# Immune-stimulating antibody conjugate (ISAC)

Source: https://onco.cc/technologies/immune-stimulating-adc/  
OnCo record `immune-stimulating-adc` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

An immune-stimulating antibody conjugate (ISAC) is an ADC whose payload wakes up the immune system inside the tumour rather than poisoning the cell.

## Summary

An immune-stimulating antibody conjugate delivers an innate immune agonist, rather than a cytotoxic, to tumour-resident myeloid cells, aiming to convert immunologically cold tumours into hot ones. TLR7/8 agonist conjugates (Bolt's BDC-1001 against HER2; Silverback) and STING agonist conjugates (Mersana XMT-2056, Takeda TAK-500) are the leading examples. In principle the approach could produce durable immune memory and combine naturally with checkpoint inhibitors. Early results have been modest, with weak single-agent activity so far; dose-limiting systemic cytokine release and the need for antigen-presenting-cell engagement are the challenges. The simple version is an ADC whose payload wakes up the immune system inside the tumour, an idea still waiting for convincing clinical proof.

## Fields

- Kind: Technology
- Status: phase-1
- Last checked: 2026-09-04
- Tags: frontier
- Principle: Antibody-targeted delivery of innate immune agonists to tumour-resident myeloid cells.
- Generation: 4th (next-gen)
- Strengths: Durable immune memory in principle; Combinable with checkpoint inhibitors
- Limitations: Weak single-agent activity so far

## Sources

- Ackerman et al., Immune-stimulating antibody conjugates elicit robust myeloid activation and durable antitumour immunity (Nature Cancer 2020): https://doi.org/10.1038/s43018-020-00136-x

## Connected records

- fronts: [Antibody-Drug Conjugates](https://onco.cc/fronts/adcs/), [Immunotherapy](https://onco.cc/fronts/immunotherapy/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/), [STING & innate immune agonists](https://onco.cc/technologies/sting-agonist/)
- companies: [Mersana Therapeutics](https://onco.cc/companies/mersana/), [NBE-Therapeutics](https://onco.cc/companies/nbe-therapeutics/), [Tallac Therapeutics](https://onco.cc/companies/tallac-therapeutics/)
- key papers: [Immune-stimulating antibody conjugates elicit robust myeloid activation and durable antitumor immunity](https://onco.cc/key-papers/paper-ackerman-nat-cancer/)
- pathways: [cGAS-STING innate sensing](https://onco.cc/pathways/cgas-sting/)
- roadmaps: [ADC roadmap: from Mylotarg to bispecific and dual-payload ADCs](https://onco.cc/roadmaps/adc-generations/)

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