in some cases.

A trial comparing a generic drug to a brand-name drug to show they have the same rate and extent of absorption in the body.

A medical product made from living organisms or their products, including vaccines, blood products, gene therapies, and monoclonal antibodies.

A measurable indicator of a biological state or condition, used to evaluate normal or disease processes, or responses to treatment.

Keeping trial participants, investigators, or assessors unaware of the assigned treatment to prevent bias. See also double-blind, single-blind.

A measure of body fat based on height and weight. Many trials have BMI eligibility requirements (often 18-32 for healthy volunteers).

FDA designation for drugs showing substantial improvement over existing treatments for serious conditions, providing expedited development and review.

Chimeric Antigen Receptor T-cell therapy - a treatment where patient's T-cells are modified to attack cancer cells, showing remarkable results in blood cancers.

Drugs that block proteins that stop the immune system from attacking cancer cells. Includes PD-1, PD-L1, and CTLA-4 inhibitors.

A condition that persists over a long period of time (typically 3+ months) or recurs frequently, as opposed to acute conditions.

The person who manages the day-to-day activities of a clinical trial, including recruiting participants and collecting data.

A research study in human volunteers to answer specific health questions about new treatments, vaccines, or interventions.

The gradual loss of thinking, remembering, and reasoning abilities. A key symptom measured in Alzheimer's and dementia trials.

A group of participants in a study who share a common characteristic or experience within a defined period.

Treatment using two or more interventions together, such as multiple drugs or drug plus radiation, to improve effectiveness.

Also called expanded access, allows patients with serious conditions to access investigational drugs outside of clinical trials.

Payment to clinical trial participants for their time, travel, and inconvenience. Amount varies by study type and duration.

The group in a clinical trial that receives standard treatment, placebo, or no treatment, used for comparison with the experimental group.

A group of lung diseases including emphysema and chronic bronchitis that block airflow and make breathing difficult.

A gene-editing technology that can precisely modify DNA. Being used in trials for sickle cell disease, cancer, and genetic disorders.

A study where participants receive multiple treatments in sequence, serving as their own control group.

Cytotoxic T-Lymphocyte-Associated protein 4 - an immune checkpoint protein targeted by cancer immunotherapy drugs like ipilimumab.

A genetic disorder affecting the lungs and digestive system, causing thick mucus buildup. New treatments include CFTR modulators.

An independent committee that reviews data during a trial to ensure participant safety and can recommend stopping the trial if needed.

A general term for loss of memory, language, problem-solving and other thinking abilities severe enough to interfere with daily life.

Dominantly Inherited Alzheimer Network Trials Unit - studies testing treatments in people with rare genetic mutations causing early-onset Alzheimer's.

The process of gradually increasing drug doses in early-phase trials to find the maximum tolerated dose while monitoring for side effects.

A trial design where neither participants nor researchers know who is receiving the treatment or placebo until the study ends.

A rare, severe form of epilepsy beginning in infancy, often caused by SCN1A gene mutations. Subject of many pediatric trials.

A genetic disorder causing progressive muscle weakness and degeneration. Gene therapies and exon-skipping drugs show promise.

The ability of a treatment to produce the desired beneficial effect under ideal conditions in a clinical trial.

The requirements that must be met for a person to participate in a clinical trial, including inclusion and exclusion criteria.

A measurable outcome used to determine whether a treatment is beneficial. Primary endpoints are the main study goals.

The process of signing up and being accepted into a clinical trial after meeting all eligibility criteria.

Treatment providing missing or deficient enzymes to patients with genetic metabolic disorders like Gaucher or Fabry disease.

Factors that disqualify someone from participating in a clinical trial, such as certain medical conditions or medications.

FDA program allowing patients with serious conditions to access investigational drugs outside clinical trials when no other options exist.

A genetic therapy approach that causes cells to skip over faulty genetic instructions, used in treating Duchenne muscular dystrophy.

A rare genetic disorder causing harmful fatty substance buildup in cells. Treated with enzyme replacement therapy.

FDA process to expedite review of drugs for serious conditions with unmet medical needs, allowing more frequent meetings and rolling review.

The U.S. federal agency responsible for protecting public health by regulating drugs, biologics, medical devices, and clinical trials.

The first clinical trial of a new drug in humans, typically a Phase I study focused on safety and dosing.

The period after treatment ends when participants are monitored for long-term effects, safety, and durability of response.

A genetic disorder where fatty substances accumulate in organs. One of the first successfully treated with enzyme replacement therapy.

Technologies like CRISPR that can add, remove, or alter genetic material at specific locations in the genome.

The process by which genetic instructions are used to synthesize gene products, usually proteins. Target of many new therapies.

Treatment that involves introducing genetic material into a patient's cells to treat or prevent disease.

