# DLL3 expression

Source: https://onco.cc/biomarkers/dll3-expression/  
OnCo record `dll3-expression` (Biomarker). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

DLL3 sits on the surface of about 85 percent of small-cell lung cancers and almost no normal adult tissue. Tarlatamab is given without a DLL3 test.

## Summary

Tarlatamab (Imdelltra) is a DLL3 x CD3 bispecific labelled for extensive-stage small-cell lung cancer after platinum chemotherapy; the DeLLphi trials enrolled without DLL3 selection and the label names DLL3 only as the target. DLL3-directed ADCs, radioligands and CAR-T cells in trials likewise do not gate on expression, and a DLL3 PET tracer is under study.

## Fields

- Kind: Biomarker
- Last checked: 2026-09-23
- Also known as: DLL3; DLL3-positive; delta-like ligand 3 expression; DLL3 IHC
- Tags: biomarker; surface-antigen; no-threshold

## Notes

- Small-cell lung cancer: DLL3 is switched on downstream of ASCL1, so its expression follows the transcriptional subtype. The ASCL1-dominant (69%) and NEUROD1-dominant (17%) tumours are neuroendocrine-marker high, TTF-1 high and DLL3 high, while the POU2F3 subtype (7%) and the other double-negative tumours are low for all three (Baine 2020). A DLL3-directed medicine is therefore addressed to the neuroendocrine-high majority rather than to the whole disease, and subtype is the reason a DLL3 stain is negative when it is negative.

## Sources

- IMDELLTRA prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1e7b6163-5d83-42ea-82c9-cf7620cdc782

## Connected records

- biomarkers: [B7-H3 (CD276) expression](https://onco.cc/biomarkers/b7-h3-expression/)
- cancers: [Extensive-stage small-cell lung cancer](https://onco.cc/cancers/extensive-stage-sclc/), [Neuroendocrine and small-cell prostate cancer](https://onco.cc/cancers/prostate-nepc/), [Small-cell lung cancer](https://onco.cc/cancers/sclc/)
- drugs: [Tarlatamab](https://onco.cc/drugs/tarlatamab/)
- terms: [Small-cell lung cancer transcription-factor subtypes (SCLC-A, SCLC-N, SCLC-P, SCLC-I) and SLFN11](https://onco.cc/terms/sclc-molecular-subtypes/)
- key papers: [Molecular subtypes of small cell lung cancer: a synthesis of human and mouse model data](https://onco.cc/key-papers/paper-rudin-sclc-molecular-subtypes-nat-rev-cancer-2019/), [SCLC subtypes defined by ASCL1, NEUROD1, POU2F3, and YAP1: a comprehensive immunohistochemical and histopathologic characterization](https://onco.cc/key-papers/paper-baine-sclc-subtype-immunohistochemistry-jto-2020/)
- targets: [DLL3](https://onco.cc/targets/dll3/)

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