Our assays provide real-time, live-cell imaging to evaluate the bystander effect of ADCs. This service allows continuous monitoring of both antigen-positive and antigen-negative cells in co-culture, tracking how the released payload affects neighboring cells over time.

Figure 1. Bystander Effect Assay in Co-Cultured SKBR3 (GFP) and MDA-MB-468 (RFP) Cell Lines by Incucyte. (A) Engineered breast cancer cell lines SKBR3 (GFP) (HER2+) and MDA-MB-468 (RFP) (HER2-) were co-cultured to evaluate the bystander effect of an ADC. T-DM1 is negative control ADC for bystander effect assay. (B)The images, captured using the Incucyte live-cell imaging system, show the interaction and cytotoxic impact on both cell types after treatment for 3 days. (C) Cell counts were performed to assess the extent of the bystander effect, indicated by the reduction in RFP-labeled MDA-MB-468 cells.

Our Flow Cytometry-Based Bystander Effect Assays offer a precise and high-throughput method to evaluate the impact of ADCs on both target (antigen-positive) and non-target (antigen-negative) cells. By using flow cytometry, we can quantify cell viability, apoptosis, and other markers in co-cultured cells, providing detailed insights into how the released payload affects neighboring cells.

Figure 2. In vitro bystander effect assay of DS-8201 and RC-48 in engineered breast caner cell lines detected by flow cytometry. T-DM1 is negative control ADC for bystander effect assay. A. Flow cytometry results of SKBR3(GFP)&MDA-MB-468(RFP) co-culture after ADC treatment. B. GFP and RFP cell counts and cell count ratio in the co-culture system.

Our Tag-expression Reporter Tumor Cell Lines are engineered to express fluorescent or luminescent tags, enabling specifically monitoring of ADC interactions and effects. These cell lines simplify and accelerate ADC research by allowing precise tracking of efficacy in target and bystander cells. With these reporter lines, researchers can efficiently evaluate ADC bystander effect, optimize linker-payload design, and understand the mechanisms of action, enhancing the development of targeted cancer therapies.

The in vivo bystander effect refers to the phenomenon where cytotoxic agents released by targeted cancer cells (those directly affected by ADCs) can diffuse and induce cell death in neighboring non-targeted cancer cells within a living organism. By using tumor cell lines engineered to express luciferase, we can visualize and monitor the bystander effect using our IVIS in vivo imaging systems. 

Using untagged Ag+ cells and luciferase-tagged Ag- cells in co-inoculation CDX models is an effective approach to evaluate the in vivo bystander effect. The luciferase tag on Ag- cells allows for precise and specific monitoring of their response to the ADC treatment, ensuring that the effects observed are due to the bystander effect mediated by the Ag+ cells. This method provides clear and valuable insights into the efficacy of ADCs in heterogeneous tumor environments.