Early relapse after rituximab chemoimmunotherapy.

Area of Science:

• Hematology
• Immunology
• Pediatric Oncology

Background:

• Relapsed/refractory childhood acute lymphoblastic leukemia (ALL) of the B-cell lineage presents treatment challenges.
• Rituximab, an anti-CD20 monoclonal antibody, has shown success in some B-cell ALL cases.
• Minimal residual disease (MRD) detection is crucial for guiding therapy in ALL.

Observation:

• A 15-year-old female with relapsed CD20-positive B-cell progenitor ALL received rituximab treatment.
• Treatment was initiated due to positive MRD signals detected by flow cytometry and real-time quantitative-PCR post-chemotherapy.
• Rituximab effectively eliminated the CD20-positive leukemic cell subpopulation.

Findings:

• The anti-CD20 therapy with rituximab was unable to eradicate more immature leukemic cells.
• Despite targeted therapy, the patient did not achieve complete remission.
• The patient succumbed to fulminant aspergillosis prior to planned hematopoietic stem cell transplantation.

Implications:

• Rituximab's efficacy in B-cell ALL may be limited by the presence of less mature, CD20-negative leukemic clones.
• Further strategies are needed to target the entire spectrum of leukemic cells in relapsed ALL.
• The case highlights the critical need for comprehensive MRD eradication and management of opportunistic infections in immunocompromised pediatric cancer patients.