Targeted Therapy of Central Nervous System Acute Lymphoblastic Leukemia with an Integrin α6-Targeted Self-Assembling Proapoptotic Nanopeptide

There is currently no effective targeted therapeutic strategy for the treatment of central nervous system acute lymphoblastic leukemia (CNS-ALL). Integrin α6 is considered a potential target for CNS-ALL diagnosis and therapy because of its role in promoting CNS-ALL disease progression. The targeted peptide D(RWYD) (abbreviated RD), with nanomolar affinity to integrin α6 was identified by peptide scanning techniques such as alanine scanning, truncation, and D-substitution. Herein, we developed a therapeutic nanoparticle based on the integrin α6-targeted peptide for treating CNS-ALL. The self-assembled proapoptotic nanopeptide D(RWYD)-D(KLAKLAK)2-GD(FFY) (abbreviated RD-KLA-Gffy) contains the integrin α6-targeted peptide RD, the well-known proapoptotic peptide D(KLAKLAK)2 (abbreviated KLA), and the self-assembling tetrapeptide GD(FFY) (abbreviated Gffy). The functional mechanism of RD-KLA-Gffy is clarified using different experiments. Our results demonstrate that RD-KLA-Gffy is highly enriched in CNS-ALL lesions and induces tumor cell apoptosis, thus reducing CNS-ALL disease burden and prolonging the survival of CNS-ALL mice without obvious toxicity. Moreover, the combined use of RD-KLA-Gffy and methotrexate (MTX) shows a potent antitumor effect in treating CNS-ALL, indicating that RD-KLA-Gffy plays an important role in suppressing CNS-ALL progression either as a single agent or in combination with MTX, which shows promise for application in CNS-ALL therapy.