Clinical Trials & Studies

Clinical trials are a key component of research. Scientists use medical knowledge to ask and answer scientific or medical questions in areas such as medication, medical device, teaching concepts, or behavioral change. Researchers first test new therapies in labs and/or animals. Treatments that are safe are moved into clinical trials to move the drug or therapy toward approval by the FDA.

Commonly Used Terms

This list was developed to provide easy-to-understand definitions of commonly used terms in clinical trials. Commonly Used Clinical Terms

Types of Clinical Trials

Treatment

Test new treatments or devices, new combinations of drugs, or new approaches to surgery or radiation therapy. Treatment trials are often categorized by phases I through III.

Natural History

Provide information about how health and disease progress over time.

Prevention

Evaluate the effectiveness of ways to reduce the risk of developing a disease or preventing a disease from returning.

Diagnositic

Develop better tests or procedures to identify/diagnose a particular disease or condition.

Screening

Assess new ways of detecting disease earlier in healthy people.

Quality of Life (or Supportive Care)

Evaluate measures to improve comfort of and quality of life for people with chronic illnesses through better therapies or psychosocial interventions.

Clinical Trial Phases

Researchers test an experimental drug or treatment in a small group of people (20–80) for the first time, often using healthy volunteers to test drug metabolism, safety, and dose ranges.The purpose is to evaluate its safety and identify side effects.

The experimental drug or treatment is administered to a larger group of people (100–300) to determine its effectiveness, optimal therapeutic dose, and to further evaluate its safety. This phase may be blinded (unknown if patient receives the study drug) or open label studies (known if patient receives study drug) in the target population.

The target population encompasses the group for which the drug is ultimately intended. Any drug metabolism, safety, or dosing difference between the Phase I healthy individuals and the Phase II target population is also evaluated.Hints of efficacy may be obtained as well.

Phase III trials are larger than phase II and involve hundreds or even thousands of participants. Phase III trials are used to confirm the benefit and safey of a treatment, on a larger scale.

After the Phase III trial, the FDA reviews the clinical trial results to make sure the treatment is safe and effective for people to use. The FDA decides whether to approve the treatment so that it is available for all patients.

Phase IV clinical trials are used to learn more about long-term side effects and efficacy for treatments and medication after they have been approved by the FDA. Researchers monitor patients while on the new medication to gather data on the long-term safety and effectiveness.

MitoAction Approved to Host FDA-Recognized Patient-Focused Drug Development Meeting on MELAS

MitoAction has been officially approved by the FDA to host a PFDD Meeting focused on MELAS (MitochondrialRelated to the mitochondria. Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes). The meeting will take place on February 10, 2026!

Click HERE to read the full press release from MitoAction

“Tisento Highlights Two Venues Advancing Patient-Focused Therapeutic Development for Mitochondrial Diseases”

Click HERE to read the full press release from Tisento, including details on our PFDD Meeting for MELAS on February 10, 2026!

“At the end of 2024, regulatory submissions of doxecitine and doxribtimine in thymidine Kinase 2 deficiency (TK2d) occurred as planned and were accepted in February 2025 for review by the European and U.S. authorities. In the U.S., the application has been granted a priority review, Breakthrough Therapy Designation and Rare Pediatric Disease Designation.”

Click HERE to read the full press release from UCB

“Stealth BioTherapeutics Announces PDUFA Action Date Extension for Elamipretide to Treat Patients with Barth SyndromeA rare, genetic disorder of lipid metabolism that primarily affects males..”

Click HERE to read the full press release from Stealth

“Saol Therapeutics announces FDA acceptance of New Drug Application for SL1009 for treatment of Pyruvate Dehydrogenase Complex Deficiency”

Click HERE to read the full press conference on SAOL’s submission for a new PDCD treatment.

“Khondrion announces publication in Brain of integrated Phase 2b program demonstrating
disease-modifying potential of sonlicromanol in primary mitochondrial disease”

Click HERE to read the full press release on this treatment development and clinical trial for Primary Mitochondrial Disease (PMD)