Zr-atezolizumab imaging as a non-invasive approach to assess clinical response to PD-L1 blockade in cancer

PET imaging offers window into immunotherapy responses

31 July 2019

Non-invasive imaging with a radiolabelled antibody drug can help predict patient responses to cancer immunotherapy, according to a small clinical trial in the Netherlands.

A Dutch clinical team partnered with scientists from the Roche subsidiary Genentech to measure expression levels of the immune checkpoint protein PD-L1 in 22 patients with cancers of the breast cancer, lung and bladder.

The researchers tested for PD-L1 status using positron emission tomography (PET) imaging and an experimental ‘tracer’ molecule — a zirconium-89-labelled version of Genentech’s PD-L1–targeted agent atezolizumab — as well as more traditional chemical and genetic analyses of biopsied tumour tissue.

They found that the PET imaging signal corresponded to PD-L1 expression at sites of inflammation and in normal lymphoid tissues.

What’s more, the imaging offered a better predictor of survival outcomes after subsequent treatment with unlabelled atezolizumab than PD-L1 staining or sequencing strategies, highlighting the value of PET scans for selecting cancer patients best suited for immunotherapy.

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References

1. Nature Medicine 24, 1852–1858 (2018). doi: 10.1038/s41591-018-0255-8