Several markers have been identified that can predict response to the immunotherapy pembrolizumab in specific tumour types. But a universal marker across all tumour types has not been established.
In research published in Science
(8 June 2017), a team enrolled 86 patients with 12 different cancer types whose disease had progressed despite previous treatment to receive pembrolizumab for up to two years. All the patients had mismatch-repair (MMR) deficiencies, meaning they had mutations in genes involved in repairing DNA errors.
The team found that 66 (77%) of the 86 patients (95% confidence interval, 66–85%) achieved disease control for at least 12 weeks, including 18 (21%) patients who had a complete response.
Given that tests for MMR-deficiency are already available, the researchers predict that in future it will become standard to test for MMR deficiency in patients with refractory cancer, regardless of tumour type.
 Le D, Durham J, Smith K et al. Mismatch-repair deficiency predicts response of solid tumors to PD-1 blockade. Science 2017. doi: 10.1126/science.aan6733