Treatment-free survival to bortezomib combined with dexamethasone in patients with refractory/relapsed pure red cell aplasia: a prospective clinical study

Immunosuppressive treatments induce and maintain remissions in a majority of patients with acquired pure red cell aplasia (aPRCA); however, salvage therapy for non-responders remains unsatisfactory. In this prospective, open-label, clinical trial (NCT04423367), patients with refractory/relapsed aPRCA were recruited and received subcutaneous bortezomib at 1.3 mg/m2 in combination with dexamethasone 40 mg weekly(BD regimen) for 12 weeks. The primary endpoint was the overall response rate at 12 weeks. In total, 18 patients were enrolled, including 10 (55.6%) with primary aPRCA and 8 (44.4%) with plasma cell dyscrasia-associated aPRCA. The overall response rate and complete response rate were 61.1% and 55.6%, respectively. Intensive short-term BD regimen led to rapid response, with a median time to response of 40 days (range 21-77 days). Extended maintenance was unnecessary after the 12-week treatment. At a median follow-up of 16.5 (6-51) months, the median treatment-free survival (TFS) was 7 (2-48) months. There was no significant difference in the overall hematological response rate between primary and secondary aPRCA (60% vs. 62.5%, p = 0.914). Adverse events were recorded in 5 patients, including infection, deep venous thrombosis, hyperglycemia, constipation, and liver injury. The BD regimen may serve as an effective second-line therapy for refractory/recurrent/intolerant aPRCA patients, with manageable adverse events and possibly longer TFS.