# Elucidating novel immune profiles for predicting infection in high‐risk cohorts: a pilot study in patients with relapsed and refractory chronic lymphocytic leukaemia

## TL;DR

This pilot study explores immune profiles in relapsed and refractory chronic lymphocytic leukaemia patients to predict infection risk during treatment with ibrutinib.

## Contribution

The study identifies novel protein and RNA immune signatures associated with infection risk in high-risk CLL patients.

## Key findings

- An inflammatory transcriptome profile at 3 months was linked to subsequent infection episodes.
- Increased protein response to PMA stimulation at 3 and 6 months was associated with higher infection risk.
- Combining protein and RNA analysis offers insights into immune interactions during immunotherapy.

## Abstract

Chronic lymphocytic leukaemia (CLL) patients are at increased risk for infection, with the risk even higher for relapsed and refractory patients. Clinical assessment of infection risk is increasingly challenging in the era of immune‐based therapies, such as Bruton's tyrosine kinase inhibitors. A pilot study was conducted to elucidate possible predictive immune markers.

Patients with relapsed and refractory CLL treated with ibrutinib were evaluated. Peripheral blood mononuclear cells (PBMCs) collected at defined intervals (baseline, 3‐ and 6 months following commencement of ibrutinib) were analysed, with or without phorbol myristate acetate (PMA)/ionomycin stimulation, using Luminex and RNA sequencing. Luminex and gene expression profiles were compared between patients that who did and did not develop infection to identify immune signatures associated with infection over a subsequent 3‐month period.

Twenty‐eight patients were included in this pilot study. Forty‐six per cent of patients developed an infection (13 patients, 17 events) over 9 months of patient monitoring. Most infections were clinically diagnosed (72.7%) with the remainder microbiologically diagnosed bacterial (18.1%) and viral (9.2%) infections. Cell populations did not correlate with subsequent infection. An inflammatory transcriptome profile at 3 months following ibrutinib was associated with a subsequent infection episode. Increased whole protein response to PMA stimulation at 3 and 6 months was associated with subsequent risk for infections. Increased whole protein response to PMA stimulation was associated with subsequent risk of infection 3 months after commencing ibrutinib.

The combination of protein and RNA analysis can provide further insight into the interactions of immunotherapies and immunity but should be validated further in large cohorts.

In the present study, we identified several unique protein and RNA signatures that could be used to predict infection in relapse and refractory patients. We highlight the need for comprehensive immune profiling of high‐risk cancer cohorts.