PD-1/PD-L1 and TROP2: Key targets linking cancer immunotherapy and tumor-targeted therapy

•  Gene Information: PD-1 (PDCD1) and PD-L1 (CD274) are key immune checkpoint molecules regulating T-cell activity, whereas TROP2 (TACSTD2) is a tumor-associated cell-surface glycoprotein. Together, these targets link tumor-targeted therapy with cancer immunotherapy.
•  Protein Expression: PD-1 is primarily expressed on activated T cells, while PD-L1 is expressed on tumor cells and various immune cells. TROP2 is expressed in epithelial tissues and is frequently overexpressed in multiple solid tumors.
• Signaling Pathway: PD-1 binding to PD-L1 inhibits T-cell activation and promotes tumor immune evasion. TROP2-associated signaling promotes tumor cell proliferation and survival, while ADC-mediated targeting can directly induce tumor cell death.
•  Model Application: PD-1/PD-L1 blockade restores anti-tumor T-cell activity, while TROP2-targeted ADCs selectively eliminate TROP2-positive tumor cells. Their combination provides a promising strategy for enhancing anti-tumor efficacy and overcoming immune suppression.

PD-1

• Exon 2 of the mouse PD-1 gene, which encodes the IgV domain, was replaced with human PD-1 exon 2 in B-hPD-1 plus/hPD-L1/hTROP2 mice.

• The endogenous mouse promoter, 5' UTR, 3' UTR, and genomic regions encoding the signal peptide, non-IgV portion of the extracellular domain, and transmembrane and cytoplasmic domains were retained. Chimeric PD-1 expression is driven by the endogenous mouse PD-1 promoter, while endogenous mouse PD-1 transcription and translation are disrupted.

PD-L1

• Exon 3 of the mouse PD-L1 gene, which encodes the IgV domain, was replaced with human PD-L1 exon 3 in B-hPD-1 plus/hPD-L1/hTROP2 mice.

• The endogenous mouse promoter, 5' UTR, 3' UTR, and genomic regions encoding the signal peptide, non-IgV portion of the extracellular domain, and transmembrane and cytoplasmic domains were retained. Chimeric PD-L1 expression is driven by the endogenous mouse PD-L1 promoter, while endogenous mouse PD-L1 transcription and translation are disrupted.

TROP2

• Exon 1 of the mouse Trop2 gene that encodes the full-length protein was replaced by human TROP2 exon 1 in B-hPD-1 plus/hPD-L1/hTROP2 mice.

PD-1 and PD-L1 expression analysis in wild-type C57BL/6JNifdc mice and homozygous B-hPD-1 plus/hPD-L1/hTROP2 mice by flow cytometry. Splenocytes were collected from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hPD-1 plus/hPD-L1/hTROP2 mice (H/H;H/H;H/H) (female, 6-8-week-old, n = 1) stimulated with anti-CD3ε in vivo (7.5 μg/mouse, i.p., for 24 hours). Protein expression was analyzed with anti-human PD-1 antibody (BioLegend, 329908), anti-mouse PD-1 antibody (BioLegend, 109104), anti-human PD-L1 antibody (BioLegend, 329706), and anti-mouse PD-L1 antibody (BioLegend, 124312) by flow cytometry.

Immunohistochemical (IHC) analysis of TROP2 protein expression in wild-type mice and B-hPD-1 plus/hPD-L1/hTROP2 Mice. Major tissues were collected from wild-type mice and homozygous B-hPD-1 plus/hPD-L1/hTROP2 mice and analyzed by IHC with anti-TROP2 antibody (Abcam, ab214488).

Establishment of an MC38 model in B-hPD-1 plus/hPD-L1/hTROP2 mice and in vivo efficacy study of an anti-human TROP2 antibody-drug conjugate (Datopotamab Deruxtecan, in-house). Murine colon cancer B-hPD-L1 plus/hTROP2 MC38 cells (Cat# 322415) were subcutaneously implanted into homozygous B-hPD-1 plus/hPD-L1/hTROP2 mice (female, 9-week-old, n = 5). Mice were grouped when tumor volume reached approximately 100 mm³, at which time they were intravenously injected with anti-human TROP2 ADC as indicated in the panel. Values are expressed as mean ± SEM.

In vivo efficacy of anti-human TROP2 ADC-individual tumor growth curves.