How to identify the right molecule for your assay

Why you should distinguish clinical-grade from research-grade molecules

Choosing the right monoclonal antibody (mAb), ADC or biologic is crucial for the success of any research project. In practice, that is not a piece of cake. There are significant differences between molecules available on the market, which sometimes are not identifiable at first glance. Let us show you what to consider! 


Monoclonal antibodies (mAbs) and other functional proteins can be split into two groups, based on their intended use: 

Clinical-grade molecules from drugs 

Clinical-grade molecules are the Active Pharmaceutical Ingredients (API) in reference drugs (RMP/RLD) or biosimilars: mAbs, bi-specific ABs, fusion proteins, or ADCs. Their efficacy and safety in treating a particular disease in humans were demonstrated in clinical trials. Clinical-grade molecules are the only reference when it comes to a known and proven function in humans, being under strict regulatory compliance. 

Clinical-grade molecules are extensively purified, so you are on the safe side regarding endotoxins and other impurities. Excipients in the formulation are FDA/EMA-approved. These molecules are concentrated in drugs at high levels of 5 – 180 mg/mL in an optimal buffer, which makes them extremely stable over time.  

For early-stage drug development assays, functional in vitro and in vivo experiments, analytical methods for molecular characterization or biocomparability studies, clinical-grade molecules are the preferred choice. 


Research-grade molecules 

Research-grade molecules are for exclusive use in in vitro and in vivo experiments. Even though having similar functional properties to clinical-grade molecules, they are not approved for human use or subject to any regulatory pathway. Their formulation carries a considerable degree of variations like buffer, product concentration or the cell line that originate the protein. The endotoxin profile of these molecules is often unknown. The formulation does not compulsory contain FDA/EMA-approved excipients, being usually formulated in PBS buffer. 

Thus, research-grade molecules cannot be equated with clinical-grade molecules based on binding behaviour, glycosylation pattern, buffer excipients, long-term (storage) stability, reproducible quality standards, endotoxin levels (HCP) or neutralization behaviour. 

Opt for a research-grade molecule if you want to perform functional studies, need positive and negative controls, conduct early-stage in vivo efficacy and ADME (absorption, distribution, metabolism, and excretion) studies, small pharmacokinetics (PK) and dose range-finding studies. 


Comparison between Clinical-grade and Research-grade molecules

  Clinical-grade molecules from drugs Research-grade molecules
Active Pharmaceutical Ingredient (API) Yes No
Regulatory pathway IND/BLA* None
Clinical trial data available Yes No
Proven therapeutic function Yes No
Usage licence Humans Research use or in vitro diagnostics (IVD)
Isotype Chimeric, humanized or fully human Human, murine or other animal clones possible
Expression clone identification Clone number not publicly available Clone number available
Degree of study Comprehensive characterization Specific characterisation (e.g. antigen binding specificity and sensitivity)
Purity Extensive purification (endotoxin level within the acceptable range) Endotoxin profile often unknown
Concentration 5–180 mg/mL < 1 mg/mL
Excipients FDA/EMA-approved excipients in original buffer Not necessarily FDA/EMA-approved excipients, usually in PBS buffer
Application examples Reference molecule with known and proven physiological function; functional in vitro and in vivo experiments; analytical methods for molecular characterization; biocomparability assays; microheterogeneity assays; comparator against new molecules Functional studies; positive and negative controls; early-stage in vivo efficacy and ADME studies; small PK and dose range-finding studies

* IND/BLA: Investigational New Drug/Biologic License Application


Research-grade molecules are easily available on multiple online platforms. In contrast, the process of procuring clinical-grade molecules from approved drugs can be time consuming, costly, and complex.


Where to procure clinical-grade molecules from drugs?

Evidentic is a provider of drug aliquots from licensed reference medicines containing these clinical-grade molecules. We have repackaged the drug GDP-compliant in small quantities for use as a research consumable. In this way, you receive an aliquot of the original clinical-grade drug formulation with the clinical-grade molecules you desire. End-to-end documentation regarding transportation, preparation and storage of each aliquot is provided (chain of custody). For biosimilar developers, we offer different manufacturing batches of the same API.


Check here which benefits others have experienced when using drug aliquots of clinical-grade molecules.


Discover clinical-grade molecules
Publishing Date:
Monday, 13 June, 2022
share on LinkedIn
share on Twitter
Share on Facebook


About Evidentic

Evidentic is a young innovative company providing original drugs for research and new drug development.
Through our unique concept, we enable our customers to buy small quantities of these drugs as consumables, saving costs and time.

Follow Us

Read more