This is an open-label, single-arm study to evaluate the safety and efficacy of bortezomib plus dexamethasone for acquired pure red cell aplasia failure or relapse after first-line treatment.

Inclusion Criteria:

• ECOG ≤ 2.
• Age from 18 to 70.
• Diagnosed with acquired pure red cell aplasia.
• Meets the criteria of first-line treatment failure or relapse.
• Organs in good function.
• Signed informed consent.

Exclusion Criteria:

• Nursing woman.
• Active bacterial, virus, fungal or parasitic infection, including HIV infection, HBsAg or HBV DNA positive, HCV DNA positive, etc.
• Secondary PRCA caused by lymphoproliferative disorders, including large granular lymphocytic leukemia, waldenström macroglobulinemia, small lymphocytic lymphoma/chronic lymphocytic leukemia, etc.
• Secondary PRCA caused by either smoldering multiple myeloma or symptomatic multiple myeloma.
• Secondary PRCA caused by either ABO major mismatched stem cell transplantation or organ transplantation.
• Secondary PRCA caused by solid tumors except for thymoma.
• Secondary PRCA caused by drugs or pregnancy.
• Secondary PRCA caused by the B19 virus.
• Have contraindications for glucocorticoids, or unable to tolerate glucocorticoids for comorbidities.
• Previously received treatment in other trials within 4 weeks before enrollment.
• Previously treated with the proteasome inhibitor.
• Experience active hemorrhage condition, including gastrointestinal bleeding, respiratory tract bleeding and central nervous system bleeding within 2 months before enrollment or during bortezomib/dexamethasone treatment.
• Have a history of malignant tumors.
• Have a history of mental illness.
• Inability to understand or to follow study procedures.