Race, Rituxmab and relapse in TTP
Dr. Anjan Patel's Thoughts
Interesting food for thought in this ethnic group regarding TTP. Large retrospective review of the TTP registry showing that among races there was no variation in mortality, however African-Americans had a reduced RFS in all metrics. Rituximab was not helpful in 1L therapy in any group. In the 2L setting, Rituximab had a significant RFS benefit in Caucasians but not in African-Americans. It did not seem that access to care was the driver in reduced RFS. African-American’s may also have shorter-lived B-cell depletion from CD20-MAb therapy.
- Race affects overall relapse risk and response to rituximab in iTTP.
- Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab.
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by recurring episodes of thrombotic microangiopathy, causing ischemic organ impairment. Black patients are overrepresented in iTTP cohorts in the United States, but racial disparities in iTTP outcome and response to therapy have not been studied. Using the United States Thrombotic Microangiopathies Consortium iTTP Registry, we evaluated the impact of race on mortality and relapse-free survival (RFS) in confirmed iTTP in the United States from 1995 to 2020. We separately examined the impact of rituximab therapy and presentation with newly diagnosed (de novo) or relapsed iTTP on RFS by race. A total of 645 participants with 1308 iTTP episodes were available for analysis. Acute iTTP mortality did not differ by race. When all episodes of iTTP were included, Black race was associated with shorter RFS (hazard ratio [HR], 1.60; 95% CI, 1.16-2.21); the addition of rituximab to corticosteroids improved RFS in White (HR, 0.37; 95% CI, 0.18-0.73) but not Black patients (HR, 0.96; 95% CI, 0.71-1.31). In de novo iTTP, rituximab delayed relapse, but Black patients had shorter RFS than White patients, regardless of treatment. In relapsed iTTP, rituximab significantly improved RFS in White but not Black patients. Race affects overall relapse risk and response to rituximab in iTTP. Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab treatment. How race, racism, and social determinants of health contribute to the disparity in relapse risk in iTTP deserves further study.