cenersen and Leukemia--Myeloid--Acute

The p53 antisense oligonucleotide cenersen has been shown to sensitize acute myeloid leukemia (AML) stem cells to DNA damaging agents.. To determine whether cenersen merits testing in larger efficacy studies, an exploratory study of cenersen in combination with idarubicin either alone or with 1 of 2 doses of cytarabine was performed in first-salvage AML patients. Patients who either had failed to respond to a single induction course or had responded to induction but relapsed within 12 months were enrolled. Stopping rules based on an expected 14% complete response (CR) rate were applied to each treatment arm.. Fifty-three patients were treated, and none of the arms was terminated for lack of activity. Nearly all patients received a single course unless they responded. Ten of the 53 (19%) patients responded (8 CR and 2 CR with incomplete platelet recovery). There was a positive trend for a better response rate with increasing intensity of chemotherapy in the patients refractory to front-line treatment compared with those who had relapsed previously. One-third (17/53) of the patients received cenersen inhibitors (acetaminophen and/or high dose antioxidants) during treatment, and none of these responded to treatment. No unique toxicity was attributed to cenersen.. The results of this study suggested that the combination of cenersen with chemotherapy may have clinical efficacy, and additional studies are warranted to explore its full potential.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Cytarabine; Female; Genes, p53; Humans; Idarubicin; Leukemia, Myeloid, Acute; Male; Middle Aged; Oligonucleotides; Oligonucleotides, Antisense; Recurrence; Treatment Failure

TP53 encodes for tumor protein p53. The suppression of p53 protein results in interruption of DNA repair mechanisms in dividing malignant cells thereby increasing the DNA damage and activating p53-independent mechanisms of apoptosis. This ultimately may translate into enhanced cytotoxic effects of standard chemotherapy. Based on this rationale, Cenersen, a phosphorothioate oligonucleotide antisense to p53-mRNA was synthesized and tested in clinical trials for patients with acute myeloid leukemia (AML). An important component of Cenersen clinical development is to develop a sensitive and specific method to quantify plasma and intracellular levels of Cenersen in different biologic matrices in order to determine tissue and intracellular distribution of the parent compound and its metabolites. Ultimately, this will allow us to determine pharmacokinetic and pharmacodynamic relationship for dose-effect correlation and design effective regimen to be rapidly translate into the clinic. An ELISA-based assay was adapted for assay development and validation of Cenersen in mouse plasma and cell lysate. Cellular uptake of Cenersen was studied in MV4-11 and KASUMI-1 AML cell lines. Real-time RT-PCR was used to measure P53-mRNA expression changes in treated cells. The assay had a limit of quantification of 35pmol/L in mouse plasma. Within-day and between-day precision of <15% and accuracy nearly 100% were observed in a linear range of 10-2000pmol/L (R(2)=0.99) in AML cell lysate. The selectivity of this assay examined as cross-reactivity with its 3'N-1, 3'N-2-metabolites, was 16.8% and 0.4%, respectively, and with its mismatch and the scramble oligonucleotides was 0.06% and 0.4%, respectively. Cenersen was stable in mouse plasma up to 8h at 37°C. When exposed to 0.1-1μmol/L Cenersen, MV4-11 and KASUMI-1 cells showed intracellular concentration in the range of 9.97-45.34nmol/mg protein and 0.1-2.1nmol/mg protein, respectively. Successful downregulation of p53-mRNA expression was observed in Cenersen treated cells. This ELISA-based assay was applicable to plasma and intracellular concentration measurement of Cenersen. Assessment of achievable concentration of Cenersen in different biologic matrices will be useful to elucidate the biological and clinical activity of this promising drug and define its recommended dose in future clinical trials.

Topics: Animals; Cell Line, Tumor; Enzyme-Linked Immunosorbent Assay; Humans; K562 Cells; Leukemia, Myeloid, Acute; Mice; Oligonucleotides; Oligonucleotides, Antisense; RNA, Messenger; Sensitivity and Specificity; Tissue Distribution; Tumor Suppressor Protein p53