Antirituximab antibodies do not greatly affect pemphigus treatment with rituximab

Results of a study showed that antirituximab antibodies are common among patients with pemphigus who have been treated with rituximab, according to data published in JAMA Dermatology.

Rituximab is a chimeric monoclonal antibody anti-CD20 that has been approved as a first-line treatment for moderate to severe pemphigus vulgaris, Alexandre Lemieux, MD, of the Centre Hospitalier de l’Université de Montréal, and colleagues wrote.

They continued that while its superiority as a treatment compared with a conventional regimen of corticosteroids has been demonstrated, the rate of relapse after rituximab treatment increases over time.

To determine the prevalence of antirituximab antibodies (ARAs) among patients with pemphigus who are treated with rituximab, the researchers analyzed 42 patients enrolled in the Ritux3 trial.

Researchers of the Ritux3 trial detected ARAs in 13 of the patients at month 12 of treatment, which did not include nine patients who experienced relapse during the first year of treatment. Those nine patients were excluded from further analysis.

At month 36, the researchers detected ARAs in nine patients, including eight of the 13 they identified at 12 months and one patient who had not previously shown signs of ARAs.

The researchers wrote that the presence of ARAs was not strongly associated with the rate of sustained complete remission, which 85% of patients with ARAs and 100% of those without ARAs were able to achieve.

“The frequency and concentration of ARAs decreased with subsequent maintenance infusions of [rituximab], which suggests that the presence of ARAs was not a contraindication to further infusions of [rituximab], as previously observed in patients with optic neuromyelitis,” Lemieux and colleagues wrote. “We also did not note an association between the presence of ARAs and occurrence of infusion-related reactions, as previously suggested in a patient with pemphigus.”

They concluded that the study’s results support the fact that, despite their frequency, ARAs are only rarely correlated with the evolution of disease in patients with pemphigus who have been treated with rituximab.