Background: Acute lymphoblastic leukemia (ALL) in adults is aggressive, with long-term outcomes impacted by treatment resistance and toxicity. CD52 is expressed in most cases of B- and T-lineage ALL. Alemtuzumab, a humanized immunoglobulin G1 monoclonal antibody that targets CD52, was identified as a potential agent to improve treatment efficacy without increasing toxicity.
Methods: In this phase 1/2 study (Cancer and Leukemia Group B [CALGB] 10102, NCT00061945), a course of single-agent alemtuzumab was intercalated into CALGB 19802 backbone chemotherapy after the third course of intensive chemotherapy in those who were CD52+ at diagnosis. Phase 1 tested three dose levels of subcutaneous alemtuzumab (10, 20, and 30 mg 3 times weekly for 4 weeks/12 doses) and demonstrated that 30 mg was tolerable. Phase 2 established feasibility.
Results: The study enrolled 295 evaluable patients (115 in phase 1, 180 in phase 2); 206 (69.8%) were CD52+. Among evaluable CD52+ patients, 43.7% (90/206) completed the first three treatment modules; 97.8% (88 of 90) were treated with alemtuzumab. Alemtuzumab was associated with cytomegalovirus viremia, which occurred in 23.3% (14 of 60) of patients during and 29.2% (19 of 65) after alemtuzumab treatment. With a median follow-up of 101.2 months, median overall survival (OS) was 26.3 months (3-year rate, 44%; 5-year rate, 36%; 10-year rate, 31%). Landmark analysis at the start of the fourth course of treatment demonstrated no difference in OS or disease-free survival between patients who did and who did not receive alemtuzumab.
Conclusion: Alemtuzumab was feasible to administer in adults with ALL receiving intensive chemotherapy, but was without evidence of benefit.
Keywords: ALL; alemtuzumab; antibody; chemotherapy; monoclonal; older.
© 2025 The Author(s). Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.