A test that measures the levels of two types of immune cells in the blood could identify which cancer patients are most likely to respond to immunotherapy.

The test gives a measure of a patient’s immune system health by comparing the number of neutrophils—which can indicate the presence of chronic inflammation and impaired immunity—with the number of lymphocytes, which are indicative of a healthy immune cell response.

In a new study, led by a team from the Drug Development Unit at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, patients with a range of cancers were flagged as either having a high or a low ratio of neutrophils to lymphocytes.

Those with a higher ratio were less likely to respond to immunotherapy drugs known as PD-1 and PD-L1 inhibitors, which include nivolumab.

They also had a shorter survival time.

Tracking patients response to treatment

As well as investigating the link between initial neutrophil to lymphocyte ratio, or NLR, and patients’ response to immunotherapy, the study team also looked at how the ratio changed during treatment.

Their research, which was published in the European Journal of Cancer, found that the NLRs of patients who respond best to immunotherapy decreased over time, compared with patients whose cancers remained stable or progressed.

This suggests that monitoring patients’ NLRs could help clinicians determine if an immunotherapy is working.

New tools to monitor the effectiveness of immunotherapies are urgently needed. Scans alone can struggle to identify progression in some tumors.

Enabling smarter, kinder treatments

Study leader Dr Juanita Lopez, Consultant Medical Oncologist at the ICR and The Royal Marsden, said:

“The neutrophil-lymphocyte ratio is widely used by clinicians as a prognostic tool, but until now it was not clear whether this association had utility in predicting patient outcomes on immunotherapies.”

“Our research shows that a patient’s initial NLR is a good indication of whether they will benefit from PD-1 or PD-L1 inhibitors, and can be used to track a patient’s response throughout their treatment.”

“Biomarkers like these are vital to the development of smarter, kinder treatments, as the sooner clinicians can predict whether a patient will respond to a treatment, the sooner they can move the patient onto an alternative therapy.”