Prolonged lymphopenia and infection risk is mitigated by antimicrobial prophylaxis in patients with indolent non-Hodgkin Lymphoma (iNHL) treated with bendamustine +/- anti-CD20 antibody: the Australian Lymphoma Alliance experience.

Abstract

Bendamustine +/- anti-CD20 antibody is a highly effective regimen for iNHL. Though initially favoured for its toxicity profile, subsequent analyses demonstrate profound and prolonged lymphopenia and the landmark phase III GALLIUM study showed a grade 3-5 infection rate of 20-26% in the bendamustine arms (Hiddemann JCO 2018). The relationship between severity and duration of lymphopenia and infection, and the role of antimicrobial prophylaxis (ppx), are not fully characterised. We performed a multicentre, retrospective analysis of bendamustine-treated iNHL patients (pts) to define the type and onset of infections, identify concomitant risk factors and evaluate the role of ppx. iNHL pts aged ≥18 yrs, treated with bendamustine +/- anti-CD20 in 1st-3rd line from 2011-2019, were identified from 9 Australian centres. HIV, prior transplant and long-term immunosuppression were excluded. Demographics, treatment, lymphocyte counts, infections and ppx were collected from baseline to 24 months post end of bendamustine treatment (EOT) or subsequent lymphoma therapy. Association between potential risk factors and infection was evaluated by logistic regression (odds ratio, OR) and negative binomial regression (incidence rate ratio, IRR) with Stata 16.1. iNHL pts receiving bendamustine are at high risk of prolonged lymphopenia and infectious complications extending beyond treatment completion, with half of infections occurring post treatment cessation. Lymphopenia duration and nadir did not correlate with infection. PJP and antiviral ppx reduced risk of bacterial and VZV/HSV infections respectively, though rates of PJP and VZV/HSV were low. Prolonged ppx to mitigate the risk of late infections should be considered, particularly in pts with additional risk factors such as concomitant obinutuzumab and anti-CD20 maintenance.