Decitabine-Induced Differentiation Syndrome in a Patient with Acute Myeloid Leukemia: A Case Report.

We report here for the first time a case of “decitabine-induced differentiation syndrome” in a patient (pt) with acute myeloid leukemia (AML). The cytosine analog decitabine, after incorporating into DNA, irreversibly binds DNA methyltransferase (DNMT) enzymes where cytosine residues are targeted for methylation. This allows replication of unmethylated DNA with subsequent re-expression of genes previously silenced by promoter methylation. It has been suggested that decitabine at low doses may have differentiating effects, as compared to cytotoxic effects at higher doses. A previous phase I trial demonstrated clinical activity of low dose decitabine in patients with myeloid malignancies (Issa, et al., Blood 2004). Given the close relationship of DNA methylation and histone deacetylation in modulating gene expression, we are currently conducting a phase I trial (OSU 0336) of low dose decitabine (15mg/m² IV over 1 hour on days 1–10) alone (step 1) or in combination with escalating doses of the histone deacetylase inhibitor valproic acid (step 2) in AML. An 82 year old male pt with untreated, secondary AML (65% bone marrow blasts, 95% marrow cellularity) was enrolled on step 1 of the study and given 15mg/m²/day of decitabine for 10 consecutive days. At the time of initiation of therapy, the pt had a white blood cell (WBC) count of 8,700/uL with absolute neutrophil count (ANC) of 1,500/uL and absolute blast count (ABC) of 3,200/uL. At day 11, the pt had WBC 1,000/uL with ANC of 450/uL and ABC of 150/uL and was clinically well. However, at day 17, he presented with cough and shortness of breath, without fever. WBC had risen to 18,700/uL with ANC of 11,000/uL and ABC of 750/uL. The patient developed worsening hypoxia and required mechanical ventilation. Chest radiograph demonstrated diffuse interstitial infiltrates, but bronchoscopy and lavage (on day 18 and repeated on day 24) did not identify an infectious etiology. Due to clinical concern for a differentiation syndrome similar to the “retinoic acid syndrome” occurring in acute promyelocytic leukemia patients treated with all-trans-retinoic-acid (ATRA), the pt was started on dexamethasone 10mg IV q12 hours beginning on day 18, in addition to broad spectrum antimicrobial coverage. Peripheral blood smears during the following week showed evidence of myeloid differentiation, and by day 25 no circulating blasts were found (WBC 4,300/uL, ANC 3,000/uL) while the overall clinical condition improved. The pt was finally extubated on day 38 but within 24 hours required emergent re-intubation due to nasogastric feeding aspiration and died at day 53. In summary, these preliminary data support the biological activity of low dose decitabine in AML and suggest that clinical precautions similar to those implemented for the “retinoic acid syndrome” in ATRA-treated APL should be considered in decitabine-treated AML when myeloid differentiation and rising neutrophil counts are observed.