Pharmacological activation of wild-type p53 in the therapy of leukemia.
The tumor suppressor p53 is inactivated by mutations in the majority of human solid tumors. Conversely, p53 mutations are rare in leukemias and are only observed in a small fraction of the patient population, predominately in patients with complex karyotype acute myeloid leukemia or hypodiploid acute lymphoblastic leukemia. However, the loss of p53 function in leukemic cells is often caused by abnormalities in p53-regulatory proteins, including overexpression of MDM2/MDMX, deletion of CDKN2A/ARF, and alterations in ATM. For example, MDM2 inhibits p53-mediated transcription, promotes its nuclear export, and induces proteasome-dependent degradation. The MDM2 homolog MDMX is another direct regulator of p53 that inhibits p53-mediated transcription. Several small-molecule inhibitors and stapled peptides targeting MDM2 and MDMX have been developed and have recently entered clinical trials. The clinical trial results of the first clinically used MDM2 inhibitor, RG7112, illustrated promising p53 activation and apoptosis induction in leukemia cells as proof of concept. Side effects of RG7112 were most prominent in suppression of thrombopoiesis and gastrointestinal symptoms in leukemia patients. Predictive biomarkers for response to MDM2 inhibitors have been proposed, but they require further validation both in vitro and in vivo so that the accumulated knowledge concerning pathological p53 dysregulation in leukemia and novel molecular-targeted strategies to overcome this dysregulation can be translated safely and efficiently into novel clinical therapeutics.
Department of Hematology, Respiratory Medicine and Oncology, Division of Medicine, Saga University, Saga, Japan; Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA. Electronic address: kkojima@cc.saga-u.ac.jp.
Kensuke
K
Kojima
Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA.
Jo
J
Ishizawa
Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA.
Michael
M
Andreeff
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D015415:Biomarkers; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects*; D006801:Humans; D007938:Leukemia / Q000175:diagnosis / Q000188:drug therapy* / Q000235:genetics*; D058990:Molecular Targeted Therapy; D011379:Prognosis; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors; D015533:Transcriptional Activation / Q000187:drug effects*; D016896:Treatment Outcome; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
D000970:Antineoplastic Agents; D015415:Biomarkers; D016159:Tumor Suppressor Protein p53; D051736:Proto-Oncogene Proteins c-mdm2