Association Between RBC Antigen Allo-Antibodies and Immune-Related Adverse Events During Immune Checkpoint Inhibitor Treatment for Advanced Cancers.

INTRODUCTION

Immune checkpoint inhibitors (ICI) have become a primary treatment modality for patients with a variety of malignancies. Given their increasing use, it is essential to be familiar with their immune-related adverse events (irAEs). Here we report a severe case of autoimmune hemolytic anemia (AIHA) associated with cold agglutinin precipitated by pembrolizumab, and a retrospective study of patients treated with ICI utilizing an institutional database where we analyzed the patterns of anti-RBC testing and their ability to predict irAE.

METHODS

Patients treated with at least one dose of ICI (PD-1, PD-L1, CTLA-4 inhibitors) for advanced cancer between November 2012 and September 2017 at our institution were included. Electronic Medical Records were reviewed to abstract data. Medians and 95% CIs were estimated using Kaplan-Meier method and differences compared using the Log Rank test. Fisher's exact test and Chi square test were used to analyze clinical associations.

RESULTS

We identified 1065 patients who received at least one dose of ICI: 180/1065 (17%) underwent direct antiglobulin test (DAT) or allo-antibody (alloAb) testing at any time; 127/1065 (12%) had either DAT or alloAb testing pre-ICI; 129 had either DAT or alloAb testing after ICI initiation; and 76 had either DAT or alloAb testing at both time points. There was a significant association between positive alloAb pre-ICI and the development of irAE while on ICI (p = 0.04).

CONCLUSION

Given the increasing use of ICI, oncologists should be aware of potential irAEs with ICI. We found an association between the presence of an alloAb pre-ICI and the development of irAE, indicating that this previous non-self antigen response may predict immune adverse events. A larger prospective study is needed for systematic evaluation of the association between alloAb testing and irAE, and whether routine testing may inform clinical decision-making for patients.