Incidence and Characteristics of CD20 Monoclonal Antibody-Induced Interstitial Pneumonitis
Authors: Stein Jacob Newton , Grover Natalie S , Rabadey Janhvi , Dittus Christopher 
Published: November 2021

Abstract
Background:
CD20 monoclonal antibody therapy is the backbone of treatment for B-cell non-Hodgkin lymphoma. Several studies have described an association between the use of rituximab and non-infectious interstitial pneumonitis, with estimates ranging from 3.9% to 8.4%. 1-3 However, several novel CD20 monoclonal antibodies have been introduced in the past decade, with obinutuzumab gaining FDA approval in 2013, ofatumumab first approved in 2014, and rituximab/hyaluronidase human approved as a subcutaneous route of rituximab in 2017. While the use of these agents has rapidly increased in clinical practice, the incidence of pneumonitis with these agents is not well known. Thus, we have performed a retrospective review of patients with B cell lymphoma treated with CD20 monoclonal antibody therapy to determine the incidence and characteristics of pneumonitis with these novel agents.
Methods:
We evaluated all patients at the University of North Carolina at Chapel Hill with B-cell lymphoma who were treated with CD20 monoclonal antibody therapy from 2014 to 2020. We performed individual chart review to verify the presence of interstitial pneumonitis, as defined by presence of respiratory symptoms (cough, dyspnea, fever, chest pain) in addition to imaging findings (pulmonary opacity on chest X-ray and/or ground glass opacities on chest computed tomography (CT)) without alternative cause (CHF with pulmonary edema, COPD flare, infectious cause including bacterial, fungal or viral pneumonia/bronchitis). We extracted demographic data, comorbid conditions, tobacco use history, and timing of pneumonitis related to CD20 monoclonal antibody exposure. We determined rates of pneumonitis based on agent and chemotherapy backbone.
Results:
We identified 18 cases of chart-confirmed interstitial pneumonitis over a six-year period, out of 2,207 patients treated with CD20-monoclonal antibody therapy. Seven (39%) were current or former smokers, with a median of 30 pack-years smoked. Five (29%) had a history of hypersensitivity reaction to rituximab infusion. Pneumonitis developed after a median of 4 cycles, and 16 days from the most recent CD20 monoclonal antibody infusion. Ten (56%) had diffuse large B-cell lymphoma, 4 (22%) had mantle cell lymphoma, and 1 (6%) each had follicular lymphoma, chronic lymphocytic leukemia, hairy cell leukemia, and Waldenstrom's macroglobulinemia. Eight cases (44%) occurred among patients being treated with R-CHOP, 2 (11%) were treated with BR, 2 (11%) were receiving single agent rituximab, although several other regimens were represented. Most cases occurred in patients being treated with infusional rituximab, but the rate remained quite low (14/1654, 0.8%). Four occurred in patients receiving subcutaneous rituximab hycela out of 167 treated patients (2.4%), less than prior estimates of pneumonitis with monoclonal antibody therapy. Most cases of pneumonitis were treated with steroids (n=15, 83%), although none required infliximab or anti-TNF agents, and no cases of pneumonitis were fatal. Most notably, we did not identify any cases of pneumonitis among patients treated with ofatumumab (n=51) or obinutuzumab (n=58).
Conclusion:
This retrospective review reinforced the safety of novel anti-CD20 agents, with low rates of interstitial pneumonitis among patients treated with infusional or subcutaneous rituximab. Cases that did occur were effectively treated with steroids, and there were no fatalities associated with pneumonitis. Ofatumumab and obinutuzumab were not associated with any cases of interstitial pneumonitis.
Bibliography
1. Katsuya H, Suzumiya J, Sasaki H, et al. Addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisolone therapy has a high risk of developing interstitial pneumonia in patients with non-Hodgkin lymphoma. Leuk Lymphoma. 2009;50(11):1818-1823. doi:10.3109/10428190903258780
2. Salmasi G, Li M, Sivabalasundaram V, et al. Incidence of pneumonitis in patients with non-Hodgkin lymphoma receiving chemoimmunotherapy with rituximab. Leuk Lymphoma. 2015;56(6):1659-1664. doi:10.3109/10428194.2014.963075
3. Liu X, Hong X-N, Gu Y-J, Wang B-Y, Luo Z-G, Cao J. Interstitial pneumonitis during rituximab-containing chemotherapy for non-Hodgkin lymphoma. Leuk Lymphoma. 2008;49(9):1778-1783. doi:10.1080/10428190802270886
Figure 1 Figure 1.

Disclosures
Grover: Novartis: Consultancy; Genentech: Research Funding; ADC: Other: Advisory Board; Kite: Other: Advisory Board; Tessa: Consultancy. Dittus: BeiGene: Other: Advisory Board; Seattle Genetics: Research Funding; AstraZeneca: Research Funding; Genentech: Research Funding.