Low Dose Cytarabine and Cladribine for Treatment of Relapsed or Refractory Acute Myeloid Leukemia: Clinical Experience

Aim. The aim of this paper is to evaluate the effectiveness of low dose cytarabine (Ara-C) combined with cladribine for the treatment of relapsed or refractory acute myeloid leukemia (AML) and to determine clinical and lab factors associated with response to the therapy. Methods. Data of 10 patients aged 26–58 years (median 48 years) were analyzed. The diagnoses were de novo AML (7 patients), secondary AML (sAML) (2 patients) and refractory anemia with excess of blasts (RAEB-2) (1 patient). Four patients had primary refractory AML. Relapse was diagnosed in 3 patients. The induction scheme 7+3 was ineffective in patient with RAEB-2. There was no response to any kind of therapy in sAML patients. The treatment scheme under trial consisted of Ara-C 10–15 mg/m2 subcutaneously twice a day for 1–14 days and cladribine 5 mg/m2 intravenously once a day for 1–5 days. The course was repeated in case of at least two-fold decrease in bone marrow blasts level in a punctate versus baseline. Medical examination and maintenance therapy were performed in accordance with protocols approved by the clinic. Results. According to the protocol, the patients received 1–2 courses. Response was achieved in 5 patients: 2 patients achieved complete response (CR) and 3 achieved partial response (PR). The most common complication was hematologic toxicity. All patients received transfusions of blood components. No lethal outcomes were observed within 8 weeks. The duration of the response was 2 to 3 months. During this period of time, allogeneic stem cell transplantation was performed in 2 patients with CR; however, in one patient, the conditioning regimen began at the same time with the increase in blast cell count in the bone marrow. The search for unrelated donors of hematopoietic stem cells for 2 patients with CR was begun. The distinct features of all patients with CR and PR were the following factors: de novo AML, absence of FLT3 or c-KIT mutations and the course duration was not less than 10 days. Conclusion. Low dose Ara-C in combination with cladribine may be considered a treatment option for some patients with relapsed or refractory de novo AML.