Marin Bio has developed hundreds of potency assays over the past 30 years and can assist you in the identifying an appropriate assay specific for your drug. Some of the assays we developed have been for small molecules, antibodies, bispecific constructs, Fab products, antibody-drug conjugates, DNA and RNA, viruses, antisense moieties, recombinant proteins and stem cells. Let our scientist guide you to find the appropriate potency assay.

A GMP lot release assay, also known as lot release testing or finished product testing, is a regulatory requirement that assesses the quality and safety of licensed products before they are released for clinical use or sale. This testing is a crucial part of Good Manufacturing Practice (GMP) requirements for the production of biopharmaceutical, pharmaceutical, and medical device products.

Lot release or finished product testing is essential for ensuring the quality and safety of biologics by evaluating their purity, potency, and identity for every manufactured batch before approving its release into the market. This process also includes stability testing, which demonstrates the short and long-term stability of a biologic after exposure to various environmental factors.



Questions about Our Cell Based Assay Services?

Contact us to discuss the specifics of your project. Our team of experienced scientists is ready to assist you with tailored solutions to meet your unique needs. Whether you need help with assay development, FDA IND, stability study,  lot release approval, or other scientific endeavors, we are here to support you.
Contact us to learn more about our cell based assay services

We will initiate your project as soon as the proposal is approved and signed by you. Our streamlined process ensures a quick start, minimizing delays and maximizing efficiency. Fill out the form below to email us or click our live chat option to speak with a MarinBio Scientist and get your project underway.

Yes, we have over 30 years of expertise in developing and validating cell based assays for FDA IND, lot release or stability study approval. Our team can also liaise directly with the FDA on your behalf, ensuring a smooth and compliant process. Please contact us to learn more about how we can assist you with your assay development and FDA approval needs.

MarinBio scientists are experienced and creative in designing, developing, validating assays. Some of the assays we perform are listed below, but there are many more that we created, developed and validated. Give us call so that we may help you.

Need help or have questions on cell based assays?

Give us a call at 415-883-8000

MarinBio Platforms for GMP Lot Release Testing

Case Study: Potency Assay of a Drug Product  for Lot Release

This assay is used for acceptance and lot release of a Drug Substance (DS) or Drug Product (DP).   Bispecific antibodies typically link killer T lymphocyte cells to a tumor target resulting in killing of the target.  A common form of a bispecific is the Fab2 binding site for the CD3-antigen binding site on killer T cells covalently linked to a Fab2 binding site for a tumor antigen. Fab2 is the antigen binding portion of an antibody comprised of part of the light chain and part of the heavy chain held together by a disulfide bond that imparts the specificity of the binding. :We develop potency assays for bispecifics with extreme precision and accuracy in the EC50 values. 

Assay method

The killer cell is a cytotoxic T cell line, avoiding variation with different donor blood T cells. The target cell is a cancer cell prelabeled with a fluorescent dye. Killing is measured by release of the dye into the supernatant.  The assay uses about one killer T cell to one target cell and the reaction is complete in 2-3hr.

Example, T cell killing of CD33 bearing myeloid leukemia with a bispecific antibody.

The assay evaluates the activity of a bispecific nanobody to direct the T cell killing of a target tumor cell.  A cytotoxic T cell is cultured with the target cells in a 3:1 ratio with doses of the drug. All conditions are analyzed in triplicate in a 96well plate.  In each assay, the test sample is compared to the Reference Standard (RS).  The target ”cancer” cells are prestained with calcein-AM dye.  Upon death, the target cell releases the dye. The cultures are centrifuged and the calcein dye in the supernatant is measured as Relative Fluorescence Units (RFU) in a 96well plate reader. >

The data are analyzed by a Four Parameter (4P) curve fit resulting in EC50 values for each sample.  The relative potency (RP) of the test sample compared to the reference standard on the same plate is calculated, RP = [EC50 RS] / [EC50 Test]. A  test sample with a weaker potency than RS requires a higher concentration to reach its EC50

The time course of the killing is shown below with ten concentrations of the bispecific construct,

All conditions are analyzed in triplicate, in a 96 well plate. There was almost complete killing at 120 minutes of co-incubation with the top concentration of the bispecific construct. 

Accuracy of the method is shown below.  Ten concentrations of fresh Reference Standard and one and two times free/thaw (F/T) material were tested.  All conditions were analyzed in triplicate, in a 96 well plate.  The graph shows that the material is stable to two freeze / thaws and that the method is highly precise and accurate


Contact Us About Our Lot Release/Potency Assay Services

For More Information about our cell based assay services, please use the following informational form