Although the therapeutic potential for cancer immunotherapies is huge, many attempts to find biomarkers that can identify the patients who are most likely to respond have so far fallen flat. Programmed cell death 1 ligand 1 (PDL1) expression levels in tumours, for example, do not sufficiently predict which patients will respond to anti-PD1 and anti-PDL1 antibodies. Pfizer has as a result now partnered with Adaptive Biotechnologies to expand its search, exploring whether the immune system holds immunotherapy biomarker clues.

Adaptive uses a high-throughput immunosequencing approach to study a patient's T- and B-cell repertoire. In 2014, working with Merck & Co. and others, the biotech found that by characterizing and quantifying the types of T cells in and near tumours it could build a predictive model of drug response to Merck's now-approved PD1-binding pembrolizumab (Nature 515, 568–571; 2014).

“Adaptive's ability to precisely measure a patient's immune response to cancer before and after treatment provides a universal tool that will help bolster our understanding of immuno-oncology approaches,” said Chad Robins, President of Adaptive Biotechnologies. The companies did not disclose the financial terms of the deal.

Pfizer's immuno-oncology pipeline includes the Phase III PDL1-targeting avelumab. The company is also working on a 4-1BB-targeting antibody and an OX40-targeting antibody.

Some data suggest that overall mutational burden might predict who will respond to immuno-oncology treatments, with anti-PD1 antibodies reportedly working best in patients with the highest mutational burden in their tumours (Science 348, 124–128; 2015).