Relapse With Rituximab More Common in Severe Pemphigus

By Reuters Staff

March 25, 2020

NEW YORK (Reuters Health) - Pemphigus patients with severe disease and those with persistent anti-desmoglein (DSG) antibodies three months after starting treatment with rituximab are more prone to relapse while on the drug, according to a new post hoc analysis of a randomized clinical trial.

"The findings suggest that these 2 factors might help differentiate a subgroup of patients with high risk of relapse who might benefit from maintenance rituximab infusion at month 6 from a subgroup of patients with low risk of relapse who do not need early maintenance therapy," Dr. Claire Mignard of Normandie University in Rouen, France, and colleagues conclude in JAMA Dermatology.

In the RITUX 3 trial, 90 patients were randomly assigned to 1,000 mg IV rituximab on days 0 and 14 and infusions of 500 mg and 12 and 18 months plus short-term prednisone (0.5 mg/kg daily for moderate pemphigus, 1.0 mg/kg a day for severe disease), or short-term prednisone only.

At two years, 89% of patients who received rituximab were in full remission without treatment, compared to 34% of those who received corticosteroids only. There were 11 relapses (23%) in the rituximab group and 20 (46%) in the standard treatment group.

Three of the relapses occurred after the second maintenance dose, the authors note, while eight occurred between month six and month 12, suggesting that an initial maintenance infusion at month 6 could benefit some patients.

They reviewed data from RITUX 3 on 47 patients who received rituximab to identify factors linked to short-term relapse. Patients who began the study with a Pemphigus Disease Area Index score of 45 or above, indicating severe disease, and levels of anti-DSG 1 antibody levels above 20 IU/mL and/or anti-DSG 3 antibody levels above 130 IU/mL, were significantly more likely to relapse.

The positive predictive value for early relapse was 50% and the negative predictive value was 94%.

"The presence of at least 1 of the 2 factors associated with relapse of pemphigus may help identify a group of patients with high risk for relapse who may benefit from a maintenance infusion of rituximab at month 6. Additional studies are needed to determine the optimal doses of maintenance therapy with rituximab," Dr. Mignard and colleagues conclude.

Roche provided the rituximab and helped funded the extension of the follow-up period of the study. One of the authors report financial ties to the company.

SOURCE: JAMA Dermatology, online March 18, 2020.


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