In Vitro Drug Resistance Studies

With our state-of-the-art technology and industry-leading expertise, Creative Biolabs has developed a comprehensive range of assays that fully support our clients' immune checkpoint blocker resistance studies. Leveraging the wealth of information that we have on drug resistance studies, we can help our clients with their studies and provide suggested assays to test.

Background of Immune Drug Resistance

As our understanding of tumor immunology is continuously improved, immunotherapy has become the center stage of cancer therapy. An essential mechanism of immunotherapy is through immune checkpoints, which help control the inflammatory response after T cell activation and protect normal cells from T cell-mediated cytotoxicity. However, most cancer patients do not benefit from immunotherapy, which is mainly due to primary or acquired resistance arising from tumor immune evasion. Accordingly, immune drug resistance studies that will help conquer drug resistance of cancers to immune checkpoint blockade are important and necessary.

In Vitro Drug Resistance Studies at Creative Biolabs

Creative Biolabs is well equipped and versed in immune checkpoint blocker resistance studies. Several in vitro technologies have been developed for drug resistance determination, including human tumor cloning assay (HTCA), differential staining cytotoxicity (DiSC) assay, methyl thiazol-diphenyl-tetrazolium bromide (MTT) assay, adenosine triphosphate (ATP) bioluminescence assay, and extreme drug resistance (EDR) assay. Our scientists are happy to lend our expertise and help clients overcome any hurdles they may face during immune checkpoint blocker resistance studies.

  • HTCA
  • HTCA is an in vitro culture system employing semisolid medium support. Using HTCA, the growth and chemosensitivity of clonogenic tumor cells present in fresh biopsy specimens of human tumors can be investigated. Single-cell suspensions prepared from tumors are cultured in vitro for several weeks. After that, the colony-forming efficiency in the presence and absence of various drugs is evaluated to determine drug resistance.

  • DiSC assay
  • DiSC assay is one of the total cell-kill assays that can be used for drug resistance testing. Tumor cells are cultured in vitro in the presence/absence of different concentrations of drugs. After several days' incubation, differential dye staining is used to identify viable cells and determine drug resistance.

  • MTT assay
  • The colorimetric assay uses the reduction of a yellow tetrazolium salt (MTT) to measure cellular metabolic activity as a proxy for cell viability. Tumor cell suspensions are cultured with various drugs for several days. MTT is reduced intracellularly to a blue dye; the intensity of uptake yields an estimate of the number of viable cells to determine drug resistance.

  • ATP bioluminescence assay
  • Tumor cells are cultured in the presence/absence of test drugs, and then cells are lysed. The amount of ATP is measured by adding luciferin. Low ATP concentration manifests as low luminescence to identify efficacious test drugs. ATP bioluminescence assay offers high sensitivity and a wide dynamic range.

  • EDR assay
  • EDR assay is an in vitro chemoresistance assay performed on tumor samples grown in culture. After successful culture, tumor cells are labeled with tritiated thymidine, and the level of uptake is tracked. EDR is identified when thymidine incorporation is inhibited in the presence of the drug.

Creative Biolabs is committed to providing overall solutions for drug resistance studies. Our team offers a portfolio of comprehensive assays for drug resistance studies. For more detailed information, please feel free to contact us or directly send us an inquiry.


  1. Korpal, M.; et al. Implementation of in vitro drug resistance assays: Maximizing the potential for uncovering clinically relevant resistance mechanisms. Journal of visualized experiments: JoVE. 2015, 106.

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