Tracking Bispecific Antibody-Induced T Cell Trafficking Using Luciferase-Transduced Human T Cells

Summary

Here, we describe a method for transducing human T cells with luciferase to facilitate in vivo tracking of bispecific antibody-induced T cell trafficking to tumors in studies to evaluate the anti-tumor efficacy and mechanism of T cell-engaging bispecific antibodies.

Abstract

T cell-engaging bispecific antibodies (T-BsAbs) are in various stages of preclinical development and clinical testing for solid tumors. Factors such as valency, spatial arrangement, interdomain distance, and Fc mutations affect the anti-tumor efficacy of these therapies, commonly by influencing the homing of T cells to tumors, which remains a major challenge. Here, we describe a method to transduce activated human T cells with luciferase, allowing in vivo tracking of T cells during T-BsAb therapy studies. The ability of T-BsAbs to redirect T cells to tumors can be quantitatively evaluated at multiple time points during treatment, allowing researchers to correlate the anti-tumor efficacy of T-BsAbs and other interventions with the persistence of T cells in tumors. This method alleviates the need to sacrifice animals during treatment to histologically assess T cell infiltration and can be repeated at multiple time points to determine the kinetics of T cell trafficking during and after treatment.

Introduction

T cell-engaging bispecific antibodies (T-BsAbs) are engineered antibodies used to provide artificial specificity to polyclonal T cells by engaging T cells through one binding arm and a tumor antigen through another binding arm. This technology has been successfully applied to hematological cancers (CD19-targeting blinatumomab¹), and numerous T-BsAbs are in preclinical and clinical development for a variety of solid tumors as well². T-BsAbs engage polyclonal T cells in a major histocompatibility complex (MHC)-independent manner, and therefore even tumors that downregulate human leukocyte antigens (HLAs) are susceptible to....

Protocol

The following procedures have been evaluated and approved by Memorial Sloan Kettering's Institutional Animal Care and Use Committee.

1. Transfection of 293T cells with luciferase and harvest of viral supernatant

1. Culture of 293T cells
   1. Prepare media by adding the following to a liter of DMEM each: 110 mL of heat-inactivated fetal bovine serum (FBS), 11 mL of penicillin-streptomycin.
   2. Thaw 5 x 10⁶ 293T cells and transfer them into a T175 flask with the media prepared as described above.
   3. Split the 293T cells 1:10 every 3 days for 6 days. Do not allow the cells to becom....

Results

As described in step 4.3, mice can be oriented in different positions during imaging to evaluate the presence of T cells in different tissues. Supine positioning allows for the assessment of T cells in the lungs, which is common at early time points after injection. Lateral positioning with the subcutaneous xenograft facing up is used to best assess T cell trafficking to the tumor. Female C.Cg-Rag2^tm1Fwa Il2rg^tm1Sug/JicTac mice were used for all experiments described in this manuscript.

Discussion

While the T-BsAb blinatumomab has been approved for CD19-positive hematological malignancies, the successful implementation of T-BsAbs in solid tumors has proven much more difficult. Catumaxomab, a T-BsAb directed against epithelial cell adhesion molecule (EPCAM), was approved for the treatment of malignant ascites in ovarian cancer patients, but production of the drug was subsequently halted for commercial reasons¹⁹. No other T-BsAbs have been approved for solid tumors, underlining the challenges.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
293T cells	ATCC	CRL-11268
BSA	Sigma Aldrich	A7030-10G
CD3/CD28 beads	Gibco (ThermoFisher)	11161D
D-Luciferin, Potassium Salt	Goldbio	LUCK-1G
DMEM	Gibco (ThermoFisher)	11965092
DNA in vitro transfection reagent (polyjet)	SignaGen Laboratories	SL100688
EDTA	Sigma Aldrich	E9884-100G
FBS	Gibco (ThermoFisher)	10437028
Gag/pol plasmid	Addgene	14887
GFP plasmid	Addgene	11150-DNA.cg
Penicilin-Streptomycin	Gibco (ThermoFisher)	15140122
Recombinant human IL-2	R&D Systems	202-IL-010/CF
Retronectin	Takara	T100B
Trypsin	Gibco (ThermoFisher)	25-300-120
VSV-G plasmid	Addgene	8454