Scientists said on Monday they had pinpointed a particular type of immune system cell that could predict more precisely if cancer patients are likely to respond to modern immunotherapy medicines.

The discovery, reported in the journal Nature Immunology, suggests doctors and drug developers will need to get smarter in zeroing in on those people who stand to benefit from the expensive new drugs, which are revolutionizing cancer care.

Drugs such as Merck’s Keytruda, Bristol-Myers Squibb’s Opdivo, Roche’s Tecentriq and AstraZeneca’s Imfinzi can boost the immune system’s ability to fight tumors, but they only work for some patients.

The current widely used benchmark when giving cancer immunotherapy is a protein called PDL-1. However, many experts view PDL-1 as a “blunt instrument”, since it does not match precisely to drug response, leading to the consideration of other measures, such as the level of mutation in tumors.

The latest research adds a further twist by highlighting therole of so-called tissue-resident memory T-cells.

Researchers from the University of Southampton and La Jolla Institute for Allergy and Immunology found that lung cancer patients with lots of this cell type in their tumors were 34 percent less likely to die than others.

“Having made the first baby steps with PDL-1 testing, we need to be smarter by using new tests,” said Christian Ottensmeier, a Cancer Research UK scientist who worked on the study.

“PDL-1 testing is a little bit like saying ‘you’ve got a Ferrari because it is red.’ Many Ferraris are red and many tumors that are PDL-1 positive will respond to immunotherapy, but on its own that is not sufficient.”

Ottensmeier and colleagues now plan further clinical trials to see how well their biological predictor can pick out patients who will benefit from taking Opdivo.

Industry analysts expect the new generation of cancer immunotherapy drugs to generate tens of billions of dollars in annual sales by early next decade, with lung cancer the biggest single market.
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