Reevaluating Patient Eligibility for Inotuzumab Ozogamicin Based on CD22 Expression: Is Dim Expression Sufficient?

Area of Science:

• Hematology
• Immunotherapy
• Oncology

Background:

• Salvage therapy for relapsed B-cell acute lymphoblastic leukemia (B-ALL) often involves inotuzumab ozogamicin (InO).
• InO targets the CD22 antigen on leukemia cells.
• The efficacy of InO in patients with dim CD22 expression is not well-established.

Observation:

• A case of B-ALL is presented where the patient exhibited only dim surface expression of CD22.
• The patient received InO as a salvage treatment.
• Flow cytometry confirmed dim CD22 expression.

Findings:

• The patient responded positively to InO treatment.
• The observed survival benefit was consistent with literature reports for InO in B-ALL.
• The patient maintained a good quality of life, becoming transfusion-independent and managing as an outpatient.

Implications:

• This case suggests InO may be effective in B-ALL patients with dim CD22 expression.
• Clinicians should consider InO for B-ALL patients with dim CD22 expression.
• Further investigation into InO efficacy across varying CD22 expression levels is warranted.