A retrospective study examined outcomes for immune thrombotic thrombocytopenic purpura (iTTP) using treatment with upfront cyclophosphamide (CTX) or rituximab (RTX). Results were published in the journal Frontiers in Medicine.
While upfront RTX has demonstrated benefits in iTTP treatment in terms of reduced rates of relapse, CTX had not been examined for upfront treatment of iTTP, the study investigators explained in their report.
The study was based on the records of patients diagnosed with iTTP at the University Hospitals Cleveland Medical Center in Cleveland, Ohio, from 2010 to 2019. All patients received plasma exchange and steroids. A group of 10 patients received no additional treatment, while 28 patients were also treated with either RTX (n=23) or CTX (n=5). Cumulative incidence of relapse (CIR) and duration of remission were the outcomes of interest in this analysis.
The average patient age at diagnosis was 44 years, and the average follow-up was 76 months.
Patients who received no additional treatment had a 2-year CIR of 50%, while patients who received either RTX or CTX had a 2-year CIR of 27.7%. The median duration of remission was 43.6 months for patients with no additional treatment, and 108.3 months for those given either RTX or CTX (P =.04). In a multivariate analysis, median time to clinical relapse was significantly worse for the group receiving no additional treatment (hazard ratio [HR], 8.7; 95% CI, 1.27-59.45; P =.027).
When compared with each other, CTX and RTX produced similar results for CIR; CIR at 48 months was 33.3% with CTX and 27.2% with RTX (P =.81).
The researchers also evaluated potential predictors of relapse. In multivariate analysis, baseline absolute lymphocyte count showed an association with a longer remission (HR, 0.74; 95% CI, 0.58-0.96; P =.02). Initial serum creatinine level showed an association with a shorter time to relapse (HR, 1.42; 95% CI, 1.03-1.94; P =.032).
“Our study is the first to examine outcomes in a subset of patients treated with upfront CTX therapy for initial iTTP, and suggests similar time to first relapse and 4-year CIR as compared to RTX,” noted the investigators. They concluded that CTX may serve a role for patients with RTX intolerance.
Abou-Ismail MY, Arafah Y, Fu P, Cao S, Schmaier AH, Nayak L. Outcomes of immune thrombotic thrombocytopenic purpura (iTTP) with upfront cyclophosphamide vs. rituximab. Front Med (Lausanne). Published online October 28, 2020. doi:10.3389/fmed.2020.588526