Antimicrobial Prophylaxis in Patients with Immune Thrombocytopenia Treated with Rituximab: A Retrospective Multicenter Analysis

S. Raso¹, M. Napolitano², G. Arrigo¹, F. Reale¹, P. Silimbiani³, A. Lucchesi⁴, A. Maggio⁵, G. Calvaruso⁵, U. Consoli⁶, M.F. Mansueto¹, S. Siragusa²

¹University of Palermo, Palermo, Italy, ²University of Palermo, PROMISE Department, Palermo, Italy, ³Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori, Oncology Pharmacy, Meldola, Italy, ⁴Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori, Oncology, Meldola, Italy, ⁵AOOR Villa Sofia-V. Cervello, Campus of Haematology Franco and Piera Cutino, Palermo, Italy, ⁶A.R.N.A.S. Garibaldi Nesima, Palermo, Italy

Abstract Number: PB1377

Meeting: ISTH 2020 Congress

Theme: Platelet Disorders and von Willebrand Disease » Acquired Thrombocytopenias

Background: In patients (PTs) affected by haematological neoplasms, therapy with anti-CD20 (Rituximab-RTX) increases the risk of viral and fungal infections. Antimicrobial prophylaxis (AP) is adopted in these PTs as well as in those with rheumatological diseases; evidences are lacking with reference to AP during RTX for relapsed/refractory immune thrombocytopenia (ITP).

Aims: We here report on a multicenter retrospective analysis of AP in patients with ITP treated with RTX.

Methods: Charts of adult ITP-PTs, treated with RTX from January 2008 to June 2018 were retrospectively reviewed, after IRB approval, for the following: demographic data, comorbidities, complete blood count (CBC), serum protein electrophoresis (SPEP),AP (type, duration, side effects), data on any infection with reference to onset, treatment and outcome. Data were analyzed with the software Open source R.

Results: Overall, we analyzed 53 patients (PTs) with ITP, treated with RTX in second (N=43) or third line (N=10). RTX was weekly administered at the dosage of 375mg/m² for 4 weeks in all cases. Overall, 47% (25/53) PTs received AP (Table 1). Reported infections were: Herpes Zoster Virus (N=2), pneumonia (N=1), cutaneous opportunistic infection (N=1), simultaneous infection by Herpes Simplex Virus and Candida Auris (N=1). At multivariate analysis, previous exposure to steroids for longer than 6 months and diabetes as a comorbidity were significantly associated with AP. Of note, the absolute neutrophil count (ANC) was statistically reduced (p=0.03), before and after a median of 32 days (range 21-90) after the last the RTX . One patient showed ANC < 500/mmc, not confirmed at the 6 months FU after RTX.

Conclusions: AP was administered in almost half (47%) of ITP-PTs. Prolonged corticosteroid exposure and/or diabetes, were judged as the most appropriate indications to AP. Subjects not under AP experienced more infections vs those treated with AP. Notably, a significant reduction of ANC after RTX was observed.

Patients (n°)	53
Age years,mean (range)	53 (18-86)
M-F (n°)	26 – 27
Follow-up after RTX, median (range), months	13(6-62)

ANC, mean + SD (range) Pre-RTX	6.4+3.2 (1.2-18)
Post-RTX	5.2 +2.8 (0.5-14)
Comorbidities (n° pt) Diabetes mellitus Hypertension Rheumatological diseases Endocrine diseases COPD	10. 22. 7. 8. 2.

[Characteristics of patients]

To cite this abstract in AMA style:

Raso S, Napolitano M, Arrigo G, Reale F, Silimbiani P, Lucchesi A, Maggio A, Calvaruso G, Consoli U, Mansueto MF, Siragusa S. Antimicrobial Prophylaxis in Patients with Immune Thrombocytopenia Treated with Rituximab: A Retrospective Multicenter Analysis [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/antimicrobial-prophylaxis-in-patients-with-immune-thrombocytopenia-treated-with-rituximab-a-retrospective-multicenter-analysis/. Accessed January 27, 2022.

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