CD123 expression patterns and selective targeting with a CD123-targeted antibody-drug conjugate (IMGN632) in acute lymphoblastic leukemia

Evgeniya Angelova, Charlene Audette, Yelena Kovtun, Naval Daver, Sa A. Wang, Sherry Pierce, Sergej N. Konoplev, Haitham Khogeer, Jeffrey L. Jorgensen, Marina Konopleva, Patrick A. Zweidler-McKay, L. Jeffrey Medeiros, Hagop M. Kantarjian, Elias J. Jabbour, Joseph D. Khoury

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


The potential of CD123-targeted therapies in acute lymphoblastic leukemia/lymphoma remains largely unexplored. We examined CD123 expression levels in a large cohort of patients with acute lymphoblastic leukemia/lymphoma and assessed the in vitro impact of IMGN632, a conjugate of CD123-binding antibody with a novel DNA-alkylating payload. CD123 expression on leukemic blasts was surveyed using multicolor/multiparameter flow cytometry. The in vitro effect of IMGN632 was evaluated on B acute lymphoblastic leukemia/lymphoma cell lines and primary B acute lymphoblastic leukemia/lymphoma blasts. The study cohort (n=213) included 183 patients with B acute lymphoblastic leukemia/lymphoma and 30 with T acute lymphoblastic leukemia/lymphoma. CD123 expression was more prevalent in B acute lymphoblastic leukemia/lymphoma than in T acute lymphoblastic leukemia/lymphoma (164/183, 89.6% versus 13/30, 43.3%; P<0.0001), and within B acute lymphoblastic leukemia/lymphoma CD123 expression was more prevalent in Philadelphia chromosome-positive patients than in Philadelphia chro-mosome-negative patients (96.6% versus 86.3%; P=0.033). In T acute lymphoblastic leukemia/lymphoma, 12/13 (92.3%) patients with CD123-positive blasts had either early T precursor (ETP) or early non-ETP immunophenotype. IMGN632 was highly cytotoxic to B acute lymphoblastic leukemia/lymphoma cell lines, with half maximal inhibitory concentrations (IC50) between 0.6 and 20 pM. In five of eight patients’ samples, low pico-molar concentrations of IMGN632 eliminated more than 90% of the B acute lymphoblastic leukemia/lymphoma blast population, sparing normal lymphocytes. In conclusion, CD123 expression is prevalent across acute lymphoblastic leukemia/lymphoma subtypes, and the CD123-targeted antibody-drug conjugate IMGN632 demonstrates promising selective activity in preclinical models of B acute lymphoblastic leukemia/lymphoma.

Original languageEnglish (US)
Pages (from-to)749-755
Number of pages7
Issue number4
StatePublished - Mar 31 2019
Externally publishedYes

ASJC Scopus subject areas

  • Hematology


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