Background

Cladribine significantly reduces disease activity and disability progression in relapsing-remitting multiple sclerosis (RRMS) through a selective but transient depletion of lymphocyte subsets. The SARS-COV-2 outbreak has raised several concerns regarding cladribine use for RRMS patients.

Objectives

To evaluate the prevalence and clinical features of COVID-19 disease among cladribine-treated relapsing-remitting MS patients.

Methods

Fifty-six RRMS patients treated with cladribine in our centre (female=39; mean age=33.8 years [y]; median Expanded Disability Status Scale [EDSS]=1.5, disease duration [DD]=5.2 y, treatment duration=1.15 y) were asked if they had developed manifestations suggestive of SARS-COV-2 infection up to June 30^th 2020. Their detailed characteristics were collected.

Results

At June 30^th 2020, nasal/pharyngeal swabs have been found positive in 0.94% of the Lombardy population. Since the pandemic start, 2/56 (3.6%) cladribine-treated RRMS complained a symptomatology suggestive of COVID-19 disease, with a prevalence similar to that of the whole MS population of our centre (84/2950, 2.8%). The first patient was a 30-year-old male with RRMS (DD=1.2 y, EDSS=1.5) and no comorbidities. He started cladribine on January 10^th 2020. One week later, he developed fever (<37.5°), ageusia, cough, fatigue, sputum production, sore throat, nasal congestion, shortness of breath without desaturation and conjunctivitis.

The second patient is a 39-year-old female with RRMS (DD=13.2 y, EDSS=3.5), and no comorbidities. She started cladribine on February 13^th 2020 and underwent the second week of the first treatment course from March 5^th 2020. On March 30^th, she developed fever (<37.8°), anosmia, ageusia, cough, fatigue, and bone/joint pain. Serology for SARS-COV-2 was positive in May 2020. For both patients, blood examinations performed before and after COVID-19 disease were within normal limits. Both patients were telephone-monitored at home and completely recovered within 15 days.

Conclusions

Only a minority of cladribine-treated RRMS patients developed a mild and self-limiting COVID-19 disease. In our cohort, this occurred in two RRMS patients within a few weeks from treatment course and the possible nadir of selective immunosuppression. Both patients recovered completely. Cladribine administration seems to be safe also in the setting of the COVID-19 pandemic.