A medication that has the same active ingredient, strength, and dosage form as a brand-name drug but is typically less expensive.

Process of advising individuals and families about genetic disorders, inheritance patterns, and implications of genetic testing.

Diabetes drugs that also promote weight loss and may have neuroprotective effects. Being tested for Alzheimer's and Parkinson's.

International ethical and scientific quality standards for designing, conducting, and reporting clinical trials.

The time it takes for half of a drug to be eliminated from the body. Important for determining dosing schedules.

A person with no known significant health problems who participates in clinical research to test new drugs or procedures.

A genetic bleeding disorder where blood doesn't clot properly. Gene therapies now offer potential one-time cures.

Health Insurance Portability and Accountability Act - U.S. law protecting patient health information privacy and security.

A fatal genetic disorder causing breakdown of nerve cells in the brain. ASO and gene therapies in development.

Treatment that uses the body's immune system to fight disease, especially cancer. Includes checkpoint inhibitors and CAR-T therapy.

The requirements that must be met for someone to be eligible to participate in a clinical trial.

FDA application that must be approved before testing a new drug in humans. Contains preclinical data and trial protocols.

The process of providing complete information about a clinical trial to potential participants so they can make an educated decision about joining.

An independent committee that reviews and approves clinical trials to ensure they are ethical and participants' rights are protected.

Analysis method including all randomized participants in the groups they were assigned to, regardless of whether they completed treatment.

The treatment, procedure, or other action being studied in a clinical trial.

A drug or device that has not yet been approved by the FDA for general use and is being tested in clinical trials.

A medical professional who conducts clinical trial research. The principal investigator (PI) leads the research team.

A rare inherited eye disease causing blindness. First disease successfully treated with gene therapy (Luxturna).

A blood test that can detect cancer DNA or cells, allowing non-invasive monitoring and early detection of cancers.

Extended monitoring of trial participants after treatment ends, sometimes for years, to assess durability and late effects.

Group of genetic diseases where defective enzymes cause harmful substances to accumulate in cells. Includes Gaucher and Fabry disease.

The highest dose of a drug that can be given without causing unacceptable side effects, determined in Phase I trials.

A stage between normal aging and dementia where cognitive decline is measurable but doesn't significantly interfere with daily life.

The specific biological process through which a drug produces its therapeutic effect in the body.

Conditions that disrupt normal metabolism, often genetic. Includes PKU, Gaucher disease, and metabolic syndrome.

Cancer that has spread from its original location to other parts of the body. Often focus of advanced cancer trials.

Laboratory-made proteins that can bind to specific targets in the body. Used in cancer, autoimmune, and Alzheimer's treatments.

Treatment using a single drug or intervention, as opposed to combination therapy.

A clinical trial conducted at multiple locations simultaneously, often to speed enrollment and ensure diverse populations.

An autoimmune neuromuscular disease causing muscle weakness. New treatments include complement inhibitors.

Advanced form of fatty liver disease not caused by alcohol. Subject of many current trials as no approved treatments exist.

Application submitted to FDA for approval to market a new drug after successful Phase III trials.

Progressive loss of neuron structure or function. Includes Alzheimer's, Parkinson's, ALS, and Huntington's disease.

Treatments or substances that protect nerve cells from damage or degeneration.

Research that observes participants without intervening or providing treatment, often to understand disease progression.

Using an FDA-approved drug for a condition, age group, or dosage not specifically approved by the FDA.

Office for Human Research Protections - U.S. agency overseeing the protection of human subjects in research.

A trial where both researchers and participants know which treatment is being given, with no blinding.

A drug developed for rare diseases affecting fewer than 200,000 people in the U.S., receiving special FDA incentives.

A measured result in a clinical trial used to assess the effect of an intervention.

A progressive neurological disorder affecting movement, causing tremors, stiffness, and balance problems.

Programmed Death proteins - immune checkpoints that cancer cells use to avoid attack. Target of many immunotherapy drugs.

Related to children and adolescents. Pediatric trials have special protections and require parental consent.

Analysis including only participants who completed the trial according to the protocol, excluding dropouts and protocol violations.

Medical treatment tailored to individual characteristics, often based on genetic testing. Also called precision medicine.

What a drug does to the body - its biological effects and mechanism of action.

What the body does to a drug - absorption, distribution, metabolism, and elimination (ADME).

Exploratory trials using microdoses to study drug behavior in humans without therapeutic intent.

First testing in humans (20-100 people) primarily to evaluate safety, dosing, and how the body processes the drug.

Trials in 100-300 patients to evaluate effectiveness while continuing to monitor safety and side effects.

Large trials (300-3,000 patients) comparing new treatment to standard care to confirm effectiveness for FDA approval.

Post-marketing surveillance studies monitoring drugs after FDA approval for long-term effects in real-world use.

