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Mapping the binding sites of antibodies utilized in programmed cell death ligand-1 predictive immunohistochemical assays for use with immuno-oncology therapies

Mapping the binding sites of antibodies utilized in programmed cell death ligand-1 predictive immunohistochemical assays for use with immuno-oncology therapies

 

Oncologica has participated in a study, led by AstraZeneca, to further improve the tests that are used to pin point the patients most likely to respond to a new type of anti-cancer treatment called “immune-therapy”. These tests are known as Companion Diagnostic (CDx) tests.

Immune-therapy is now becoming a front-line treatment for many tumour types. Immune Checkpoint Therapy, is an immune-therapy which targets a protein called PD-L1, expressed on the surface of tumour cells, which exploits the bodies’ immune system to attack cancer cells. The NHS use Immune Checkpoint Therapy to treat patients with the most serious form of skin cancer (melanoma) and aggressive tumour types such as lung cancer. The impact of this revolutionary new treatment was recently recognized by the award of the Nobel Prize for Medicine to Prof A Prof Allison (University of Texas) and Prof Honjo (Kyoto University) who discovered this new approach to cancer therapy.

Immune-therapy doesn’t work for everyone, in some patients it appears to work incredibility well, completely destroying tumours even after they have begun to spread around the body, but for other patients the response can be less dramatic.

Several PD-L1 CDx tests have been approved for use, including the VENTANA PD-L1 (SP263) Assay, VENTANA PD-L1 (SP142) Assay, Dako PD-L1 IHC 22C3 pharmDx assay and the Dako PD-L1 IHC 28-8 pharmDx assay. PD-L1 CDx tests are used to pin-point which patients are most likely to respond to anti-PD-L1/PD-1 directed immune-therapies. During the clinical use of these CDx tests a degree of variance between their performances has been observed and it has been hypothesized that such variances may be caused by the different PD-L1 antibodies, used in these tests, recognizing different parts (epitopes) of the PD-L1 protein.

The AstraZeneca/Oncologica study, identified that any variances in performance between CDx tests (inter-assay variability) are more likely attributable to tumour heterogeneity or test/instrument variables than they are to the antibody epitope. This information will help to further the understanding of CDx testing in PD-L1 immune-therapy in the clinical testing community, maximize the benefits of this type of treatment for cancer patients and drive the adoption of CDx testing.