Usually a Phase III trial that provides the primary evidence for FDA approval of a new treatment.

A genetic disorder where the body can't process the amino acid phenylalanine. Requires lifelong dietary management.

An inactive substance that looks like the study drug but contains no medicine, used for comparison in trials.

Improvement in symptoms from receiving a placebo, due to psychological factors rather than the treatment itself.

A rare genetic disorder causing muscle weakness due to glycogen buildup. Treated with enzyme replacement therapy.

Laboratory and animal studies conducted before testing in humans to evaluate safety and biological mechanisms.

Study testing whether an intervention can prevent disease in people at risk but not yet showing symptoms.

The main outcome measure used to determine whether a treatment is effective in a clinical trial.

Group of disorders where part of the immune system is missing or not working properly from birth.

The lead researcher responsible for conducting a clinical trial at a site and ensuring it follows the protocol.

FDA designation reducing review time from 10-12 months to 6 months for drugs addressing serious conditions.

Extremely rare genetic disorder causing rapid aging in children. Life expectancy typically 13-14 years.

A condition that worsens over time, such as Alzheimer's, Parkinson's, or ALS.

The detailed plan that describes what will be done in a clinical trial, how, when, and why.

Any change or departure from the study protocol. Minor deviations vs major violations affecting safety or data.

A measure of a patient's physical, emotional, and social well-being, often assessed in clinical trials.

Process of randomly assigning trial participants to different treatment groups to prevent bias.

Gold standard trial design where participants are randomly assigned to treatment or control groups.

In the U.S., a condition affecting fewer than 200,000 people. Also called orphan disease.

The process of identifying and enrolling eligible participants in a clinical trial.

A database of patients with a specific condition or who are interested in research, used to facilitate trial recruitment.

Decrease or disappearance of signs and symptoms of disease. Can be partial or complete.

The percentage of patients whose disease shrinks or disappears after treatment.

A rare genetic neurological disorder affecting brain development, primarily in girls, causing loss of motor and language skills.

U.S. law allowing terminally ill patients to access investigational drugs without FDA approval in certain circumstances.

The comparison of potential risks of a treatment against its potential benefits, crucial for ethical approval.

A biological process where RNA molecules inhibit gene expression, used therapeutically to silence disease-causing genes.

Initial period of a trial where a small number of patients receive treatment to confirm safety before full enrollment.

Rare genetic disorder causing life-threatening infections due to absent immune function. Treatable with gene therapy.

The process of testing potential participants to determine if they meet eligibility criteria for a trial.

Additional outcomes measured in a trial that are not the primary focus but provide supporting information.

An adverse event that results in death, hospitalization, disability, or requires intervention to prevent permanent damage.

A fake procedure or device used as a control in trials, especially for surgical or device studies.

Inherited blood disorder causing red blood cells to become sickle-shaped. Now curable with CRISPR gene editing.

Trial design where participants don't know which treatment they're receiving, but researchers do.

A location where a clinical trial is conducted, usually a hospital, clinic, or research center.

Genetic disease affecting motor neurons, causing muscle weakness. Gene therapy (Zolgensma) offers one-time treatment.

The current best treatment or practice widely accepted for a particular condition, often used as comparison in trials.

Mathematical determination that results are likely due to the treatment rather than chance, typically p<0.05.

Treatment using stem cells to replace or repair damaged cells or tissues. Used in blood cancers and regenerative medicine.

Person who manages daily trial activities, schedules visits, collects data, and serves as main contact for participants.

An additional research component within a main trial, often optional, studying specific aspects or subgroups.

A marker used in place of a clinical endpoint, like tumor shrinkage instead of survival, to speed up trials.

Treatment that targets specific genes, proteins, or tissue environment contributing to disease, especially cancer.

Protein that forms tangles in brain cells in Alzheimer's disease. Target of many new Alzheimer's drugs.

Type of white blood cell central to immune response. Modified in CAR-T therapy to fight cancer.

Remote healthcare delivery using technology, increasingly used in clinical trials for follow-up visits.

The range of drug doses that produces therapeutic response without causing unacceptable adverse effects.

The degree to which a substance can cause harm to the body. Closely monitored in all phases of trials.

Research that transforms scientific discoveries from laboratory into clinical applications, "bench to bedside."

A group of participants receiving a specific treatment or intervention in a clinical trial.

Study testing a vaccine for safety and effectiveness in preventing disease or treating existing conditions.

A vehicle, often a virus, used to deliver genetic material into cells in gene therapy.

Clinical trial conducted remotely using digital tools, reducing need for in-person visits. Also called decentralized trial.

Most common inherited bleeding disorder, affecting blood clotting. Less severe than hemophilia.

Time between treatments in a trial to allow the first treatment to clear from the body before starting another.

When a participant chooses to leave a clinical trial before completion, which is their right at any time.